The constitutive model based on the generalized potential theory is established directly by mathematical methods, and the complicated concepts such as plastic potential functions in traditional plasticity theory are avoided, which gives a new approach to study the soil constitutive model. Through the multi-potential surface model in stress space of the generalized potential theory, mathematical principle of the energy equation hypothesis in the Cam-clay model is analyzed and a similar Cam-clay model is established by mathematical methods, in which the modified Cam-clay model etc. can be regarded as its special cases. Rationality of the proposed model is verified through experimental data under the condition of different stress paths; and it is also compared with the Cam-clay model. The results show that parameters of the proposed model can be determined conveniently and freely; and the calculated results agree with experimental ones, which even better than those calculated by the modified Cam-clay model. Mathematical principle of the proposed model is more clear and the difficulties and errors which are brought by the determination of plastic potential functions and energy equation are avoided; it is proved that the proposed model has better practical value.

In order to provide technical assistance to the safe landing of space landers, the bearing capacity of lunar soil is studied in this paper. The lunar soil is too extremely precious to be used in in-situ tests. Therefore, TJ-1 lunar soil simulant which was developed by the authors recently was selected as the substitutive material. Firstly, about 255 tons of TJ-1 lunar soil simulant was used to generate an experimental base. Its dimensions were 13 m×12 m×1.2 m. After that , 6 cone penetration tests (CPT) measuring points and 2 plate load tests (PLT) measuring points were uniformly arranged within the test area. Then, the cone resistance was recorded in the process of penetration test and the settlement was recorded in the process of plate load test. Finally, the results of these two experiments were discussed based on Terzaghi classical theory of bearing capacity and 12 empirical formulas. The results show that the bearing capacity calculated from semi-empirical Terzaghi formula was evidently smaller than the predicted value. However, one empirical formula ( ) was found to be able to predict the bearing capacity of lunar soil from the results of cone penetration tests. It is shown that the calculated results can match the results of plate loading tests very well .

According to the stability of red sandstone bedding rock slope, a mechanical model is established; the hydraulic effect on slope under rainfall infiltration is calculated. Selecting a typical structural plane, through dry-wet cycling test, strength attenuation law of structural plane is analyzed. Comprehensive considering the rainfall infiltration and dry-wet cycling, the stability analysis of red sandstone bedding slope is analyzed; and the stability attenuation law is achieved. At last, by slope stability monitoring of Yan-Ru expressway, theoretical calculation results are verified. The results show that the hydraulic action is proportional to the water height in rock crack. Under dry-wet cycling, the cohesion of structural surface decays in the form of power function; and the internal frictional angle decays in the form of quadratic function. The slope stability has linear relationship with water height in rock crack and exponential relationship with dry-wet cycling. The dry-wet cycling has a greater influence on slope stability than that on water height in rock crack. Under the combined action of rainfall infiltration and dry-wet cycling, slope stability coefficient reduces by about 66%. Compared with considering single influence factor, the stability coefficient attenuation range has a great increase. The slope stability monitoring results agree well with theoretical results, the validity of theoretical results is further proved.

The dynamic loading leads to instability and failure of rock slope. Especially, the role of force increase mutation has a great influence on slope stability. The rock mechanical properties are analyzed under static and dynamic loadings. And then, the nonlinear equation of rock slope is established. The dynamic deformation model of rock slope and the nonlinear dynamic response are studied. The amplitude of the sliding body suddenly increase, resulting in the sudden jump up and continue to increasing with the increase of the force, when the disturbance frequency to a certain extent. Conversely, the amplitude of the landslide suddenly reduces, resulting in the sudden decreases when the perturbation amplitude reduces to a certain extent. Tiny changes in initial conditions can cause a huge difference of the system response. The movement of the entire system can be regarded as an independent superposition of the two sports when the amplitude(A) is very small. As the amplitude(A) increases to more than its amplitude between the three singular points of the nonlinear system interval, the system can oscillate back and forth between these singular points. With the amplitude(A) increasing, the system changes from the period-doubling motion to mix sports. The results can provide guidance for the dynamic stability of the rock slope.

In high-level radioactive waste(HLW) repository, buffer backfilling material should be pre-compacted to a certain density. The compression properties of buffer backfilling material have an important influence on the safety design, construction and operation for geological HLW repository. At present, bentonite-sand mixtures are considered to be the ideal buffer backfilling material in the geological HLW repository in China. the compression properties of bentonite-sand mixtures with different dry densities and sand ratios, whose water content is constant, are performed by WG oedometer. It is found that the compression coefficient a1-2 decreases quadratically with the increase of dry density, but it increases nonlinearly with the increase of sand ratio. Based on the concepts of effective clay density and effective water content, we try to explain the changes of the compression coefficient a1-2 with dry density and sand ratio. The regression analysis model of bentonite-sand mixtures with various dry densities and sand ratios are fitted based on the experimental data, and it hopes that this result can be used to provide a related basis of the optimization of buffer backfilling material.

The mechanical properties of soil-reinforcement interaction are of utmost importance for the design and stability analysis of reinforced soil structures. Using large-multifunctional interface shear apparatus, a series of horizontal cyclic shear tests are carried out between geogrid and standard sand. The mechanical behavior of geogrid-soil interface is recorded and analyzed. Then the influences of the characteristics of horizontal cyclic load on the interface shear strength and vertical displacement are studied. In the end, the mechanism of soil-reinforcement interaction under horizontal cyclic load is investigated. The results of this research indicate that the curves of shear force and displacement merge into one curve gradually with the increase of shear cycles; the change of shear stress summit is not obvious; the interface shear modulus increases with the cyclic load and reaches stable. The influence of the amplitude and velocity of shear displacement on shear strength is not evident; but the amplitude and velocity of shear displacement have significant effects on the vertical displacement of the samples during horizontal cyclic shear tests. In the process of horizontal cyclic shear tests, the sample takes obvious vertical displacement. The reinforcement has effective confinement to the vertical deformation of test samples.

Based on the theory of saturated porous media, the dynamic characteristics of vertical vibration of an end-bearing pile in a stratified saturated viscoelastic soil layer was investigated. The dynamic impedance of the soil to vertical vibration of the pile was obtained firstly with the Novak’s layer method. Then, regarding the pile as a Rayleigh-Love rod, the general analysis method for the vertical vibration of the end-bearing pile in the stratified saturated viscoelastic soil was presented; and the analytical expression of the complex dynamic stiffness at the pile top was obtained. The dynamic characteristics of vertical vibration of an end-bearing pile in a two-layer saturated viscoelastic soil were analyzed specifically; and the variations of the dynamic stiffness factor and equivalent damping of the pile top with respect to the frequency were given in figures. The influences of the physical and geometry parameters on the dynamic stiffness factor and equivalent damping were examined in detail. It is revealed that the length-radius ratio of the pile, the modulus ratio of the soil layers and the modulus ratio of the pile-soil have remarkable influences on the dynamic stiffness factor and equivalent damping of the pile top. Compared with pile in a uniform soil layer, the amplitudes of the dynamic stiffness factor and equivalent damping of the pile are increased as the elastic modulus of the upper soil layer is increased or the elastic modulus of the lower soil layer is decreased; and changes of the dynamic stiffness factor and equivalent damping with frequency are in form of the oscillation for large radius pile. Furthermore, the influences of the interaction coefficient between soil and pore water and the pile’s Poisson ratio are trivial relatively. The results can provide data base of pile design for dynamic foundation and dynamic detection of pile.

Previous research on liquefaction flow characteristic indicates that liquefied sand can be modeled as shear thinning non-Newtonian fluid. A flow constitutive equation of liquefied sand is established by using a power function relationship between the shear stress and the shear strain rate. A simplified method for large deformation analysis of liquefied sand is established through implementing the flow constitutive equation into the FLAC3D package. A case study of gradient foundation is performed by applying the proposed method to validate the constitutive model. The numerical results show that the displacement of gradient foundation can be described by a sinusoidal curve, which is in good agreement with the theoretical solution of Prof. Towhata. Parametric sensitivity analyses are conducted to investigate the influences on the deformation of liquefied sand from variables including the liquefaction layer slope, consistency coefficient, flow index and elastic parameters. The results indicate that the liquefaction deformation develops with the increase of the slope of the liquefied layer. What’s more, the consistency coefficient and the flow index of the liquefied sand have significant effect on the deformation of liquefied sand; while influence from the elastic parameters is inconsiderable. A further research on these parameters should be conducted in engineering practice.

The acoustic emission(AE) signals are obtained through uniaxial load tests on sandstones. Performing the fast Fourier transform(FFT) on AE signals, the analysis result shows that the peak frequency of AE signals reduces from 60 kHz to 40 kHz as load process proceeding, and the average peak frequency is 1 kHz lower than that of in natural situation. By analyzing the relationship between energy and acoustic emission events of rock, it is found that the bigger ratio of energy to acoustic emission events means the energy comes from the deeper degree rock fracture, the smaller ratio(order of magnitude <104 ) means that energy is accumulated by some lighter degree rock fractures. The power spectral density (PSD) of AE signals is done with Welch method; it is found that the power spectrum of AE signals can be divided generally into two classes(Type A and Type B), the phase of Type B has obvious discontinuity. Some larger-energy signals are chosen, probability of Type B power spectrum before these larger-energy signals is computed; it is found that the closer to the rupture time, the greater the probability of the type B. The research results provide a new way to analyze the AE properties of the whole rupture procedure of rock, and lay a certain working foundation for the application of acoustic emission in the prediction of rupture and instability.

The retaining wall and the backfill soil are taken as a whole system. For a rotational failure mechanism assumed, the paper studies the external work rate and internal energy dissipation rate by combining the slice method and limit analysis upper bound method. Based on virtual power principle, the formulae are obtained to calculate the horizontal yield acceleration coefficient, numerical solutions of the inclination of the failure surface and the horizontal yield acceleration coefficient are obtained by MATLAB. Case studies are given to illustrate the method, the influential factors such as cohesion and internal frictional angle between filling and wall, vertical seismic coefficient, cohesion and internal friction angle of filling are considered and analyzed. The results show that cohesion and internal friction angle between filling and wall, and vertical seismic effect have a significant influence on the horizontal yield coefficient, the design of retaining wall ought to pay enough attention to this aspect in order to achieve the purpose of economy and security.

On the basis of test studies of performance of geogrid-reinforced retaining walls subjected to load from strip foundation at the top surface of wall, the comprehensive effects of distance between panel and strip foundation on the ultimate bearing capacity, deformation characteristics, reinforcement strains and failure mode of retaining wall were analyzed. The experiment results show that ultimate bearing capacity of strip foundation exhibits a remarkable increase tendency with increase of (D, offset and H, height of retaining wall) before reaching at 0.3, and maximum ultimate bearing capacity can be obtained when 0.3, which is followed by a significant decrease with continuing increase of . Before reinforced retaining walls failing, the ratios of settlement of foundation and height of wall are less than 2%; and the ratios of horizontal deformation of panel and height of wall are less than 1%; moreover, horizontal deformations at the top of walls are significantly greater than the deformation in the middle and at the bottom of walls while is less than 0.6. Additionally, the maximum strains of reinforcement happen to the positions where being away from panel with the increase of ; and the maximum values of strains will occur at the top layer of reinforcement and then shift to the middle layers. Lastly, three main failure modes of retaining walls, shallow failure with blocks at the top of walls squeezed out, failure surface occurring at the verge of foundation developed deeper and global failure of retaining walls, are presented.

To build the tunnel project by slurry shield method in a variety of complex environments needs to solve the problem that how to form safe and effective slurry membrane support timely on the excavation surface. The isotropic consolidation curves of the normal consolidation clay in the modified Cambridge model is used to establish the relationship between the membrane solid holdup and the effective stress of slurry membrane. Combining this with the permeability of ideal model of round sphere particle pore and the relationships among the membrane solid holdup, permeability and specific resistance of slurry membrane, a new constitutive model for the formation process of slurry membrane is established. The one-dimensional model is expanded to two-dimensional one, and the incremental analysis method of the formation process of slurry membrane is also given to study the increasing rules. Based on this, the relationship between slurry membrane filtration loss, and factors such as location, time, unit weight ratio and shield diameter are established. The results show that the modified Cambridge model could well characterize the compression consolidation properties of slurry membrane. Under high operating pressure, unit weight of slurry has little effect on membrane growth; but its influence cannot be ignored for super-large diameter shield.

Block theory is a commonly used method in stability analysis of geotechnical engineering, but there is no research on non-coalescence structural planes, which makes the key block searching neither accurate nor adequate. It is an essential issue for block theory studies that how to deal with the non-coalescence structural planes and whether they should be connected. Coalescence strength and peak strength of rock samples containing two coplanar structural planes in different rock bridge angles, frictional coefficient of structural planes, lateral press, and connectivity rate are calculated through numerical simulation method. Coalescence coefficient is introduced to quantitatively describe the relationship between coalescence strength and peak strength. The coalescence strength is a standard to estimate whether the rock bridge is coalescent or not. The function is established between coalescence strength and rock bridge angle, frictional coefficient of structural planes, lateral press, and connectivity rate, which is the rock bridge coalescence law of rock mass containing two coplanar structural planes. The law can accurately determine that whether the rock bridge should be connected for the rock mass containing two coplanar structural planes. Key blocks, which are slipped due to rock bridge coalescence, are searched by block theory based on rock bridge coalescence law.

The gas injection and recovery casing structure is an important hub to ensure the normal operation of underground salt rock gas storage. During the operation of gas storages, the casing concrete is vulnerable to tensile failure because of the volume contraction caused by creep. Therefore, in order to understand the mechanical and deformational characteristics of the casing cement ring, the three-dimensional geomechanical model test technology is adopted and the physical model test on operation process of Jintan salt rock gas storage casing under the influences of different risk factors including different gas recovery rates, different gas production pressures and cavern pressure loss is carried out. The 3-D geomechanical model test can reflect the mechanical and deformational characteristics of the concrete ring of gas storage casing better. The results show that: (1) the axial tensile strain of casing cement ring gets greater as the increase of gas recovery rate, in order to ensure the operation safety of the casing, the maximum gas recovery rate should be less than 0.65 MPa/d. (2) The axial tensile strain and the creep compressive stress acting on the casing increase with the decreasing of the distance between the casing shoe and the top of the cavern. In order to ensure the safety of the gas storage, the distance between the bottom of the casing and the top of the cavern should be more than 10 m. (3) The creep compressive stress acting on the casing increases significantly with the decrease of the gas production pressure, so the minimum operating pressure of storage should be more than 3 MPa, and the accident of pressure loss should be prevented to the minimum.

Based on the results of cyclic loading tests of two types of deep buried marbles and from Jinping II hydropower station, evolution of elastic parameters of marble under different confining pressures is studied. The results show that the elastic modulus changes significantly with the development of confining pressure and internal variable; while Poisson's ratio does not change significantly with confining pressure. Quantitative relationship between elastic modulus, confining pressure and internal variable is proposed based on the test results; and an elasto-plastic coupling model is set up considering the effect of confining pressure and implemented in FLAC3D by using C++ language. Then, the result of triaxial compression test is simulated. By comparing the simulating results with and without considering the effect of confining pressure, it is shown that there is significantly better agreement between the simulating results considering the effect of confining pressure and test data. Efforts of this paper can give an important reference to numerical accuracy for rockmass of deep engineering, especially for brittle rockmass with the characteristic of fracturing under small deformation.

For the significant influence of the interface between salt rock and interlayer on the stability and tightness of gas (oil) storage caverns in bedded salt rock, related research of meso and macro-aspects on the fracture properties of the interface has been launched. On meso-aspects, scanning electron microscope(SEM) has been carried out; and the results reveal that the grains embedded with each other very tightly so the cementation near the interface is good; it supplies advantageous guarantee for the tightness of the caverns. On macro-aspect, based on the mechanical theory of composite laminated rocks, the expressions of stresses near the interface of bedded salt rock have been established; and the characteristics of deformation and fracture of interlayer have also been analyzed. The research above indicates that the stress state of the interface is very complex. The anchoring effect of hard interlayer exerting to salt rock has been indicated; and the research also reveals that the stress concentration tends to occur near the interface between hard interlayer and salt rock. Combining the aspects of meso and macro together, the research shows that the mechanism of fracture initiation and propagation, and the formation of percolation paths, are induced by both the meso-structure properties and the macro stress state of the interface. The analysis provides some references for further study of the stability and tightness of storage caverns in bedded rock salt.

Seepage tests under different loading and unloading confining pressures and different hydraulic gradients are conducted on single granite fracture to study the effects of stress history on fracture permeability evolution. Experimental results show that during loading process, flowrate is approximately linear with hydraulic gradient; under the same hydraulic gradient, flowrate decreases with the increase of confining pressure at a step-down rate, but with further increase of confining pressure, the reducing amplitude of the flow becomes smaller and smaller. Under the same confining pressure and hydraulic gradient, the flowrate of the single granite fracture deceases obviously during unloading process compared with that during loading process. Furthermore, flowrate is no longer linear with hydraulic gradient during the unloading process of confining pressure. Comparison between roughness coefficients before and after test shows that, joint roughness coefficient(JRC) of the fracture after test decreases dramatically due to the normal compression and scouring of the seepage fluid. Obvious hysteresis of fracture permeability recovering is also observed, indicating inelastic deformation of the fracture occurs under combined effects of normal stress and fluid scouring.

To investigate stability characteristics of landfill cover system with different slope length types (i.e. finite length or infinite length), and different interface types (i.e.weak interface or strong interface), the failure mode of landfill cover with different slope length types and different interface types at limit state is obtained by model test. Based on the test results, an allowable landfill cover failure mode and the velocity field are established. Meanwhile, the consistent stability analysis model is obtained by using the upper-bound solution theory, which agrees well with those from the model tests. The stability of new environmental protection technology of ecological sludge evapotranspiration technology (EST) is studied by this model. The results show that: the upper part of the failure plane is straight, which is under the carrying soil and parallel with original slope surface; but the lower part is approximate straight line connected with the upper-part with a angle. With decreasing the length of slope, the safety factor of cover system will be increased; but the relation between thickness and safety factor of cover system is to be related to interface types. The stability of cover system is mainly controlled by shear strength of interface; and it is not obvious to increasing the safety factor of cover system by increasing substrate shear strength; it is better to increase the safety factor of cover system by increasing the cohesion of interface than increased the internal frictional angle of interface.

It is of great importance for studying mechanical effect of initial support system in tunnel engineering when analyzing distribution and variation of fully grouted rock bolt’s stress in elastoplastic surrounding rock. A bolt’s axial displacement differential equation is established according to the stress equilibrium in a small section of a rock bolt and the shear stress transfer mechanism of anchorage body interfacial layer between rock bolt and surrounding rock. Then the axial load distribution function and the shear stress distribution function on the interface of the fully grouted bolt are obtained by solving the differential equation under the interaction between rock bolt and surrounding rock mass. The reaction of the shear stress on interface of the fully grouted bolt on the surrounding rock is assumed to be symmetric radial action. The plastic zone radius of circular tunnel for bolt-shotcrete support can be solved by means of Mohr-Coulomb yield condition. On the basis of the model and function above, the mechanical effect of system for surrounding rock and initial support is analyzed. According to the analysis of example, it is shown that selection of supporting time has great influence on anchoring effect and surrounding rock stability. It is suggested that increasing the thickness of the grouted layer properly can decrease efficiently shear stress concentration at bolt end and also can improve the reinforcement effect of fully grouted rock bolt.

The increase amplitude of residual strength of rock is larger than the rock peak intensity of rock with the increase of confining pressure. Gradually, residual strength becomes the main factor of complete stress-strain curve of rock at the stage after peak intensity. While establishing statistical damage constitutive model, it’s necessary to modify the residual strength. Based on the strain strength theory and hypothesis of rock particles intensity obeying Weibull random distribution, a statistical damage constitutive model for rock under triaxial compression，which can describe the characteristics of rock post-peak softening，is established by adopting Hoek-Brown criterion, and the residual strength to modify the damage parameter is considered. Then, all these model parameters analytic solutions are deduced according to the geometric features of rock complete stress-strain curve. On the basis of experimental results of granite specimens, the influences of Weibull distribution parameters on the rock damage constitutive model are studied. At the same time, the value of modified coefficient and the damage process of rock are discussed. Finally, the achieved theoretical curves by the damage model of rock under different confining pressures are comparatively analyzed with the results of conventional triaxial compression test of four kinds of rock: porphyaceous adamellite, fine-particle marble, sandstone and silty mudstone. The results indicate that this statistical damage constitutive model is able to provide an accurate description for complete stress-strain curve and residual strength for rock. All these are meaningful to the research of rock damage as well as to choose suitable measures to strengthen rock mass.

For high permeability strata underlying a low permeability confining layer, vacuum can occur in the vadose zone during drainage of groundwater and can slow down the drainage. The dynamic characteristic of this vacuum decay effect is still an unresolved subject in the area of seepage in rock and soil. Drainage experiments of double-layer sand column are carried out using fine sand (thickness is 2-7.5 cm) as the confining layer of coarse sand (thickness is 80.5 cm). Vacuum is observed in the vadose zone which increases rapidly up to 25-35 cm H2O and then decreases gradually. As a result, drainage speed is significantly smaller than that without the fine sand layer. The more the thickness of the confining layer, the role of the vacuum decay effect is more essential. In comparison, no vacuum can be observed for a column with uniform coarse sand. Based on seepage theories, simplified flow equations of water and air are proposed to explain the phenomena in the experiments. Approximate analytical solutions are obtained for the early and late periods of the drainage, indicating that the maximum vacuum increases with increasing of the thickness of the confining layer under a nonlinear trend. It is found through parameter identifications that the air-permeability in the late period is significantly higher than that in the early period, which reflects the influence of water-content on confining layer. This study shows the significance of air flow in groundwater drainage from sands if a low permeability soil exits on the top.

In order to study the disintegration mechanism of unsaturated granite residual soil, a serious of samples with different moisture contents and compaction degrees are made from granite residual soils from Guangzhou, south of China. Homemade apparatus is used for test, and meliorated method and computation formula were utilized for analysis. This meliorated method considered gas evolution during immersing into water so as to reduce the avoidable errors. Meanwhile, simplified model of particles with low degree of saturation is analyzed from the microscopic perspective. The disintegration mechanism of unsaturated granite residual soil is analyzed. The main controlling factors had been regarded as effective void ratio and matric suction. Relationship between above two control factors and disintegrating velocity has been established on the basis of effective void ratio analysis and estimation of soil water characteristic curve (SWCC). The results reveal that it shows exponential function and logarithm function relationships respectively.

The consolidation coefficient is not a constant in the process of soft-soil consolidation. The variation regularity of consolidation coefficient is related to engineering properties of soil, preconsolidation pressure and effective consolidation stress. When the consolidation stress is less than the preconsolidation pressure ( ), the consolidation coefficient decreases with the increasing of consolidation stress. When the consolidation stress equals to the preconsolidation pressure ( ), the consolidation coefficient takes the minimum value. When the consolidation stress is greater than the preconsolidation pressure ( ), the consolidation coefficient of silt increases with the increasing of consolidation stress. There is an apparent double logarithmic linear correlation between consolidation coefficient and consolidation stress(ln( or )- ) of Wenzhou silt. The fitting formula is a piecewise function according to the preconsolidation pressure( ). The variation regularity of consolidation coefficient during soil consolidation gotten by improved Kadota method further illustrates and verifies the expression presented. The consolidation coefficient of silt during the entire loading procedure could be calculated by the double logarithmic fitting formula accurately, which provides the important parameter for the consolidation settlement calculation.

The process of sedimentation and consolidation of soil particles in dredged slurry is very complex, and it is not clear about the sedimentation and consolidation of soil particles. A modified experiment method which is called multilayer extraction sampling is adopted in laboratory test. The volume distribution regularity of soil particle is firstly obtained, and then the average settlement velocities of soil particles in different soil fractions by using volume flux function method are calculated. The result reveals that: there are three different zones existing during the sedimentation and consolidation of soil particles in dredged slurry. They are hindered settlement zone, floc compression settlement zone and self-consolidation zone separately. During the first hour and the next 6 hours, the velocity of soil particles is much smaller than the velocity calculated by using Stokes equation in hindered settlement zone, and it is related to the particles diameter of 0.488 1 and 0.111 7 th power. There is no separation of soil particles in floc compression settlement zone and self-consolidation zone. All soil particles in these two zones are belong to the sediments. The density of floc compression settlement zone is about 1.04 g/cm3.

The earthquake induced permanent deformation is a key index for aseismic safety evaluation of rockfill dam. In order to calculate the permanent deformation reasonably, both residual volumetric strain and residual shear strain induced by the earthquake loading should be taken into account. For this reason, the method presented by LIU Han-long is modified. In the modified method, the residual volumetric strain is modeled by a shear-dilation-based approach. The derivation of the dilatancy modulus matrix is given in detail; and the calculation parameters and the analysis steps are also introduced. To test the reliability of dilatancy modulus matrix, the permanent deformation mode of a typical element is analyzed, the computed shear strain and volumetric strain are in good coincidence with the theoretical values. After that, the proposed method is used to calculate the earthquake induced permanent deformation of a core rockfill dam and a concrete faced rockfill dam. The computed distributions of the vertical, longitudinal and transversal permanent displacements are studied in detail. By comparing with the measured results, it is found that the dam deformations are mainly residual settlement; and the horizontal displacements are relatively small. It is proved that the proposed method can catch the features of the permanent deformation behavior of rockfill dam and it can give more reasonable results.

In order to explore the calculation method of the inflatable anchor bearing capacity, according to the model test, the stress characteristics and failure forms of the inflatable anchor during pullout are analyzed as well as the variational characteristic of the load displacement curve of anchor. Based on the theory of cavity expansion, the formula for the inflatable anchor side resistance and end resistance calculation are derived through a simplified mechanical model. The calculation values by the theoretical formula are compared with the experimental results. The results of the study show that: (1) the elastoplastic deformation mechanism of the expansion body end to soil can be well described by the spherical cavity expansion theory, as well as the estimation of end resistance value. Due to the inflated pressure on the soil extrusion expansion effect, the anchor side resistance is greatly increased. (2) The results from the ultimate bearing capacity theory formula are coincident with those from the pullout test, so as to validate the ultimate bearing capacity theory formula. (3) With a case of comparison to screw anchor, inflatable anchor shows the 4.3 times of the bearing capacity over single anchor sheet screw anchor and about 1.9 times over double anchor plate screw anchor, so as to show the obvious advantages of the inflatable anchor bearing capacity.

The internal displacements of surrounding rock are generally surveyed after the excavation of working face, which results in a certain measuring loss for the field observation. In order to get the change law of its internal displacements during tunnel construction, the multipoint-displacement testing equipment is developed, which is applicable to measuring the vertical full displacement of the vault surrounding rock. This equipment is featured by the simple test principle, the convenient field planting and the high-accuracy test data, and it has more measuring points than that of the traditional multipoint-displacement testing equipment has. The internal displacements of vault surrounding rock of the Alatan tunnel is measured by this equipment to obtain its change law in the tunnel’s shallow section. It shows that if the internal displacements of surrounding rock are generally surveyed by the traditional multipoint-displacement testing equipment, 25 percent of internal displacements of surrounding rock is lost through analysis. The range of the surrounding rock relaxation is found through surveyed data, the result is significant to the tunnel’s excavation and supporting.

Based on the introduction of surrounding pile-soil coupling anti-slide structure, a numerical analysis model of this new structure is set up. By analyzing the characteristics of stress and strain, soil-arching effect about surrounding pile-soil and coupling effect of the entire structure are discussed. Furthermore, by the model test, soil pressure distribution before and after surrounding pile and sorrounding pile bending moment distribution are tested. The mechanism of surrounding pile-soil coupling effect is proved. Finally, according to relative horizontal displacement of pile-soil coupling, the influences of the distance of behind pile, different depths of plan and different parameters of soil strength and varying effect of soil arching effect are discussed. Then, the main conclusions are drawn as follows: (1) There are four arch forms among the couple structure, such as expanding arch close to the surrounding piles, hyperbola arch between surroundind piles, hyperbola arch protruding outside between surrounding piles and hyperbola arch protruding inside between surroundind piles. (2) Anchoring to a definite depth, it can form a coupling anti-slide structure in the condition of about 4 times diameter space between surrounding piles, horizontal section using hexagon and the top using a ring girder. It can provide a guide to use the new anti-slide structure.

For understanding rock crack initiation, propagation and development in hard rock destruction (rockburst, spalling, collapse etc.) pregnant process under high in-situ stress clearly, according to the observation and description of the characteristics of rock fracture surface, a method for calculating its attitude is presented here based on the moment tensor theory. The estimation of the fracture type using the motion angle is also conducted in this method. This method is applied to analyzing the formation mechanism of rockbursts encountered in the deep headrace tunnels in the Jinping Ⅱ hydropower station. In the case study, in the estimation of rock fracture type, the technology of moment tensor decomposition is proved accurate. Based on the comprehensive study of the strikes and dips of rock fracture surfaces and the representation features of the pit of rockburst, it is concluded that strain-structure slip rockburst forms tension crack firstly; and cracks develop from the shallow into the deep in rock mass at the beginning of the excavation disturbance because of the surface of the rigid structure. When tensile crack tip is close to the surface of the rigid structure, the surface of the rigid structure will slide; and if there is the surface of the other rigid structure in the relative deeper rock mass, the first surface will continue to the deeper rock mass based on tensile cracks, except continuing to the excavation wall because of the tangential stress increase in the shallow rock mass. When tensile cracks deepen into the second surface, the surface slides. At last, the damaged rock mass is thrown out from the failure boundary which is assembled by the shear slip planes.

Based on the Biot’s theory of porous media, the dynamic response of heterogeneous saturated soil subjected to strip loading is researched. Applying the Helmholtz vector decomposition and Fourier transformation, the calculation formula of reverberation ray matrix method (RRMM) is established for two-dimensional transient response of fluid-saturated soil. Assuming that the material properties of the saturated soil have an exponential law distribution along the thickness-coordinate, by using numerical inverse Fourier transformation, the displacement, the stress and the pore pressure are obtained. The effect of heterogeneity on transient responses of graded saturated soil is demonstrated and discussed. The numerical result shows that there is a significant difference on dynamic response between heterogeneous saturated soil and homogeneous saturated soil. The amplitude of fluid pressure and stresses that right below the middle point of the strip load is increased when the soil heterogeneous degree becomes high. In addition, the vibration frequencies of displacement, fluid pressure and stress increase with the increasing of soil heterogeneous degree along the horizontal direction.

Martin-Finn dynamic pore water pressure incremental model simplified by Byrne is used to describe the liquefaction characteristics of the soil. Davidenkov viscoelastic constitutive model is used to describe the nonlinear characteristics of the soil. Then a two-dimensional analysis model about the nonlinear static-dynamic coupling interaction between liquefiable foundation and metro station structure is established. The dynamic effective stress analysis method is used to analyze the dynamic response of two-layer three-stride island-type metro station structure in liquefiable foundation; and then the results are compared to the case of dynamic total stress numerical analysis. The results show that, the soil which is adjacent to the both sides and bottom of metro station are easier to be liquefied; the liquefaction of foundation has a significant influence on the ground acceleration response; the metro station is obviously floated under the influence of liquefaction and has a convex deformation in the middle of the station. The failure modes of the station are as follows: the tensile failure in upper roof and both ends of bottom plane, the arch bending failure in the middle of lower base plate side span , the compressive failure in interior column, the bending failure in bottom of side wall.

The effect of stress dispersion and shear strength of dry crust has been considered, the effect of intermediate principal stress is studied; and the realistic coefficient of lateral earth pressure has been undertaken. Reference has been made to the Flamant formula of polar coordinate system and unified strength theory. Therefore, new formulas of the critical edge pressure and critical loading of natural soft soil foundation are deduced. A calculation method of the critical height of embankment on natural soft soil foundation is also proposed. In accordance to a practical example, this paper also expounds a comparative analysis which has been made on calculation results of the critical height of embankment, different values of coefficients of lateral earth pressure of soft soil layer and dry crust and intermediate principal stress b are taken into consideration. This paper also studies the effect of these factors on the critical height of embankment . It is shown that the changes of and b have significant influences on the critical height of embankment . New formulas can more accurately reflect the essentials of soft soil foundation bearing capacity. It is of great significant to the construction of embankment in the natural soft soil foundation covered with dry crust.

According to the in-situ stress measurement results with the method of hydraulic fracturing measurement at three nuclear power stations in Guangdong province, the distribution characteristics of current in-situ stress state at each nuclear power station are obtained. The results show that the horizontal stresses are dominant at each nuclear power station; and that horizontal principal stresses increases linearity with the depth at Dayawan and Yangjiang nuclear power station, while the phenomenon is not obvious at Taishan nuclear power station; and that the direction of maximum horizontal principal stress is NW-NWW at Dayawan and Yangjiang; however, is NNW at Taishan. Based on the data of stress and the interrelated theories as well as criterions, it is concluded that major axis orientation of tunnels at Dayawan goes against the stabilities of the tunnels; while these are beneficial to tunnels’ stability at Taishan and Yangjiang; and that the favorite shapes of all tunnels’ cross-section are ellipses with horizontal long axis, vertical short axis and long to short axis ration as lateral pressure coefficient; and that the rock burst is not happened during tunnels excavation at different buried depth. Finally, based on the sliding friction criteria of fault, the stabilities of the active faults are discussed.

Structure reliability calculation problem which contains relevant random variables can be solved conveniently by establishing iterative formula of check point in generalized random space directly. A kind of iterative formula of check point with better convergence is derived in generalized random space; and it is applied to reliability analysis of slope stability. According to the reliability analysis of Kajiwa concrete face rockfill dam slope stability under seismic conditions, it shows that: (1) The input parameters used in safety coefficient method are determined values, so that the random fluctuation influence of parameters can not be considered in calculation. Reliability analysis can reflect the influence of randomness of parameters; it is beneficial to evaluating engineering safety and risk resistance capacity. (2)The reliability index of structure will increase by considering the earthquake and the dam slope instability probability occurring simultaneously, and the increased range is related to the probability of earthquake. (3)Nonlinear strength index of rockfill has positive correlation; the reliability of slope stability will increase when the correlation of strength index is considered.

Abutment pressure zone and roof unloading area in the roadway intersection are superimposed. Therefore, in the roadway intersection, perturbation range of the surrounding rock is greater than other parts, which leads to intensified deformation and increased original support stress, is not conducive to the stability of the roadway. In order to analyze the stability of roadway intersection, finite element simulation software is used to simulate the five kinds of typical examples and analyze the deformation of the roadway intersection. At the same time, because most of the geomaterials have the strain-softening characteristics, the rock mass characteristics of strain softening are taken into account. The result shows that: in the roadway intersection, due to the abutment pressure superimposed, the surrounding rock deformation of the roadway is further increased. For the roadway intersection, different crossover angles influence the deformation of roadway intersection differently. The specific performances are for the main roadway (roadway1), the smaller the cross-angle is, the greater the deformation degree of acute angle side is; the bigger the cross-angle is, the greater the deformation degree of obtuse angle side is. Because the cross angles of these five model are different, the largest roof settlement areas of the main roadway (roadway 1) show different degrees of offset to the acute angle side, and the smaller the cross-angle is, the more obvious offset phenomenon is. The results also show that: the deformation of support lane (roadway 2) is also affected by cross-angle. The smaller the cross-angle is, the greater the deformation of the roadway is. The results can provide reasonable references to design and support for similar engineering.

Numerical analysis has become the most important method for analyzing and predicting the deformation of excavations in close proximity to sensitive properties. One of the key problems in a numerical analysis is to select proper soil constitutive models and their corresponding parameters. HS-Small model including HS model parameters and small strain parameters is suitable for numerical analysis of deep excavations because HS-Small model can not only reflect shear and compression hardening but also account for shear modulus attenuating with strain in tiny strain range. However, it is difficult to obtain the whole set of parameters of HS-Small model. Parameters of HS model which determined by soil tests are firstly checked through numerical analysis of five excavation histories in Shanghai area. Determination of some parameters of HS-Small model is then modified based on parameter sensitivity analysis. The most sensitive parameter is determined by back analysis of the field measurements of five case histories. Validity of the whole set of parameters of the HS-Small model is verified by numerical analysis of several typical excavations in Shanghai.

Compared with rock fragment by static stress, there is a stress transition from compression to tension in the specimens under dynamic loading, e.g. the compression stress will be changed to tension during wave propagation. Based on damage theory and FE method, rock fragmentation mechanism induced by a drill bit subjected to dynamic loading is investigated. To exclude influence of reflection wave from the boundary, the viscoelastic boundary is considered in the simulation. Firstly, the validation of the viscoelastic boundary in homogeneous and heterogeneous media is examined. Then, the response of rock with different heterogeneities under dynamic loading is analyzed. The results show that: in elastic situation, when the rock is loaded, the area, which locates the edge of contact area between the drill and rock and near the free surface, is the tension sphere, and the highest tension lies in former. The highest shear stress lies near the contact surface but exists a distance. If the homogeneity is high, the rock fragmentation process can be divided into three phases, e.g. Hertz cracks, radial cracks and lateral cracks. As Hertz crack propagation, the stress by confinement becomes smaller; the process of wave propagation is changed and the emergency of tension is the key of crack initiation and growth. When the homogeneity is low, fracture pattern shows a wide spectrum, in other words, shear failure of proportion is increased and the failure mechanism becomes complex. The results are also noted, as the granular rock, if the size and proportion of grain can’t be negative; the homogeneity of grain and matrix should also be considered. When the granular rock is subjected to dynamic loading, the crack can across the grain or along the grain-matrix boundary. In all, the tension stress during the wave propagation is the key of crack initiation and growth.

There is a large terrain gap to some sections of cut-off wall for Daning reservoir, on both sides of wall and the top of lower wall, which affected by construction significantly, need a large amount of backfill soil. A three-dimensional numerical simulation is adopted based on experiment and monitoring data to analysis the effect of backfilling construction. The interaction between cutoff wall and backfilled soil is considered in the simulation. The stresses and deformations of the wall forms affected by different distances and contact are analyzed; the distribution of internal deformation and stress along the construction proceeding is obtained at the same time. The analysis shows that the upper wall tilts toward inside of reservoir, and the maximum principal stress appears at top of transfer position of the two walls. The inclination of the lower wall is very small and its maximum principal stress appears at the bottom of guide wall. No tensile stress exists in the lower wall. The stress and deformation of the wall have some variances along the wall, and the greatest change presents at the corner. The simulation results are comparatively close with the monitoring results.

By simulating the “trapdoor” test of Terzaghi using discrete element program, the characteristics of displacement of particles and load transfer are studied from granular and microcosmic viewpoint when soil arching existing in frictional geotechnical material; moreover, the influences of particle diameter, porosity, particle frictional coefficient, width of trapdoor and trapdoor displacement on soil arching are also studied. The results indicate that due to the effect of soil arching, the vertical loading above soil arching is transformed to horizontal loading within a certain range above the arch foot; then the horizontal loading will transfer to both sides of soil, which leads to horizontal displacement of soil. When the trapdoor moves downward, the effect of soil arching evolves continuously; and enlarging the particle diameter and frictional coefficient, decreasing porosity and trapdoor width will not only enhance the effect of soil arching but also narrow the influence range of soil arching.

In order to investigate the scale effect of coarse-grained materials, the gradations of Sanbanxi and Shuibuya dam rockfills are statistically analyzed. The Talbot curve can be used as the original “average gradation” for high rockfill dam after analysis. This original gradation curve is scaled utilizing the mixing method which is widely used in projects to compound samples whose maximum particle size distributed from 20 to 180 mm. The relationships between characteristic parameters such as dry density, initial elastic modulus and bulk modulus and the maximum particle size of each group samples are revealed after many sets of numerical experiments which conducted by PFC2D. The results show that the scale effect is related to density control standard. The mechanical parameters are monotone function about the maximum particle size, and the original gradation has 1.5 to 1.6 times anti-distortion capacity of scaled laboratory gradation under the same relative density condition. On the other hand, mechanical parameters are non-monotone function under the same dry density condition. Finally, the mechanical mechanism of scale effect is interpreted with mesomechanics. The particle size and thought are expanded on the basis of PFC2D numerical test.

Affected by various factors, the stiffness difference of the building adjacent to the excavation is significant. In order to understand the effect of the stiffness difference of building, the response of the building with different stiffnesses adjacent to excavation is analyzed subtly considering the small strain stiffness behavior of soil. The analytical results show that when the building with different stiffnesses locates over the lowest point and the hogging zone of the settlement trough, the tensile strain of the wall is the most obvious. In this case, the locations for any stiffness buildings are in most adversities. With the increase of the stiffness of the building, the deflection and the tensile strain of the wall decrease as the logarithmic curve. For the building with low stiffness, the tensile strain of wall chiefly depends on the extent of the settlement trough and is less affected by its stiffness. When the stiffness of the building is large, the performance of the building affected by the excavation primarily appears as rigid body motion, but the internal deformation of the building is relatively small.

On account of existing problems in rock elastic wave velocity inspecting, such as low signal to noise ratio(SNR), difficulty in reading the prime time of echo and inspecting large volume rock, pulse compression method is proposed. Linear frequency modulation (LFM) signal is mostly used as exciting source due to its remarkable properties, such as wide bandwidth, high energy and high SNR. While receiving terminal, echo signal is filtered by a matched filter, and the compression signal of high SNR is obtained. The wide time and band characteristics of LFM signal are introduced. In addition, the pulse compression principle and digital implementation process are also analyzed. The influence of the bandwidth of transducer on exciting signal is studied; elastic wave velocity of several rocks is inspected with a conventional method and pulse compression method. The wave velocity differences of two testing methods show a limited error. The detailed implementation and calculating process of pulse compression inspecting method are also described. The advantages and prospects of the method are analyzed. Results show that pulse compression method can be applied to inspect the elastic wave velocity in rock and access engineering quality.