Fissure is one of the important characteristics of expansive soils. Shrinkage fissures induced by the wetting-drying cycle effects and the specific inherent fissures distributed in atmospheric influential depth of expansive soil are often confused. In the study of expansive soil slope failure mechanism, the significant impact of the inherent fissure on slope stability is often ignored. In order to study the failure mechanism of expansive soil in middle route of South-to-North Water Transfer Project, a 2.05 km test channel is constructed on the outskirts of Nanyang, Henan province. Geological survey, field observations and sampling tests during excavation, as well as on-site sampling and analysis of slope failure are conducted to study the material composition of expansive soil fissure and the density, water content and strength characteristics of the surrounding soil. Combined with field observations, the relationship between fissures and channel landslide is analyzed. It is shown that there are two types of inherent fissures for the expansive stratum: one is smooth waxy fissure; and the other is filling clay fissure with a certain thickness. The material composition of the fissure surface is slightly different with the adjacent soil, featured by low natural density and high moisture content; and the intensity is much less than the strength of the adjacent soil. Once the formation is consistent with the slope tendency, it would slide along the fissure surface.

Calcareous sands are consisted of marine biogenic granular materials with carbonate content often greater than 50%. From the microscopic viewpoint, calcareous sand grains demonstrate highly angular and irregular in shapes and contain intra-pores. This unique intra-pore structure of calcareous sand particle is prone to crush under stress. Therefore, the calcareous sand has a relatively low strength. The intra-pore structure has a significant effect on the geotechnical properties of calcareous sands. Calcareous sand samples from the lagoon of Yongshu Reef atoll, Nansha Islands, were cut by femtosecond laser for the optical microscopic studies. The intra-pore structures were quantitatively analyzed throughout the MATLAB digital image process tool. The results indicate that, larger porosity can be found on the breakage section of larger size calcareous sand and a larger number of small pores with small total volume are in the intra-pore structure. For sand grains with a size greater than one millimeter, the number of slit shape intra-pores is far less than the number of intra-voids with equiaxed or unequal axed pores. The amount of the equiaxed and unequal axed pores are approximately the same.

The effects of water-saturation (WS) and water-loss (WL) on bank-slope became obvious over a period of time as reservoir water level fluctuated cyclically when the Three Gorges reservoir became operational in 2003. According to the natural processes of WS and WL during 2005-2009, purple soil samples were collected from the Shiliushubao landslide of Three Gorges to determine chemical and mineral compositions by full quantitative analysis of soil samples and mineral composition analysis of soil samples, and to observe microstructure of samples by soil samples electron microscopy. The impact of water-rock interaction on bank-slope soil and its mechanical law were analyzed during the processes of WS and WL. The study results show that the effects of WS and WL processes on the chemical and mineral compositions of soils from different elevations of the slope are different; soil from higher elevation (172 m) of landslide is impacted more heavily. After the WS and WL processes, the contents of SO2, Al2O3 and Na2O in soil increase while CaO and loss on ignition (LOI) in soil decrease. With the variations of chemical compositions contents, the microstructure of soil changes from dense plaque structure to random flocculation structure; and it is a huge impact on the mechanical effects of bank-slope.

The open pit slope stability is one of the main problems for the safe production of coal mine project. It has become the main factor of production in coal mine. Taking working face 29211 of Anjialing open pit for example, the impact of underground mining on deformation and rupture process of open pit slope is analyzed by similar material model test. Similar model tests results show that the “arch” structure formed by overburden deformation leads to a great horizontal displacement toward the free surface of slope; and it also results in varying degrees of tensile failure. When working face 29211 advancing to reasonable stopping line 2, local cracks appear in the slope rock mass. The clacks gradually run through and extend to the bottom of the slope when advancing to design stopping line. So, reasonable stopping line 2 is suitable for the location of the stop mining. The above of working face 29211 is the biggest settlement; and the maximum amount of subsidence is about 8 m. The slope which includes through cracks has an extruded trend. The results provide theoretical guidances for safety of open pit exploitation.

The postliquefaction undrained shear strength of low-plasticity silt from Mississippi River Valley in Central America was studied after the silt experienced reconsolidation. It is found that postliquefaction undrained shear strength of the normally consolidated silt increases with an increase in reconsolidation level; and apparent overconsolidation phenomenon is shown in the silt. Similar to the silt without previous cyclic loading, normalized ratio of undrained shear strength for postliquefaction specimens Su,OC/Su, NC with complete reconsolidation has a power function with overconsolidation ratio OCR; but the power exponent for postliquefaction silt is a little higher than that for the silt without previous cyclic loading. With an increase in OCR, the reconsolidation induced change of undrained shear strength ?Su, recon increases first and then decreases; and then it reaches the peak when the OCR is 3.42. The postliquefaction silt with reconsolidation does not have quasi-steady state during undrained shearing; and deviator stress keeps increasing with an increase in axial strain until the silt reached critical state. In addition, the stress-strain curves of postliquefaction silt with complete reconsolidation can be normalized by effective consolidation pressure ? ′c. Finally, an equation is proposed to calculate undrained shear strength of postliquefaction low-plasticity silt with complete reconsolidation.

To expose the deterioration rule of cemented soil eroded by sewage, soaking the cemented soil blocks made of two types of cement (ordinary Portland cement, slag Portland cement) and silty clay in three different solutions (tap water, domestic sewage and industrial sewage), the laboratory experiments were conducted. First, the effect of sewage on liquid-plastic limit of soil was described. Second, the influence of curing age, cement type and sewage type on compressive strength and electrical resistivity of cemented soil were discussed. Then, the relationship between electrical resistivity of cemented soil and compressive strength was analyzed. The results show that: After contaminated by sewage, the liquid-plastic limit of soil increases; whereas the plasticity index decreases; the compressive strength and electrical resistivity increase with increasing curing age; the sewage reduces the compressive strength and the resistivity of the cemented soil; however, the compressive strength and electrical resistivity of slag Portland cemented soil are higher than that of the ordinary Portland cemented soil; therefore slag Portland cement can improve the ability of resistance to degradation. Under different curing ages, no matter what type of cement and sewage, the electrical resistivity and compressive strength of the cemented soil vary follow the same rule. The relationship between electrical resistivity and compressive strength is linear.

The uniaxial compression failure mechanism of jointed rock mass with cross-cracks was studied through similar material uniaxial compression tests and numerical computation with Abaqus. The study results show that when the angle between the main crack and loading direction is at 35° or 45°, the main crack is the key crack of crack propagation and rock mass failure. At these cases the strength of rock mass with cross-cracks is higher than that of rock mass with single crack. The reason is that the maximum hoop stress σθmax of main crack tip is less than that of single crack. When the angle between the main crack and loading direction is at 0° or 90°, the secondary crack is the key crack of crack propagation and rock mass failure. When the angle between the main crack and loading direction is at 0°, the maximum hoop stress σθmax and the maximum stress intensity factor KⅡmax of most secondary cracks are higher than those of single crack. So at these cases the strength of rock mass with cross-cracks is lower than that of rock mass with single crack. The KⅡmax of the case with 45° between main crack and secondary crack is the maximum stress intensity factor in those cases that the angle between the main crack and loading direction is at 90°. So the strength of rock mass with 45° between main crack and secondary crack is the lowest one in this case group.

The field tests of 46 uplift-loaded belled piers were carried out at 7 gobi gravel sites in Gansu and Xinjiang, respectively. Based on the characteristics of the measured load-displacement curves, the L1-L2 method was used to obtain the ultimate bearing capacities and corresponding displacements. In addition, a normalized hyperbolic equation was applied to fit the measured load-displacement data. Accordingly, the fitting parameters of hyperbolic curve were provided and analyzed. A method was suggested for determining the allowable displacement and corresponding load by considering the uncertainties in the ultimate capacity model and the normalized load-displacement hyperbolic model. The uplift load-displacement curves of belled piers in gobi could be simplified to a generic load-displacement curve with three distinct stages: an initial linear stage, a nonlinear transition stage, and a final linear failure stage. The normalized load-displacement hyperbolic equation could be used effectively to fit the measured load-displacement data. The uncertainty in the normalized load-displacement hyperbolic curve could be studied by the corresponding fitting parameters of hyperbolic curve. The method to determine the allowable displacement and corresponding load would be more safety by considering capacity and displacement together.

A study of the effect of particle size on mechanical behavior of granular materials is reported, by conducting a series of direct shear tests on a special granular material-glass bead. In this investigation, three approximately parallel grading curves are taken into consideration; and also four types of inter-particle friction conditions are concerned, including dry state, water-lubricated state, flooded state and oil-lubricated state. The test results indicate that particle size exerts a pronounced effect on mechanical behaviors of granular materials and that dilatancy is enhanced with the increase of particle size. On the basis of test results, a stress-dilatancy relationship is brought forward to appropriately take into account the effect of particle size on the dilatancy of granular materials. The dilatancy coefficient in this proposed relationship is revealed to be a variable dependent on particle size, inter-particle friction and other basic particle attributes. In the meantime the critical state friction angle is found to increase with the increasing particle size. In addition, an energy-work model of particle sliding behavior is proposed from a perspective of mesoscopic particle motions. Based on this proposed model, the energy-work equation is derived and the essential mesoscopic mechanisms underlying the effect of particle size on critical state friction angle are accordingly elaborated.

The soil-water characteristic curve (SWCC) is defined as the relationship between the suction and the water content or degree of saturation. The soil-water characteristics and related mathematical models can be used to model the unsaturated soil properties such as the permeability and the shear strength. Conventionally, only the drying soil-water characteristic curve of soil is determined. In this work, the influences of initial water content, initial dry density, the vertical stress and drying and wetting cycles are examined and discussed in detail. The SWCCs and hysteresis loops of residual soils in Xiamen were obtained by the filter paper method. The results show that the initial water content has negligible effect on SWCCs. The specimen at the wet of optimum moisture content (OMC) has the higher air entry value and the larger hysteresis loop than that of the soil specimen at the dry of OMC. The specimen with OMC lies between them. While, the initial dry density has considerable influence on SWCCs. The specimen at lower initial dry density exhibits smaller air entry value and higher rate of desorption than that of the specimen at higher initial dry density. The size of hysteresis loop decreases as the initial dry density increases. The specimens subjected to different vertical stresses have different SWCCs. The higher the applied load on the specimen, the higher the air entry value, the higher the rate of desorption, the smaller the size of hysteresis loop. In the drying and wetting process, the size of hysteresis loop has been substantially affected by the first drying and wetting cycle. With the increasing of drying and wetting cycle, the air entry value and the size of hysteresis hoop decrease. Since the features of soil-water characteristic of sandy clay are not well defined especially for the residual state of saturation, which desaturates continuously without a distinct break point, the residual suction or residual water content, one of the key parameters in the mathematical models of SWCC, is not well defined. As a result five improved models without the residual water content are proposed to describe the SWCCs of residual soil. The improved Gardner model has been found to be the most suitable model for all SWCCs of the residual sandy clay in Xiamen.

Based on Tianjin marine soft clay, triaxial tests are carried out on the intact soil and remolded soil in different test conditions, such as consolidation pressure, stress path, loading rate, drainage condition. The structural damage is described by the relationship between stress ratio structural parameter and strain. The character of structural damage under different loading modes is studied. The results indicate that when the consolidation pressure is below structure yielding pressure, the initial structure and damage rate in the shearing stage are not influenced by consolidation pressure. When consolidation pressure is above structure yielding pressure, the initial structure and damage rate decrease with the increasing of consolidation pressure. When the direction angle of stress path ? is in the ranges of 0<? <?/2 and ?<? <3?/2, the damage rate increases with the increasing of angle ?. When the angle ? is in the ranges of ?/2<? <? and 3?/ 2<? <2?, the damage rate decreases with the increasing of the angle ?. In every ?/2 range, the amount of initial structure falls and rises when the angle ? increases. The initial structure and damage rate increase with the increasing of shearing rate. The initial structural and structural damage rate in drained shearing are larger than that of undrained shearing.

Combined with the pile foundation engineering constructed in loess slope for supporting super bridge, field experiments on two neighboring piles at the same slope region are conducted to investigate transmitted characteristics as well as distribution feature of axial force, skin friction and lateral earth pressure of both upslope side and downslope side under different vertical load cases. The test results show that load transmitting of pile foundation can be obviously classified into 3 regions. The first region covers from pile head to about the depth of three times pile diameter; within this region, the axial force developed in pile upslope side is less than corresponding position at downslope side; moreover, its decrease extent with pile depth and work efficiency of skin friction are greater than pile downslope side. The second region is within about pile depth of three times to ten times pile diameter, which shows a less axial force decrease extent with pile depth in upslope side and higher work efficiency of skin friction along downslope side at the same elevation. The third region starts from the pile depth of about ten times pile diameter and ends with pile tip. For pile body in this region, the difference of axial force and skin friction for two sides at the same elevation are insignificant; and the load from super region could be even and well-distributed transmitted downwards. For the special issue of uneven earth pressure of pile foundation installed in loess slope, certain reduction in some degree for vertical bearing capacity of pile design is conducted; and some necessary revision of the calculation formula is made. The acquired study results can provide a reference for other similar pile foundation.

Considering the problems of lacking sealing theory, poor effect and high cost of sealing material and unreasonable sealing length for hydraulic fracturing drilling sealing in mine, mechanical models of sealed drilling for hydraulic fracturing were established. Relationships between the maximum bearing capacity of sealing material and sealing material property, sealing length were obtained. The reasonable sealing lengths of hydraulic fracturing under the sealed conditions, drainage conditions and constructional conditions were analyzed; and the field experiments were conducted. The results show that sealing material property and sealing length are the main factors influencing the maximum bearing capacity of sealing material. The maximum bearing capacity of sealing material increases with the increase of the strength of sealing material, the elasticity modulus and the sealing length. However, when the sealing length reaches a certain value, the maximum bearing capacity of sealing material verges to a constant value along with the increase of the sealing length. Taking Chongqing Songzao mine area as an example, the reasonable sealing length of crossing boreholes for hydraulic fracturing is considered to be 10 m; and the reasonable sealing length of coal seam boreholes for hydraulic fracturing is considered to be 13 m. The results of field experiment and the theoretical analysis are virtually consistent.

Taking a rigid retaining wall with cohesionless backfill for example, considering the soil arching, the active earth pressure factor is derived for retaining wall under translation mode with different internal friction angles and wall-soil friction angles. The Shubhra Geol parabolic soil arching expression is modified. Based on horizontal differential element method, new formulations are proposed for calculating the active earth pressure, the resultant earth pressure and its action point. In order to check the accuracy of the proposed formulation, the predictions from the equation are compared with the results of full-scale test and existing classical theory. The results show that the active earth pressure is related to wall-soil friction angle, the internal friction angle, the unit weight of backfill and the height of retaining wall. It is shown that the earth pressure is nonlinear and the previous research results show great agreement with each other; and the correctness of the results is verified.

A large-scale shaking table model test is conducted to study the dynamic behavior of entrance slope and its interaction with lining structure of mountain tunnel under earthquake loading. Test results show that the acceleration response of tunnel entrance slope exhibits obvious amplification effect and surface effect along both vertical and axial directions. Significant nonlinear behavior is observed when the earthquake loading amplitude is larger than 0.6g; and after that, amplification factor decreases with the increase of input loading amplitude and additionally the distribution of acceleration becomes more even in the slope body. It is also found that the dynamic response along axial direction of entrance slope does not affect much by existence of tunnel structure; thus it could be evaluated by treating the entrance slope as a natural slope for simplification. On the other hand, however, the potential instability of entrance slope has much influence on the safety of tunnel structure. When the loading amplitude is relatively small, internal force induced by vertical acceleration is larger than that caused by horizontal acceleration. As the loading amplitude becomes larger, the horizontal component of earthquake plays a dominant role in affecting the lining structure. The failure surface is located at the upper part of entrance slope, especially on the shoulder. The failure process could be described as five steps: (1) earthquake excited; (2) slope shoulder cracked due to tensile failure; (3) the cracked rock of shoulder toppled and collapsed downwards; (4) the collapsed rock fell along the slope and crushed to debris; (5) rock debris accumulated at the slope toe. The experimental result provides valuable basis and guidance for analysis, calculation and design of mountain tunnel portal.

Based on the actual condition of engineering, the finite element analysis software PLAXIS is adopted to simulate two different asymmetric excavation conditions of the foundation pit: (1) different excavation depth differences, (2) different excavation interface places. Based on study of practical engineering simulation, with the increase of the excavation depth difference, surface settlement on the two sides both increase; settlement value and effect range on the deep side are also larger than the shallow side. Meanwhile, there is a large diversity deformation of bottom heave on the interface; the deformation difference becomes obvious with the increase of excavation depth difference. With the interface movement to the shallow side, the bottom heave on the deep side tends to be stable; and the variation tendency of the bottom heave increases to the shallow side. Through research, there is a better understanding of characteristic and negative factor of stress and deformation on asymmetric excavation pit, which can guide the construction and control excavation depth difference and interface location of asymmetric excavation, then reduce the engineering risk.

Usually water drainage in saturated sandy soil site occurs when a shock takes place. A similar phenomenon happens in pile driving and in vibroflotation for ground treatment. However, at present the simulation of water drainage cannot be performed in the context of conventional soil dynamics. Based on the Green functions in the frequency domain in the axisymmetric coordinates for a poroelastic medium, combining Lamb integral representation in drainage condition, equations for drainage of piles in saturated soils are performed. This paper reveals the comparative results of computational drainage and measured drainage at a project site in Jintan city, Jiangsu province, where some piles are driven. The expected value of average measured drainage is 4.82 L. The relative error between measured and computed drainages is 34%. Hence, the proposed method for drainage of pile in saturated soil is suitable in the view of conventional dynamic soil mechanics. And it may benefit further research on dynamic property of a pile driving in the saturated soil. The computation is under the pile-soil elastic system, without considering the nonlinear deformation of soil. So it needs further study to make it more realistic.

Based on a dam foundation engineering in Fujuan province, single-hole acoustic test, cross-hole acoustic test and seismic wave test were carried out to detect the P-wave velocity of dam foundation rock mass before and after consolidation grouting. The elastic theory was used to calculate dynamic elastic modulus; and the change of deformation parameters before and after consolidation grouting were studied. A modified Hoek-Brown criterion was proposed to calculate the parameters in Hoek-Brown criterion. The results show that the consolidation grouting effect is controlled by the groutability of rock mass and effected by the rock mass structure. The consolidation grouting effects in different directions are different. For strongly weathered rocks, the consolidation grouting effect in vertical direction is better than that in horizontal direction. For medium weathered rocks with gently dipping discontinuous faces, the consolidation grouting effect in horizontal direction is better than that in vertical direction. The functional relationship between the increasing rate of dynamic elastic modulus and the increasing rate of velocity is quadratic. The functional relationship between the increasing rates of m, s (where m is Hoek-Brown parameter, s is parameter related to quality of rock mass) and the increasing rate of velocity for strongly weathered rocks are both linear and for medium weathered rocks are both cubic. It is of important significance for design and construction of grouting.

A simplified reliability and risk analysis method of foundation bearing capacity based on combined coefficients of variation of random variables is proposed using first order second moment technique. The laboratory results and historical published ones of coefficients of variation are taken into consideration as the combined coefficients of variation, which are adopted as the calculated coefficients of variation. The most likely values and their possible ranges of degrees of reliability, probabilities of failure and average expected losses can be obtained using suitable coefficients of variation besides the conventional deterministic analysis. This enables to make optimal design scheme and engineering decision. It has shown that the degrees of reliability of foundation bearing capacity are more sensitive to the internal friction angle compared with the unit weight and the cohesion. The width or area of foundation can be decided upon in terms of the required factor of safety, degree of reliability and probability of failure. Moreover, the combined coefficients of variation of random variables will gradually decrease with the weights increasing of coefficients of variation based on the in-situ investigation results; the corresponding degrees of reliability will increase and the probabilities of failure decrease due to that decrease of combined coefficients of variation.

Zonal disintergration phenomenon will appear after excavation in deep high stress roadway; and its stability is not very good according to the original control design. According to the on-site monitoring results of the surrounding rock deformation, through theoretical analysis and supporting test, a new bolting and grouting integrated control method is proposed. The new method includes six important issues: improving normal constraints, toughening crack arrest of bolt, coordinating of coupling support, transferring stress into internal, filling grouting of the partition, enhancing rock strength. The corresponding integrated support technology is also proposed. Firstly, high strength and high pre-tightening force bolts are used to support surrounding rock in time. The length and number of bolts is determined by the results of monitoring and partition support energy criterion respectively. Secondly, the pressure relief high-strength anchor-beam coupling support system is used to support the roof of roadway; and surrounding rock deformation compatibility is achieved and stress is transformed internally. Finally, a hollow segmented spiral delayed grouting technology is used to reinforce the cracked surrounding rock of zonal disintegration. According to above bolting and grouting integrated control method and techniques, the roadway support is designed optimizedly and applied to site tests. The monitoring results show the roadway is in stable condition.

The current researches on bolt anchoring effect are rarely concerned with self-bearing characteristics of whole anchorage surrounding rock. For its sensitive response to mechanical changes of surrounding rock bearing structures, tangential stress ?? curve with different bolt lengths and different bolt strengths is researched, which can provide important references to research the bolt anchoring effect. The ?? curve shape of whole anchorage roadway is related to the anchorage end position in elastic and plastic surrounding rock. When bolt anchorage end is located in the plastic zone of surrounding rock, the peak value and its corresponding position of ?? curve are slightly influenced. With the increasing of bolt anchorage end depth in the elastic zone, distribution curve of ?? will have internal and external peak values from the surface to the depth of anchorage surrounding rock gradually; and its alternative elastic and plastic zones gradually appear. And bolt strength should match the self-bearing strength of surrounding rock. Accordingly, a new method to determine the bolt anchoring effect based on the double peak values of ?? curve of anchorage surrounding rock is put forward, which can well explain the problems of canceling the systematic anchor bolts in weak strata.

In order to achieve predicting the surface subsidence caused by solid compacted backfilling mining scientifically, it is necessary to establish the completed prediction model and its parameter system according to the evolvement rule of the structure form and movement characteristics of overburden rock. By means of similar material simulation and borehole peep, it is shown that overburden rock of mining with solid compacted backfilling is given priority to sagging zone, which appears complete layer structure, only develops some height of the fault zone near the roof strata, but not caving. The strata movement characteristic is similar to bending deformation of the laminated plates under the longitudinal loading, after a simplified mechanics. Based on the theory of laminated plates, surface subsidence prediction model of mining with solid compacted backfilling is established. It is shown that surface subsidence form of mining with solid compacted backfilling is still suitably described with probability integral model; and further discuss on parameters system of the surface subsidence prediction mode based on “equivalent mining thick” theory is carried out. Finally, the surface subsidence prediction model is applied to a real project, which obtains a good effect.

Slope is a system with visible uncertainty, illegibility and time-varying characteristics. Safety factor and reliability theory have both advantages and disadvantages in slope stability evaluation. Dual index system is a slope stability comprehensive evaluation system which is established based on a specified index (safe factor) and an uncertain index (reliability). It has both benefits of the indices, and important theory significance and practical value. Considering the interval distribution of material indices and the stable slope's safety factor cannot be less than the critical value, the pure mathematics model is modified. A more realistic dual index system of slope stability is proposed. At the same time, the Monte Carlo simulation method is selected. The dual index system is blent in GeoStudio software. With the help of the powerful computing ability of GeoStudio, a complete and efficient dual index analysis method of slope stability is formed. This method has been applied to analyzing stability of a slope of granite residual soil deposits under rainfall condition. And then some useful conclusions are drawn. It is proved that the method is feasible and efficient.

Based on the observed data of the creep deformation of surrounding rock and creep constitutive model for weak rock mass, back analysis of elastoplastic parameters of surrounding rock for roadway in mudstone is done. The rock mechanical parameters are obtained by back analysis; the obtained elastic modulus is 2.0 GPa; cohesive force is 1.31 MPa and angle of internal friction is 24º. The range analysis results for the mean values of inversion parameters show that the size of the range can be used to judge the sensitivity of rock mechanical parameters. For the creep character, cohesive force is the first influence factor; the second one is the angle of internal friction and the third one is the elastic modulus. Then, deformation of the surrounding rock is calculated using the basic mechanical parameters obtained by back analysis; the creep displacement increment in each observed point is calculated; and they are in good agreement with the measured values. These results show that the actual situation of roadway is reflected by the deduced rock mechanical parameters. Finally, the displacements and plastic zone range of roadway are predicted.

Blasting vibration characteristics of shallow tunnel under-passing hillside buildings in short-distance were investigated. Based on the engineering background of New Hongyan tunnel of Chengdu-Chongqing High-speed Railway, the vibration characteristics of tunnel blasting were measured. Then by analyzing the results of ground vibration on shallow buried side (the lower part of slope) and deep buried side (the upper part of slope), the characteristics of vibration velocity, principal vibration frequency and safety assessment method were discussed. In the blasting near zone of shallow tunnel, the incident p-wave is the primary wave. Moreover, the major components of the horizontal and vertical ground vibrations can be considered as the projection of the incident p-wave in both horizontal and vertical directions. Besides, the ground vertical and horizontal velocities in shallow and deep buried sides have relationship with the distance from explosive source to measurement points and the angle between the incident p-wave and the vertical direction. Compared with applying non-electronic detonators for the tunnel blasting, using digital detonators one by one can effectively reduce the ground vibration strength and improve the ground vibration principal frequency. In addition, the ground vertical principal vibration frequencies are generally higher than the horizontal principal vibration frequencies. Furthermore, the ground vertical and horizontal principal vibration frequencies of the shallow side are higher than the corresponding directions principal frequencies of the deep buried side. With respect to shallow tunnel under-passing hillside buildings in short-distance, the blasting vibration characteristics should be measured in the deep and shallow buried sides simultaneously. The safety of structures nearby can be assured by judging the vibration velocity and the relationship between the principal vibration frequencies of the deep and shallow buried sides of tunnel and buildings simultaneously.

Starting-elastic-impulsive acceleration mechanism of high-speed rockslide is the foundation of carrying out the research of full course dynamics mechanism of high-speed rockslide. The starting-elastic-impulsive acceleration mechanism of high-speed rockslide is systematically expounded and attributed to two acceleration effects of energy release of sliding zone and energy release of locking block. In order to explore the releasing law of elastic strain energy in rock, cyclic loading and unloading tests of rock are carried out. Meanwhile, the results are applied to calculate the releasable elastic energy for determining elastic-impulsive velocity. Considering the problems in determining the elastic-impulsive velocity in current methods, a new formula for calculating starting-elastic-impulsive velocity is deduced based on the constitutive equation of the sliding zone and the releasing law of elastic strain energy in rock. Jiweishan rockslide is studied using this new method. The results show that starting kinetic energy is mainly provided by the elastic energy of sliding zone rather than the elastic energy of locking block. The total starting-elastic-impulsive velocity of Jiweishan rockslide is 1.261 1 m/s. Finally, the extreme velocity ranges from 2.6 to 4.4 m/s obtained by a generalized sliding model.

Conducting the advanced surrounding rock classification is a necessary working in the process of tunnel construction, which is directly related to subsequent excavation and supporting construction scheme. In order to conduct surrounding rock classification ahead tunnel advancing effectively, the advanced surrounding rock classification method based on digital drilling technology and quantum genetic algorithm (QGA)-radical basis function (RBF) neural network is put forward. The method extracts useful information from the drilling parameters; and it establishes the indicators system of advanced surrounding rock classification. In the progress of establishing advanced surrounding rock classification index system based on QGA-RBF neural network, the genetic algorithm are improved by quantum calculation principle; and the parameters of RBF neural network could be determined by quantum bit and rotation gate renew population. Finally, the method is applied to the subsea tunnel across Qingdao Jiaozhou bay engineering. The results show that the method has higher prediction accuracy and provides a new idea in advanced prediction of surrounding rock classification.

For the piles beneath deep excavations, the distribution of pile shaft resistance is different from that under conventional condition. Based on the field tests and numerical simulation of super-long bored piles, theoretical analysis is conducted to investigate the different settlement behaviors caused by the shaft resistance distributions under both conventional and excavation conditions. The results show that due to the low tip resistance of the super-long pile under working load, the comprehensive coefficients of pile compression depend on the distributions of shaft resistance. The comprehensive coefficients of pile compression recommended in the current code are reasonable for super-long bored pile under conventional condition. However, it is found that the comprehensive coefficient of pile compression under excavation condition is 20% larger than the recommended value in the current code. Therefore, the settlement of pile may be underestimated without considering excavation effect. Furthermore, for the pile under deep excavation condition, the comprehensive coefficient of pile compression decreases with the increase of the slenderness ratio l/d; while for the pile under conventional condition, there is no direct relation between the comprehensive coefficient of pile compression and the slenderness ration.

The combination of soil nails and stabilization piles (CSNSP) has been widely used as a reinforcing technique to retain excavations and stabilize slopes, but few relevant applications are found for high loess slope. Based on a high steep loess slope strengthened by CSNSP, the behavior of the strengthening system is investigated by field monitoring and finite element method. The results show that the lateral displacement, shear force and bending moment of piles increase gradually with the increment of excavation depth; and the displacement tends to be steady gradually. The location of the maximum shear force in the pile body shows a declining trend which indicates that the potential failure surface develops downwards. The distribution of soil pressure around piles in CSNSP system is compared with which appeared in deep foundation pit. The soil pressure on the back side of piles shows a trend of decrease with excavation while the soil pressure on the front side appears to be fluctuant. With the growth of excavation depth, the measured stress of the reinforced soil nails increases significantly, which indicates that the slope deformation is limited by the soil nails. The most dangerous rupture surface of the slope above piles appears to be a circular arc and the shear opening locates at the head of the piles. In addition, the proportion of soil nails to stability for the overall system is larger than the stabilization piles when the excavation depth is shallow, but the situation changes with the increment of the excavation depth.

Based on the strength theory of rock, a width reduction method for determining safety size of pillar is proposed in room and pillar mining. Through reducing pillar width gradually, the process of pillars from stable state to limit equilibrium state is studied; and the pillar critical width is obtained. Then the pillar safety width can be determined via introducing the pillar safety factor. By the width reduction method, the pillar safety width of Mofang mine No. 3 is studied to obtain the pillar safety widths in different spans. It is shown that the pillar safety width calculated by width reduction method is in good agreement with that by the Lunder theory through comparison; and the former is safer. According to the mining conditions of Mofang mine No. 3 and the results calculated by width reduction method, the pillar widths are determined to be from 5 m to 5.5 m, responding to the pillar span of 13 m. By monitoring the goafs overlaying strata of Mofang mine No. 3, it is found that the strata movement is relatively stable; the values of ground surface settlement are controlled in the range between 120 mm and 150 mm. To a certain extent, the fundamental parameters of room obtained by width reduction method are reasonable.

The governing equations of the propagation of shock waves in compressible fluid saturated deformable porous media are improved by the way the porosity gradient terms are treated in the flow flux vector. An updated space-time conservation element and solution element (CE/SE) method, which is a new approach in computational fluid dynamics (CFD), is presented to depict global and local flux conservation in space-time domain. The physical model and the CE/SE method are both validated with the experimental study based on the head-on collision of a planar shock wave through a rigid porous material; and then good agreements are found to be evident. After that, the two-dimensional Riemann problem in the porous media is established. It is found that the wave structures of the pore pressure consist of shock waves, compaction waves, expansion waves and the contact discontinuity. To our best knowledge, this is the first time that pore pressure waves have been successfully simulated with the CE/SE method inside a multiphase deformable porous medium. The findings are potentially applicable to CO2 geological storage, CO2 enhanced oil recovery, shale gas exploration and earthquake rupture processes.

In the conventional effective stress method of site seismic response analysis, the changes of small strain shear modulus Gmax are only with the effective stress and void ratio. While the latest experimental studies show that under large amplitude vibration, there exists additional attenuation of Gmax. 298 groups of Gmax data of different types of soil under large amplitude vibration are collected and analyzed, based on which the computational equations corresponding to two additional attenuation modes of Gmax are provided. A one-dimensional site seismic response analytical program has been compiled based on effective stress principle, to account for the influence of additional attenuation of Gmax. A typical example and a dynamic centrifuge model test of sand field are separately simulated using the compiled program. It turns out that, the additional attenuation of Gmax has influence on both the response of accelerations and shear stresses. Besides, it can speed up the liquefaction of site and expand the final liquefied range. Numerical simulation of the centrifuge model test shows that, the acceleration and pore pressure responses are in good agreement with the experimental results when considering additional attenuation of Gmax. However, in case of strong acceleration, liquefaction comes soon, and the influence of additional attenuation of Gmax on site dynamic response becomes weakened instead.

In order to simulate initiation and propagation of rock crack, Munjiza proposed FEM/DEM coupling analysis method. Because the cracks extend along the cell boundary, i.e. the propagation of crack has mesh-dependency problems. For the purpose of a better crack propagation shape, dense initial mesh is needed. To solve the above problems, the FEM/DEM adaptive analysis methods of local unit dynamic splitting is proposed to overcome mesh-dependency problems of crack morphology based on FEM/DEM coupling analysis method. However, very fine elements will not be necessary in this procedure; and dynamic splitting can take place in the local elements containing crack tips with increasing loading, which provides more possible expansion direction for subsequent expansion of the crack. Cracks are not confined along edges of elements. Cracks can grow in more natural way, which can be extended inside the element and more smoother. While original FEM/DEM coupling method divides very dense mesh, the proposed method can divide initial mesh relatively sparsely; so the cost of calculation is low. Finally, the numerical example of Brazilian disc indicates that the proposed method overcomes the dependence of crack morphology on the initial grid.

Based on granular mesomechanics, this paper sets up the relationship between the macro stress-strain and the mesoscopic quantities including the contact force, contact displacement and branch vector in granular materials. The method of improved Voronoi-Delaunay tessellation for granular materials in geometry and physics is further modified into two cell systems of Bagi. Taking solid cell systems as the basic elements, the average stress tensor that includes particle rotation vector and acceleration of gravity is derived based on Newton’s second law of motion and Gauss theorem. It avoids a static hypothesis. The average strain tensor expression including the void surface vector is derived based on the void cell with compatibility requirement. Two cell systems average equivalent stress-strain is correct combined with the literature of experimental resulting in two dimensions. Compared with two cell systems average equivalent strain and best fitting stress results under three dimensions, granular material stress-strain relationship based on the two cell systems is also validated. Therefore, the granular material stress-strain relationship of the two cell systems provides a theoretical basis for numerical simulation of mechanical properties of granular materials.

Based on the finite element method with a posterior error estimation and the Delaunay triangulation, an adaptive mesh scheme is set up to simulate the saturated sand behaviors when being compressed statically and when being liquefied during earthquakes. The bilinear recovered function, usually being used for quadrilateral elements in superconvergent patch recovery (SPR) error estimation, is confirmed to be available and reliable for triangular element mesh. In both the static and dynamic examples of saturated sand, the changing laws of deformation, strain, excess pore water pressure ratio, etc. due to the adaptive mesh calculation are maintained in the same trend as the normal finite element calculation. The displacement of the reference point is approaching to the exact value as the mesh is regenerated, so is the average relative error of the whole area. The suitable adaptation degree for an initial mesh is discussed and applied to the adaptive numerical simulation of the seismic liquefaction. Also, some improvement for the initial mesh is implemented in the Delaunay triangulation. This adaptive mesh scheme is proved to improve calculating efficiency, and to ensure the desired accuracy as well.

The anchoring effect of granular mixture is studied using the mesoscopic numerical simulation method. Three-dimensional polyhedral particles and their distributions are built based on stochastic simulation technology. With the stochastic granule discontinuous deformation model and the simulation of anchors, the numerical implementation of the bolted gravel experiment is realized. The macroscopic and mesoscopic mechanical performances of anchored granular material are analyzed. The impact of the anchor density and its relationship with the particle size on the mechanical properties of granular mixture is studied; and the anchorage mechanism of granular mixture is discussed. Samples with different anchor spacings and different particle sizes are generated. The simulated results show that the numerical anchored granular mixture experiment can well reflect the deformation and anchoring effect of the different anchored granular structures; and their macroscopic properties have some relationship with the evolution of mesoscopic fabric. The anchorage mechanism is that the compression zone is formed in granular mixture, and the contact forces between granular materials are reinforced by the squeeze effect. Granular structural integrity has been strengthened and the structure is able to withstand a certain load. Without considering the anchor length, when the anchor spacing is less than three times the average particle size of granular mixture, the anchors can effectively reinforce granular mixture and a stable structure can be formed.

In order to study the seismic response of shallow diversion tunnel considering sloshing amplitude of the water, an analytical model of tunnel-soil-fluid is proposed taking account of nonlinear material behavior of soil, viscoelastic artificial boundary, the effective rigidity ratios and fluid-solid coupling. Firstly, the hoop, radial and axial structural rigidities of tunnel lining are obtained by numerical rigidity reduction tests. Furthermore, the orthotropic material is used in tunnel lining model. As an application, the seismic responses of a project of large-diameter parallel diversion tunnels, which is one of the key projects in Shanghai, are calculated using the multi-material arbitrary Lagrangian-Eulerian (ALE) method. The equivalent density method is then used to validate the established simulation model. Finally, two seismic input modes, the uniform and nonuniform excitations, are involved in the seismic analyses of the tunnel-soil-fluid system. The numerical results show that under horizontal earthquake excitation the influence of fluid on tunnel's displacement is small; however, the influences of fluid on both stress and deformation of the section are great. The tunnel moment are always focused on the position of the tunnel 45° cross-hatched. Comparing with the uniform seismic input, the results show that the nonuniform excitation can remarkably increase both displacement and deformation responses of the tunnel.

In recent years, building a 3D geological model for water resources and hydropower projects has become a new useful method for geological workers to know layer structure and analyze geological phenomenon. Based on CATIA software, a 3D geological modeling platform is built using Visual Basic.net language, which contains several basic modules, such as overburden layer, geological layer, hydrological layer, model analysis, model cutting, finite element analyses, etc. Based on the 3D geological modeling platform developed by authors, the modeling process for overburden layer is proposed. Some key technology issues are analyzed in detail, such as original data processing, surfaces splitting and surface stitching. Besides, the platforms have the functions of quality testing and repairing work for building 3D geological model which guarantee the reliability of the model. At last, a 3D geological model is built using 3D modeling platform to simulate the geology for a hydropower station. 2D figures can be exported by cutting the model at any angle and anywhere in 3D space to satisfy the designing requirement in engineering.

An experimental apparatus for calibration chamber penetration test is designed. The device can fulfill the cone penetration test at any point on the chamber plane; and it can also accomplish the inclined cone penetration test with different inclined angles under the controlling penetration velocity. The apparatus is used to investigate the mechanical properties in the vertical cone penetration test for TJ-1 lunar soil simulant. The test results indicate: (1) The superficial layer of TJ-1 lunar soil simulant ground occurs shear failure. (2) The cone tip resistance increases with the increasing of penetration depth. (3) The horizontal earth pressure increases to maximum as the cone approaching to the soil earth cell and decreases to zero when passed by; the maximum value of each layer increases with the penetration depth; the horizontal earth pressure also appears axisymmetric property. (4) The vertical earth pressure under the penetration point increases with the penetration depth. It is shown that the design of calibration chamber is rational based on the experimental research. The study of mechanical property of TJ-1 lunar soil simulant is of great importance to the corresponding experiments related to such material.

In order to study the precision and reliability, when the global positioning system (GPS) precise point positioning (PPP) technology is used to monitor the deformation of landslide or other geological hazards, some monitoring points are set on the landslide body and GPS PPP technology is used to monitor the landslide with real-time combined a big physical model experiment of a kind of landslide. Through the processing and analysis of monitoring data of the landslide from stable condition, start sliding to breaking down, the monitoring results of GPS PPP, GPS single epoch differential positioning and carrier wave phase real-time kinematic positioning are contrasted. The results show that the internal accordant accuracy of GPS PPP technology can achieve about 10 mm and the external accordant accuracy can achieve about 40 mm. And GPS PPP technology also has some superiority which the differential GPS does not have, such as without base-station, low cost, high efficiency and can obtain the absolute coordinates of monitoring points under the international terrestrial reference frame. The GPS PPP technology can be used to monitor and forecast the dynamic deformation of landslide and other geological hazards.