The investigation on shear band of natural clay has always been main topic in geomechanics. In this paper, quantitative analysis was made on microstructure of the soil inside and outside shear band in Zhuhai clay by means of scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP). The results indicate that the stress-strain curves of Zhuhai clay show obviously strain-softening behavior at low confining pressures. In comparison with microstructural parameters of the intact samples, the change of microstructural papameters is maximal inside the shear band, then on the edge of shear band, and the outside is minimal. The orientation of particles on the edge of the shear band is parallel to the direction of the shear band, while the particles are generally random distributed inside the shear band, as a result of a significant breakage of the aggregates and the large particles. Distribution of particles is slightly affected in the area outside shear band by the shearing. In addition, the entrance pore size distribution of marine clay in Zhuhai demonstrates a continuous unimodal distribution, and its peak value and its corresponding pore radius decrease along the direction of outside, on the edge and inside shear band. Finally, the orientation of shear band predicted by the classical Mohr-Coulomb theory is generally consistent with the measured data, whereas the predictions by Roscoe theory and Arthur formula is significantly smaller than the experimental data.

In order to investigate the strain softening characteristics of geogrids under cyclic loading, the geogrids were researched using cyclic load-extension test under stress control. The test considered mechanical properties of geogrids at different cyclic tensions, pretensions and frequencies of cyclic loading; the influences of the dynamic strain and cyclic softening characteristics were studied emphatically for every factor. It is observed that the dynamic strain increases with the cyclic numbers, cyclic tension or pretension increases; the dynamic strain decreases with that the frequency becomes higher in same cyclic times. The softening index is reduced with the increases of cyclic numbers, cyclic tension or pretension; the softening index is reduced with that the frequency becomes higher in same cyclic times.

Tests of dynamic shear modulus and damping ratio of dam inverted filler are carried out by multi-function triaxial apparatus; and testing contrast analysis is made of the influencing factors. A comprehensive formula, which takes into consideration the consolidation stress ratio, void ratio and test grading curve, and can be used to calculate the maximum dynamic shear modulus, is proposed. The test and analysis results show that the influence of consolidation stress ratio can be fitted by power function, that of void ratio can be fitted by exponential function, and that of test grading curve can also be fitted by linear function with nonuniform coefficient Cu and curvature coefficient Cc. All kinds of influences affect the damping ratio. But the test results are in a narrow range, which means an average value can be used to calculate the damping ratio under different influences.

A new method to describe the behavior of consolidated-undrained compression of structured soils is presented based on the theory of disturbed state concept (DSC). The characteristics for relationships between shear stress, axial strain and pore water pressure of structured soils are analyzed by triaxial consolidated-undrained shear tests in laboratory. According to the modeling method of disturbed state concept, a new constitutive model to describe consolidated-undrained shear behavior of structured soils is suggested, in which Dancun-Zhang nonlinear model is used to define the stress-strain behavior of soils in a relative intact state; and a new disturbance function is defined by taking pore water pressure as a parameter. The suggested model is verified by test data of two samples with different depths from the west area of Liaoning province; and the result shows that the model calculation is in a good agreement with test data. It can express the types of strain-softening and strain-hardening stress-strain relations.

During the compression estimation and deformation calculation of soft ground, compression modulus is an important soil parameter which is generally obtained from compression curve of lateral confined compression test; and it usually is a constant. But actually, during the process of foundation consolidation, compression modulus will develop gradually along with the growing up consolidation degree; therefore, it is necessary to study the variation law of compression modulus of soft clay under external loads. Two kinds of silt soil samples of natural state and after overloading pre-compression were taken from a typical soft ground of a certain highway in Pearl River delta to carry out consolidation tests with different pressure levels respectively. By analyzing the experimental results, the quantitative relations between compression modulus and pressure of these two kinds of silt soil are obtained; and the evolution law of compression modulus with pressure and time is summarized. On this basis, combined with the microstructure images of natural state and after overloading pre-compression silt soil samples before and after indoor compression, the evolution mechanism of compression modulus with pressure and time of these two kinds of silt soil is analyzed. It provides a useful reference for giving reasonable values of deformation calculation parameters of soft clay and has important significance for controlling loading rate and various stages loads during the surcharge preloading process of soft foundation.

Behavior of compression type rock bolt in soft sedimentary rock is studied by the scale model test in laboratory. Well-designed test rock bolts have good constructional detail of bearing plates and reliable unbonded steel strands. The full load-displacement curves are obtained by test rock bolts with different fixed anchor lengths. Compression type rock bolts show much higher ultimate bearing capacity，better ductility and residual strength than usual tension type rock bolts in the same condition. The test data accord with analytic solution. Optimum anchorage length is obtained based on failure patterns. The research is a good reference for related studies, tests and engineering practice.

Due to the conventional Mohr-Coulomb criterion used for geotechnical materials with its limitation for overestimation of tensile performance, a modified Mohr-Coulomb model is established considering maximal tensile stress criterion. The main contents of the implicit constitutive integration algorithm are discussed systematically; and the consistent stiffness matrix is deduced. Based on the implicit Euler stress integration algorithm, the UMAT subroutine of the modified Mohr-Coulomb model is developed in ABAQUS. With the new developed model, the numerical simulation of uniaxial tensile test and triaxial compression test is implemented respectively. The study shows that the developed modified Mohr-Coulomb UMAT subroutine could effectively depict the tensile performance of geotechnical materials and fill up the deficiency of the Mohr-Coulomb model in ABAQUS.

An improved hierarchical model of rock joints was proposed based on the work of Dong et al. (Dong J J, Pan Y W. A hierarchical model of rough rock joints based on micromechanics[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, 1996, 33(2): 111-123). According to this model, joint macro-asperity is decomposed into multi-level micro-asperity; joint behavior is decided by the performance of the lowest level asperity(also basic surface) through homogenization. Joints fail progressively from the lower level to higher level asperity, after the basic surface break down, the second lowest level asperity converts to the basic surface. The roughness of joint is represented by equivalent asperity angle. The model also include the effect of variation of contact area and roughness on the permeability of joints. The model can simulate the mechanism of elastic deformation, sliding, damage, shear-off, crush and separation of joints. Model verification and parameters sensitivity analysis were carried out by UEL of commercial soft package ABAQUS.

The study of strength characteristics of rocks under unloading condition is of very importance to the safety evaluation of the underground engineering. There are many factors affecting the strength in unloading test, such as lithology, initial unloading stress, unloading stress path and unloading rate, etc. Among these factors, the unloading rate is concerned in this study. Yield approach rate (YAR) is proposed to denote the stress varying rate under loading and unloading conditions. The YAR under loading and unloading conditions is almost equal when the unloading confining pressure rate is 0.2-0.3 of the loading axial stress rate in general triaxial tests. The simulation by EPCA2D (Elasto-Plastic Cellular Automaton) and the unloading test on marble indicate that the strength of the rock will increase as the unloading rate is higher and the strength under loading and unloading conditions is equal when the unloading rate is 0.2-0.3 of the loading rate. Then the conclusion can be drawn that if the YAR is given and the initial unloading stress is in the elastic state, the unloading stress path has little influence on the strength.

For the stress path of soil around pit in the excavation process, by using true triaxial apparatus the lateral unloading tests are carried out considering initial stress, and comparing routine triaxial test results with those of true triaxial test in lateral loading. Then some conclusions from analyzing contrastive results are made. The curve, which is hyperbolic relation, is similar to the curve of routine triaxial shear test. The incipient strength of soil with true triaxial apparatus has increase because of intermediate principal stress. True triaxial incipient tangent slope is always higher than that of routine triaxial test during loading. Soil sample unloaded in minor direction collapses at smaller strain. The stress strength of soil in loading path is bigger than that in unloading path.

Based on the results obtained from the lab and in-situ data of the soft soil from Jieyang-Puning expressway, the principles, advantages and disadvantages, applicability of the common computational methods for lab and in-situ consolidation coefficient are detailed. Compared with other lab methods, the three point method and square root of time method are better than others. Study shows the discretization of consolidation coefficient from different samples at the same unit soil strata. In practical applications, multiple consolidation tests should be carried out to calculate consolidation coefficients at the same unit soil strata, the average value is reasonable.

The discontinuous deformation and failure of jointed rock mass is one of the important topics in the scopes of rock & soil mechanics and engineering at present. Rock mass which consists of joints and rocks is intervenient of continuous and discontinuous. The uncertainty of inner structure induces the complexity of its mechanical behavior in macroscopic view. The research scale of the rock mass’ failure first of all. Taking the continuous problem, the discontinuous problem and the conversion from the continuous to the discontinuous into account, a discontinuous sub-block model is brought forward from the view of multi-scale coupling. The discontinuous sub-block model is on the base of the method of discontinuous deformation analysis in theory. In the discontinuous sub-block model, rock from the cutting of rock mass by joints is defined as block. And the block is cut into smaller block which is defined as sub-block. The sub-block is isotropic and homogeneous. It’s the basal element in numerical simulation. It is assumed that the rock mass and rock belong to the macroscopic view and the sub-block belong to the meso-scopic view. The contact between the sub-blocks is also redefined and divided into two kinds. One is the continuous contact and the other is discontinuous. And the continuous contact can change into the discontinuous one under some condition. The extended Lagrange multiplier method is adopted to deal with the contacts; and the exact contact force can be calculated.

An effectual method of seepage-rheology coupling experiment was developed by the improvement on test apparatus and technics. The rheological properties of rock in seepage field under different stresses and water pressures were investigated by this method using porous limestone specimens. Based on the experimental results, the strain of specimen will increase along with the stress. The variation of vertical strain is larger than the other directions under lower stress; but when raising the stress level gradually, the strain of seepage direction will increase more remarkably. The results still show that the permeability coefficient and volume of the specimen have certain relation, the volume shrinkage of the specimen under lower stress will cause the decrease of permeability coefficient. When raising the stress to certain value, the volume of specimen will expand gradually; this so-called dilatancy effect will increase the permeability coefficient. If raising the water pressure, this variety of permeability coefficient and volume will be more notable. The rheological rate of specimen has deceleration and stable stage. The acceleration stage of rheological rate will appear and cause the specimen failure under certain high stress.

Based on the change of rock microstructure under chemical corrosion, corrosive effect of water and chemical solutions on crack is studied. Using geochemical kinetics of mineral-water interactions and checking ion concentration in chemical solution under different periods, the ways of quantitative methods for equivalent crack propagation under chemical corrosion of water-rock interaction are approached. According to conservation of mass, the evolution equation of crack is obtained and chemical corrosion of water-rock interaction is equivalent to effective crack length. The computational formulation of equivalent crack propagation is set up; and the stress intensity factor is also calculated. An example of sandstone is given; the results show that the influence of water-rock chemical interaction on crack propagation is notable and time-dependent. At the same time, the influence of the solutions with different ion concentrations and different pH values are investigated. The pH is an evident factor which affects the fracture mechanics effect. The greater the acidity or alkaline of solution, the greater the erosion to sandstone and the faster the crack extending. The crack will be propagated slowly when solution is distilled water (pH=7). A new thought way to quantitatively studying the micromechanism of fractured rock mass in the interaction of water-rock is suggested.

Coarse granular aggregates are subjected to breakage during excessive stress changes. Most of the available constitutive models do not consider particle breakage during shearing. In the current model, the energy equation during shear deformation has been developed incorporating the plastic work; and the plastic flow rule is deduced. Adopting linear type yield locus and non-associated flow and hardening function derived from an undrained stress path, a constitutive model for coarse granular soil incorporating particle breakage is set up. It is shown that the proposed model can realistically describe the strength and deformation characteristics of soils at every confining pressure.

In order to cater for the operation requirements of high speed train, it is necessary for subgrade of track to be high stability and comfort; as the subgrade of track, strength and stiffness of roadbed structure, is very high and at the same time its stability and durability is very good. However, as for red bed mudstone, its engineering properties is bad as follows: it is easy to collapse and its strength is very low, which belongs to weak rock. As the stuffing of surface layer of subgrade bed, its stiffness is apparently lack, so in order to make up for the shortage of surface layer of subgrade bed, it is necessary to add a layer of cement stabilized grading crushed stones; to verify the effects of these disposal measures and guide the design and construction works, through dynamic full-scale model test in simulating actual loading conditions; it is indicated that by the use of cement stabilized grading crushed stones as stuffing of subgrade bed surface layer, static and dynamic deformation significantly can be reduced; and what’s more, permanent deformation of subgrade bed can be also reduced; and the stability of the track structure can be enhanced.

The great shearing deformation energy accumulated in the slope will be released in critical landslide phase; and energy releasing rate of the slope body has the dimension of force. When the amplitude of energy releasing rate of the slope body is greater than the shearing strength of latent slide belt of locked segment, the deformation energy released by the slope body in critical landslide phase will be greater than the energy needing for failure of rock of latent slide belt; and the superfluous energy amount will convert into kinetic energy of landslide mass; and the landslide like this is called acute-moving landslide. Contrarily, the landslide is called slow-moving landslide. The impulse velocity at the cross section of acute-moving landslide is in direct proportion to the tangential stress intensity at it. The tangential stress and the tangential strain energy density of slope body media near to the latent slide surface are the biggest; the impulse velocity of acute-moving landslide is the biggest too. The curve of elastic potential change rate of slope and its expression, which have wealth of information, are deduced. The deformation energy accumulation of the slope body, and the relationship between the deformation energy releasing amount in critical landslide phase and starting velocity including starting method of landslide mass, are described in forms of analysis and illustration drawn by the Matlab software.

Landslide/slope stability assessment not only depends on the calculation method itself, but also depends on the reliability of calculation parameters. It is closely related to the success or failure on the establishment of landslide/slope stability assessment, whether the selection of mechanical parameters is reasonable or not. Basing on the value range of (potential) sliding surface of the cohesive force, internal friction angle by the results of the comprehensive tests and the establishment of calculation model, the selection of stability factor at different developing conditions when mechanical parameters of landslide/slope are back-calculated and the methods of calculation are deeply studied. A set of the comprehensive selection methods of landslide/slope mechanical parameters and stability assessment system are advanced, which are applied to a landslide. Finally, stability assessment system is verified by corresponding numerical simulation and physical simulation, its applicability is good.

Focus on settlement analysis and calculation of municipal solid waste (MSW) during landfilling. After discussing parameters of PTH creep model of MSW, relation curves between landfilling course and MSW landfill’s height are obtained with the creep equation, based on landfilling process and landfilling program of Chongqing Changshengqiao sanitary landfill. Comparing with the method of soil consolidation theory, it is found that parameters selection still lies on experiences in the method of soil consolidation theory; and its hypothesis is not accordance with the practical situation. While all parameters in PTH creep equation can be acquired on an adequate basis by creep compressive test indoor. The results by PTH creep equation indicate that the total settlement of 25.7% occurs during landfilling in Chongqing Changshengqiao waste sanitary landfill. Economic analysis will lead to a wrong conclusion if this datum is ignored while estimating the capability of landfills.

Usually, two methods are adopted in using the pressure plate extractor, namely, including the weighing soil method(WSM), which measures the water content by weighing the soil sample when equilibrium is reached; and the weighing outflow method(WOM), which measures the water content by weighing the outflow from the soil sample after equilibrium is attained. In the measurement, however, there are some factors that can adversely influence testing results. For example, with the WSM, part of soil mass may lose, and in using the WOM, the outflow could be overestimated because the air-bubble accumulation and the air-water interface. All these factors may result in error. To resolve the problem, an adjusted method of weighing ouflow is introduced. By comparing the weighing soil method and the weighing outflow method to the adjusted method of weighing outflow, it is shown that at the same matric suction, the saturations determined with the weighing soil method and the weighing outflow method are less than that determined with the adjusted method of weighing outflow. The reasons for this are sought; and the applicabilities of these three methods are discussed.

The h-type combined anti-sliding pile is a retaining structure with a back pile and an corresponding anterior pile firmly connected by a horizontal beam at the top of the anterior pile. The structure is like “h” shape and can resist large landslide thrust. Its anti-sliding mechanism is discussed. According to its mechanical features, the structure can be analyzed by dividing it into two parts in light of the location of potential slip surface. Judging by laboratory test results and corresponding theoretical analysis, it is provided that internal forces of the part above the slip surface can be calculated by plane rigid frame model exerted by landslide thrust in the form of linear load and constrained by lateral elastic strata. In addition, slope pressure between the two piles in the h-type pile is involved in the model. So the other part under the slip surface can be further computed directly by elastic foundation beam theory. The given method is successfully used for designing the structure against a large excavated slope which consists of crushed stone mixed with clay in Guangyuan-Bazhong expressway projects in Sichuan, China. The practical results are reasonable.

The vulnerability assessment of debris flow in the past mainly aimed at the economic, social, material and the environment vulnerable degree. There is no assessment about the vulnerability of engineering either. So the concept of engineering vulnerability has been proposed in this paper. By taking Zhuofu tunnel in the Zhi-Liu railway suffering from debris flow as background, according to the characteristics of the tunnel bearing the disaster and the characteristics of debris flow to cause disaster, the paper systemically analyzes the influences of the tunnel's geological selected location, the engineering design, the construction, the operation maintenance as well as the disaster factor of debris flow, which influences the engineering vulnerable degree, determines evaluating indicator system of the engineering vulnerability. With the aid of the AHP method and the fuzzy comprehensive evaluation, the assessment method of the engineering vulnerability is established; and the serviceability of this method is confirmed by the example. The method may provide the reference for the determination of prevention rank and the assessment of the disaster-bearing capability of the tunnel.

Based on the nonlinear finite element method, the basic characters of road widening engineering are studied. It is found that the vertical settlements, lateral displacements of widening part of subgrade are lager than those of old subgrade. The lateral displacements of road widening engineering get its maximal value at the conjunction between old and new subgrades, which make the longitudinal cracks along road easy to be generated. With a fixed width of widening, it is easy to reduce differential settlement of road with widening at two sides of road than that at one side. The vertical settlement of road is decreased with increase of deformation modulus of soil, which is increased with increase of gravity of soil. Furthermore, the stability of road increased with enhancing of soil strength, which decreased with increase of gravity of soil or equivalent uniform load of vehicle. It is more available to fill the widening engineering with the soil charactered with less dead-weight, large deformation modulus and higher strength.

In order to delineate the complex coupling behavior of the soil under the rocking loading, the analytical solution for an elastic strip foundation on saturated soil under a rocking moment is developed under the framework of the Biot’s coupling theory. By employing the method of Fourier transform, the dynamic governing differential equations for saturated poroelastic medium are solved. Considering the mixed boundary-value conditions at the bottom of the foundation, a pair of dual integral equations governing the rocking vibration of an elastic strip footing are then derived, which are further converted to linear equations by means of infinite series of orthogonal functions--the Jacobi polynomials. A numerical procedure is proposed to solve the equations. The dynamic compliance functions for rocking vibration are also derived. The effects of plate flexibility, ground permeability and Poisson’s ratio on the dynamic compliance are investigated; and some meaningful conclusions are drawn.

Non-prestressing frame anchor is a new slope prevention technology which sets surface ecological protection, shallow and deep reinforcement in one, but regardless of its reinforcing mechanism, or engineering design method, academia has not yet reached a consensus. On the basis of analysis of failure mechanism and stability operating during slope excavation, according to stress dispersion principle and Mohr-Coulomb strength theory, the reinforcing mechanism of non-prestressing frame anchor is discussed, including two-way compaction effect, anchor-pull effect, pin effect, skeleton-hoop effect and soil arching effect. These comprehensive effects can effectively improve the loading states of slope and actively constrain the deformation of slope in unsteady zone by initiatively transfering the mechanical strength of steady zone. According to the general principles of optimization design and relevant codes, the optimization design model of frame structure and associated constraint equations are constructed. The automatic optimizing programs of the model are compiled in Matlab7.0. The processes of optimization calculation are detailedly introduced by the practical application of a slope treatment project in the Three Gorges Area. The optimization design method can achieve savings in project cost and the purpose of optimization design results comparing with original design based on analogue method.

Based on lots of experimental studies, a moisture, thermal and dynamic coupled model for frozen embankment is deduced by using fundamental principles of physics of frozen soil, mechanics of frozen soil, numerical heat transfer, advanced soil mechanics and soil dynamics; and then, its corresponding numerical program is written. Lastly, taking a typical section of Qinghai-Tibet Railway for example, the seismic response of frozen embankment is analyzed in detail; and safety stability of the embankment is assessed under the EI Centro earthquake loading. By this study, it is found that the dynamical model for frozen embankment proposed is reasonable and can well simulate the seismic problem of frozen embankment. In addition, the Qinghai-Tibet Railway will not be destroyed heavily under the seismic loading, of which the intensity is less than design value; and it can be immediately put into operation after simple repair.

3D laser scanning technology has been successfully applied to static surface measurement because it can measure 3D coordinate with high speed, high precision and high density to describe the surface detail. At present, the deformation analysis of the landslide surface is carried out mainly with some observed characteristic points by GPS or total station, but because of few data, this analysis is not complete. The detailed deformation of landslide has an important role for the correct deformation analysis. To introduce this technology to the landslide monitoring is significant for detailed deformation analysis, if a lot of natural rocks are used as monitoring points. In this paper, the theoretical analysis and the practical tests have been carried out; and the preliminary result has been obtained.

Asphalt concrete is the main waterproofing material of core wall in hydraulic projects. The effects of temperature on mechanical properties of asphalt concrete is studied through testing of mechanical characteristics of asphalt concrete with two kinds of asphalt contents under different temperatures by high-pressure triaxial apparatus. Test results indicate that: the stress-strain character of asphalt concrete sample is closely related to the temperature. Stress-strain shows stress softening when temperature is 0℃, however, with temperature rise, stress softening disappears and stress hardening appears. In same asphalt content, the higher the temperature is, the smaller the maximum deviatoric stress is. The shear strength of specimen reduces with temperature rise. Creep of specimen increases with temperature rise.

Content of clay particles in debris flow is not much, but it significantly affects the occurrence of debris flow. Indoor artificial rainfall experiments are carried out in self-designed model with nine different graded soils, three different dry densities (1.64 g/cm3 (loosely accumulation dry density), 1.79 g/cm3, 1.94 g/cm3 (natural dry density)), rainfall intensity 85 mm/h, impact which content of clay particles on debris flow occurrence is preliminarily studied. As a result, it’s found that debris flow can occur when content of clay particles is between 5% and 18%, it needs shorter time when content of clay particles is 10% than others; clay content has criticality. The greater the dry density of accumulation, the more difficult debris flows to occur with long start-up time, shallow depth and small scale, but accumulation dry density does not change the criticality of clay content. Under the condition of rainfall, the higher the soil infiltration rate of soil, the stronger the water-holding capacity of soil, the easier debris flow to occur. The internal mechanism of forming debris flows can be revealed deeply through above experiments; it also develops new ideas on debris flow forecasting.

Based on the shear displacement method, the Mylonakis & Gazetas model for mutual action between pile and soil, and the Winkler foundation model were introduced; then the flexible factors for mutual actions between pile and pile, pile and soil, soil and soil were provided. An analysis method to pile-soil-cushion mutual action in the composite foundation was deduced; and the correlated program was also developed by Matlab software. In order to validate the feasibility proposed approach in this paper, two static load model tests for the composite foundation with tapered piles and cylindrical piles were done in laboratory respectively; and the method was used to analyze two models. Experimental and theoretical results indicated the reaction force distribution of surrounding soil in pile-top plane keeps saddle type, which is similar to natural foundation; the bearing capacity of composite foundation with tapered piles is higher than that of composite foundation with cylindrical piles; and the average pile-soil stress ratio of composite foundation with tapered pile is lower than that of composite foundation with cylindrical piles obviously; tapered pile can relief pile-tip stress concentration in composite foundation effectively; and it has good regulation on using the bearing capacity of natural foundation fully.

In order to know well the deformation characteristics of slope soft-soil foundation under the action of embankment loading and find a reasonable foundation treatment measure, taking a special project about reconstruction of newly-built Da-Cheng railway project as a prototype, this paper designs 5 groups centrifugal model tests based on the mixed-in-place pile to deal with the foundation's strategies. According to the analysis of the experimental data, the conclusions are drawn as follows. 1) By adopting different pile spaces layout style at the upside and downside directions of the slope, it can reduce the different deformations of the slope soft-soil foundation along the lateral side and improve the uniformity of the foundation treatment. 2) It has better deformation binding effect by setting up the tilted pile in the downhill side of the slope soft-soil foundation; but it has less effective performance in controlling the vertical subsidence. 3) The slope soft soil foundation deformation that appeared at the downhill side will give rise to the same direction deformation at the uphill side, and the horizontal deformation is more obvious. The foundation treatment should put emphasis on the deformation controlling of downhill side. 4)The varying law about horizontal deformation along the depth direction shows para-curve style which is first adding then reducing and hyperbola style that is humdrum reducing, attribute to the density of the pile layout.

The additive mass method is one of nondestructive methods used for the compacted density testing of coarse materials. The theory of it is introduced; then its theoretical model is introduced too. The additive mass method is successfully used in the compacted density testing in Kunming new airport. The result shows: (1) the linear interrelation between foundation stiffness tested by the additive mass method and density tested by the water replacement method is about 0.81, relative error between the density from demonstration test and density from empirical relationship of calibration test is about -1.78%—1.75%, which shows that the testing accuracy of the additive mass method satisfied the requirement of construction testing accuracy; then the empirical relationship of compacted density of coarse material in Kunming new airport is given; (2) because of its advantages, such as convenient operation, fast testing and nondestructive for tested coarse material, etc., the additive mass method is one of the most prospective nondestructive methods.

Jet grouting soil-cement-Pile strengthened Pile (JPP) is a new kind of composite pile, and its technology has more advantages, such as high penetration force, being constructed quickly, good economic performance, etc. A simplified calculation formula for bearing capacity is proposed; and its validity is verified by engineering example. Influencing factors of bearing capacity, such as different elastic moduli of soil-cement, different thicknesses of soil-cement, different combination form, etc. are analyzed by means of numerical simulation model based on field load test. The simulation results show that: unconfined compressive strength of soil-cement should be no less than 1.5 MPa; the thickness of soil-cement should be not only no less than 100mm but also be not more than the radius of core pile; base strengthening combination form of JPP pile is beneficial for improving bearing capacity. These results have some practical significance for guiding engineering practice.

According to the characteristics of the decision factor of supporting schemes for foundation pit, such as fuzziness, uncertainty and their gray correlation, a grey fuzzy variable decision-making model is established based on gray theory and fuzzy mathematics theory. In order to more rationally solve the critical problems which affect the accurate degree of the result of the model, a combination weighting approach for the weight of evaluation indexes is put forward based on the maximum closeness degree; and qualitative indexes are quantified by set-valued statistics methods. The model is proved to be scientifical and effective by a case study and easy to realize programmed. More importantly, the present method can heighten the rationality and reliability of decision-making and provide worthy reference for decision-maker. So it has some generalization and application value.

During shield-tunneling under soil with poorly permeable parameters, it has been observed that higher are the advance velocities, higher support pressure is needed to keep stability of the tunnel face. the governing equations for head distribution with shield advance velocity and permeable parameters involved are deduced by residual-Galerkin method; a finite element program with Fortran codes is developed and used to solve the governing equations numerically. The minimum support pressure to keep stability of tunnel face is equal to the sum of the seepage pressure acting on the face and the effective support pressure, which is obtained by using limit theorem and limit equilibrium analysis. It is found that the shield advance velocities have significantly effect on head distribution around tunnel face in poorly permeable ground; the increase of advance velocities leads to the obvious variation of the support pressure; and the analytical results are consistent with the measured data in engineering.

Based on the large field testing settlement data of Dongguan-Gangkou Road trial section, the influence of lasting carry preloading time on settlement calculation by Asaoka method is analyzed, which predicts the soft ground embankments settlements in the Pearl River tri-angle areas that need four months lasting preloading time at least. A formula for correction coefficient of ultimate settlement of soft soil subgrade with Asaoka method is proposed to diminish the deflection of the settlement prediction for the shorter preloading time.

The objective of this research is an attempt at applying the empirical mode decomposition (EMD) and Hilbert-Huang transform (HHT) to decomposing the vibrating signal and analyze the frequency spectrum of the pier foundation. To receive the vibrating signal produced by the moving heavy vehicles, the devices set up for detecting the signal on one side of the deck of the bridge. In EMD method of decomposing the vibrating signal from the pier, the intermittency criterion is used to obtain the better obviously components and improve the judgment of the HHT frequency spectrum. From this study, the process of analyzing EMD, which may produce mixed phenomenon in mode, will result in the frequency loss and the shortening in reading range in HHT graph. Through appropriately applying the intermittency criterion, these problems mentioned above can be solved and receive the higher confidence on the judgment both in HHT graph and in the marginal frequency graph. Besides, the result of HHT graph proves that the instant frequency variation in direction Y of the pier system is regarded as the frequency range between 1-4 Hz. And the marginal frequency graph shows that the frequency energies of P1 and P2 are centered around 2.5 Hz and 1.7 Hz. So, the stiffness of the foundation P2 obviously lower than that of the foundation P1. According to the result, the bearing capacity loss of P2 can be showed clearly by using HHT method.

On the basis of seepage theory of gas flow in coal seams, elastic theory of coal deformation, together with the coupling relationship between gas permeability and porosity, a mathematical model for coupled gas-solid in coal collieries is established. By using the gas-solid coupled model, the mining induced pressure relief, the gas pressure changes, gas drainage and the associated characteristics of gas permeability and gas pressure in coal seam during mining were numerically simulated. The numerical simulation is helpful for understanding the gas drainage mechanisms and for taking effective measures to prevent the occurrences of gas outbursts in collieries.

In order to apply an elastoplastic constitutive model for overconsolidated clay based on the revised Hvorslev envelope to numerical analysis of shear bands, a subroutine is developed for the implementation of the model into a nonlinear finite element software ABAQUS by using the return mapping algorithm. Numerical simulations of triaxial compression, triaxial extension and plane strain tests are performed. The algorithm is verified by simulating the mechanical behaviour of overconsolidated clay with different initial overconsolidation ratios. By using the implemented program, three-dimensional finite element analysis of shear band is carried out under triaxial compression, triaxial extension and plane strain stress paths. The numerical results show that, onset of strain localization occurs in the softening regime under triaxial compression and triaxial extension conditions; and under plane strain condition onset of the strain localization occurs in hardening regime; and the shear dilatancy of overconsolidated clay plays an important effect on the formation of shear bands.

By tracking borehole expansion and the propagation and coalescence of cracks in surrounding rock medium, calculating instant blasting chamber pressure based on the detonation pressure equation of state, and loading this pressure on the wall of the borehole and the surface of connected cracks, discontinuous deformation analysis (DDA) method to simulate the blasting process only considering the effect of explosion product in jointed rock mass is developed. A horizontal column borehole cast blasting case in jointed rock mass is simulated with this method. In the simulation, the chamber volume expanding and pressure attenuating histories are obtained. The process of borehole expansion, rock medium failure and movement, and blasting pile formation in rock blasting is well duplicated by the simulation.

The transient unsaturated seepage in soil slope is systematically investigated; and the stability of a slope is analyzed by shear strength reduction finite element method (SSR-FEM). Emphases are given to discuss the influence of location of phreatic surface, soil permeability, drawdown ratio, drawdown rate and matric suction subjected to transient unsaturated seepage on the slope stability. The results show that the drawdown rate has a remarkable effect on the pore-pressure in high permeability soil slope than that in low permeability one; and also a significant effect over 15% on the safety factor of a slope can be also drawn.

Based on the geological conditions of culvert of the South to North Water Transfer Project, control criterion of concrete temperature drop is put forward during culvert construction using theoretical analysis and numerical calculation. Considering the worst position, internal temperature of concrete must be controlled below 26.7 ℃, which can bring good predict effects on selecting reasonable temperature drop measures. According to numerical analysis results of lining temperature field, considering terrain condition, structural characteristics and climate, some engineering measures such as optimizing concrete mixing ratio, reducing cement content, adding proper fly ash and establishing shading shed and furrow, are taken during construction. Internal temperature of concrete is controlled effectively; concrete cracking caused by temperature changes is solved successfully; and construction quality is assured. The difference between measuring data in-situ and calculating data is very small; so it is shown that the calculated model is correct and the parameters are reasonable. The results can act as reference for the design and construction of similar projects.

Analyzing three dimension is the developmental trend of numerical manifold method. Three-dimensional manifold element with hexahedral finite element covers is constructed by cover displacement function of numerical manifold method, strain matrix, stiffness matrix and equilibrium equations are derived. Simultaneity, linear elastic model is mostly adopted on numerical manifold method for problem analysising persently, but nonlinear model is researched very little, calculating formulations of numerical manifold method for nonlinear analysis based on the characters of numerical manifold method and constitutive models of rock and soil mass is presented. The elastic modulus of model and model is altered to describe the nonlinear relationship by midpoint incremental method; in fact subsection linear ralationship is substituted for nonlinear ralationship. Finally, an example of foundation settlement calculation is given; the calculation result shows the validity of nonlinear analysis of three-dimensional numerical manifold method for rock and soil mass.

Some problems have not still been solved smoothly in slope stability analysis using shear strength reduction finite element method (SSR-FEM) until now. The effect of mesh shape, size and order on the factor of safety is systematically discussed at first; triangular second-order element is thought to be the optimal one, as it can be able to both simulate the failure process of slope and obtain the accurate solutions during the relative element size from 0.1－0.15. When a slope arrives at the critical failure state by SSR-FEM, the four failure criteria as plastic zone extension from the toe to the top of slope, equivalent plastic strain exceeding a certain value developed along the potential slip surface, uncontrollable increase in characteristic nodal displacement on slope surface; and the iteration non-convergence of nonlinear FEM numerical calculations can be found in turn. Calculation results show that the four evaluation criteria are highly consistent. Location of potential slip surface and out-slip point is associated with cohesion, internal friction angle and slope angle. The bigger cohesion, smaller friction angle or the lower slope angle can make slip surface deepen, and the out-slip point is far from the slope toe.

When subgrade lies in areas which have abundant groundwater and high water level, it was vulnerable to erosion. For treatment subgrade diseases caused by water capillary rise, it is needed to acquire the law of capillary rise in the soil. Based on improving the horizontal absorption test, a set of capillary rise test apparatus has been made to conduct three groups of initial dry density specimen experiment. The results show that the relationship between capillary rise height and water content similar to the soil water characteristic curve; with the dry density of specimen increasing, the capillary rise height became smaller within the same time interval; there was an optimum moisture content during the diffuse capacity changed with the initial water content. Finally, The distribution regularity of moisture distribution along with the height of samples is simulated with FEM. comparing the calculated results with the measured field data, it is proved that the calculated results can be fitted well with the measured field data.

Regarding the filled garbage as a kind of special soil, the multi-field coupled simulation analysis model which comprehensively describes saturated and unsaturated seepage of leachate water, landfill settlement, releasing, transport and transformation of organic pollutions, and growth and decay of microorganism in landfill was developed. The Lagrangian- Eulerian (ALE) method was introudued to solve the coupled model. And based on the self-developed program, the numerical simulation analysis of the effect of surface water infiltration on water quality and quantity in landfill was carried out. The numerical simulation results showed that 300-day infiltration of surface water and the generation of inner source water could make the saturated level of this landfill unit reached 6 m height mostly; the infiltration of surface water had significant effect on the distribution of soluble and degradable organic pollutants and anaerobic microorganism in aqueous phase, and indirectly affected the ones in solid phase.

The seismic wave is input through artificial truncated boundaries, and the stress and deformation of the slope induced by seismic loading are determined by time-integration method. The effect of foundation radiation damping is simulated by adopting viscoelastic artificial boundaries condition on artificial truncated boundaries. Safety factor of slope stability is solved by finite elements strength reduction method. The displacement saltation of feature points when the connection of plastic zone occurs is considered as an instability criterion of the slope. The slope aseismic stability analysis method based on static and dynamic finite elements is put forward through combining the dynamic finite element method with the viscoelastic artificial boundaries conditions. On the definition of safety factor, the method is consistent with the traditional grid limit equilibrium method. Finally, taking Shilipu Hydropower Station for example, the slope dynamic stability of the reservoir slope is analyzed; and the time history of the slope dynamic displacements and the safety factor of dynamic stability are obtained. The calculation results agree very well with geological survey and are close to the actual situation, so as to indicate that the method can be used to evaluate dynamic stability of the practical engineering.

In this work, the thermodynamic responses of porous elastic foundation subjected to time harmonic normal force and thermal source are investigated in the context of the theory of generalized thermoelasticity. The material of foundation, obeying Biot’s dynamic poroelastic theory, is idealized as a uniform, fully saturated poroelastic half-space stratum. The coupling thermo- hydro-mechanical governing equations are derived by employing Biot’s dynamic poroelastic theory and generalized thermoelastic theory. The general solutions of stress, displacement, temperature distribution and excess pore water pressure are obtained by employing Fourier transform. Considering the normal force and the thermal source acted on the surface of foundation and permeable boundary condition, analytical solutions in the form of integral are derived using the inverse Fourier transform. Furthermore, numerical results are obtained to analyze the differences among coupled thermo-hydro-mechanical theory, coupled hydro-mechanical theory and thermoelastic theory. In addition, the effect of the thermal loading frequency on the components of displacement, stress, temperature distribution and excess pore water pressure are investigated in the numerical results.

To recover a large percentage of coalbed methane in coalbeds, reservoir pressure must be reduced significantly in the primary production. Two distinct effects are associated with the reduction of reservoir pressure during methane extraction: (1) the release of gas, and (2) an increase in effective stress. The increase in effective stress causes a decrease in the permeability of the coal owing to mechanical closure of flow paths. However, an opposing effect of coal-matrix shrinkage can occur, one that is attributed to a desorption phenomenon. This shrinkage widens the fractures that are primarily responsible for gas flow in coalbed reservoirs, and thus increases permeability. Some permeability models such as Shi-Durucan model, Palmer-Mansoori model and Gray model incorporating the effect of matrix shrink and effective stress influence were developed. These models were based on two key assumptions: coalbed is under uniaxial strain condition and constant vertical stress. According to this, a coupled seepage-stress coalbed methane flow model considering matrix shrinkage was used to examine the accuracy of these assumptions; then this model was used to analyze permeability change during primary production; the result suggested that the assumption of uniaxial strain appears valid, while constant vertical stress may introduce error; it varies as gradients in strain are induced towards the production well; and its contribution to permeability can be significant; then that existing coal permeability models could underestimate permeability change.

The self-boring pressuremeter(SBP) has proved to be a useful tool for geotechnical engineering to determine the in situ properties of soils due to its small disturbance, long measurement depth, versatile data such as stress-stain, excess pore pressure-time. The conventional interpretation methods of the SBP testing (Gibson et al, 1961) have typically been based on the one-dimensional expansion of a cylindrical cavity by assuming that the pressuremeter can be treated as infinitely long, leading to an overestimation of soil shear strength by pressuremeter testing. The study of two-dimensional geometry effects and choices of strain range in pressuremeter curves on undrained shear strength based on modified Cam clay model is performed. Strain ranges for different stress histories have been proposed by comparing the results of finite element method with the solutions of cylindrical cavity expansion. And corrections of undrained strength in proposed strain range for the effect of length diameter ratio of SBP are carried out.

The new high strength and high pretension yieldable bolts have been successfully applied to the entry support of deep coal mine in China. Compared with the high strength and high pretension bolts used in coal mine, the new bolts have the high strength, high pretension and yieldable characteristics. Based on the mechanical model of the high strength and high pretension yieldable bolt, a finite element numerical model of the adjacent rock-bolts interaction is constructed. The stress and displacement distribution around entry and roof bolt loading are analyzed through FEM model. The results show that the yieldable mechanism of the bolt system can reduce the bolt load, thus prevent the bolt system from yielding in the condition of large deformation and deep coal mine.

Aiming at the uncertainty and variation of geo-material parameters in foundation pit engineering, the reliability analysis method of soil-nailing wall is discussed based on the response surface method, genetic algorithm and taboo search techniques. A modified Morgenstern-Price limit equilibrium method for analysis of the interior stability of soil-nailing wall is presented by considering the reinforcement effect of soil nails. An approximate reliability calculation method of soil-nailing wall, in which the response surface function is constructed by these sample points that are obtained from the modified Morgenstern-Price method instead of traditional FEM numerical simulation method, is established based on the response surface principle. Taking soil shearing strength parameters and as the random variables? a global optimal algorithm?adaptive taboo search genetic algorithm (ATSGA) is presented for soil-nailing wall reliability, which can effectively locate the critical slip surface associated with the minimum reliability index. An example is given; and the calculation results computed by proposed method show that if taking the minimum reliability index and the minimum safety factor as the target function respectively, the two critical slip surfaces are significantly different.

Many large-scale shear experiments show the whole relationship between the axial strain and the radial strain of rockfills is not of hyperbola as Duncan-Chang model presumed. According to the test result, the above curve can be divided into two parts, depicted by the hyperbola and the line in turn. Moreover, an equation used to calculate the radial strain of the inflexion with the confining pressure is proposed. Then the computation of Poisson’s ratio in Duncan-Chang model is modified. Analysing the characteristics of experiment results, a fitting method using eight parameters to model the stress-strain and the volumetric strain curves is established. And by comparing the calculated results from this method and Duncan-Chang model with those original test data, the precision of proposed fitting method is validated.