Most of slope failures of existing open-pit mines in China occurred in composite-bench slopes and single bench slopes but other types of slopes are safe generally，which indicates that the traditional method using the same standard of safety to evaluate the stabilities of different kinds of slopes needs to be improved. The concept of assessment accuracy of slope stability was proposed. The relationships between the error of stability coefficient and the safety factor，between the recent static accuracy and the static safety factor during the evaluation period and between the long-term dynamic accuracy and the dynamic safety factor during the service period were presented. A deterministic solution for the uncertainty problems in determining the safety factor was proposed. A method of equal accuracy assessment was presented. The spatial locations of rock joints should match the corresponding parts on the slope，and the size of rock joint should match the size of slope. All the slopes were systematically analyzed to find out the key joints and their combinations. The slopes were classified into the stable and potentially unstable ones using the graded analysis method. The calculation models of slope stability for those unstable slopes were established，the potential sliding surface and sliding direction were exactly determined，and the shear strength of rock joints was determined precisely to raise the computational accuracies. The random errors of the stability coefficient are eliminated to reduce the error level in slope stability calculation with the method of equal accuracy assessment. According to the results of the case study with the method of equal accuracy assessment，the single bench slopes have the best results，the composite-bench slopes the second.

A series of hydraulic experiments are conducted to investigate the morphology of fractures in deep shale under high difference of horizontal in-situ stresses using a triaxial fracturing system. The results indicate that the hydraulic fractures always crack in the direction perpendicular to the minor principal stress，and extend，penetrate，connect or deflect when encounter the bedding planes and natural fractures. The fracture morphology have four categories：simple fracture，fractures with bedding planes opening，fractures with deflection and complex fractures affected by natural fractures. The increasing of horizontal stress difference leads to a higher penetrating ability of fractures. The higher the initial pressure，the more complex the fracture morphology. Stimulated reservoir volume can be improved by injecting the high viscosity fracturing fluid to generate the main fractures and by injecting the low viscosity fluid to open the branching fractures.

The effects of T-stress on the behavior of closed cracks under compression were investigated. According to the stress conditions on crack surfaces，the analytical solution of stresses near the crack tip was obtained through the Muskhelishvili method of complex functions. The rectangle specimens of sandstone with an inclined crack were tested under uniaxial compression. The calculated results were compared with the test results of sandstone specimens and the previous test results of PMMA specimens to validate the theoretical solutions. The analytical solution of stresses at the closed crack tips has two parts：the singularity terms which are the same as the traditional stresses expressed in terms of stress intensity factors K，and non-singularity terms expressed in terms of three components of T-stress，i.e. Tx，Ty and Txy. The theoretical results considering the three components Tx，Ty and Txy  fit the test results of both PMMA and sandstone specimens better. The theoretical analysis shows that the tangential stress increases and initiation angles decreases when T-stresses are not considered. When T-stresses are considered，the predicted values which contain three T-stress components(Tx，Ty and Txy) are situated between the results which only consider Tx and the results which consider both Tx and Ty. Thus，the T-stress near crack tips should have three components Tx，Ty and Txy，and all of them affect the crack behavior obviously.

The experiment to investigate the shearing performance of sandstone at different moisture states after cyclic freezing-thawing was carried out. The shear failure mechanism of sandstone specimen was discussed. The variations of internal friction angle and cohesion with the fractal dimension of failure surface of sandstone specimen were analyzed. The results show that with the increasing of freezing-thawing cycles，the characteristics of shear stress-displacement curves of sandstone change obviously，meanwhile，the peak shear stresses decrease in varying degrees，but the shear displacements increase significantly. After the cyclic freezing-thawing，the internal friction angle and cohesion of sandstone are deteriorated differently，and the degree of deterioration increases gradually with the increasing of the degree of saturation. When the moisture content is the same，the relationship between the fractal dimension of failure surface and the number of freezing-thawing cycles is a power function，and the relationship between the cohesion damage factor and the fractal dimension is an exponential function. The relationship between damage factor of internal friction angle and fractal dimension is an exponential function in the dry state，but is linear function in the moisture state.

In order to explore the influence of different loading rates on toughness of mode I fracture of layered shale，three types of shale specimens(Crack-arrester，Crack-splitter，Crack-divider) were tested for fracture toughness by using three point bending test. The toughness of mode I fracture of shale is positively correlated with the loading rate, i.e.，the toughness of mode I fracture increases gradually with the increasing of loading rate. The effect of loading rate on the fracture toughness of rock is mainly the duration of action of the damage development in the rock. The bedding direction has certain influence on the toughness of mode I fracture of shale. Layered rocks of the same matrix，due to the difference in structural orientation caused by its bedding，can result in differences in the resistance to fracturing. The Crack-divider type has the highest fracture toughness，the Crack-splitter type has the lowest fracture toughness，and the fracture toughness of Crack-arrester type is in between. This is mainly due to that the shale bedding surface is not obvious，the matrix body is complete and has high strength. For the shale with less obvious bedding and better integrity，the toughness of mode I fracture of Crack-splitter type and Crack-splitter type has little difference. The effect of layering direction on the toughness of mode I fracture of rocks corresponding to UCS Test. The relative toughness magnitude of mode I fracture of Crack-arrester and Crack-divider types can be determined by the relative values of UCS for vertical and parallel bedding.

Qianjiangping landslide is the first large scale rock slide in the area of Three Gorges Reservoir(TGR)  after impoundment. Most of the researchers agreed in the previous studies that reservoir impoundment and rainfall were two main factors triggering the landslide. However，there were different views regarding the degree of influence of two factors on the failure of the landslide，one considered that the influence of reservoir impoundment was greater than that of rainfall，the other considered that the influence of rainfall was greater than that of reservoir impoundment. In order to clarify this issue，the rock near the rock bridge that was part of the slip zone after sliding was selected. The triaxial compression tests on the influence of reservoir water immersion on strength and deformation of rock mass were carried out. The seepage field of groundwater and stresses in the slope under three conditions(reservoir impoundment，rainfall，and combined effect of reservoir impoundment and rainfall) were calculated with the software ABAQUS. Failure approach index was improved based on the constitutive relation of the rock obtained experimentally，and the improved failure approach index was applied to analyze the failure characteristics of the landslide under each condition. Under the influence of reservoir impoundment，the elastic modulus and shear strength of rock decrease remarkably when the rock is soaked. The influence of rainfall is greater than that of reservoir impoundment on the failure of the landslide，and the influence of combined effect of reservoir impoundment and rainfall is greater than that of rainfall. The sliding surface runs through under the combined effect of reservoir impoundment and rainfall. The study results suggest that the water immersion after reservoir impoundment reduced the strength of discontinuous rock bridges in the gently dipping discontinuous structural plane at the toe of the slope，the rainfall increased the sliding force of the slope，finally，the rock bridges fractured，and the failure of the slope occurred.

In this paper，a new system of rock suitability classification named QHLW is introduced to evaluate the suitability of the host rock for high-level radioactive waste(HLW) disposal at different scales. The system is developed on the basis of Q-system，and considers both the long-term safety and constructability requirements of the host rock for disposal. Some additional parameters，including the fracture zone distribution，groundwater chemistry and thermal effect are also taken into account in light of their significant influence on the long-term safety of HLW disposal. In the QHLW system，the suitability of host rock is classified into three classes at the repository and tunnel scales. The suitability of nine potential sites of underground research laboratory(URL) for HLW disposal located in Beishan，Xinjiang and Inner Mongolia regions are evaluated with this classification system. The Xinchang site in Beishan region is classified as the most suitable URL site according to the results of analysis.

This paper focused on some issues relating to the decomposition and prediction of stochastic displacement，the weight calculation of input vectors in support vector regression(SVR) and the determination of optimal training combination. A modified model of displacement prediction integrated with the gray wolf optimizer(GWO)，the maximum information coefficient(MIC) and the SVR，was proposed based on the time series theory and the variational mode decomposition(VMD). In this model，the time series analysis and the VMD were firstly applied to decompose the cumulative landslide displacement into the trend displacement，the periodic displacement and the stochastic displacement. Subsequently，some reasonable inducing factors were selected according to the response analysis of landslide，and then the single step prediction supported by multiple data was implemented by using the GWO-MIC-SVR model. Finally，the optimal training combination was confirmed based on the timeliness analysis of training sets，and the optimal values were superposed to achieve the prediction of cumulative displacement. Baishuihe Landslide，a typical colluvial landslide in the area of Three Gorges Reservoir，was taken as an example. The monitoring data of ZG93 and ZG118 from January 2004 to April 2013 were analyzed. The results show that compared with previous studies，this model has longer period of effective prediction and higher accuracy in prediction.

The field pull-out tests were conducted to the steel rebar and GFRP anti-floating anchor with sockets of different lengths and diameters buried in medium weathered granite. The distribution of the axial force and shear stress in GFRP anti-floating anchor body，anchorage body center and second interface(anchorage body/rock) were synchronously measured with the triple fiber grating sensors. The relative slippage between the anchor and anchorage body was obtained by the improved slippage test device and the multi-interface shear behavior of GFRP anti-floating anchor was studied. The synergy between GFRP anti-floating anchors was found to be better than the steel anchor in anti-floating. The bearing capacity of the GFRP anchor with diameter of 28 mm，anchorage length of 4.5 mm was up to 400 kN and its pull-out displacement was small，which meet the engineering needs. The maximum axial force of GFRP anchor is only 1 200–1 800 kPa，with the effective length of 1.5–1.8 m，and has a section of axial force attenuation. The maximum shear stress is 160–260 kPa，with the effective length of 1.8 m and significant stress concentration. The maximum axial force of the second interface is 1/6 times that of anchorage body and the section of axial force attenuation also exists but with a downward trend. The maximum shear stress occurred at 1/3 in anchorage body，with the effective length of 1.2 m.

The key structure model is optimized in order to study the microseismic precursory characteristics of coal and gas outburst. Based on the optimized physical model of coal and gas outburst，a three-dimensional model with the mechanical properties of coal changing gradually in space is constructed by COMSOL Multiphysics. Firstly，the distribution and development of the original rock stress and the mining stress before and after the tunnel excavation are analyzed. Then the effects of ground stress，gas pressure and mechanical properties of coal on the acoustic emission in fracturing process of coal are analyzed. Finally，the development of microseismic signals before coal and gas outburst is analyzed according to the coal distribution，gas storage and the variation of the mining stress in the excavation process of tunnel around the dangerous area of coal and gas outburst. The places with the mechanical properties of coal changing drastically have areas of local high-stress，low-stress and large stress gradient. The peak stress in the high-stress area is located in the boundary surface of hard coal，while the stress valley in low-stress area is located in boundary surface of soft coal. In the tunneling process from the hard coal area to the boundary of soft coal area，the peak mining stress has experienced three stages：a normal period，a high value period and a low value period. The acoustic emission parameters of raw coal and briquette for outburst coal generally have a positive correlation with the loading stress during the failure process in conventional triaxial loading. Especially in the unstable development stage of the crack，the AE parameters increase rapidly and reach the maximum value. Besides，compared with the soft coal，hard coal has higher strength and acoustic emission intensity. Before the coal roadway tunneling meets the regional tectonic coal，the microseismic signals experienced three stages，a safe period，a foreshock period and a quiet period. And with the gradient of soft coal decreases gradually，the peak in the foreshock period decreases gradually，the quiet period increases gradually，the microseismic precursor of coal and gas outburst gradually becomes fuzzy，and the suddenness of coal and gas outburst is enhanced. However，before the uncovering of cross-cut coal，there is no quiet period，and the foreshock directly develops into the main shock.

The measurement of dynamic fracture parameters of mode-I crack with the strain gauge was performed through the three-point bending tests under impact loading. Based on the analytical solution of strain field around crack tip derived according to the linear elastic fracture mechanics，two strain gauge methods for the measurement of dynamic fracture parameters of mode-I crack were proposed. A couple of stain gauges were mounted along the crack track at the specific orientation angles of acute and obtuse. The specific acute and obtuse angles between the strain gauge and running crack track were given. A two-parameter formula was established to characterize the crack tip location and the strain field around it. Thus，both the running speed and dynamic stress intensity factor (DSIF) of the crack tip can be precisely calculated. The running speed obtained from both the acute and obtuse strain gauge method and DSIF calculated from the obtuse strain gauge method were close to results from the caustics experiments that conducted simultaneously. In addition，the difference between DSIF of the dynamic caustics method and the obtuse strain gauge method was small in the middle of the specimen，and was large in other positions.

An equivalent discrete fracture network model to simulate two-dimensional unsteady seepage process is proposed. On this basis，a new numerical model of hydraulic fracturing process is established by introducing the progressive failure criterion of fracturing energy and the extended rigid-body spring method. The processes of stress，deformation and crack propagation are simulated with the extended rigid body spring method，while the unsteady seepage problem is solved with the equivalent discrete fracture network model. To obtain the equivalent macroscopic permeability characteristics，a method is used to determine the mesoscopic seepage parameters. The applicability of the equivalent discrete fracture network model is verified through comparison with the analytical solution of a one-dimensional unsteady seepage problem. The hydro-mechanical coupling procedure is deduced through combination of the extended rigid spring method with the equivalent discrete fracture network model. The coupling method is verified by comparing with the elastic analytical solutions of thick wall cylinder under the condition of steady flow. An example is given to demonstrate the capability of the model to simulate the hydraulic fracturing process. The comparison with similar lattice model proves the superiority of the proposed model.

The geodynamic disaster is the process of development and nucleation of fractured structures in rock mass. With the aid of acoustic emission(AE) monitoring，the failure process can be monitored to realize the accurate early-warning of the disasters. In this paper，the AE response varying with time including the AE counts，multifractal and frequency spectrum of fractured sandstone were measured in the entire loading process under different loading rates. The AE behaviors at the key points of crack propagation and the loading rate effects were studied using 3D locating according to the AE events. The loading rate was found to have significant effects on the propagation of macro-cracks and AE behaviors of fractured sandstone. The peak AE counts，the multifractal spectrum width  ，and the amplitude of dominant frequency increase gradually but the dominant frequency and multifractal   decrease gradually with the increasing of loading rates. The dynamic and nonlinear characteristics of rock failure process become more obvious，and the failure modes change from shear failure to tensile failure. In the whole loading process，the AE counts，the multifractal spectrum width and the low frequency component proportion increase gradually，while the multifractal parameter   decreases gradually with the increasing of axial stress. The AE multifractal and spectral parameters show fluctuation characteristics，and the AE counts show“pulse + calm”feature for multiple times when the sandstone specimen enters into the meta-instable stage. These time-varying trends of AE can be used to early-warn the dynamic disaster. The initiation，propagation，coalescence and nucleation of macro-cracks are the processes of rupture of locked bodies inside rock. An event of fracturing of locked body corresponds to a drop of stress，a large value of AE count，and an extremum value of the multifractal and spectral parameters. The loading rate effects and the AE response precursor behaviors of repeated suddenly increasing then quiet at the meta-instable stage can all be explained reasonably with the established theory of rupture nucleation of multiple locked bodies.

Most of the rock masses after dynamic disturbance return to the original state of stress or have the stress redistributed within a certain time period. One dimensional coupled dynamic and static loading tests were carried out under a new type of static and dynamic-static loading combinations to compare the characteristics of mechanical properties，permeability，wave velocity and acoustic emission of granite. The damage variable defined according to the ultrasonic velocity increases gradually with the increasing of the static axial pressure(ASP)，decreases first and then increases with the increasing of frequency. The maximum damage degree reaches 16%. The permeability and Poisson's ratio of samples are larger than the results of undisturbed samples，increase with the increasing of ASP，and increase at first and then decrease with the increasing of frequency. Both show high sensitivity to the high ASP. The strength and elastic modulus are less than the results of undisturbed specimens，increase with the increasing of ASP，and vary differently at the different levels of ASP with the increasing of frequency. Compared with the energy release of undisturbed rock samples，the specimen after the dynamic loading in the uniaxial compression process have no initial and latent stages of energy release and enter directly into the active stage of energy release with the duration prolonged and a lag phenomenon exists in the relative stress at the end and the energy release peak.

The in-situ stress condition of shale gas reservoir is a very important index to evaluate the gas extraction. A calculation model of 3D in-situ stress tensor of deep shale based on borehole wall stress relief method is presented considering the anisotropy，temperature changes and pressure at borehole wall. The distributions of stress around borehole wall are studied through numerical examples. The results show that the formulas between the borehole strains and far-field in-situ stress tensor are related to the mechanical and thermal parameters. At least 9 normal strains at different directions and combined laboratory test are needed to solve the 3D stress tensor around the measured area. The borehole pressure and temperature changes affect the distributions of stress within the range about twice of the borehole radii and the different degrees of mechanical and thermal anisotropy in deep rock also influence the results of stress measurements. When the 3D stress tensor of deep rock is calculated using the method of stress relief in borehole wall，the measurement environment and lithological conditions must be considered.

The tension of an anchor cable in deep underground caverns is affected by many factors，such as the creep of rock mass，the water and the chemical erosion. The interaction between the rock mass and the anchor cable is complex and the reduction rate of prestress cannot be accurately defined. The relationship between the anchor stress and main parameters of rock creep was determined according the coupling theory of force reduction of prestressed anchor cable with rock creep. The difference and similarity between the monitored data and theoretical value of prestressed anchor cable in large underground powerhouse were compared and the causes of the differences were analyzed with numerical simulation. The initial stress state of rock mass and the deformation difference of surrounding rock at different positions were not considered in the theoretical calculation model, which is the main reason of the error of calculated results. An optimization scheme of the initial tension of the anchor cable was proposed.

The coefficient of heat expansion and the viscosity varying with temperature are introduced into Merchant model of three components to establish the three-component thermo-rheological model of saturated soil in order to describe the rheological properties of soil under thermo-mechanical coupling. The analytical solution is deduced under the condition of instantaneous loading at single-side drainage boundary and the case analysis is given. The results show that when the consolidation pressure is constant，the increasing of temperature accelerates the consolidation of soil. The elastic modulus has great influence on the pore pressure and the degree of consolidation. The elastic modulus of the Kelvin spring has greater influence on the pore pressure than the elastic modulus of the independent spring. The expansion coefficient of spring has no effect on the dissipation of pore pressure in soil. The variation of pore pressure is related not only to the variation of viscosity coefficient，but also to the increasing of temperature. The increasing of temperature causes the spaces between the pore pressure curve to be narrower gradually，indicating that the change of pore pressure is related not only to the change of viscosity coefficient but also to the growth coefficient of temperature.

Two types of indoor flume experiments on the breaching process of the dams in loose and dense conditions respectively were carried out to study the influence of compactness on the mechanism of overtopping erosion of landslide dams. The experimental results show that the compactness has a significant effect on the process of overtopping erosion of landslide dams. Under the loose condition，the dam body suffers mainly from surface erosion，gully erosion，lateral erosion and undercut erosion，while the effect of headward erosion is very limited. The breach flow rate rises and drops fast and the dunes are formed when the dam-breaching is close to completion. The breach side is mainly subjected to shear failure in such a situation. Under the dense condition，multiple over falls and scour pit are formed and the effect of headward erosion is obvious. With the development of headcut erosion，the breach flow transforms from the non-weir flow to broad weir flow and then to practical weir flow. When the multiple over falls merged into a single upstream migrating head cut，the reverse swirling flow is formed which accelerates the failure of dam body. The breach side is mainly subjected to gravitational collapse under such a condition.

The ground surface subsidence outside the foundation pit caused by the incomplete well dewatering in the foundation pit under the condition that the aquifer inside and outside the foundation pit is not separated completely is studied in the foundation pit in Shenzhen Metro hub by means of the model tests and theoretical analysis. The effective depth due to incomplete well dewatering in the phreatic water stratum and the variation of the soil pore water pressure outside the foundation pit are revealed. The calculation formulas for the effective depth due to the incomplete well dewatering，the varying curve of water level outside the foundation pit and the percolation zone partition are put forward respectively. A simplified calculation method for the surface subsidence outside the foundation pit is proposed. The theoretically calculated trend of the surface subsidence curve is basically consistent with the measured results. However，the theoretical results tend to be conservative. Therefore，the simplified method is revised further by using the seepage principle of a by-pass seepage zone，which improves effectively the precision of theoretical calculation. Finally，the comparison between the in-situ monitoring data and theoretical calculated results shows that the proposed method is applicable in practical engineering.

To find out the attenuation of stress wave in the dried coral sand，an experiment was carried out to the long specimen by using the improved split Hopkinson pressure bar(SHPB) device. The average velocity of stress wave in the coral sand was quantitatively measured，and a formula relating the attenuation rate of the peak stress to the propagating distance was proposed. The experimental results show that the stress wave attenuates in the coral sand significantly，the peak value of stress wave attenuates to 10% and 1% as the stress wave propagate to the distance of 75 and 225 mm，respectively. It is concluded that the peak stress velocity decreases with the propagating distance，and decreases with the decreasing of dimensionless peak stress. The comparison of experimental results with the current specification and standard shows a much greater attenuation effect of stress wave in the coral sand than in the terrigenous sand.

This paper presented three-dimensional(3D) distinct element method(DEM) at the micro- and macro- scale to investigate the strength behaviour of cemented sands in true triaxial tests. A DEM program incorporating a 3D bond contact model was used to simulate the true triaxial tests on cemented specimens under two mean stresses(i.e.，pre-yield and post-yield stresses，100 and 800 kPa，respectively)，and the DEM results were compared with the available experimental data. The underlying mechanism of the strength behaviour was discussed at the microscopic scale. The results show that，when the applied mean stress is lower than the structural yield stress，the stress-strain relationships exhibit obvious strain softening，and that，when the applied mean stress exceeds the structural yield stress，the strain hardening occurs. The stress-strain relationships are affected by the intermediate stress ratio. As the intermediate stress ratio increases，the normalized peak strength decreases gradually，which is in agreement with the experimental data. The modified Lade-Duncan failure criterion can predict the peak strength under p = 100 kPa and 800 kPa，while the extended SMP failure criterion can predict the peak strength under p = 100 kPa，but overestimate the peak strength under p = 800 kPa. At the microscopic scale，the macroscopic mechanical responses of cemented sands are primarily controlled by the contacts transmitting greater-than-average forces within the whole specimen. As the intermediate stress ratio increases，the distribution of the normal contact forces tends to be non-uniform，which leads to lower strength.

To precisely simulate the macro and meso mechanical properties and the failure mechanism of soil-rock mixture(SRM)，an improvement on the three-dimensional discrete element(3D DEM) modeling for the flexible membrane boundary method used in the triaxial tests is made with 3D wall-arrangement method. 3D DEM models of SRM to simulate the large-scale triaxial specimens are constructed using the previously developed 3D DEM modeling method for rock blocks and SRM with irregular shapes. The meso-mechanical parameters of numerical SRM specimens are calibrated by large-scale numerical triaxial tests and verified through comparison with laboratory results. The insight into the macro and meso mechanical properties and failure mechanism of SRM are obtained from the detailed simulation of large-scale triaxial tests. The results show that the proposed modeling method for 3D flexible membrane boundary has many advantages, such as fewer parameters，easy to implement and better results. The stress-strain characteristics，strength properties and failure modes of SRM are reproduced nicely with the numerical simulation of large-scale triaxial tests using the generated DEM models. With the increasing of rock block proportion，the skeleton-effect of rock blocks on numerical SRM specimens becomes more and more obvious. The particle rotations of soil matrix are larger while the particle rotations of rock blocks are generally smaller，indicating that the shear planes propagate bypassing the larger rock blocks.

The strength increase and volume shrinkage during freezing of unsaturated soil may relate to the capillary cohesion and ice cementation. In this paper，shear strength，three dimensional deformation and compaction characteristics of compacted，frozen and air-dried samples were experimental studied using silty clay. The saturation degree and void ratio were considered as variable parameters. The contributions of ice cementation and capillary cohesion to strength were investigated experimentally. The experimental results demonstrate that the strength increase of unsaturated frozen silty clay is due to the capillary cohesion enhanced by suction increase and ice cementation. The capillary cohesion is remarkable in frozen soil with low initial degree of saturation，and the ice cementation is major source of cohesion in frozen soil with increasing of the initial degree of saturation. The volumetric ice content has a linear relationship with ice cementation on the assumption that capillary cohesion of frozen soil equals to that of unsaturated soil at the same matric suction. For the silty clay used，the samples with degree of saturation lower than 0.75 shrink upon frozen while the samples with degree of saturation higher than 0.75 swell. So，the sum of shrinkage induced by cohesion and expansion induced by icing are the total deformation of unsaturated frozen soil. Such shrinkage strain can be inferred from the curve of soil compression. The expansion induced by transformation from water to ice has a linear relationship with volumetric ice content on the assumption that compression caused by load equals to shrinkage caused by increasing of capillary cohesion.