When the situation that the anchor is over the planning red line is restricted, the double-row piles supporting for excavation has been widely used. The practice shows that the calculation model of double-row piles in current specifications is simple and convenient, but for the soft soil excavation the calculation results of displacements are not well reasonable. Meanwhile the same time, the soil between piles is simplified as compression springs and the effect of pile and soil column is not fully considered, which makes the calculation results of displacement larger. In order to improve these deficiencies, a new earth pressure model is proposed that the additional pressure under the foundation pit is regarded as elastic stress, the equivalent soil column stiffness is added to strengthen the pile-soil interaction, the larger value of spring stiffness under the foundation pit between compression stiffness and stiffness of “m” method is chose, which is to make the calculating displacements more reasonable. At last it is compared to the results of the finite element method and the engineering tests, and its rationality is preliminary verified.

The previous analysis of the rock pressure of shallow bias tunnel is based on the particular friction angle to reflect the material characteristics of rock mass. However, the rock internal friction angle and cohesion are not as the independent parameters in their studies. Based on the standard method, a simplified theoretical analysis method for the rock pressure of shallow bias tunnel is proposed to consider the horizontal earthquake action and rock cohesion. The theoretical expressions of the vertical rock pressure at the location of tunnel top, the lateral pressure at the location of both sides of tunnel and the rupture angle of sliding surface are obtained. The factors affecting the top vertical and horizontal lateral pressure of surrounding rocks, and fracture angle are studied. The results show that the top vertical pressure of surrounding rocks is positively correlated with the friction angle of sliding surface and the slope angle, and negatively correlated with the level of seismic effect coefficient and slip surface. The greater the internal friction angle, the cohesion of sliding surface and the slope angle become, the greater the rupture angle becomes, while the greater the horizontal seismic acceleration coefficient becomes, the smaller the rupture angle becomes. The horizontal lateral pressure decreases with the increasing of the internal friction angle and cohesion, increases with the increasing of seismic effect coefficient and slope angle. The results can provide a theoretical basis for the calculation of surrounding rock stress of the shallow bias tunnel.

Pore water pressure and water table in the tension crack will increase gradually under the long duration rainfall with high intensity and it will be adverse to the slope stability. In combination with transient unsaturated seepage calculation, an improved numerical procedure for critical slip field of slope with tension crack under intensive rainfall is proposed. In this procedure, transient pore water pressure field, the location of crack and hydrostatic pressure in crack can be taken into account, put forward under the condition of rainfall has a crack slope critical sliding field numerical simulation method, and its are verified. This procedure has been applied to the stability analysis of a typical clay slope. The results show that: (1) The method can search for any shape of the dangerous slip surfaces under the condition of considering the location of tension crack and hydrostatic pressure in crack; and the safety factor is reliable. (2) Hydrostatic pressure in crack has great influence on slope stability and searching for the sliding surface. (3) Crack location has great influence on slope stability under rainfall; and the closer to the slope shoulder the location of tension crack is, the more unstable the slope is. (4) There is a most disadvantageous depth of tension crack when tension crack is located at the most disadvantageous position.

In the course of driving through the gas fault or cutting through the coal seam, it often encounters the problems that the thickness of rock pillar protection and delay outburst issues in mine roadway. In order to explore the nonlinear coupling relationship between thickness of rock pillar protection and time, compression creep test of sandy mudstone, sandstone and mudstone are conducted by using triaxial rock creep apparatus RLW-2000 under step loading in this article. By analyzing the combination of classical rheological models and Matlab least squares iteration, an improved seven elements nonlinear constitutive model of viscoelastic plasticity is established as well as the calculation model based on the pillar of rock rheology critical safety thickness. The results of case study of Daping Mine in Western Henan show that when the life spans of anti-burst pillar of mud roadway in the depth of 612 m are 10, 20, 30 years, the corresponding protection thicknesses are 8.73, 23.56, 39.41 m. The theoretical safety rock pillar thickness is consistent with outburst case of Oct. 20th; the calculation model has certain reference significance for similar engineering.

Compared with the ordinary landslide, factors affecting the stability of the reservoir bank ancient landslide are much more. In addition to the regular factors, the stability is influenced by the water level change obviously. Moreover, the reservoir bank ancient landslide would become geological hazard easily, which causes great danger to human life and property. On the basis of an ancient landslide project of a reservoir, mechanical properties of sliding zone are investigated by the in-situ shear test, laboratory shear test and standard penetration test; and the regularity of influence of water level change on the ancient landslide stability is analyzed. The U-shaped changing regularity of safety factor of Egongdai landslide with water level is obtained. Methods presented in reference [12] are that landslide type can be identified by stress field, and then in high stress level sites reinforcement can be used to reduce stress level to increase safety factor. By the above methods, the upper region of Egongdai ancient landslide has thrust load-caused features; while the bottom region has retrogressive features. Therefore, the Egongdai landslide can be defined as combined landslide; and the upper and bottom regions should be reinforced. The influence on stress field of landslide by different reinforcement schemes are compared; and relationship between stress and displacement fields of the landslide and factor of safety of anti-sliding pile is studied. Results show that the optimal reinforcement site is the one of higher stress level and displacement. As for Egongdai landslide, the bottom region is also with high stress level. Considering the construction conditions and economy, an earth berm was finally constructed at the toe of Egongdai landslide 3 years ago. It is proved that determination of reinforcement site by stress level is reasonable. Research results can provide good reference to other similar projects.

The vertical column is a key step of the design of foundation pit using top-down method; and the lateral restraint under dynamic construction is the main factor to determine the stability of the vertical column. For the axial compression stability of the vertical column under top-down construction, the finite element method is used to obtain the buckling load; and then through Euler formula of rods, the calculation length coefficient of the vertical column is obtained by inverse derivation. The linear eigenvalue buckling analysis is applied to study the capacity and stability of the vertical column under the dynamic variation of the excavation by steps of foundation soil and the lateral restraint. Then the fitting formula of the calculation length coefficient is put forward in the analysis of the stability bearing capacity for the vertical column. Nonlinear buckling analysis takes into account the influence of the geometric large displacement; and then the equilibrium path of post buckling is obtained by applying the initial geometric imperfection. It is shown that the actual bearing capacity of the vertical column with initial imperfection is smaller than that of the eigenvalue buckling load; and the lager the initial imperfection amplitude, the smaller the stable bearing capacity of the vertical column.

A simple and effective method is proposed for elastic stress analysis of an infinite plane including a regular polygon hole, subjected to symmetrical loading on the hole boundaries. The inner boundary of the hole is extended to far point where the magnitude of stresses is negligible. The outer area of the boundary consists of a semi-infinite plane body. The adjacent two semi-infinite plane bodies share a common domain, the extending boundary of one semi-infinite plane body stretching into another. With the values of loadings on the inner boundaries of the hole known and the traction on the boundaries stretching into other semi-infinite plane bodies firstly presumed, the stress distribution within the semi-infinite plane body can be calculated using the theory of elasticity. By symmetry, the traction on the two boundaries stretching into adjacent semi-infinite plane bodies can be calculated, and further modified with iteration method, and converge to analytical solutions. The presented method features straightforward computation process and high precision. The results of presented examples show that the stresses of engineering scale thus obtained by this method agree well with ones obtamed by function of complex variable method and finite element method; and the order of stress singularity near the corner of hole is also approximately equal to theoretical value.

In order to reveal the creep characteristics of red bed mudstone with wide distribution in Southwestern China under different water content conditions, the rock triaxial creep testing machine YSJ-01-00 is used to carry out the triaxial compressive creep test. Experiment results show that: (1) On the whole, with increasing of water content and the lifting of the axial load, the ratio of creep strain and instantaneous strain is increasing. Also, the ratio range is 0.117-0.985, and the average ratio is maintained at 0.348-0.480. (2) The initial, steady and ultimate accelerated creep rate increase with the rise of water content. (3) The long-term strength of red bed mudstone decreases with the rise of water content. By quantitative comparison, it is found that the nonlinear creep degree of red bed mudstone is more obvious with the increase of water content. Therefore, in the construction of important project, the influence of water content on the creep characteristics of red bed mudstone should not be neglected. Based on the nonlinear characteristics of red bed mudstone, a viscoelastic modulus is proposed; and a new improved Burgers model is established by introducing a nonlinear viscoplastic body. Based on the BFGS algorithm and the general global optimization method, the creep test curves are identified; the model parameters are determined; and the reliability of model is analyzed; and the correctness and rationality of the model are verified.

In order to research the nonlinear rheology of expansive soil, the samples of cement-improved expansive soil have been selected to conduct the long-term one-dimensional compression tests. The stress-strain curve family for the improved expansive soil under different stress levels has been gained. The nonlinear rheology reflected by the curve can be divided into the linear viscoelastic creep deformation, linear viscoplastic creep deformation and nonlinear viscoplastic creep deformation. Based on the model theory and genetic creep theory, the rheology model for every category has been built accordingly. For the linear viscoelastic creep deformation and linear viscoplastic creep deformation, the model theory has been adopted to build the component model. For the nonlinear viscoplastic creep deformation, the genetic creep theory has been utilized to formulate the integral creep equation. The materials and equation parameters have been gained through the fitting of experimental data. It is found that the creep curve is consistent with the experimental result well.

For rock or loess shallow tunnel, the entire area and time effect solutions of tunnel construction under slope boundary are formulated considering viscoelastic rheological properties of rock and supporting effect. According to the solving method of general viscoelastic problem, the solutions of stress and displacement are derived by using the function of complex variable method, Laplace transformation and the superposition principle of viscoelastic problem. These solutions consider the supporting effect by applying the varying supporting force with time and space and are applicable to arbitrary viscoelastic model of rock, initial stress state and supporting time. And the solutions are consistent with finite element results of the same model. According to the solutions, the excavation of shallow tunnel is analyzed basing on the generalized Kelvin viscoelastic model of rock. The influences of lateral pressure coefficient, angle of slope and depth of tunnel on the stable subsidence value and range of surface, the stress and displacement of tunnel border are given; and the depth of tunnel is recommended to regard the shallow problem as the deep buried problem. Solutions can be used in the preliminary design of the rock and loess tunnel and provide free displacement field to the analysis method of two stages in the interaction between tunnel and underground structure.

Pile group foundations with high cap, as a common form of high-speed railway bridge foundation, are generally subjected to lateral loading due to wind action, earthquake, etc. In this paper, indoor physical model tests and three-dimensional finite element analyses using ABAQUS are both conducted to study the bearing capacity of laterally loaded single pile and pile foundation in soft soil layer. Soft soil is modelled by the modified Cam clay constitutive model in 3D FEM. The test results and finite element calculation results are in good agreement. The research of group pile are carried out by varying the piles number and pile spacing. The results show that the average lateral bearing capacity of pile foundation (total capacity divided by number of piles) is substantially higher than that of the single pile; and it also increases with the increase of the pile spacing in the direction of laterally load. Three- dimensional spatial effect is found in laterally loaded pile group foundation. The magnitude of internal force in pile varies with its spatial location. The corner pile has the maximum force, then the side pile, and the minimum force is found in the middle pile. The difference between the maximum and minimum bending moments is up to 20%. The range of surrounding soil influenced by pile group foundation is about 16 times pile diameter from the peripheral edge of the pile foundation. The pile and pile interaction effect of pile group is disadvantageous to its laterally loading capacity; and the cap constraint effect is favourable for the bearing capacity. The computing method for the effect coefficient of pile group is presented. The calculation results show that the presented computing method can be applied to the design of high cap pile group foundation in soft soil area in terms of laterally loading capacity.

For some of granular materials with large cohesive force, such as strong bond soil or cementitious sand and gravel and so on, their macroscopic creep behavior is mainly dependent on the properties of particle contact under low stress conditions. This paper aims at proposing a two-dimensional isotropic creep property of granular materials through the granular micromechanical approach. To achieve this objective, firstly an appropriate rate-dependent force-displacement relationship is introduced to describe the discrete inter-granular properties of granular materials. Secondly, with help of the Laplace transform, the solution for overall behavior of granular materials in the framework of linearly elasticity can be directly used for the solution of the associated linearly viscoelastic problem in the Laplace space; and then, the main problem is to accurately produce the inverse Laplace transform in the time domain. Thirdly, by taking respectively Reuss static, and Voigt and general kinematic localization assumptions, we obtain analytically the corresponding overall creep behavior of granular materials. Further, the upper and lower bounds of overall creep property are established. Finally, the obtained results compared with the numerical simulation by PFC2D are provided to illustrate their validation.

Total ground settlement caused by adjacent level parallel twin shield tunnel construction which conforms to the normal distribution curve is put forward. Based on the stochastic medium theory of single tunnel, aiming at the existing deficiencies, a modified simplified method of stochastic medium theory is established to calculate its ground settlement caused by adjacent level parallel twin shield tunnel construction; and it is able to consider the settlement curve asymmetry at the same time. As is shown in analytical calculation, the proposed method is relatively consistent with the measured values; and the calculation is relatively simple. The calculation parameters are studied; and measured data statistical results show that the radial constringency of twin shield tunnel is greater than the first tunnel; but the influential angle becomes smaller due to impacts of the first tunnel construction. Formula (6) is proposed to define the distance range and the total ground settlement curve shape is connected to the value of P. The definition of distance range is when P less than or equal to 1.1.

The purpose of this paper is to analyze the prevention effects of the upper protective seam mining on the rockburst induced by thick conglomerate. The gateway of 25110 coal face is used as the research object based on the geological and mining conditions of the mining area 25 in Yuejin Coal Mine. Theoretical analysis is used to study the mechanism of the rockburst induced by the dynamic-static loads and the theoretical basis of the prevention effects provided by the upper protective seam mining. Numerical simulation is performed to determine the change of displacement, velocity, stress and plastic distribution of the roadway floor under the same strength of dynamic disturbed stress; and simulation experiment is also conducted to study the response rules of acceleration and dynamic stress of the floor with artificial seismic source under the circumstances that when the upper protective seam was mined or not. The results show that the upper protective seam mining can effectively release the high stress inside the surrounding rocks and the soft and loose rock strata is formed after the roof rock strata of gob naturally caving, which can efficiently attenuate the dynamic disturbed stress wave and reduce the occurrence of rockburst. Therefore, the prevention effects are achieved to a certain extent when the upper protective seam mining is applied under thick conglomerate. Under the thick conglomerate rockburst prevention has certain guiding significance.

On the basis of the relations between energy dissipation, energy release and global failure, with integrated experimental test and numerical simulation, a new strength criterion has been proposed for hard and soft rocks. By adopting the combination of experiment and theory analysis method, the rock yield and failure criteria are studied. The strength criterion of rock mass is build based on criteria strength and structural failure of rocks and the diffusion coefficient of elastic strain energy; The failure strength for rock salt and granite is calculated and with the following criteria respectively: Mohr-Coulomb criterion, Murrell criterion, triple shear energy yield criterion, unified energy yield criterion, Hoek-Brown criterion and yield and failure revised criterion. The results show that based on the elastic strain energy of rock strength criterion of the calculated result is more accurate and the error is more stable as well especially under true triaxial tests and the intrinsic mechanism of above-mentioned results is analyzed. The strength criterion has less parameters and has simple, so, it is significant for the accurate quantitative analysis of rock yield and failure characters.

Drawdown is one of important causes to landslides, and soil nailing is an effective reinforcement. Centrifugal model tests were conducted to observe the deformation and failure process of soil nailing-reinforced slopes during drawdown. The histories of displacement of slopes were measured. The test results show that, under drawdown conditions, the slip surface of the reinforced slope goes across the nails and develops from the slope top downward to the slope surface. The failure process of the slopes exhibit significant coupling with the deformation localization. The soil nailing reinforcement mechanism is that the nail-soil interaction decreased the deformation and deformation localization and resulted in the increase of stability of slopes. Increasing the length of soil nails made the slip surface move to interior of the slope and significantly reduced the deformation localization of the slope, which in turn increase the stability of slopes under drawdown conditions.

Bentonite is buffer/backfill material needed in high level waste engineering barrier, and the high plasticity of bentonite affects the quality of buffer/backfill block. In a process of adding water for sample preparation, soil agglomeration and uneven distribution of water content affect the quality of blocks. Compared with traditional spray water method, this experiment explored a new water adding technic, mixing ice powder with bentonite powder (shortly the ice-soil mixing method). Water content is controlled between 5%-30%. In order to evaluate the ice-soil mixing method, the mixing efficiency, mass loss rate, the deviation between actual water content and target water content, the relationship between water content and agglomerated particle size, distribution and contents of agglomerate are measured. Besides, microwave-assisted thawing method is proposed to decrease thawing time. The results show that compared with spray water method, the ice-soil mixed method is less time consuming, less causing adhere to the container, and less causing water content deviate to targets. Moreover, the size and percentage of agglomerate in mixture are also decreased obviously; and water content distribution is more homogeneous; furthermore, microwave-assisted thaw method can significantly accelerate the thawing rate without affecting the amount of agglomerates and water content of specimens. This research provides a reference for the production of buffer/backfill material for High Level Waste (HLW) disposal, and can also be referenced by water content adjustment of other cohesive soil.

A series of physical model tests is performed to investigate the influence of shield tunneling on adjacent underground pipelines based on a particular section of Shanghai Metro Line 11. The scaling law of the model tests is firstly derived using the dimensional analysis method; based on which the shield machine and the tunnel models are designed. Then stiffness tests are carried out to determine the model pipelines that meet the scaling criterion. The fuzzy judgment approach is used to determine the ingredient of model material. The testing results are then compared with some theoretical solutions. It is shown that the self-developed shield tunneling apparatus can effectively simulate the excavation process with a smaller disturbance to the ground in comparison to manual excavation. The vertical deformation of pipelines caused by shield tunneling presents a symmetrical distribution about the tunnel axis which can be approximated by Gaussian curves. The maximum pipeline deformation is located directly above the tunnel axis, and the inflection point is located about twice the tunnel diameter horizontally away from the tunnel axis. The influence of tunneling process on pipelines decreases and the inflection point moves inwards with the increasing distance between the tunnels and pipelines. It is also shown that the effect of the pipeline stiffness on vertical deformation is relatively small.

Fractured rock mass under loading and unloading environment is ubiquitous with the influence of natural geological and artificial disturbance; the fracture surface geometry and the influence of unloading environment on fracture seepage characteristics can not be ignored in actual engineering. Using the methods of combining experimental and numerical simulation, to do the seepage flow experimental of fractured core with different roughnesses under loading and unloading, the thermo-hydro-mechanic coupling seepage flow system are used, to import the three dimensional morphology of fracture surface obtained by laser scanning into ABAQUS, the self-developed program is introduced. Both experimental and numerical simulations show that: The width and permeability of rough fracture decreases with the increase of load. With the increasing of load, the contact stiffness of fracture increases and the sensitivity of width and permeability decrease. The plastic deformation caused by points contact can not be recovered, The increasing amplitude of width and permeability of fracture decrease in stage of unloading, and less than that in loading stage under same conditions. Permeability, width and roughness of fracture were positively correlated. The greater the contact stress distribution is, the greater the roughness is. The field of flow in the crack is flow around islands, the greater the roughness, the phenomenon of flow around islands more obvious.

Expansive soil channel in seasonal frozen region is easy to be affected by freeze-thaw cycles, so as to will affect its stability and safety. In order to explore the effect of freeze-thaw cycles on the physico-mechanical properties of expansive soil, Nanyang expansive soil is taken as an example, which is prepared with different water contents and then on which deformation measurement, unconfined compressive test and microstructure test are carried out after different freeze-thaw cycles. The results show that in the progress of freeze-thaw cycles, the volume change of expansive soil samples with low water content could be expressed as “frost shrinking and thaw expanding”, in contrast, the samples with high water content could be expressed as “frost expanding and thaw shrinking”. Freeze-thaw cycles affected heavily the stress-strain curve, strength and elastic modulus of expansive soil, especially the first freeze-thaw cycle. The higher the water content of the expansive soil sample is, the greater the degree of its mechanical parameters affected by freeze-thaw cycles is. The relationship between porosity and pore orientation and mechanical parameters of expansive soil samples is generally negatively correlated, which can be inferred that the change of microstructure of expansive soil affected its mechanical parameters directly in the progress of freeze-thaw cycles.

Tensile strength, like compressive strength and shearing strength, is one of the most important engineering indexes to describe the properties of soil. Tensile strength is also the base of studying the characteristics of soil tensile damage; but tensile strength is always neglected in geotechnical engineering practice because it is relatively small on the value and hard to measure. With tension failure of the project more and more problems, the tensile strength properties of the soil caused by the concern of many scholars, research results are more and more. The paper on soil tensile strength test conducted systematic research methods and summarized, comparative analysis of the advantages and disadvantages of every method; it is recognized (1) The methods used in tensile strength tests can be cataloged into two classes of direct tensile test and indirect tensile test generally; in direct tensile test, tension force is directly applied on both ends of the specimen until the fracture occurs; then, tensile strength can be calculated with the maximum tension and fracture surface area; indirect method is mainly through a number of theoretical assumptions, the compressive stress is converted into the corresponding tensile stress and tensile strength of soil calculated based on some theoretical formula. (2) According to different stress conditions, the direct tensile test can be divided into uniaxial tensile test and triaxial tensile test. Generally speaking, both these two methods need special test apparatus to apply tensile load and realize its effective transfer within the specimen. Different designs are used in the apparatuses, such as glue, anchoring, mould and friction. Every design has its advantages and disadvantages; but mould is convenient for use comparatively; indirect tensile test mainly includes the split tensile test (Brazilian test), soil beam bending test and the axial fracturing test. These methods are adapted to stiff soil better, like chemical reinforced soil. Finally, some important research topics that should be well investigated in the future are proposed, including the establishment of standard tensile strength testing methods, developing simple soil tensile test apparatus, finding the method to measure and control the suction, acquiring the strain field information and numerical simulation research during the test.

Model test of coastal excavations is based on the excavation of Gongbei tunnel located in the Ling-ding Ocean, which is a part of the famous Hong Kong-Zhuhai-Macao Bridge project. The physical size of the testing model is determined by theory of similar scale. A series of model tests are carried out in the multifunctional wave-current flume to study the pore pressure response to wave around clayey silt excavation. This study shows that the excess pore pressure around near-sea excavation consists of oscillatory and accumulated excess pore pressure. For the oscillatory excess pore pressure, the amplitude decreases and the lagging phase increases gradually along the seepage path from the active zone to the passive zone of the excavation; and the more amplitude attenuated, the more phase lagged. Excess pore pressure accumulates at a rate decreasing with time. The worse of the drainage condition or the larger of the dynamic stress generated by the wave load, the easier for the excess pore pressure to accumulate. The oscillatory and accumulated excess pore pressures are all relatively small in the passive zone of the excavation.

The expanding ratio and the embedment depth in rock are considered as the two most significant factors influencing the ultimate uplift resistance of the hole digging foundation in rock. In order to investigate the influence of the embedment depth in rock and the expanding ratio upon the ultimate uplift resistance of the hole digging foundation in rock, the uplift static load tests of full-size foundations in site are carried out to analyze the response of displacement verse load, the ultimate uplift resistance of the hole digging foundation and the failure mode of foundation rock mass with different expanding ratios and different embedment depths in rock. Results show that the expanding ratio has the significant impact on load-displacement curve in initial liner phase, Using graphic method, three different parameters QL1, QDLI, QL2 representing uplift bearing performance of low, medium and high respectively are achieved. Further analysis shows that the ultimate uplift resistance will increase with the increase of the expanding ratio and the depth of the rock respectively. But the difference of influence mechanism is found that the QL1 value representing lower uplift resistance in initial elasticity phase are affected obviously by the expanding ratio; and the QDLI, QL2 values representing medium and higher uplift resistance respectively in plasticity phase are affected significantly by the embedment depth in rock. Through the analysis of the distribution of surface cracks in the rock mass on ground damage characteristics, the following conclusions can be achieved. The failure mode of the rock mass upper foundation had nothing to do with the foundation structure style. Cracks are generated from the bottom edge of foundation at first, and then extended to the ground along opening with a predetermined angle until failure of foundation occurs. At the same time, destroy range decreases with the increase of the embedment depth in rock. Comprehensive considering construction safety, economy and mechanization degree, measures to increase the embedment depth in rock shall be preferred.

Gas pressure is the major impact factor on gas adsorption of coal shale. Based on the typical high gassy mine, the coal shale of Qinghemen Mine in Fuxin is taken as research object. The sample is placed into the low field Nuclear Magnetic Resonance(NMR) instrument. Through increasing gas pressure, the adsorption process of coal shale gas is simulated. The amplitude integration of T2 spectrum of nuclear magnetic resonance is used as a quantitative index to reflect the gas adsorption capacity. From the micro-quantitative perspective, the influence law of gas pressure on adsorbed gas and free gas is presented. The results show that (1) The ranges of T2 spectrum curve for adsorbed gas and free gas can be determined by the two cutoff thresholds. (2) Gas pressure has significant influence on the increment of adsorbed gas and free gas in coal shale. The incremental change of adsorbed gas is controlled by the interaction force between coal shale and gas molecule. The increment of free gas is mainly related to the pore structure of coal shale. (3) The relationship between adsorbed gas and gas pressure is in accordance with the Langmuir isothermal adsorption equation. The relation between free gas and gas pressure is cubic function. (4) The mean value of gas T2 spectrum is used to quantitatively describe the expansion deformation of the average pore radius. With the increment of gas pressure, the medium- macro pore structures are expanded, and the average radius increases 1.47 times. But the micro-pore structures are not affected.

Granite residual soil is a regional special kind of soil which also has strong structural feature in general case. The accurate evaluation of its mechanical properties is a precondition for foundation pit and other engineering design of granite residual soil. Based on the results of a series of mechanical tests of granite residual soil in Guangzhou area, which includes plate loading test, standard penetration test and some routine laboratory test including confined compression and direct shear tests, comparative analysis and verification of the common mechanical parameters of granite residual soil are presented in this paper. The results show that the ultimate bearing capacity of foundation calculated by parameters (cohesion c, friction angle ) of granite residual soil obtained by the direct shear test, and the deformation parameter of granite residual soil obtained by the confined compression test are both significantly lower than the measured results; while the p-s curves results calculated by parameters (c, and deformation modulus E50) of granite residual soil obtained by the plate loading test are close to measured results. The E50 of granite residual soil obtained by the standard penetration test is also close to the E50 obtained by the plate loading test. Therefore, the plate loading test and standard penetration test are proved to be one of the rational ways for determining mechanical parameters of granite residual soil, which can be for reference.

In order to study the influence law of crustal stress on the fracture pressure and hydraulic fracture during hydraulic fracturing, the physical simulation experiment which used similar materials and hydraulic fracturing experiment system is conducted; and then the information of hydraulic fracture is extracted with the help of 3D scanning device for coal rock section and displacement meter. The research results show that with the principal stress difference increases, the fracture pressure decreases gradually; the break-up time becomes shorter progressively; the superficial area of fracture surface becomes larger with the principal stress difference increases; the fracture surface also turns into rough increasingly; the fracture is easier to appear steering, bifurcation when confining pressure is close, the dynamic effects of fracturing fluid is more obvious; the fracture opening decreases with the principal stress difference increasing. The research results can provide reference and data support for the further study of hydraulic fracturing experiment and building the fracture network system.

By discretizing the pile-soil system into finite segments, the interaction of the annular projections at the interface of adjacent pile segments can be simplified as a Voigt model. The spring constant and damper coefficient of the Voigt model is then derived. Combining the displacement and stress continuity conditions at the interface of adjacent pile segments, a new relationship between impedance functions of adjacent pile segments is derived, which is called amended impedance function transfer method. Taking the transverse inertia effect into account, the pile segment is assumed to be a Rayleigh-Love rod. Taking Laplace transform on the governing equation of pile segment and combining the boundary condition at pile toe, the impedance function at pile top could be derived through the amended impedance function transfer method. A comparison study between the solution proposed in this paper and existing analytical solutions is conducted to give insight to the effects of vertical reaction of the surrounding soil on the complex impedance at pile top and velocity response at pile top subjected to transient excitation. Then a parameters study is conducted to give insight to the coupled effects between the vertical reaction of the surrounding soil and the parameters of pile-soil system on the complex impedance at pile top.

Reasonable determination of bearing capacity of foundation soils is a most important part of making full use of the bearing capacity of foundation soils. This paper analyzes the method suggested by the present code, and points out some shortcomings such as the corresponding relation between safety factor and settlement value is not clear and definite. In the practical application, the determination of the bearing capacity of stiff soil or low compressive foundation soils is usually conservative; while the soft soil, high compressive foundation soils and large-size foundation will at risks due to large settlement. Thus, a new solution method is proposed in this paper. That is, computing strength and deformation of a specific foundation by using strength and deformation parameters. Then, according to the double controlling method, the settlement requirement and strength safety factor requirement of the foundation soils, the bearing capacity of the foundation soils can be determined. Finally, by obtaining specific safety factor, settlement value and more reasonable bearing capacity of foundation, it is helpful to make better use of the bearing capacity of foundation soils in engineering design. At the same time, safety and engineering value are reached. When the in-situ plate loading test hasn’t reached limit state, one suggestion on determining strength parameters is using maximum test value. The simple double controlling principle is also suggested in this paper. A case study is presented to make application easier.

Qiangtang alluvial layers are mainly composed of sandy silt and have “highly silty and weakly clayey” characteristics. Seepage failures can be easily induced in these layers by the hydrodynamic pressure of underground water. Silt is a kind of complex transitional soil between sand and clay; and its property is different from both sand and clay. Seepage stability tests are conducted with the testing apparatus developed by authors on samples of five typical types of silt in Qiangtang alluvial layers (including sandy silt and clayey silt) as well as samples of undisturbed soil with horizontal beddings. The results of the tests show that Qiantang alluvial silt has poor seepage stability and low impermeability. In terms of the sandy silt from Qiangtang alluvial layers. (1) The critical hydraulic gradient (icr) of sandy silt ranges from 1.01 to 1.25. (2) It turns into local flowing soil when failure occurs. (3) Its transition from the critical state to the failure state occurs instantaneously; and thus deep excavation in such sandy silt layers can very easily cause seepage failure. As with the Qiangtang clayey silt. (1) Its critical hydraulic gradient increases with the content of clay. (2) Its transition from the critical state to the failure state is relatively slow compared to the sandy silt. (3) It fails in the form of whole flowing soil. The tests also reveal that the seepage stability of Qiantang alluvial layers is anisotropic. The seepage perpendicular to the horizontal beddings has the maximum icr, which is about 2.5 times the icr of the seepage parallel with the beddings. The research provides more knowledge on the prevention of silt seepage failure.

By a series of shearing model test, the effect of anchor cable on shear resistance behavior of smooth joints are studied under different normal stresses, prestresses and anchorage conditions. In the model test, shear resistance of dowel force, prestressing force and increment of axial force is separated and the shear contribution of three forces is discussed deeply to joint planes. Contribution to shear strength of joints is discussed due to dowel effect, prestress and increment of axial force in the shear progress, and failure mode of cable simulant is analyzed. Experiment results show that prestressed anchorage improve shear resistance and shear stiffness in initial phase of shear, and prompt joints to show characteristic of plastic-hardening. Experiment results also reveal that effect of prestress on joint shear strength is related with test condition, condition of joint planes and anchorage angle. Experimental and theoretical analyses show that prestress force and dowel effect play a major role in the initial phase of shear displacement and the increment of axial force play an important role after formation of plastic hinge. Cable failure usually occurred in the vicinity of the shear joint due to the combination of shear load and axial load.

Rheology is a kind of long-term deformation characteristics of soft soil, which has an important influence on the settlement of soft soil foundation. Existing researches show that high viscous rheological material in soft soil is the material basis which produces rheological properties. When the soil rheological material size is less than the critical size, soil creep characteristics are only related to the content and properties of rheological material, but not related to its shape and distribution form. Through creep test to study the effect of rheological material on soft soil rheological parameters, regarding super-hydrophilic bentonite particles as rheological material with high viscosity, using artificial soil specimen evenly mixed with different bentonite contents to conduct one-dimensional compression creep experiment. Introducing component model based on Duncan nonlinear elasticity, fitting and analysis of the creep test curve are made. The change rule of rheological model parameters is determined for the first time; according to the properties and content of rheological material, The relations between equivalent viscous coefficient, equivalent elastic modulus, Duncan nonlinear elastic modulus and the content of bentonite (rheological material) is established. Model fitting analysis shows that the rheological component model based on Duncan nonlinear elasticity has a good consistency with the test results; and relationships between model parameters and rheological material content conform to the hyperbolic equation.

The plate loading test is considered as the most wide and reliable method for determing bearing capacity, However, it can be affected by many factors, for instance, the size and buried depth of the load plate, the homogeneity of the soil, the criterion of determining ending of settlement, among which the size of load plate is the most important one. Mass engineering projects show that relatively error can be found between monitoring and predicted settlement when the plate load test is applied for determining the bearing capacity of foundation. Due to the above-mentioned problem, the paper considers the size effect of plate load test and the method for determining bearing capacity based on previous studies by others. The contents include: (1) Summarizing the defects of currently used methods for bearing capacity determination. (2) Analyzing the size effect of load plate. (3) Deriving the method of obtaining the p-s curve for real foundation by plate load test with plate in small size, based on Professor Yang’s theory of nonlinear tangent-modules method. (4) Proposing the method for determining the bearing capacity based on the p-s curve of the real foundation, the method is able to guarantee the safety of foundation and predicting the settlement. (5) Due to the fact that the plate load test is normally used for soils in shallow depth, the paper proposes a method to determine the bearing capacity in deeper soils by pressuremeter test; A project results show that the settlement calculated based on the soil parameters derived from small-size load plate test is closer to monitoring data. The research on deriving soil geotechnical parameters through small-size plate load test not only improves the accuracy of settlement calculation, but also promotes the development of foundation design theory.

In order to determine the extent of excavation damaged zone around roadway more reasonably, a new prediction method is proposed based on the dimensional analysis theory. Some physical quantities such as rock uniaxial compressive strength Rc, joint coefficient of rock F, unit weight of rock ?, depth of roadway H, maximum horizontal principal stress ?Hmax and span of roadway B are selected; the dimensionless relations among the thickness of excavation damaged zone L and above mentioned physical quantities are established by means of dimensional analysis. Among them, L/H represented that the thickness of excavation damaged zone is proportional to depth of roadway; F represented structural characteristic of surrounding rock; both ?H/Rc and ?Hmax/Rc represented mechanical characteristics of surrounding rock; B/H represented geometric characteristic of roadway. The quantitative function formula among these dimensionless relations is derived by combining with some field test data, the residual sum of square is 0.003 1, and the correlation coefficient is 0.937 9. Finally, the prediction model of the excavation damaged zone is validated with some testing examples from 3 mines. The results show that the calculation results satisfyingly agree with the measured data at the average relative error of 7.38%, which can be of interest from a practical viewpoint.

Magnesium phosphate cement(MPC) is used to stabilize/solidify lead-contaminated soils. Unconfined compressive strength test and permeability test are conducted to investigate the variation of mechanical properties of MPC treated lead-contaminated soils along with MPC dosage and water content. Results show that the unconfined compressive strength increased significantly with MPC dosage, while the hydraulic conductivity changed oppositely. There is a threshold value for water content of 0.45 of its influence on unconfined compressive strength and hydraulic conductivity. The unconfined compressive strength increased with the water content before the threshold value, while the hydraulic conductivity changed oppositely. “MTP” test results show that the total void volume reduce as the MPC dosage, the total void volume of soil reduce as the water content before the threshold value. SEM test results show that a larger aggregation formation, with a smaller void space in soils as the MPC dosage increase, more obvious aggregation and cementation occur in soils space as the water content less than the threshold value. These results can be attributed to the decreases of the pore volume of soil pores, which the diameter larger than 1 ?m.

In order to research the road performance of granite residual soil subgrade filling materials, compaction characteristics and mechanical properties of compacted residual soil are researched by using compaction test, California bearing ratio(CBR) test consolidation test and indoor test method for coefficient of subgrade reaction. The deformation properties of the soil under dynamic loads are studied by using cyclic loading test on the optimum moisture content and saturated samples. The results show that compaction works more efficiently with K of 91%-97% for granite residual soil. Improving the degree of compaction is effective to enhance the local deformation resistance of the soil. K30 was obtained from indoor triaxial test, and the value is 188.25 MPa/m. The dynamic stability of granite residual soil is comparatively well under the optimum moisture content. However the plastic deformation increases substantially and dynamic elastic modulus reduced with water content increasing. The increasing water content is not conducive to the deformation stability of the soil. So as filling materials, it shall be considered as spare materials of embankment which suffers low effect of environment. If used as subgrade body and highway roadbed, shall be modified and making choice based on the requirements of deformation. This study may provide technical reference for the construction process of granite residual soil as embankment filling and soil conditioning.

Bamboo is a kind of high strength and environmental protection building materials that can be used to solve the problems of high cost for both traditional shallow excavation supported and the temporary structure removed. The bamboo pile bending test and the single row bamboo micro-piles model tests were put foreword. The results show that the elastic modulus of bamboo pile decreases gradually with increase of the net cross-sectional area in the bending test; the elastic modulus is mainly distributed in 8.0-12.5 GPa. In model test, the strain of pile increases gradually up to peak with the increase of the depth and then gradually decays to 0. The reverse strain appears after reaching 0; and then the reverse strain decays to 0 after reaching the peak. According to the results of strain of pile and displacement of pile top, the use of single row bamboo micro-piles can get better support effect in the support of shallow foundation pit. The research results would provide experimental basis for studying the supporting mechanism of the single row bamboo piles and provide a reference for engineering design as well.

Silicification is one of the chemical methods of collapsible loess treatments. Sodium silicate is modified by potassium silicate for better reinforced effect. The mercury intrusion porosimetry (MIP), scanning electron microscope and energy dispersive spectrometer tests (SEM-EDS) are performed on the loess specimens reinforced by compound modified sodium silicate. The microscopic characteristics, such as the entrance pore size distributions, particles' morphology and chemical composition, are carried out. Meanwhile, the relationship between microstructure, chemical composition and macroscopic mechanical behavior is also discussed. Based on the results of MIP, similar entrance pore size distributions, the dual-porosity structure, were found in both modified and unmodified reinforced loess specimens. And the entrance pore size distribution ranges from 0.06 to 8 ?m. According to the decreasing size, the pores can be labeled as large, medium, small and micro-pore, among which the three critical values are 8, 2 and 0.06 ?m, respectively. Moreover, gel-filled effect can be observed if reinforced effect is not significant. The results of SEM-EDS tests show that loess specimens retain granular, trellis pores, contact-cement microstructure after modification. The surface of loess particles became rough and floc was adsorbed after adding potassium silicate material. The EDS data represents that the K element content increases with the increasing of incorporation of potassium silicate. And the unconfined strength of specimens is positively correlated with the percentage of K element. It is also shown that connection strength of soil particles and the structure morphology are the main factors of the macroscopic mechanical properties of loess. The mechanism of loess reinforcement by compound modified sodium silicate is reinforcement of the bond strength of cement in microstructure and formation of three-dimensional networks of frame.

In order to analyze the applicability of Brazilian disc splitting method in tensile strength test of layered rock mass, by analyzing Brazilian splitting test results of the layered rock mass, selecting the bedded sandstone as test subjects, a kind of Brazilian disc split test considering sandstones’ different bedding angles has been designed and then carried out. The results show that：(1) The anisotropy of the tensile strength of layered rock is very obvious; and the influence of bedding angle on the splitting tensile strength of layered rock mass is substantially similar, but the degree of influence is different. (2) The difference of different bedding angle disc samples’ fracture surface shape is large; the failure modes can be summarized as linear，bent and arc. (3) When the bedding angle is in the range of 0°＜β＜90°，the development law of rupture surface can not strictly meet the assume of Brazilian splitting test disc mechanics model; the splitting tensile strength calculated by the equation (1) can only be an approximate value. (4) When the rock sample materials and bedding structure are symmetry distributed on both sides of the disc samples` load line, the stress distribution in the disk during the loading process can better satisfy its theoretical calculation model; the test results are more accurate. The research results can provide a good reference for the tensile strength’s accurate determination of the layered rock.

The maximum and minimum dry densities are important parameters to evaluate the relative density of sand. This paper reveals the effect of particle breakage to the maximum dry density of calcareous sand, and analyzes the correlation between the characteristics of the maximum and minimum dry density and particle size, water content. Judging from the test results, test methods of the maximum and minimum dry densities are summarized and suggestions are drawn. The results show that dry density of calcareous sand firstly decreases and then increases. Particle breakage occurred in the maximum dry density test, which increases the test result of dry density. The amount of particle breakage increases firstly and then decreases with grain size. The minimum dry density decreases with the increasing of particle size; and the minimum dry density is affected by gradation and water content. The maximum dry density of calcareous sand should be tested by electric relative density meter is recommended; and the minimum dry density should be tested by measuring cylinder method.

Expansive soils always have high plasticity and strong hydrophilicity. Because of high clay mineral contents, high cation exchange capacity, and relatively larger specific surface area, the electrical conductivity of expansive soils increase with swelling capacity. Strong, middle and weak expansive soils are selected to study the relationships between conductivity and swelling capacity. By using non-contacting electrical resistivity device and portable conductivity probe, the electrical conductivity of both the soil slurry and the pore water are tested. And atomic absorption spectrometer is used to detect ion species and contents of pore water. Researches show that the conductivity of slurry and pore water both increased with swelling capacity, and the increasing trend show a good linear relationship. Thus, conductivity can be a good method for rapid identification of expansive soils.

Guanshan railway tunnel, located in Gansu Province, China, is a deep tunnel in hard and brittle diorite rock mass under high in situ stress. Meanwhile, this tunnel is also located in the Liupan Mountain, which is an active tectonic region of the compression uplift with a high horizontal movement rate and significantly changes of movement direction on the northeastern margin of Qinghai-Tibet block. On the contrary of the good rock mass classification predicted in investigation stage, the real situation after excavation shows a great change of rock mass parameters and structure, revealing not only the degradation of rock mass quality also the significant anisotropy of rock mass. The degradation and anisotropy of rock mass is described and analyzed based on the statistic analysis of the rock structural plane in field. Meanwhile, self-developed borehole camera is adopted to further observe the progressive deformation and failure of rock mass in an interval after excavation. As one of the hard and brittle plutonite, the uniaxial compressive strength (UCS) of diorite is a relatively high index on investigation stage, which is obviously larger than the in situ stress. However, the deformation and failure of diorite rock mass happened prevailingly. As the evidence obtained by borehole camera, the micro fracture or closed rock structural plane under high in situ stress will re-open and develop quickly after the excavation, which degraded the stability and quality of rock mass structure. To figure out the deformation and failure process, an angle rotation of uniaxial compressive test is designed. The uniaxial pressure is lower than the uniaxial compressive strength of diorite. This test has good agreement with the borehole camera test results, fully presents degradation of rock mass structure, induced by stress field change after excavation and proves the feasibility of the progressive deformation and failure process of hard and brittle diorite rock mass during the strongly stress field change after excavation. Besides anisotropy of rock mass, stress field change is always a significant consideration factor in deep excavation project under high in situ stress.

Based on the stress theory, a three-dimensional earth pressure cell was designed for measuring three-dimensional stress state in soil. The device is composed of a slotted dodecahedron base and six conventional earth pressure cells. According to relationship between any normal stress in a direction and the six components of general three-dimensional stress, a transformation matrix was established from test data obtained by three-dimensional earth pressure cell to general stress state. The calculation method of the test data to the general stress state was given; and the error analysis was carried out. Considering machining convenience of the base and simplicity of the test procedure, the paper focuses on illustrating the principle, production process, test method and data processing for the rhombic dodecahedron three-dimensional earth pressure cell. One-dimensional compression experiment on an unsaturated remolded soil was performed and a device measuring normal stress in six directions was given herein. The conventional stress results deduced by test data show that the two horizontal stress is substantially equal and less than the vertical stress. At the same time, the three shear stresses of the conventional stress are small and near zero. That is consistent with mechanical characteristics of one-dimensional compression on soil. Therefore, the design of the device is reasonable.

Through the Global Distribution System (GDS) resonant column tests on soft clay foundation with cement soil mixing piles samples, the effects of shear strain, cell pressure and replacement ratio of cement soil on dynamic properties are analyzed. The test results shows that, the change tendency of the dynamic shear modulus G and damping ratio D of the cement soil mixing pile soft clay foundation is the same as that of soft clay, the dynamic shear modulus G and damping ratio D of the soil are significantly influenced by the cell pressure and the replacement ratio in the small strain range; the influence is weakened with the increase of strain. The Gmax of soft clay foundation with cement soil mixing piles shows linear relationship with cell pressure; the enhancement effect on Gmax of the replacement ratio is significant at high cell pressure. The results can provide a reference for the dynamic parameters of the soft clay foundation with cement soil mixing piles.

The slag-clay mixtures made of construction waste slag mixed with certain proportion clay have been used as filling materials, which have significantly social economy and environmental protection benefits. In order to reveal the compaction properties of slag-clay mixtures, a series of compaction tests are conducted to investigate the influence of the slag content and initial gradation on the behavior of compaction and particle breakage. The results show that the optimum moisture content is smaller for slag-clay mixtures than for clay, and the maximum dry density is larger for slag-clay mixture than for clay. As the slag content increases, for the slag-clay mixtures the optimum moisture content increases, and the maximum dry density increases firstly and then decreases. Therefore there exists the optimum slag content of 30% in the slag-clay mixtures despite the different initial gradation of slag. The relative breakage of slag particles increases with slag content during the compaction. The relative breakage is greater for uniformly graded than for well-graded slag, but is not much affected by the initial particle size of slag at the same slag content. The maximum dry density is greater for larger size than for smaller size particles of slag, which leads to well compaction of wide-graded slag-clay mixtures. The compaction properties of slag-clay mixtures are explained by linking the structural response of slag-clay mixtures with the slag content and behavior of particle breakage.

Most methods to determine sliding surface of soil nailing wall are based on the assumption that all circular sliding surfaces pass the foot of slope; but the assumption is not always true. In this paper, four kinds of circular sliding surfaces that may appear in reality are summarized and an approach to search the most dangerous sliding surface that does not pass through the foot of slope is put forward using the relationship between the center coordinate and three location parameters of this circular sliding surface. In addition, the calculation formula for the factor of safety of soil nailing wall in Technical specification for retaining and protection of building foundation excavations is discussed and improved. Through comparing and analyzing sliding surfaces and the factors of safety obtained by different methods in three examples, the results show that sliding surfaces and the factors of safety got by the method established in this paper is quite close to those obtained by other methods, so as to verity the feasibility of the method established in this paper. In some cases, sliding surface got by the method established in this paper is very different from traditional method because of the assumption that the all circular sliding surfaces pass the foot of slope. The improved formula which takes the anti-sliding force produced by soil weight along the tangential direction of sliding surface into account can get a slightly greater safety factors under the same sliding surface for other three kinds of sliding surface except for the sliding surface got by traditional method.

Preparation of microbial induction of calcium carbonate precipitation(MICP) cemented sand samples injected twice bacteria solution with different concentrations of nutrient salt treatment, triaxial tests and CaCO3 quantitative chemical tests are conducted on cemented sand to analyze the effect of nutrient concentration on the mechanical properties of cemented sand and the relationship between the calcium carbonate content and the strength indexes of calcium carbonate precipitation samples. The results show that: The strength of the sample increase gradually with the increase of nutrient concentration; and then decrease after reaching a certain peak value under the same reaction time and volume of nutrient solution. The deformation modulus increases with the increase of dry density of samples under the condition of good distribution of calcium carbonate crystals. The distribution of calcium carbonate crystals and calcium carbonate content affected the increase of MICP specimen strength. The strength of 0.5 M is the highest in the experiment, and the content of calcium carbonate, cohesion and internal friction angle are 6.03%, 46.9 kPa and 41.31° respectively.

Burgers model could only describe the first two stages of rock creep, it is difficult to reflect the accelerate creep stage. In order to describe the whole process of creep and expand its range of application, considering time effect of creep parameters and the effects caused by damage, the following methods should be taken to improve the Burgers model: non-stationary viscous element is used to replace stationary viscous element in a series of Burgers model so as to describe the accelerate creep stage. At the same time, according to the change of damage variable characteristics, a function is assumed and can be put into Kelvin model by Lemaitre strain equivalence principle; finally got the model to describe the creep decay stage. Through combining all divisions, a non-stationary model for rock creep considering damage is obtained. Through analysis, the results show that: the accelerate creep stage can be well described by improved Burgers model; the non-stationary Burgers model curve and experimental curve both approximately consist with each other; the correlate coefficient is high and all parameters are in reasonable ranges. Therefore, the non-stationary Burgers model is feasible and correct; in addition, it is more suitable to describe creep curve of rock under different stress states.

Combined with a high cutting rock slope near a 220 kV substation, the parameters of the anchors are analyzed based on the limit equilibrium method and numerical method. The design parameters are optimized by comparative analysis of the slope stability results that are calculated by setting different angles and lengths of the anchors. The anchor reinforcement effect is evaluated by surface displacement monitoring, deep ground displacement monitoring and stress monitoring of the anchors. The results show that: (1) With the increase of anchorage angle, the safety factor increases at beginning and then decreases; so there exists an optimum anchor angle. 22°for this project. (2) The anchors in the lower part of slopes exhibit larger axial force; so it is important to focus more on the design parameters of anchors in the lower part of slopes. If the slope safety factor could not satisfy the design requirement, increase the cross-section size or length of the anchors in the lower part of slopes as appropriate. (3) The length inequality design of the anchors is suggested. The anchor length shall be determined by measuring the distance between the slip surface and slope surface at first; then check the calculation results by the limit equilibrium method. (4) The in site monitoring results show that the optimization design of anchors achieves relatively high performance and good economic benefits.

Rock uniaxial compressive strength (UCS) is one of the most important mechanical parameters of rock, which is vital to the design of rock engineering and stability analysis of country rock. Since the rigid procedures of rock drilling and coring, sample processing and testing conditions in rock UCS test, a high-precision model is urgent required for rock UCS prediction, among which the parameters should be easy to get. Based on inherent links of rock physico-mechanical parameters, a relation between rock UCS and P-wave modulus is established. According to the test data of rock dry density, P-wave velocity and UCS from dacite-porphyrite and shale, a UCS prediction formula based on P-wave modulus is obtained by using the linear fitting method, which is verified by statistical test and compared with the traditional prediction formula based on P-wave velocity. The results show that the general prediction formula is simple in form, high in accuracy, and the modulus is easy to obtain, which can be easily applied to practice.

Based on 19 field pile load tests in 6 sites of Zhengzhou third ring rapid road engineering, pile bearing and deformation characteristics, load transfer laws, pile tip bearing capacities and pile friction behaviors of the pile tip grouted large-diameter bored pile are studied by comparing the field test results of the post grouted pile and pile without grouting. The results show that the bearing capacity of large-diameter bored pile is significantly improved under the condition of pile tip grouting. The influence of the capacity increasing amplitude is significantly influence by the grouting age. In alluvial deposits with soils mainly of medium dense to dense silt, fine sand and plastic to hard plastic silty clay in the middle and lower reaches of the Yellow River, the large-diameter bored pile with a length of about 40 m shows characteristics of friction pile. However, the loads that are transferred to the lower part of the pile shaft and pile bottom of the pile tip grouted pile are smaller. Hard cement sediment concretion body be form under the pile tip by the pile tip post grouting, which is effectively deal with the problem of the sediment under the pile tip. Moreover, cement bond body with mesh distribution be also form in the soil with a depth of nearly 1 m under the pile tip through the fracturing and penetration effect of the post grouting. Coupled with the compaction effect of pile tip soil by the high pressure grouting, the bearing performances of the pile tip and the bearing stiffness are significantly improved; pile side friction ultimate resistances of the large-diameter bored pile is significantly improved by the pile tip post grouting. However, the pile-soil relative displacements which are correspond to the pile ultimate side friction resistances are reduced by the grouting. These are why the post grouted large-diameter bored pile shows higher bearing capacity in the small settlement.

Microbial-induced calcite precipitation(MICP) is a newly emerged ground treatment technique in geotechnical engineering to treat the soil with poor engineering properties. However, differences on the particle size may occur in different types of soil, which will have influences on the properties of treated soil. In this study, three different ranges of particle size are adopted to be treated by MICP method; and then the effect of particle size on the strength of bio-cemented sand is investigated based on the unconfined compressive strength(referred to as strength hereafter), porosity and calcite content of each sand specimen from macroscopic level, which are obtained via unconfined compression test, porosity measurement and acid treatment, respectively. Meanwhile, this effect is also analysed at the mesoscopic level according to the images of scanning electron microscope (SEM). The research results show that calcite crystals are precipitated on the surface of sand particles, as well as in particle-particle contacts. Calcite crystal clusters will be formed as the MICP process continues; meanwhile, its size increases with the superposition of calcite crystals. The pore space of sand with smaller particle size can be tightly filled and a higher proportion of effective calcite crystals can be obtained. Hence, the bio-cemented sand is able to present a higher strength due to the stronger structure established by the calcite crystal clusters.

Tailings is the main filling material for mines, which belongs to the typical loose medium and has obvious compressibility under the action of external force and its gravity. Its physical mechanical properties will change with the compaction conditions, but there is no reasonable calculation method to predict these properties of the tailings so far. The tailings of Dahongshan copper mine are used as an example in this study, where a mathematical relationship between density of the tailings and the load which meets the characteristics of the power function is obtained employing a user-defined function in original software that is fitted with the results of the high pressure consolidation test. The mathematical relationship between density of the tailings filling body of a large goaf and the height which meets characteristics of the power function is derived by analyzing the vertical forces balanced of the unit volume of the tailings, the function is integrable, it can be known form the function, density of the tailings increases with the height, the growth rate decreases gradually. The results of the numerical simulation and the industrial field test show that the compaction model of the tailings filling body under its dead weight is in agreement with the real conditions; so that the model has high practical value in engineering.

A large number of underground rock discontinuity data can be collected by borehole camera technology. The in-depth analysis of these data will help to further reveal the spatial distribution regularities and geometrical relations of discontinuities. In view of the particularity of geometric parameters from discontinuities obtained in borehole, a new method called feature point which includes the angle, inclination and depth parameters is proposed. The paper mainly focuses on description and calculation process of feature point under the local and global coordinates. The conversion formula between the geometry parameters and feature point coordinates is derived. Distribution regulation of feature points under spatial coordinate system is discussed. The results show that: (1) The feature point is a comprehensive reflection of geometric parameters of discontinuity and spatial location. (2) The distribution of the feature points in space reflects the spatial association relationship of discontinuities. This study provides a new idea and analysis method for the statistical analysis of discontinuities; and helps to research on the discontinuities distribution regularity and intersection relationship, on the development of borehole camera technology and on the basis of the discontinuity geometry characteristics of rock mass stability evaluation with a positive role.

The pipe-pile with holes can effectively accelerate the spatiotemporal dissipation of excess pore water pressure and reduce the negative effects of sinking-pile influence for the surrounding environment. However, the bearing capacity of pile will be weakened by the stress concentration phenomenon caused by opening hole. In order to explore the effect of the bearing capacity of pipe-pile due to opening holes, the static load tests of single pile have been carried out for the pipe-pile without hole and the pipe-pile with holes in soft soil foundation by using of the model tests, which are three kinds of opening holes. The settlement of the pile top and the pile strain in different positions caused by vertical load have been measured and analyzed. The Q-s settlement curves, axial force and side friction distributions of the all piles can be obtained. From the comparative analysis, it can be concluded that the decrease of axial force of pile of radial direction pipe-pile with holes is the minimum; the side friction of double direction pipe-pile with holes is the maximum.

In order to understand the influence of fiber on the mechanical properties of cement soil, the unconfined compression test and fatigue test of cement soil and fiber reinforced cement soil are carried out. The results show that the compressive strength of cement soil can be improved slightly by adding fiber. Compared with plain cement soil, the strain of fiber cement soil increases obviously at the stress peak point; and its residual strength after failure also increases. The addition of fiber improves the ductility of the cement soil, reduces the crack development and improves its mechanical properties. After the fiber is added, the antifatigue ability of cement soil is significantly increased. The degree of the improvement of cement soil fatigue resistance is much greater than that of unconfined strength of cement soil. The relationship between stress level and fatigue life of cement soil is single logarithm linear. The cement soil is characterized by low stress rupture under cyclic loading.

Rock mass quality classification plays a very important role in the practical engineering. Based on the combination of principal component analysis(PCA) and Fisher discrimination analysis method, a rock mass quality grade discriminant model is established. Uniaxial compressive strength, rock volumetric joint count, sonic compressional wave velocity, the jointed surface weathering coefficient of variation, the jointed surface roughness coefficient and permeability coefficient are selected as the discrimination factor of the rock mass quality classification. 20 training samples were selected from engineering rock characteristics data in the area of open pit of Yongping Copper Mine and 10 test samples is used to test the model and application. Moreover, comparing with the traditional RMR law and Fisher discriminant analysis, the corresponding correctness rates are 87%, 70%, 77%. The results show that: the combination of principal component analysis and Fisher discrimination analysis method is more accurate than the traditional one.

Project practices show that the narrow foundation pits, behaving a significant size effect, have better stability and smaller deformation than wide ones; so the embedded depth of envelope structure for narrow pits can be properly reduced at same excavation depth. However, most present stability analysis method of foundation pits design did not consider the influence of the excavation width on the safety factors, which leads to conservative design for a narrow pit. In order to make slip surface come into being for narrow pits, by moving the center of the slip arc, let the slip arc through the bottom of the enclosure wall and the intersection of excavation bottom and contralateral enclosure wall. The safety factor of stability calculated based on this slip surface can consider influence of excavation width. According to this idea, foundation pits are divided into different types by different widths, corresponding to the different calculation methods of This method can be transformed to the calculation method in the existing norms at wide pit, which can ensure the its unity with the existing specifications; for narrow pit, . The analysis shows that ignoring the size effect in the excavation design and one-sided emphasis on the insertion ratio is unscientific. Because applying traditional slip surface form of safety factor of heave-resistant stability and no excessive change on the calculation method; the calculation method are suitable for use in the design and construction of foundation pits. This calculation method of provides a theoretical basis for the narrow pit to reduce insertion depth.

Based on analyzing the deformation mechanism of composite foundation, the maximum settlement calculation of rigid-pile composite foundation by method of compression of cushion between pile top and foundation is proposed. In the calculation the pile settlement is estimated from pile loading test data in the past. The main problem is then to focus the compression calculation of the cushion between pile top and foundation. The variation of the compression modulus of the cushion with loading level is considered in the calculation. The calculated results are compared with that collected from 28 actual projects, and three projects of them are introduced in detail. The calculated results accord well with all measured data.

The displacement analytic solution of a circular tunnel in transversely isotropic rock mass considering shear stress is deduced firstly; and then the uniqueness of displacement back analysis of a circular tunnel in transversely isotropic rock mass considering shear stress is investigated by means of parameters identifiability conditions. The results show that no matter how many measuring points are set, all the 7 parameters can not be determined simultaneously. It is possible to determine other parameters only when there are at least 3 parameters are known in advance; whether the horizontal and vertical components of ground stress are 0 has certain effect on the uniqueness of back analysis. The ground stress components show the best identifiability, the elastic modulus and Poisson’s ratio in the isotropic plane are the second; and the elastic modulus and Poisson’s ratio in the direction vertical to the isotropic plane are the worst. Compared with the uniqueness results of displacement back analysis without considering the shear stress, the order of identifiability for the parameters is unchanged. But the proportion of the conditional uniqueness decreases; while the proportion of the non-uniqueness and absolutely uniqueness increase, which show that taking shear stress into account may raise the proportion of the uniqueness of displacement back analysis. The case studies show that the inversion calculation of rock mass parameters can be conducted well by the displacement analytic solution and the uniqueness results of the displacement back analysis.

Based on model test method, pile-soil interaction characteristics of 2×1 and 2×2 belled wedge pile groups embedded in sand under vertical load are carried out. The load versus settlement of pile top, pile tip resistance and the axial force of pile distribution along depth are measured. Meanwhile, model test on vertical bearing capacity of single belled wedge pile are also carried out for comparative analysis. Considering the coefficient values of cap effect and group effect noted in JGJ94 code, the ultimate bearing capacities of belled wedge pile groups are calculated. In this model test conditions, the results show that the group effect coefficients of 2×1 and 2×2 belled wedge pile groups with low cap equal 1.16 and 1.10, respectively; and those of pile groups without cap equal 0.95 and 0.88, respectively. The values of cap effect and group effect coefficients for traditional equal section pile can be used for belled wedge pile.

Swelling pressure is an important parameter for the design and construction of geotechnical engineering in swelling rock and soil regions. The swell and load method, the no-swell method, and the load-swell method are the three most commonly used methods for determining swelling pressure. Swelling pressure depends significantly on test method. To explore the effect of testing method on swelling pressure, swelling pressure tests of Yanji swelling rock specimens with different initial water contents were carried out using the above-mentioned three methods; and characteristics of three methods and their application scopes were analyzed and compared. The results indicate that three methods show different values in swelling pressure; and there is a clear effect of hydro-mechanical path on swelling pressure. The swell and load method provides the highest value of swelling pressure; while the load-swell method provides the lowest. There is a significant negative linear relationship between the swelling pressure and the initial water content. Relationships between the swelling pressure and the initial water content obtained by three methods tend to be close to each other with the increasing initial water content, which illustrates that the effect of hydro-mechanical path on swelling pressure is weakened. Every method has its respective characteristic and specific application scope; so testing method of swelling pressure should be determined by practical engineering conditions.

The uplift bearing capacity of spread footing can be obtained through the footing uplift static loading test. At present, the load-displacement curves at the top of footing are usually used as the basis in this process. However, the deformation and failure behaviors of the soil around footing are ignored frequently, which often occurred in footing projects. Aiming at this problem, the difference of the uplift resistance characteristics between the spread footing and the foundation soil are studied. The uplift static loading tests of nine full-size spread footings are carried out. And the load-displacement curves at the top of footing and the ground surface are obtained. The comparative studies are carried out through analyzing the changing features of the load-displacement curves and the values of the uplift bearing capacity. The results show that both the load-displacement curves at the top of footing and the ground surface vary gradually. Under the same load, the displacement at the ground surface is less than that at the top of footing. And the difference between them is most significant at the elastic stage. Moreover, the values of the elastic limit load QL1 obtained from the curves at the two positions show the obvious difference. With the transition from the initial straight line to the final curve, the difference will decrease gradually. Finally, they get the same values of the plastic limit load QL2. Based on the analysis of the failure behavior of spread footing, the incompatible deformation between the footings and the ground soil is regarded as the main reason for this discrepancy. At the beginning of the tests, the footing displacement value is the sum of the soil compression quantity and the pulling out amount of the footing, and when the soil upon the enlarged head of the footing is compacted completely, the footing together the soil form a whole and the displacements for the footing and the ground soil tend to coordinate.

The S transform(ST) time-frequency analysis technique is introduced to microseismic signal analysis field; the correlation between rock deformation-failure and microseismic signal frequency characteristics is investigated based on fracture scale. A large-scale seismicity observation is carried out in three hydropower engineering in Southwestern China; a significant amount of data is used as the statistical samples to minimize the influence of external factors on parameters calculating. Based on the statistical samples, the correlation between the source fracture scale and the frequency characteristics of microseismic events is analyzed. An engineering verification research is carried out combining with the monitoring data of microseismicity and multipoint extensometers in Houziyan hydropower station underground powerhouse. The research results show that the high frequency components decrease and microseismic signal displays low-frequency characteristic as the fracture scale increase; the microseismic high frequency components decrease at first and then increase during the deformation process of surrounding rock; and the frequency of microseismic events shifts from high band to a lower one before deformation. It can be believed as precursory information of deformation-failure that the frequency of microseismic events in concentrated area starts to decrease. Results can provide references for the stability analysis and hazards prediction of rock engineering based on microseismic monitoring.

On July 10, 2013, a high-position landslide-debris flow was triggered by the heavy rainfall at Wulipo Sanxi village, Dujiangyan city, Sichuan province. The landslide-debris flow caused serious damages to Sanxi village. On the basis of further field investigation and previous research results, the formation mechanism and evolution process of the Wulipo landslide-debris flow are analyzed. Considering the actual mechanical behavior of the Wulipo landslide, the crack extending criterion under hydrostatic pressure and landslide start-up criterion under rainfall are calculated. The results show that the evolution process of the Wulipo landslide-debris flow includes following steps: formation of unloading crack, crack extending under hydrostatic pressure, slope sliding along the potential sliding surface under the effects of both hydrostatic and hydrodynamic pressures, rift trough forming, landslide reactivation due to heavy rain, rock blocks falling and accelerating, shoveling and moving along the valley, stacking and stop moving. By deducing minimum depth of water in the crack leading to crack automatically developing, critical water height in back crack and critical rainfall intensity causing slope instability, it is concluded that the crack could automatically develop when the depth of water in the crack reached 11.3 m; and the slope would lose its stability once the height of the water level in back crack reached 9.8 m.

As “the cancer of the engineering”, expansive soil is widely distributed in China. To systematically evaluate the risk grade of expansive soil cut slope stability during construction, based on research results of 22 expansive soil road sections constructed in Guangxi, Yunnan, Henan, Beijing of China, the risk surroundings, factors and feedback information of risk management are analyzed; and the hierarchy model is established consisting of two indexes layer with 8 main evaluation indices. Grading standard of evaluation indices are established by statistics and theoretical analysis; and the weights of evaluation indices are obtained by using analytic hierarchy process. The dynamic recognition model of expansive soil cut slope stability is eventually established by using fuzzy recognition theory and analytic hierarchy process (FAHP). The preliminary assessment of risk surroundings and secondary dynamic assessment of risk factors and feedback information of expansive soil cut slope of Nanyou road was carried out by using the established model; and then the calculated results are compared with field situation. The results indicate that the assessment results are basically in a good agreement with the observed results, so as to verify the rationality and practicability of the proposed model. The dynamic risk assessment methodology and model can provide a powerful tool for quantitative assessment of expansive soil cut slopes stability during the whole construction process.

In the past studies, the toppling has much research on anti-dip slope while little on the dip slopes, and lots of vacancies exist in the comparisons of the toppling mass formed by the two bedded slopes with different structures. Based on many instances of toppling mass, characteristics of forming condition and development scale about the toppling in dip and anti-dip slope have been studied in detail. The results show that, if the dip slope toppling, it’s usually characterized by the slope height of 100 m, slope angle 35, strata dip angle 60°, and the slope with soft or alternating soft and hard strata that is thin or thin-middle layer structure. With slope angle of 30° and strata dip angle 30°, the anti-dip slope can appear topping-deformation. And its lithology varies from soft to hard with thin to medium thickness layer structure. The concept of “toppling critical dip ” about the layered rock slope is proposed. As for dip slope, the is about 60°. When , the slope can appear the failure of toppling, while , it usually appear the failure of “slide-bending” or “sliding-tension”. The of anti-dip slope is about 30°. Only when can it evolve into obvious toppling; while , the slope won’t dump or dump slightly. As for the two slopes with basically the same geological condition but different slope structures, the distribution area and the toppling depth of toppling mass formed by anti-dip slope are usually greater than that of dip slope, and once the topping formed; the scale of both are usually deep, large or super-large. Besides, the distribution area and the toppling depth of toppling mass present a trend that they increase with the increasing of the slope height. When the slope height is about 250 m, the distribution area and the toppling depth is increase steeply, and the increasing amplitude of anti-dip slope is greater than that of dip slope.

The sliding surface of the expansive soil slope affected by fracture surface, always locates in the severe and mild weathered layer interface and approximates to a straight line. The trailing edge of landslide is generally vertical tension crack. The lower main slip bed is nearly level. Based on the above characteristics, a simplified model of three-broken line rigid bodies is proposed, where strength of soil in sliding body uses stable values after repeated wet-dry cycles. According to the static equilibrium of the whole rigid body, the solution formula of the safety factor of the slope is established. Taking the Qinhuai River expansive soil slope as an example, dry and wet cycling laboratory test of expansive soil is carried out. The formula is used to calculate the long-term stability coefficient of the slope, and the result is close to that of the FLAC strength reduction method. And it can also reflect the adverse effect of the fracture on the force of the sliding body. The influence of the thickness of the severe weathered layer and the thickness of the expansive soil layer on the value of the safety factor of the slope is analyzed by designed program. It is found that when the former two thicknesses increase, safety factor of the slope firstly decreases sharply and then tends to slow. And considering the shallow soil layer strength and the severe weathering depth changes, the safety factor of severe weathering layer interface in different stages of dry-wet cycles is analyzed. It is discovered that the safety factor exhibits the trend of exponential decay; and the slope loses stability mainly after six cycles of wetting and drying. The depth of sliding surface is about 1.83 m.

Surface settlement estimating methods are summarized on the basis of Peck method and measurements, and discussed by collecting large amounts of references data. The surface settlement characteristic parameters of more than 20 cities are back analyzed by using Peck method. The variation regularities of maximal surface settlement , settlement trough width ratio k and volume loss are obtained. The results show that: (1) Geographic variations and detailed construction technologies shall be deeply taken into account by using Peck method based on the measurements. The statistical results show that the relative buried depth of tunnel is 0.55-4.09; is -1.5 to -146.0 mm; k is 0.13-1.60; is 0.06%-6.90%, among them and k are negatively correlated to ; and has a significant relationship with the construction technologies and stratigraphic conditions. (2) For effectively controlling the ground movements, shallow tunneling method and assisting construction method are more flexible than the shield tunneling method in the sandy strata; on the contrary, the latter is superior to the former in the clayey soil for reducing the volume loss.

Axis deviation easily occurs during shield tunneling in soft clays due to the overlarge settlement, while adjusting the slope ratio of tunnel difficulty, even affecting the running speed of trains during the operation period. Grouting uplift is a solution to axis deviation. In order to not cause structural failure, not affect construction period, and improve the tunnel line shape, a case of uplifting practice for overall tunnel structure in an inter zone with overlarge settlement of Ningbo metro construction is studied in this paper. Through the analysis of the geological condition, structure calculation, grouting process research, lower part of tunnel structure grouting, internal support, real-time monitoring, real-time ideas adjustment, the process of grouting slurry adjustment timely; and the fine management, the integral structure of tunnel is uplifted about 3cm without causing any damage; so that the tunnel line shape is improved effectively. The engineering practice shows that the grouting process and internal support play an important role to uplift stage general ring structure safety; slurry choice is very important to late stability. And by the practice, control measures for uneven subsidence of tunnel construction in soft clays are explored to provide references for other similar engineering and shield tunnel uplift designing.

Landslide displacement in Three Gorges Reservoir area is of periodicity due to water level change, rainfall and so on. Based on the time series analysis, landslide displacement can be divided into the trend displacement reflecting the long-term trend of landslide, which is the response of geologic structure; and the periodic displacement reflecting the volatility of landslide, which is mainly affected by external factors such as rainfall. Taking Taping landslide in Three Gorges Reservoir area for example and considering the influences of water level change and rainfall, the trend displacement and periodic displacement are evaluated by Hodrick-Prescott (H-P) filter forecasting method. Difference auto-regressive integrated moving average (DARIMA) model is utilized to smooth the curve of trend displacement, and then compute the predicted value of trend displacement. Vector auto-regressive (VAR) model is used to predict the periodic displacement. The overall predicted displacement is obtained by adding the predicted values of trend displacement and periodic displacement, which is compared with the monitoring displacement and one predicted by other forecasting methods. The results show that the predicted displacements by this proposed method are in better agreement with the monitoring data; the proposed comprehensive model can better reflect the trend and volatility of landslide displacement.

To a deep and narrow foundation pit for a subway underground station in a soft ground of Shanghai, a detailed statistical analysis based on the site monitoring database has been conducted on the settlements of the ground surface and the surrounding buildings, the horizontal displacement of diaphragm wall, the uplift of the diaphragm wall and the upright column. Then, the spatiotemporal developing characteristics of deformation and the corresponding incentive are analyzed. Meanwhile, the relationships among the maximum lateral displacement of diaphragm wall ?hm, the maximum ground surface settlement ?vm and the existing statistical results are also compared and analyzed. The results show that the deformation spatiotemporal effect of a long and narrow deep foundation pit in soft ground is quite obvious. Compared with the predicted results obtained from the site monitoring database of some deep foundation pits in Shanghai area, the relationship curves between the ground surface settlement and the depth of the foundation pit is lower than that given before ones obviously. To the maximum ground settlement ?vm of the ground surface, the above finding is also existing. The main reason is that the supporting system for a narrow and long foundation pit is different from that for a general deep foundation pit, which proves that the diaphragm wall with the multilayer horizontal inner symmetrical supports can control the deformation of a narrow and long foundation pit for subway underground station built in soft ground.

The effect of above deep excavation on existing tunnel is of great concern because the excavation unloading can induce longitudinal deformation of existing tunnels. A prediction model based on the method of beam on Kerr elastic foundation is proposed. The existing tunnel is simplified as Euler-Bernoulli beam and Timoshenko beam, respectively, to consider the effect of the tunnel shear stiffness on the longitudinal uplift caused by the above excavation. The impact of unloading on the existing tunnel can be obtained based on the Mindlin Solution. The effect of tunnel shear stiffness on the longitudinal uplift of existing tunnel cause by above excavation is investigated. The results of Timoshenko beam are consistent with those of Euler-Bernoulli beam when the tunnel shear stiffness is big enough. The effect of tunnel shear stiffness is very significant when the equivalent shear stiffness ratio is less than 1/4. Based on the proposed method, cement-soil effective coefficient of unloading is proved to be 0.22 through the measured data analysis. The ribbon-unloading method of rapid excavation and equivalent load quickly is assuming to be equal to the accumulation of relatively independent excavation. The proposed method is finally validated using the field monitoring in Zhengzhou.

This paper proposes a Bayesian Copula identification method for shear strength parameters of soils and rocks. First, the characterization of dependence structure between shear strength parameters using Copulas is presented. Two commonly-used methods, namely least square method of Euclidean distance and akaike information criterion(AIC), for identifying the best-fit Copula, are given. Then, Monte Carlo simulations are conducted to validate the Bayesian Copula identification method. Moreover, the identification accuracy in the three methods is compared, and the main factors affecting the accuracy in the Bayesian Copula identification are identified. Finally, a total of twenty-three sets of shear strength data are compiled to demonstrate the application of Bayesian theory Copula model identification. The results indicate that with limited project-specific data and prior information, the Bayesian Copula identification method can successfully identify the best-fit Copula from a set of alternative Copulas for shear strength parameters. In comparison with the least square method of Euclidean distance and AIC, the Bayesian Copula identification method produces more accurate results for identifying the best-fit Copula. The sample size, correlation, the type of the true Copula and prior information of shear strength parameters has a significant impact on the accuracy of the Bayesian Copula selection method. Furthermore, the commonly adopted Gaussian copula for characterizing the dependence structure between shear strength parameters does not always provide the best fit to the shear strength data.

To solve the problems about the technology and economic rationality of the surrounding rock control in the air-return gate of 1232(3) face in Xieqiao coal mine, it is concluded that bolt diameter and row spacing are the main sensitive factors that affect the surrounding rock control results of the air-return gate by using orthogonal experiment method to analyze the experiment data of different factors in different levels with the roadway’s sides and roof-to-floor convergence as indexes. Meanwhile, two locally optimization schemes are obtained by analyzing the key factors that affect the surrounding rock control results after taking the techno-economic indicators into consideration. The final optimization scheme is reached by comprehensive analysis and decision-making of the two schemes according to the method of grey correlation analysis. The actual application shows that the deformation of surrounding rock of roadway is controlled effectively and the techno-economic benefit is remarkable after the optimization of the support parameters.

Deformation types of landslides generally include retrogressive landslide, load-caused landslide and complex landslide, which present regressive progressive failure mode, advancing progressive failure mode and composite progressive failure mode, respectively based on the development form of sliding zone. Based on the strain-softening behavior of sliding zone, the nature of progressive failure of landslide is weakening process of mechanical parameters of sliding zone which is revealed from the mechanical point. The movement and mechanical characteristics of three types of landslides in the process of progressive failure are determined preliminarily; and evolution process of different types of landslides are revealed. The distinguish criterion of sliding block of critical state is proposed based on the unbalanced thrust method and progressive evolution process. The calculation model and calculation formula of stability of progressive failure of landslides are established and the parameter value method of sliding zone is proposed, and the process to achieve stability calculation of the progressive failure is described. The method shows a complementary relationship in solving the stability problem of strain-softening landslides. Moreover, the progressive failure and stability variation for three typical examples of landslides are analyzed. The results show that the law of reducing speed of retrogressive landslide and complex landslide is from large to small to large; and the law of reducing speed of load-caused landslide is from small to large. In addition, the different part of landslide plays a different role on stability in the progressive failure process of three types of landslides; and the deformation regularity of different types of landslides is verified. The research results can predict the development of stability for different types of landslides preliminarily and provide guidance for landslide control.

The design of offshore monopile is generally governed by its accumulated response to lateral cyclic load, e.g. loads induced by winds and waves. In order to investigate the characteristic of this accumulated response, a user subroutine of degradation stiffness model (DSM) is developed and incorporated into a commercial finite difference program. Based on this program, the effect of load cycle number and load character on the displacement development of monopile is quantified; and the applicability and reliability of two mostly used models for prediction of accumulated displacement are evaluated. The results show that: In dense sand ground, cyclic loading with larger load amplitude leads to a continuous increase in monopile displacement as the number of loading cycles increasing; and the maximum load in each load cycle is suggested to be less than 0.58 times its static load capacity to produce a plateau of accumulated displacement after a certain number of load cycles; logarithmic model is capable of predicting accumulated displacement induced by smaller load and underestimates the displacements for larger load levels; the power model shows its advantage over the logarithmic model for its validity under various load levels; and the value of model parameter α increases linearly with increase in the load levels. Finally, parameter values of power model are given for various load conditions.

Restricting the heave of underlying tunnels is crucial to the construction control of excavations, as pit excavations will cause structure deformation of tunnels in the excavation engineering on existing tunnels. This paper detailedly introduces the characteristics of excavations above existing tunnels, including the crossing directions, tunnel deformation modes, and common controlling measures. 39 similar projects recently constructed in China are categorized and analyzed. Based on the influence of every factor on maximum tunnel heave in longitudinal direction, a model is established to predict the tunnel heave. The results show that the engineering geology conditions have a greater influence on the tunnel deformation in such projects. The worse the engineering geology conditions are, the harder the controlling of tunnel heave will. The other important factors of the tunnel deformation are excavation depth, pit area and shapes of excavations. The tunnel deformation will increase with the excavation depth and pit area. The more irregular of the foundation pit, the harder the controlling of tunnel heave. In soft clay area uplift piles can effectively reduce the maximum deformation of tunnels in the large and deep excavation engineering.

The decision-making of retaining schemes of foundation pit is a complex and uncertainty problem since it involves the fuzziness and uncertainty of influenced factors and the risk attitude of decision makers. A novel coupling model using cumulative prospect theory and the connection number is introduced here to determinate the optimal scheme for the foundation pit supporting system. In the model, the positive and negative ideal schemes are first specified from the original and normalized information. And then the set pair analyses are carried out to analyze certainty and uncertainty relationships between proposed schemes and the positive and negative ideal schemes. A prospect value function and a comprehensive decision-making model are described to specify the weight sectors and the optimal scheme. The results from the case study and comparison with other methods show that the proposed model used to select the foundation pit support schemes is effective and feasible. It also enables us to analyze the certainty and uncertainty relationships between proposed schemes and the positive and negative ideal schemes, and transformation trend from a uniform way and avoid the irrationality during the decision-making process.

In recent years, many piled mountains were built up; the characteristics of piled mountains are that the loads are staged applied; the construction period is long, and total load is huge. Ground bearing capacity frequently cannot be satisfied by conducting common ground treatments. Considering the time interval between staged applied loads is usually long, consolidation occurred and the effective stress increase in this period; thus the strength of soil increases and ground bearing capacity increases correspondingly. Utilizing the increase of bearing capacity caused by the increase of soil strength is the key factor for the success of piled mountain. The increase of soil strength caused by consolidation is analyzed by effective consolidation stress method; a ground bearing capacity analysis method considering the increase of soil strength is proposed; and two piled mountain cases are analyzed by this method. Finally, some suggestions are offered for similar engineering.

Back-filling mining method with whole tailings as material can not only reduce the mining cost, but also recycle solid wastes. At the same time, filling solid waste underground protects environment and maintains ecological balance. Since whole tailing’s particle size is small, whole tailings shall be mix with rod-mill tailings and Gobi sand for mine filling. It is necessary to research the optimal proportion of mixed filling aggregate. First, we tested the particle-size gradation and the nonuniform coefficient of rod-mill tailings, Gobi sand and whole tailings. Then we carried out 9 sets of strength tests of cemented fillings with different mixing ratios. On this base, we built the artificial neural network model for strength predictions and trained it with the experimental samples. Finally, we predicted the strength of mixed filling aggregate of orthogonal design by using the prediction model, and we revealed the relationship between filling body’s strength and characteristic value of mixed filling aggregate by using range analysis and regression analysis. The research results show that, with different mixed aggregate’s average sizes and nonuniform coefficients, the filling body has significant strength differences between early and late stage. Mixed aggregate with smaller average particle size has a higher strength in early stage; while the larger is more inclined to increase the filling body’s strength in late stage.

Ground fissure is a typical geologic hazard in loess field and the propagation law of seismic wave in ground fissure field is widely concerned in engineering world. To analyze the propagation law of seismic wave across ground fissure, the equivalent rigid coefficients of ground fissure in Xi’an field and discontinuous condition of fissure interface are selected. Considering the converted waves, frequency domain equations used to solve the transmission and reflection coefficients are obtained based on the fundamental solutions of the equation of motion. The influence of the incident angle, frequency of incident wave and medium parameters of ground fissure on the propagation law of seismic wave is analyzed. A brief conclusion from the results is obtained that ground fissure possesses the high-frequency filtering properties with the propagation of seismic wave. In low frequency condition, the transmission coefficient is more larger than others. Equivalent normal rigidity only influences the propagation of P-wave, but equivalent shear rigidity influences P-and SV-wave. Relative to equivalent normal rigidity, the influence of the changes of equivalent shear rigidity on transmission and reflection coefficients is more obvious.

Engineering surrounding rock is a highly nonlinear complex dynamic system, and its influence factors are so numerous that single evaluation index can accurately not describe the surrounding rock classification. At present，there are many methods to evaluate surrounding rock classification via considering various indicators together. However，the correlations exist in these evaluation indexes more or less. That is to say，these evaluation indexes are indicators of non-Gaussian distribution; so it is difficult to meet the request that sample layers of probabilistic neural network(PNN) must adopt Gaussian distribution as radial basis function. Given this，we presented a symmetric stable distribution (SaS) which not only has a wider range of mathematical expression than the Gauss distribution，but also it could act as the radial basis function of sample beds in probabilistic neural network (PNN). The model of the surrounding rock classification evaluation in the second-stage project of Guangzhou pumped storage power station can be established based on the SaS distribution. The predicted results show that the model has a good effect and its false-positive rate is 4.55%. This model can provide a new way for predicting the effect of surrounding rock classification in underground engineering.

The plastic tube pile applied to soft ground treatment of highway, is comprised of pre-driven plastic tube filled with concrete. According to the steel stress gauges embedded in plastic tube pile, the load transfer mechanism of plastic tube pile under embankment load is completely measured during the periods of construction and precompression. And the modified method of steel stress gauge is proposed. The test results show that under the static load of single pile, the axial load of plastic tube pile decreases with the depth increasing, and there is no negative skin friction; under the embankment load, the axial load of plastic tube pile increases first and then decreases, and the distribution of negative skin friction is in the upper 3/5 of pile length; with the increasing of embankment load, the negative and positive skin frictions are gradually increased; however, the location of neutral point of negative skin friction stay the same during the observation period.

The basic hypothesis of residual thrust method is only suitable for perfect-plastic materials or strain-hardening materials. For the slope with strain softening properties, the applicability of this method will be limited. This paper based on the strain softening properties of soil aims to explore the relationship between shear strain and the shear capacity, by introducing equations of strain compatibility at the bottom of the bars, the method for landslide thrust calculation is improved; and then a new method for calculating designed thrust of anti-slide pile considering strain softening properties is proposed. The case studies show that the coefficient of landslide stability calculated by improved calculation method is between the values respectively computed on the condition of peak strength and residual strength; and the designed thrust of anti-slide pile obtained by improved method is much lower than that obtained by residual strength, but is higher than that obtained by peak strength, is between the two sides all the same. The method proposed is based on the current status of the landslide; so it can curb the further development of the landslide and also conform to the actual situation of the slope at present.

Based on the theoretical analysis of displacement of tunnel and station induced by the foundation pit excavation, the disciplinarians of tunnel and station are summarized. The uneven deformation parameter is defined in the form of quantization, and the influence of the station on uneven deformation of tunnel and its prediction are researched. The results show that the subway station is uplifted, but the tunnel subsided during the pit excavation. The differential displacement between tunnel and station are great, and it is serious damaged to tunnel lining. The affected range of tunnel is 4 times as much as the depth of pit excavation. The range of uneven deformation region of tunnel is 1 times as much as the depth of pit excavation. The obtained formula of can predict the size and distribution of the uneven deformation of the tunnel caused by station. The results of this paper can provide useful reference for similar projects.

In order to study the mechanical characteristics of short anti-sliding steel pipe pile for stabilizing the slope, four groups indoor physical model tests of short anti-slide steel pipe pile for reinforcing debris landslide with different lengths are conducted in the geological disaster prevention technology center completion of China Geological Survey. Through measuring the soil pressure at the rear and fore of short anti-slide steel pipe pile with stress-strain sensors as the sliding force impelled by the heaped load, observing the deformation and failure of the leading edge of landslide in the whole experimental process, analyzing the distribution of landslide thrust, soil resistance at the fore of steel pipe pile and bending moment of short anti-slide steel pipe pile. The results show that the distribution of landslide thrust and soil resistance at the fore of steel pipe pile are triangular-quadrilateral, bending moment is S-shaped distribution; the maximum bending moment and the critical section of short anti-slide steel pipe pile which are located at the vicinity of the sliding surface. And comparative analysis of mechanical characteristics of short anti-slide steel pipe pile with length changing , the limit length value of short anti-sliding steel pipe pile can be developed which totally play the anti-sliding effect; that the length of short anti-slide steel pipe pile should be not less than 2/3 of the slip thickness.

Evaluation of the cohesive soil ground engineering properties is one of the important research subjects. Many engineers take their attention to this subject. Resistivity method is widely used in the environmental monitoring and geological exploration, which has the characteristics of comprehensive, in-situ nondestructive and fast. Five typical cohesive soils sites in Shanghai are used in this article. And the resistivity log test and engineering properties test are performed. The change rule of the resistivity, water content and density is analyzed; and the evaluation method of engineering properties method based on resistivity is presented. It is shown that from the researches that the resistivity increases with moisture content in an exponential function, and decreases with the density in a linear function. There is an exponential function relation between resistivity and plasticity index. Meanwhile, the shear and compression properties are related to the pore properties of cohesive soil; and the resistivity is one of the parameters of soil pore characteristics. There is an exponential function relation among resistivity, cohesive force and compression coefficient; and a linear function relation among resistivity, friction angle and compression modulus. It is concluded that the resistivity can be used as an index to evaluate the engineering properties of cohesive soil site based on above analysis.

For the stability analysis of jointed rock slopes, the strength reduction method based on the Hoek-Brown failure criterion is studied. Failure of slope is progressive. The attenuation degree of each strength parameter is different during the destroy process; so the reduction factors are different in the strength reduction method. Thus, the determination of the correlation between different reduction factors and the definition of the comprehensive safety factor is worthy of investigation. From the softening and hardening regularities of geomaterial perspective, the correlation between the three reduction factors in Hoek-Brown criterion is deduced in this article, based on the attenuation law of rock mass strength parameters from peak strength to residual strength. The slope stability can be evaluated with a comprehensive safety factor defined by the ratio of the anti-slide force on the sliding surface before and after reduction. Numerical simulation model is established based on the Hoek-Brown failure criterion; and the safety factor of slope is calculated using the strength reduction method. It is concluded that the calculated results based on Hoek-Brown failure criterion are similar to those calculated by other methods. The resemblance of their output validates the suggested method. The method proposed can be used in the jointed rock mass engineering, providing reference for the rock mass slope stability analysis.

Excavation of a spherical cavity in an infinite isotropic rock mass subject to a hydrostatic stress field can be regarded as an axisymmetric problem. In order to analyze and evaluate the stability of the excavation of 3D spherical cavity, by invoking the finite difference approximation of the equilibrium and compatibility equations, the distributions of displacement and stress in the potential plastic zone which is divided into a series of spherical shell can be obtained from the outmost shell for which the boundary is known to innermost of the spherical cavity in a successive manner. Linear strain-softening behavior is taken into account, and linear Mohr-Coulomb(H-C) criterion and nonlinear Hoek-Brown(H-B) yield criterion are employed respectively in the procedure. With the increment of the number of the spherical shell, a convergent numerical solution is gotten, and the presented procedure is validated through case studies. On the basis of it, a set of strength parameters which obey cohesion weakening and frictional strengthening law(CWFS model) is studied and the corresponding solution is analyzed. Comparisons of the results from CWFS model and the normal strain-softening model are made and the results from CWFS model seem more reasonable.

Model ranges have important influence on calculation accuracy and efficiency in numerical simulation. According to the problem of numerical simulation of deep tunnel excavation, the model longitudinal range value is investigated with the finite difference software FLAC3D and the compound failure criterion. First, the general law of deformation of surrounding rock in longitudinal direction and the influence of unexcavated rock plug on the deformation of surrounding rock in deep tunnel excavation is analyzed. Further, the influence of the proximal and the remote boundary on the deformation of surrounding rock at monitoring section is yielded by the error analysis with the Least Square Method, to present the suggestions of the model longitudinal range. The results show that when the distance between the tunnel front and the monitoring section is more than 10 times tunnel diameter, the constraint of unexcavated rock plug on the deformation of surrounding rock can be ignored. The remote boundary distance, as well as the proximal boundary distance, has a power function relationship with the maximum numerical error of the displacement. Moreover, the remote boundary distance has greater influence on the numerical error of the deformation than the proximal boundary. When the longitudinal range of model is not less than 7.5 times tunnel diameter for the deep tunnel excavation simulations, the accuracy of general numerical simulation will be satisfied.

In order to analyze the influence of geostress on the stability of karst cave, a geostress model was developed based on the geostress database in China and the geostress formula in the research region. In-situ measurement was executed to bridge the gap between the geostress model and the engineering application. For the convince of evaluating the magnitude of shear stress and plastic zone, the karst cave was modeled through the finite difference software with applications of the geostress model and Hoek-Brown yield criterion. Special attention is paid to the stability evaluation of the karst cave under various geostress conditions during modelling. Several beneficial consequences obtained from the evaluation suggest that the role of the geostress condition is quite important in influencing the stability of karst cave. The geostress is decomposed into the mean stress and the shear stress for the sake of exploring its explicit influcement. An empirical equation was summarized via regression analysis to explicitly depict the approximately linear relationship between the ratio between the mean stress and the shear stress and the capability of karst cave. An in-situ investigation considering the collapse site and the ultimate subgrade height was conducted to compare with the numerical results. The results suggest that a reasonable consideration of geostress is necessary for evaluating the stability of karst cave.

The selection of particles’ parameters is of vital importance to simulate rock cutting by the tunnel boring machine(TBM）. The parallel bond shear/tensile strengths between particles, in particular, their ratio is one of the key controlling parameter, which directly determines the ductility or brittleness of the specimen and influences the process and the cutting result. In order to explore the effects of ductility brittleness on rock cutting, this paper conducts the following researches: (1) Creating 9 numerical models by applying different parallel bond strength ratios, and simulating uniaxial compression test and Brazilian tensile test respectively so as to examine the macromechanical behavior and failure mode of every model with different ductility-brittleness. (2) Making double-cutter rock cutting simulation on the nine models above, and monitoring every model’s crack propagation and cutter force condition. (3) To reduce the impact of randomness on the simulation results, making five repetitive simulations for every model by changing random seeds and analyzing the computation of five results comprehensively. Through these simulation researches above, it is discovered that as the ratio of shear bond strength to tensile bond strength( ) grows, brittleness increases and the failure mode of rock samples changes gradually from shear failure to brittle tension failure; and the crushed zone of cutter rock breakage reduces and the tension cracks are more likely to extend between cutters, thereby producing larger bulks of rock pieces. As the brittleness of the model increases, the normalized specific energy decreases and the efficiency of the rock cutting increases. With the same bond strength radio, by applying different random numbers, the specific failure condition of every model is somewhat different; but the overall failure mode is comparable.

Post-cyclic undrained strength degradation happens to the saturated soft clay under wave cyclic loading for the excess pore pressure produced, resulting in the significant loss of bearing capacity of the breakwater. Based on the development model of pore pressure and the rule of shear strength of normally consolidation soft clay, the dynamic degradation law of soft clay strength is derived considering the effect of initial static deviator stress. Based on the dynamic degradation law and Mohr-Coulomb yield strength, the numerical development and dynamic calculation process for post-cyclic undrained strength degradation is implemented into software ABAQUS. Numerical simulations of the dynamic and static triaxial tests of Tianjin soft clay are conducted using the proposed dynamic finite element method. Results show that the development curve of maximum excess pore pressure and values of post-cyclic undrained strength predicted by the finite element method are acceptable compared with tests. Moreover, the proposed method can predict the process of post-cyclic strength degradation.

EPR nuclear power plant circulation water pump house(HPX) which is the seismic 1 item supplies water for circulating cooling water (CRF) system. So the influence of heterogeneity is particularly important in the site foundation. Based on the actual conditions of a domestic nuclear power plant site, a three dimensional finite element model of the pump house foundation is established by ANSYS platform. And the mechanical properties and spatial distribution pattern of xenoliths are simulated in detail. The static and dynamic time history analysis method is proposed based on Newmark method. This method can be used to comprehensively evaluate the vertical deformation of the foundation, bearing capacity, the base of the bottom surface rate, anti-sliding and anti-overturning stability, etc. The results of analysis show that, in the distribution of the site under practical, the existence of xenoliths has a little influence on the safety of pumping house foundation. Part compressive stress out of specification has no influence on overall stability. The foundation does not need to be processed because the index of the evaluation can meet the requirements of the specification. At the same time, the calculated results also verify reliability and good engineering applicability of the Static-Dynamic coupling analysis model. The model has the potential to solve the nonlinear dynamic problem of the complex nuclear power structure, with the combination of the ANSYS which has rich unit model and the capacity of nonlinear analysis.

3D numerical model construction of real geological body is the challenge faced by numerical analysis in rock mass engineering, resulting in that the comparative study between different constructing methods of 3D numerical models of large and complex geological body has great significance. Based on 3DMine digital model, the coupling modeling methods of 3DMine-FLAC3D and 3DMine-Surfer-Rhino-ANSYS-FLAC3D are put forward; and then the concrete steps of every modeling method are described in detail. Besides, the advantages, disadvantages and applicability of every modeling method are further analyzed. Through contrasting the advantages and short boards between each modeling method and learning from each other, the defects that exist in coupling modeling method of 3DMine-FLAC3D are improved; and the constructing problem of 3D numerical model of complex geologic body is solved as well. With the background of zinc-polymetallic ore body in Guangxi Tongkeng Mine, the 3D numerical modeling method of large and complex geologic body is utilized to construct the 3D numerical model of zinc-polymetallic mine and analyze the surface subsidence law for ascending mining. Research achievements play an important guiding role in accurately constructing the 3D numerical model of large and complex geological body.

Crack propagation caused by vibration of lithosome is a common concern in the fields of subgrade, bridge, vibration construction and earthquake prevention etc. Through combining the home-made inertia loading device with the platform of vibration, we implement 12 groups of vibration loading experiments on similar rock plates with penetrating cracks, observing the propagation and coalescence mechanism. Moreover, we establish the corresponding model in PFC software to analyze mechanism of crack propagation further. The results show that the phase difference of vibration deformation in different regions promotes the crack propagation behavior. The dipping angle between the direction of vibration and the initial propagating direction of notches is a little bit small, within the scope of ±10 degrees. Besides, in the direction of vibration, the notch is easier to propagate; while the couple of notch-middle fracture is prone to coalesce. The frequency of crack collapse shows positively correlative to the crack spacing. With the increase of the dipping angle between the crack inclination angle and the vibration direction, crack propagation becomes more and more difficult; and it’s the most hardly when the crack is perpendicular to the vibration direction. The same as what in static process, the path of crack propagation by vibration is the nearest route, which is consistent with the minimum energy principle.

The maximum excavation depth of one foundation pit in Henan Province is 5.8 m, the fields are mainly composed of saturated mucky silty clay, the minimum distance between the foundation pit and surrounding existing buildings is only 1.2 m, and I-steel cement soil mixing walls and prestressed bit expanded anchor are adopted to support the foundation pit. PLAXIS finite element software is used to numerical simulate the foundation pit supporting structure, and soil displacement, axial force and bending moment of I-steel cement soil mixing wall, anchoring force of prestressed bit expanded anchor and total multiplier are simulated and calculated. Some conclusions are drawn as follows: the simulated horizontal displacements of soils are near to the monitored data, which verified the rationality of FEM model of I-steel soil cement mixing wall; the deformation characteristics of structures and soils during the excavation of foundation pit are simulated reliably with the PLAXIS software, and PLAXIS is one appropriate method to simulate foundation pit engineering; the simulated and monitored horizontal displacements of soils, axial force of anchors, multiplier with strength reduction method during the excavation stages all meet with the requirement of foundation pit design; and so I-steel cement soil mixing wall is proved to be feasible for the foundation pit supporting engineering, so as to provide references for the similar engineering.

Cluster element in particle flow code (PFC2D) is used to construct numerical specimen in light of the large internal friction angle and brittleness at post-peak stage of tested sandstone. A set of micro-parameters that can reproduce the macromechanical behavior of sandstone were calibrated through comparing with the experimental results under triaxial compression. Then two different radial unloading paths are simulated. The numerically simulated results show that the peak strength increases with the increasing of initial axial stress, and has a similar trend with the experimental results. The evolution characteristic of microcrack numbers under two radial unloading paths is analyzed. The damage extent under radial unloading is more serious than that under axial loading. Furthermore, the ability to withstand damage enhance with the increasing of initial axial stress. From the analysis of displacement field under different loading paths, it is clear that sandstone fails due to the discontinuity of displacement.

The decrease of pile’s skin friction of super-long pile is a common phenomenon. In this study, a new hyperbolic load transfer model which includes the stage of decrease of pile’s skin friction is proposed. The characteristics of nonlinear and decrease of the interaction of pile and soil is fully considered in this model. Furthermore, a UMAT subprogram is compiled in FORTRAN on the basis of the new model. Based on a history case, a comparison among situ data, the results calculated by the origin contact analysis in ABAQUS and the results adopting the procedure developed in this paper. It is shown that, the curves of Q-s relationship of pile’s top, the distribution of pile’s skin friction and the relationship of pile’s skin friction versus pile-soil relative movement are more consistent with field test data. It is proved that by adopting the load transfer model in this paper, the nonlinear characteristic and decrease of pile’s skin friction is well simulated of the interaction of pile and soil. Also, the estimation of the capacity of the pile is more reliable.

Ground settlement monitoring is an important component of shield informatization construction, and it has a very important significance in optimization of shield tunneling parameters and safety of construction. In order to share and feedback monitoring results timely, improve efficiency of monitoring information management and data analysis, an automatic monitoring and mobile data publishing system of ground settlement is developed by using Microsoft Visual Studio. Net programming technology and MySQL database to realize 24 hour automatic acquiring, analysis and mobile publishing of monitoring data. And then the system is applied to the project of shield tunneling of Nanning Metro Line 1 traversing below tracks and buildings of Nanning Railway Station; the variation law of ground and track settlement caused by shield tunneling has been obtained. By the in-time feedback of monitoring data and analysis results, the construction parameters of shield machine is optimized so as to effectively ensure safety of shield tunneling and surrounding environment.