Large amount of triaxial shear experimental evidences show that the mechanical behaviour of soft rock is dependent on the confining stress. The strain softening and shear dilation of soft rock were reduced with the increase of the confining stress. When the confining stress is large enough，the strain hardening and shear contraction occur. The original thermo-elasto-viscoplastic model for soft rock has different parameters for different confining stresses and is therefore difficult to be applied to engineering problems. In order to describe the mechanical behaviour of soft rock with one set of parameters，the original constitutive model was modified to consider the confining stress dependence. The parameters of the modified model have explicit physical meanings and can be determined from triaxial tests. The accuracy of the modified model was verified by comparing with the simulated results and experimental data.

Fault influenced zone is one of the key factors in site selection and design for high-level radioactive waste repository. Field survey and chart analysis were used to obtain the relationship between the fault distance and mean length of traces，the midpoint density of both sides of fault. When the distance increases，the mean trace length increases and the midpoint density decreases. The correlations obey a negative exponential function. When the distance exceeds the width of the fault influenced zone，the mean trace length and the midpoint density fluctuate at a certain value. Accordingly，both sides of the fault can be divided into two regions：serious influenced zone I and influenced zone II. The width of the maximum influenced zone and the distribution are markedly different among different fault types，the one of the normal fault is the smallest，the one of the strike-slip fault is the second，and the one of the reverse fault is the largest. Meanwhile，the influenced zone of the strike-slip fault shows a symmetrical distribution，and the normal and reverse faults show asymmetrical distribution. The width of fault influenced zone and the length of fault obey a power function approximatively.

Based on the analysis to the rheological model proposed by Shao-Zhu-Su for geomaterials，it was found that the traditional computational algorithm for solving the convolution integral had obvious shortcomings regarding the storage of time-dependent variables and computational efficiency. In this paper，a nonlinear explicit integral algorithm(NEIA) and a simplified linear explicit integral algorithm(LEIA) were developed with the help of mathematical transformation and Taylor expansion. The proposed algorithms were validated and compared through numerical creep tests and relaxation tests. Since the new method reduced significantly the number of variables to be stored and avoided the accumulation operation over loading history，its computational efficiency was improved remarkably and therefore more suitable for large-scale numerical analyses of rock structures. It is pointed out that the proposed numerical treatment is also applicable to other integral-type rheological models.

The rock mechanical behavior under the two-phase pore fluid condition of CO2-water is one of the key scientific issues in geological storage of CO2. The fracturing experiments of sandstone in two-phase fluid of CO2-water were conducted with the test device named hollow-cylinder tensile tester in two-phase fluid developed in-house. An effective stress model in two-phase fluid of CO2-water was studied based on the experimental results. The internal，confining and axial pressures were imposed on the hollow cylinder sample to build a true triaxial stress state so that the minimum principal stress was negative，which was similar to the stress state in surrounding rock of borehole. A semi-permeable disk method was used to flood water to precisely control the partial pressure and saturation of two-phase fluid of CO2-water in the sample. The fracturing pressure was measured by fracturing the sample with internal pressure. The function of fracture pressure and effective confining pressure was fit with the results of the fracturing tests of samples in water under different effective confining pressures. Finally，the prediction models were deduced based on the fitting function and four types of unsaturated effective stress formula were proved to apply to rock. The prediction models were compared with the experimental result to indirectly verify the applicability of these formulas for describing the effective stress under the two-phase fluids of CO2-water condition. The results indicated that Bishop?s unsaturated effective stress formula was the most appropriate to describe the issue for the tested sandstone，which can be directly used as the effective stress model in two-phase fluids of CO2-water.

Hydro-mechanical triaxial coupling tests were conducted on granitic gneiss with a servo-controlled triaxial equipment. The variations of permeability with seepage pressure，confining pressure，effective confining pressures，volumetric strain and stress paths were investigated based on the results of conventional triaxial compression and triaxial cyclic loading test. During the failure process of rock under two different stress paths，the permeability at each stage decreased with the increase of effective confining pressure. The influence of seepage pressure and confining pressure on permeability was described through the change of effective stress coefficient，effective confining pressure and internal micro cracks and pores in failure process. In triaxial cyclic loading test，the unloading permeability was significantly greater than the corresponding loading permeability. Before the turning point of volumetric strain，permeability decreased during loading and increased during unloading，forming a relatively complete permeability hysteresis loop. After the turning point of volumetric strain，unloading permeability can not be fully restored. The volumetric strain clearly and acutely reflected permeability variation. The turning volumetric strain or its corresponding stress can be regarded as an index of rock permeability change.

In order to reveal the dynamical shearing behaviors of rock avalanche debris under the effect of entrapped gas，an annular shear shell was designed based on the flow characteristics of rock avalanche debris under the effect of entrapped gas. A series of ring shear tests were conducted to record the dynamical shearing values of rock avalanche debris as the variation of gas entrapment. During the motion of debris，the entrapment of gas reduced the dynamical shearing resistance between debris and top disk obviously. The shearing resistance between the debris and top disk fluctuated with time. With the increase of shearing time，the shearing resistance between the debris and top disk increased slightly. And the larger the shearing rate was，the more obvious this trend.

Based on the elasto-plastic analysis of shear stress distribution in anchorage section，field destructive tests were carried out on the tension-concentrated anchor cable(TCAC)，the tension-dispersed anchor cable (TDAC) and the pressure-dispersed anchor cable(PDAC). The comparative analysis was made regarding the shear stress distribution characteristics，the bearing capacity and the load-displacement curve. In the elastic stage，the peak shear stress appeared in the range of 0.5 m near the acting point of concentrated force and increased with the load growing. In the plastic period，debonding slippage occurred in the range of 0.5 m near the acting point of concentrated force，and the peak shear stress was shifted to the middle of anchorage body gradually. The residual shear stress on debonding section was about 1/3 of the peak value. TDAC has more uniform shear stress distribution and longer effective anchorage length，its carrying capacity was 31.1% higher than TCAC. Due to the radial expansion of anchorage body under pressure，the bond strength between PDAC and soil was improved，which made the PDAC?s carrying capacity to increase by 17.7% compared with TDAC. It can be seen from the load-displacement curve that the PDAC had better displacement ductility and deformation resistivity，therefore，it had advantages in soil anchoring.

Evaluation of landslide susceptibility for Wanzhou district of Evaluation of susceptibility of landslide hazard plays an important role in landslide hazard risk management and urban planning. In previous studies，few scholars had done any in-depth analysis and discussion on the state division of index factors. Wanzhou district of the Three Gorges Reservoir region where landslide disasters take place frequently is the focus of this study. Seven influence factors including stratum lithology，geological structure，water distribution，gradient，direction and structure of slopes，and land utilization were chosen to be the evaluation indexes. The state of each index was graded based on the variation of gradients of the cumulative frequency curve of landslide，the landslide area ratio curve and the grading area ratio curve. The information value model and the logistic regression model were used to build the susceptibility evaluation systems based on the data of 655 landslides in the history of the district. The susceptibility results of the two methods above were graded by adopting the K-means cluster analysis. A zoned map of landslide susceptibility for the whole district was obtained based on GIS platform. The two models were compared with respect to the modeling results，the accuracy，the application condition etc. The results showed that the prediction accuracies of the information value model and the logistic regression model reached 73.0% and 54.9% respectively，indicating that the information value model had better performance than the logistic regression model.

In order to reveal the mechanism of rock breaking of abrasive water jet，experiments of abrasive water jet erosion on typical brittle rock(siliceous limestone) were carried out and CT scanner was used. The image processing technique and binarization processing of CT image were used to directly capture the rock fracture and damage under the abrasive water jet. The results showed that in the process of rock erosion，in addition to the rock removal and an erosion hole in the interior of the rock formed by circular cross-sections and “V” shape vertical structure. A large number of small cracks appeared on the hole wall，which damaged rock within a range. The results verified the existence of damage properties under abrasive water jet erosion.

Based on the beam-spring and shell-spring models for shield tunnels with double-layer lining，the compound and overlapping structures on a three-dimensional model were established respectively according to the different structure form of contact surfaces between the segment lining and the secondary lining. The plastic-damage model was adopted to represent the nonlinear characteristics of concrete. Considering the effect of rebar built in segment on the mechanical behaviors，the existing model was adopted to simulate the yielding，hardening and softening phenomenon of the reinforcement. In this model，the connecting bolts were simulated by the three-dimensional elements instead of spring elements. The discontinuity among the segments，connecting bolts and the secondary lining was faithfully reflected in this model. Two kinds of three-dimensional models were established for the Shiziyang tunnel on Guangzhou—Shenzhen—Hong Kong passenger dedicated railway. Three-dimensional models were verified by the results of similarity model test. The results show that the contact surfaces are separated and zero pressure zones appeared due to the local incompatible deformation between the segment lining and the secondary lining under the loading. The local stress concentration at the place of the key block in the secondary lining occurs easily. In this position，the axial force bending moment vary unevenly and the contact stress pressure is larger than that in other location.

The high ground stress，high temperature，high osmotic pressure and strong time effect cause the deep fractured rock to show certain ductility and creep in mechanical characteristics of soft rock. The current anchoring theory lagging behind the engineering practice leads to the common usage of the empirical and semi-empirical methods in most of the anchoring engineering. During the last several decades，a number of on-site and laboratory tests and numerical calculations were carried out by many scholars home and abroad，and significant achievement in the theoretical research of bolt anchorage mechanism in rock mass were made. The universality and accuracy of these results are low because of the complexity of deep geological conditions. Combined with the existing anchorage theory，it is of great significance to use a reasonable numerical simulation method and on-site and laboratory tests to investigate the rock and soil anchoring mechanism and to guide the design and construction of anchoring engineering. Systematic summary was made regarding the deep fractured rock anchoring mechanism，and the key issues for the study of the deep fractured rock anchoring mechanism were concluded，including the choose of a reasonable calculation model for anchoring force transfer，the correct description of the stress distribution of the anchoring force and the establishment of the reasonable mechanical model for anchoring interface. The factors such as the effect in engineering application，the condition of anchoring rock mass and the effect of anchoring components should be considered in the research of the deep fractured rock mass.

A new method of stability analyses of thrust-type landslides was established based on the current methods of landslide stability analysis. A critical state between the failure and stable states was suggested based on the mechanism of thrust-type landslides and its determination was also proposed. Two failure modes were proposed for the progressive movement landslide. For the mode I，the whole slope failure occurred along the soft-weak layer. For the mode II，the landslide failure occurred in the rear edges along the soft-weak layer，and the shear failure happened at the front edge along the sliding body. The critical state moved from the rear zone to the front zone of the landslide progressively，i.e.，new critical state and failure zone are obtained for a progressive failure landslide during the deformation. The“S”shape curve of time and deformation is shown for the different points on the sliding face during deformation period. The relationship of deformation at different points on the sliding face and the height of landslide presents parabolic curve characteristics. Three kinds of curves between time and deformation were proposed based on the mechanical behavior classification of rock-soil mass. Types a and b are the unstable and stable curves between time and deformation of type I respectively，type c is the stable curve between time and deformation of type III. The stable analysis method for computing comprehensive sliding- resistance，main thrust force and displacement based on deformation was suggested. The cause of divergence of FEM was analyzed. A new method to take the sliding face as a boundary condition of FEM was proposed for landslide stability analyses. The condition of sliding face boundary method was described not only with the perfect elasto-plastic model(PEPM)，but also with the new constitutive model(JCM).

In deep tunnel construction，TBM faces the rock stress problems induced by overburden or anisotropic stress，which had been under more and more attention. In this paper，full-scale cutting tests are presented to investigate the effect of different confining stresses，i.e. 0，5，10，and 15 MPa，on rock fragmentation of large intact granite sample with dimension of 1.0 m?1.0 m?0.6 m induced by TBM cutter. In these tests，the characteristics of force-time curves，normal forces，rolling forces，specific rock mass boreability index，chipping thickness and specific energy affected by confining stress were analyzed.

Coupling analysis of rock mass and liners was carried out for deeply buried tunnel in TBM excavation process and sequential installation of liners. Analytical solutions of stress，displacement and radii of softening and broken zone were presented for the tunnel constructed in the strain-softening elasto-plastic rock mass with two liners installed at different times. The criterions for softening and fracture occurring in the rock mass were also given. The dilation during the softening and residual stage was taken into account in the derivation. The influence of installation times of the first and second liners on the displacement，radii of softening zone and broken zone and supporting pressure on the rock were analyzed. The variation of the pressures between two liners was discussed. If the second liner was installed when the distance to the tunnel face is about three times of tunnel radius，the displacement occurred during the second liner stage can be controlled within 6% of total displacement. The pressure between two liners was sensitive to the installation time of the second liner，however，the supporting pressure to the tunnel was affected by both the installation times of the first and second liners. The advancing rate of TBM，the geometric and material parameters of the two liners and the optimum installation time of the liners can be preliminary determined in design phase，and the time dependent displacement and stresses can also be predicted with the solution presented in the paper.

With respect to the collapse of Youfangping tunnel crossing fault at Changsha to Kunming Section in Shanghai to Kunming High-speed railway of China，the macroscopical history of the tunnel deformation was summarized，and the influencing factors of the collapse in water-rich soft rock tunnel crossing fault and the surrounding rock failure mode were analyzed. The treatment measures were proposed. The results showed that the synergistic effect of geological structure and groundwater had the most significant influence on the tunnel collapse，and to some extent，the atmospheric precipitation promoted the tunnel collapse. The impact of construction methods and supporting measures on the tunnel collapse reflected the insufficiency of knowledge. It was a combination of multiple factors that contributed to the tunnel collapse. The surrounding rock failure mode of water-rich soft rock tunnel crossing fault was concluded as the synergistic failure mode of flexural deformation and bedding slippage. Based on the analysis of tunnel collapse mechanism，the comprehensive treatment measures inside and outside tunnel were proposed to prevent the occurrence of collapse effectively.

The current solutions of cylindrical cavity expansion are based on an elastic-perfect plastic assumption. The consistency in shear deformation and shear failure is not warranted and the over-consolidation ratio and three-dimensional strength characteristic of soil also are not incorporated into the solutions. Therefore，a large deviation between the theoretical solutions and the actual conditions exists. To obtain the exact solution of elasto-plastic expansion of cylindrical cavity，the SMP criterion revised by Cam-Clay model was adopted using the associated flow rule in the stress transformed space，which can incorporate the over consolidation ratio and the soil strength in three-dimensional stresses state. The problem was reduced to a system of first order ordinary differential equations in the plastic region using the large strain deformation theory. The accurate solution to cylindrical cavity expansion was obtained by means of a numerical method under the elastic-plastic boundary conditions. Finally，the stress around the cavity during the cavity expansion process was discussed by comparing with the solutions based on the MCC model. The results showed that the solutions with SMP-MCC model reflected the change of stress field more actually，because the three-dimensional strength of soil was considered in the present solution.

In order to investigate the influence of shear rate on cyclic and post-cyclic shear behavior of sand-geogrid interface，a series of large scale direct shear，cyclic shear and post-cyclic direct shear tests were performed. The effect of shear rate on shear stress and volumetric strain at interface was studied. Moreover，comparison was made between the direct shear and post-direct shear test results. The results showed that the shear rate had little effect on shear behavior of interface in direct shear tests. On contrary，the cyclic shear stress softening and hardening were observed in the cases of low shear rate and high shear rate respectively. The interface behavior was significantly affected by the shear rate in cyclic shear tests and the shear strength of interface was impaired by cyclic loading. Overall，the influence of shear rate in post-cyclic direct shear tests was evident.

The permeability and permeability coefficient from water pressure test in boreholes are limited to the semi-infinite domain of rock. The cut-off wall is a strip domain，so it is clearly inappropriate to calculate the flow parameters using the equation for semi-infinite domain. The method of complex variable was used to transform the strip flow domain into the semi-infinite domain and permeability coefficient for strip domain was thus derived. The ratio Q?/Q of flux and k?/k of permeability coefficient for the semi-infinite and strip domains were analyzed. The influence of cut-off wall and drilling geometry L/r0 and r0 was discussed. When L/r0＜104.7，r0＜75 mm，k?= k or Q?=Q，the flux Q? and the water permeability q? in strip domain were greater than ones in the semi-infinite domain，namely Q?＞Q，q?＞q，and the permeability coefficient k?＜k. The conditions of seepage flow equation for cut-off wall measured with water pressure test in borehole were set according to the recharge boundary conditions on both sides of the strip domain and cut-off wall. Engineering examples showed that the calculated results with the proposed method agreed with the measured ones when the soil and the wall permeability ratio k1/k2＞100.

To study the mechanical effect of slope protection by halophytes and to investigate the influence of grain size on the shear strength of the rooted soil，Qaidam Basin in Qinghai province was selected as the test site and 2 halophytes(Triglochin maritima Linn. and Carex enervis C.A.Mey) were selected for study. To investigate the contribution of halophytes to the shear strength of the rooted soil and the variation of shear strengths，undrained-unconsolidation triaxial compression tests were conducted on the rooted soil and non-rooted soil samples with the grain size d≤0.25 mm and d≤0.5 mm prepared by sieving and remolding. The results showed that halophytes played significant roles in soil reinforcement. The shear strengths of rooted soil for T. maritima and C. enervis were notably larger than those of non-rooted soil and the shear strength of the vertically rooted soil was larger than that of horizontally rooted soil. The grain size influenced the shear strength of the soil. Under the same root content，the rooted soil with smaller grain size had larger value in cohesion force. The horizontally rooted soil of C. enervis was notably influenced by the grain size than the vertically rooted soil of T. maritima in shear strength of the soil.

To better understand the cracking process of expansive soil，rainfall-evaporation tests in laboratory were conducted to expansive soil. The specimen was weighed and photographed regularly during the test process in order to record the development of cracks. The image processing technique was employed to quantitatively extract the parameters of crack features，such as the crack ratio. In addition，the method of wax filling was used to observe the ultimate shape and measure the volume of cracks. It was found that the cracking process consisted of phases of slow→rapid→slow growth. 80%–90% of cracks appeared in the 2nd phase. The cracks appeared when the matric suction approached to the air-entry pressure and the development almost stopped when the water content was close to the shrinkage limit. During the drying-wetting cycles，the new cracks did not always grow along the old tracks. In the drying-wetting cycle，the cracks of expansive soil developed gradually，the crack ratio and the total number of cracks were increased. The development of cracks ceased when it reached a certain stage. The iterative presence and healing of cracks significantly weakened the soil structure that resulted in the reduction of tensile energy. The volume of the cracks is 167.8 cm3 and about 4.8% of the total volume of the sample.

Based on the centrifuge modelling of a reinforced soil retaining wall(RSW) with flexible/rigid facings on yielding foundation，an elaborated three-dimensional finite difference numerical model was established to investigate the behaviour and bearing mechanism of the wall under uniform surcharges on top. The numerical results agreed with the centrifuge modelling，showing that the RSWs with flexible/rigid facings have good bearing properties and can adapt to the large deformation of the yielding foundation. The deformation increments and the bearing properties of the structures are closely related to the location of the inner potential slip surface in the fill. When the potential slip surface cuts behind the anchor embedment，the function of the anchors decreases，leading to the apparent increase of wall deformation increment，reinforcement load increment and differential settlement，but leading to the decrease of the lateral earth pressures acting on the back of rigid facing and the embedded anchor loads. Due to the tension membrane effect，the load forces of the reinforcement directly on top the anchors are larger compared to the reinforcement with no anchors below. The lateral earth pressures caused by the surcharge loading can be calculated with the Rankine?s active earth pressure theory. In practice，the embedded anchors can be designed to bear more lateral earth pressures.