A bonding particle model for hard brittle rock has been established to simulate the effect of rock burst. To make the microscopic model reflecting properties of hardness and brittleness，the following steps were used. Firstly，the microstructure of simulated rock samples was measured with the X-ray diffraction testing for granite rock. Secondly，the mechanical properties of the rock samples were analyzed, supported with the evaluation indicators of hardness and brittleness(indicators were determined in terms of the energy and stress-strain characteristics). Finally，a visual framework of the bonding particle model(depending on the tendency and magnitude limitation of the existed microstructure，the parameters of particles and bonds) representing the properties of hardness and brittleness was established. The model and the particle flow code(PFC3D) were used to simulate the triaxial unloading test and to analyze the effect of rock burst. The fractures are found to be mainly tensile in the unloading tests with the low and high confining pressures. Bigger proportion of tensile fractures and larger stress dropping(more brittle) occurs under the high confining pressure than under the low confining pressure. The kinetic energy of particles under the low confining pressure develops uniformly in the whole fracturing process of simulated sample，and the rock burst is a continuous type. However，the kinetic energy of particles under the high confining pressure developed non-uniformly，and the rock burst occurred suddenly and explosively.

The existence of bedding planes，cracks and other structural planes is the precondition of stimulated reservoir volume of shale formations. In order to analyze the effect of bedding planes on propagation of hydraulic fractures in shale formations，three-point bending tests of notched cylindrical specimens with different bedding orientations were carried out，based on the distribution of stress field around a crack tip of anisotropic materials. The mechanisms of anisotropic failure were revealed through the analysis of the anisotropy of Mode-I fracture toughness. The important role of bedding planes in the formation of fracture network was discussed according to the extension of hydraulic fractures in shale formations under true triaxial stress conditions. The results show that the stress and displacement fields around a crack tip of anisotropic materials depend not only on the stress intensity factor but also on the elastic constants. The notable anisotropy of Mode-I fracture toughness of shale is observed with the fracture toughness to be the largest when the pre-crack is crack-arrester orientated and to be the lowest when the pre-crack was crack-splitter orientated. The cracking of weak bedding planes and the deflection of fracture path were found to be the main mechanisms led to the strong anisotropy of Mode-I fracture toughness of shale. Bedding planes are weak in preventing crack propagation due to smaller fracture toughness induced by weak cementation，while the matrix is strong in preventing crack propagation due to much larger fracture toughness. Branching and re-orientation of hydraulic fractures in bedding planes and then interconnecting with natural fractures or bedding planes are found to be the main mechanisms of the formation of fracture network when the fractures extending perpendicular to the bedding planes.

Considering the distribution of stress field in coal rock and the features of outburst hole，a three-dimensional structural model describing the coal and gas outburst was established based on the analysis of the stages and the energy dissipation of coal and gas outburst. The elastic potential of rock was introduced into the model and the mobile power and crushing energy were calculated according to the stacking states of coal and surface energy of fracturing. A model of energy conditions and a model of intensity assessment for outburst were established and verified with real cases. Based on the energy condition of outburst，Morris screening method was used to analyze the sensitivity of the influencing factors of outburst. Gas energy is found to be the main energy source of coal and gas outburst and plays the leading role in the process of outburst. The results from the models of outburst energy condition and outburst intensity assessment deviate little from the ones of the actual outburst cases. In the cases of the coal mines at Zhongliangshan and Huachu，the coal gas content is the primary factor affecting the intensity of outburst，the gas emission and the outburst energy and had the highest sensitivity. The gas diffusion coefficient，gas pressure and porosity are found to be secondary and the sensitivity of other parameters of the rock is close to zero.

The dynamic compressive tests were carried out with ?75 mm split Hopkinson pressure bar(SHPB) on the plate-shape marble specimens(size of 60 mm×60 mm×15 mm) with a single circular or an elliptical hole in the center of the specimen. The dynamic strain signals in the incident bar and the transmitted bar were monitored with the ultra-dynamic strain indicator. The process of crack initiation，propagation and coalescence in the marble specimens was recorded with a high speed video camera. The dynamic strength，failure mode and crack propagation characteristics of the specimens were analyzed and discussed. It is found that the rock dynamic strength is influenced by the size，the shape and the spatial location of the water jet cut hole. The strength of the holed specimen is obviously smaller than that of the intact marble specimen. Axial tensile cracks parallel to the loading direction and X-type shear cracks surrounding the hole are the dominant factors for the failure of the specimens. With the increase of the diameter of the round hole，the speed of shear crack propagation increases while the speed of tensile crack propagation decreases. For the specimens containing an elliptical hole，the eccentricity and the angle between the loading direction and the long axes influence the cracking behavior and dynamic strength under impact loading. The average speed of dynamic crack propagation of the marble specimens is in the range of 100–450 m/s at the loading rate of 30–45 s－1.

In order to investigate the clamping effect and failure pattern of surrounding rocks as well as the limit of the pullout capacity of tunnel-type anchorage，field model tests on the conical frustum anchorage and cylindrical anchorage were conducted inside two parallel caves within the oblique cave of exploration in the anchorage area of Puli bridge. The side surface areas and the heights of two anchorage models are identical for quantitative comparing the differences of the clamping effect of surrounding rocks. The magnitude and the range of deformation before failure and the limit of load for the conical frustum anchorage are considerably larger than those for the cylindrical anchorage due to the clamping effect. For the cylindrical anchorage，brittle failure occurs remarkably in the contact area between the anchorage concrete and the surrounding rocks. For the conical frustum anchorage，the failure of the surrounding rocks occurs along the unfavourable fractures and experiences a long period of yielding deformation. The failure patterns for two anchorages are quite different. A concept of the coefficient of clamping effect and a corresponding method of calculation were suggested. The coefficients of clamping effect in the elastic period and at the period of strength limit are found to be 4.48 and 4.54 respectively. The pullout capacity induced by the clamping effect is significantly larger than the effect caused by the shear strength between the concrete and the rock mass. The clamping effect is the primary factor accounting for the pullout capacity of tunnel-type anchorage.

The technology of the segmented slug tests in a single borehole was developed based on the theory of slug test and the expression of hydraulic conductivity tensor. A set of test equipment，comprising of a multi- functional probe，a seal valve，an operating screen and a pneumatic pump，etc. and capable of capturing the borehole image，the fracture orientation，the water pressure and the temperature and transmitting the data to the data collection system on the ground was developed. A program was written to calculate the hydraulic conductivity of fissures and the hydraulic conductivity tensor of rock mass，and specific water storage in fractured rock based on the data of single-borehole slug tests. A single-borehole slug test was carried out in site and the corresponding methods for determining the hydraulic conductivity tensor were described in detail.

The large size(150 mm×80 mm) and single cleavage drilled compression(SCDC) specimens were impacted by the large-diameter(?100 mm) split Hopkinson pressure bar(SHPB)，and the dynamic toughness of fracture initiation and propagation of sandstone were determined using the experimental-numerical-analytical method. The time of crack initiation and the speed of crack propagating were sequentially measured with the crack propagation gauge(CPG) glued near the crack tip of the specimen，which were proved to be more accurate and sensitive than the ordinary strain gauges on the corresponding position for the same specimen. The experimental-numerical-analytical method considered the effect of inertia and the speed of crack propagation on the dynamic stress intensity factor with the finite element calculation and the semi-analytical modification for the determination of dynamic fracture toughness of rock and was more suitable than the quasi-static method. Both the dynamic toughness of crack initiation under the different dynamic loading rates and the dynamic toughness of crack propagation with different cracking speeds obtained with the experiment-numerical-analytical method were increased with the increasing of dynamic loading rate and cracking speed respectively. Finally，the possibility of achieving crack arrest using SCDC was discussed through analysis of cracking time of the strain gauges positioned on the path of crack propagation.

To study the dynamic response of homogeneous slopes supported by lattice beams under earthquake，a small slopes model made of silica gel on shaking table was designed at the geometric scale of 1∶15. Under the same sinusoidal loading，the range of the strains at the same measuring point on the lattice beam is found to be largely unchanged before the failure and the strains varied sinusoidal accordingly. But in the stage of failure，the dynamic strains vary irregularly and reach very large values finally in the destruction phase. Additionally，the stress level of the horizontal lattice beam is the same as that of the vertical lattice beam under the same seismic excitations. For the horizontal lattice beams，the strains at the middle of the beams are larger than those at two ends of the beams. And for the vertical beams，the strains from the top to the bottom exhibit a feature of larger- smaller-larger-smaller variation，indicating that the slope deformation along the vertical beams are restrained by the anchors. When the frequency of the sinusoidal loading is the same，the dynamic strains on the lattice beams increase with the increasing of the seismic acceleration. When the input acceleration is the same，the measured strains are larger at low frequency cases than those at high frequency ones. The reason is that the input low frequency is close to the natural frequency of the model and thus the dynamic responses in low frequency conditions are stronger. The results demonstrate that the silicone slope model is suitable for studying the dynamic response of the slope with supporting structure. The model can be used repeatedly and greatly reduces the cost of test.

An experimental platform to simulate the coal and gas outburst of large scale coal uncovering by cross-cut was built in laboratory based on the similarity laws and geological mechanics. The laboratory model tests and the numerical calculations were carried out to simulate the process of soft coal uncovering by cross-cut. Stress concentration exists in the surrounding rock ahead of the working face in the process of tunnel excavation. The elastic potential energy is accumulated in coal because of the stress concentration，which is the energy preparation and inoculation for outburst. The tectonic stress concentration area occurs in the vicinity of geological structure faults. The concentrated tectonic stress and the concentrated stress due to excavation superposed together lead to deeper and larger outburst in soft coal.

The stress relaxation tests of dry and saturated silty mudstone under triaxial compression were performed with the servo-controlled rheology testing machine RLJW–2000. The effects of water on the magnitude，the level and the time of the total relaxation and the average relaxation rate were analyzed according to the experimental results. A damage variable was proposed to consider the weakening of rock parameters. A new nonlinear damage model was established by introducing the damage variable into Hooke-Kelvin model. The Levenberg-Marquardt algorithm was adopted to identify the model parameters of dry and saturated rock. The effects of water on the parameters of the nonlinear damage model were studied according to the results of identification. For water saturated rock，the total relaxation decreases but the degree and the time of the total relaxation increase after stress relaxation. The effects of water on the magnitude and level of relaxation are reduced with time increasing during the period of stress relaxation. The average rate of relaxation and the rate of relaxation at different time decrease due to the effect of water，and the effect of water on the reduction of relaxation rate of rock increases with the increasing of time during the stress relaxation. The viscosity of rock was affected significantly by water and the instantaneous elastic and viscoelastic properties of rock are less affected. The damage of rock due to stress relaxation is related to these factors，the strain level，the time and the occurrence of water. The nonlinear damage model effectively reflect the deterioration of rock properties induced by these factors. Overall，water has significant effects on the properties of stress relaxation of silty mudstone，which should not be ignored in design and construction of major projects.

A system of rotary penetration was developed combining the advantage of rotary drilling and static penetration with verifications from laboratory tests and theoretical study. According to the mechanism of rotary penetration，the relationships between the drilling pressure，the torque and the feed per rotation in the processes of cutting，the direct pressing and the bit pressing have been found. The formulae for the compressive strength，the elastic modulus，the internal friction angle and the cohesion of rock were derived on the basis of laboratory test results. The method was applied to the fly ash blocks and the measured results were in good agreement with the calculated ones，which indicated the feasibility of the proposed method.

The adaptability and the effect of simultaneous hydraulic fracturing in sandstone reservoirs of ultra-low permeability was investigated in the field tests in two adjacent horizontal wells，Yangping-1 and Yangping-2， located in Longdong area，Changqing oilfield，China. The simultaneous fracturing treatment was performed in the two testing wells. Micro-seismic monitoring analysis of fracture propagation during the stimulation treatment indicates that hydraulic fractures present a pattern of complicated network expansion. The test data after fracturing show that the daily production of the well Yangping-1 and the well Yangping-2 reaches 132.3 and 109.5 m3/d respectively，which are approximately 9.4 times and 7.8 times the daily production of a fractured vertical well in the same area. It is also shown that the simultaneous hydraulic fracturing of two adjacent horizontal wells enlarge the expansion area of hydraulic fractures to obtain a larger drainage area and to realize the full stimulation of ultra-low permeability sandstone reservoirs in Changqing oilfield.

The portal section of mountain tunnels was simplified into a slope with single free face based on the theory of elastic wave. The effect of wave reflection was considered to deduce the solution of free field ground motion on the axis of tunnel under incident SH wave. The 3D shell theory was employed to provide earthquake- induced strains. Shaking table tests were conducted for the portal section of tunnel to validate the theoretical solution. The dynamic response of lining was regarded as the superposition of the ones in cross section and in axial direction. The shearing deformation occurs in the cross section of tunnel under action of SH wave propagating parallel to the cross section. The arch spandrel and arch springing can be seen as the weak parts in seismic design of lining structure. As the distance to the tunnel portal increases，the deformation effect increases slightly. The shearing deformation occurs in longitudinal direction under the action of SH wave propagating parallel to the axial direction of tunnel. The deformation effect is gradually weakened. The dislocation occurs easily at the position of construction joint of tunnel portal due to longitudinal SH wave. Therefore the seismic design in longitudinal direction of tunnel is also worthy of consideration.

Reliability-based slope stability analysis has great prospect in design but few attempts have been made to study the reliability of rock slopes in three dimensions. In order to evaluate the reliability of 3D rock slopes during the construction period，an abutment slope at the left bank of Jinping I hydropower station was taken as an example. The computational costs for stability analysis of 3D rock slopes are high and the factor of safety can not be explicitly expressed as functions of input parameters when the finite difference based shear strength reduction method is incorporated in slope stability analysis. In this paper，a parametric sensitivity analysis was carried out to reduce the number of random variables and the non-intrusive stochastic finite difference method was proposed for reliability analysis of the 3D rock slope. The effects of the failure of two main reinforcement measures，including the pre-stressed cables and the shear-resistant concrete plugs，on the deformation，stability and reliability of the slope were investigated. The variation of the displacement perpendicular to river flow，the factor of safety and the reliability of the slope during the construction period were also studied. The proposed approach of parametric sensitivity analysis identifies effectively the rank of the sensitivities of different random parameters，which lead to greatly improved efficiency of calculation. The non-intrusive stochastic finite difference method provided an effective way for analyzing the reliability of the practical 3D rock slopes，where a decoupled data interface between a probabilistic analysis module and the software FLAC3D is implemented and the results of the slope stability analysis in the parametric sensitivity analysis are further used in the slope reliability analysis. The jointed measure of stabilization with the pre-stressed cables and the shear-resistant concrete plugs in the left abutment slope at Jinping I is found to be able to effectively control the slope deformation and ensure the slope stability. The disturbances induced by the slope excavation during the construction period are found to have a significant influence on the slope reliability.

A new approach for back analysis the rock/soil permeability based on the transient flow was developed considering the transient nature of the seepage flow in rocks and soils during construction and operation of engineering works. The proposed method utilizes the measured transient data of both piezometric head and flow rate is based on the orthogonal design，the finite element analysis of transient seepage flow，the BP(back propagation) neural network and the genetic algorithm. In order to avoid the dimensional inconsistency induced by different types of measurements，normalized error terms of the transient pressure head and seepage flow rate are used for constructing the objective function，and a weight coefficient w is introduced to balance the contributions by the piezometric head and flow rate terms. The proposed method is applied to back calculate the hydraulic conductivity around the foundation pit for construction of the rockfill dam with gravel wall core on Changhe river. The measured water leakage is much higher than the one expected in the design period. The back-calculated piezometric head and flow rate are in good agreement with the measured results. The back-calculated hydraulic conductivities of the foundation rocks are strictly within the ranges of permeability of graded rock mass determined with the in site borehole packer tests，which demonstrates the effectiveness of the back-analysis method and the reliability of the back-calculated results.

Based on the supporting structure of the railway from Dali to Ruili and the Wenchuan earthquake excitation，the dynamic characteristics of 3 kinds of retaining structures against slopes of bedrock and overburden layer were studied with the methods of numerical analysis and shaking table experiment. The responsive acceleration under the action of input XZ-excitation of Wenchuan earthquake is the main focus in the study. The results from two methods are found to be largely similar to each other. The horizontal acceleration of three types of retaining walls increases with the height of retaining wall increasing，and the vertical acceleration on anchor frame beam increased with the height of monitoring point rising. So，as far as the earthquake acceleration is concerned，the shaking table test is reasonable and the numerical modeling is reliable. However，the results of numerical modeling are slightly bigger.

The choices of landslide displacement prediction models and relevant parameters are two of the most important issues in the landslide displacement prediction. The existing models have many limitations and shortcomings in predicting the landslide displacements. In this study，the trend displacement and the periodic displacement of Baishuihe landslide in the Three Gorges Reservoir area were separated based on the method of time series analysis. The former was considered to be mainly controlled by the internal factors of landslide(the composition，the geological structure，the topography，etc.)，and was fitted and predicted with the polynomial function. The latter was caused by the external influence factors(the seasonal rainfall，the water level changes of reservoir，etc.). Taking the rainfall of current month，the cumulative rainfall of anterior two months，the reservoir level，the fluctuation of reservoir level of current month，the fluctuation of reservoir level of anterior two months and the cumulative increment of total displacement in current year as the influencing factors of periodic displacement，a combination of the particle swarm optimization algorithm(PSO) optimizing the parameters of model and the support vector machine regression(SVR) method for the periodic displacement prediction was proposed. The predicted values of the two kinds of displacements were superimposed to obtain the cumulative displacement. The result showed that the landslide displacements based on the time series prediction and PSO-SVR model were better than those from the grid search SVM and the BP neural network models.

Pipeline leakage is one of the important issues during shallow tunnelling in urban area. To determine the deformation patterns and the failure mechanisms of a shallow tunnel influenced by pipeline leakage is of great importance for the safety of the tunnel project. Plane strain model tests were performed to study the influence of the range of pipeline leakage on the deformation and failure of the surrounding rock of class VI during shallow tunnelling. It is found that notable ground surface settlement occurs due to the pipeline leakage before tunnel excavation. With the increase of the range of leakage，the magnitude and the range of the ground surface settlement also increases. However，when the pipeline leakage reaches the tunnel vault，the influence of the range of leakage on the ground surface settlement decreases significantly. There are several vertical cracks visible on the surface due to the pipeline leakage before tunnel excavation. With the increase of the ground surface settlement，the depth and width of the cracks increase simultaneously. However，the variation rates of the depth and width of the cracks with the ground surface settlement decreases after tunnel excavation. The larger the range of the pipeline leakage is，the more severe the failure of the surrounding rock after tunnel excavation. When the range of leakage is small，the shape of fracture plane of surrounding rock is scarcely influenced. However，when the range of leakage is large enough，the fracture plane is closely related to the boundary of the pipeline leakage and the fracture plane is steeper than that one without leakage.

Geomembrane with optical fibers is a new type of anti-seepage material，which provides a function of determining the cleft places itself. To study the stability of slope of the laterite dam embedded with the geomembrane with optical fibers，shear strength tests and anti-slide model tests were performed，so that test data about the membrane-soil interface，for example，the cohesion，the friction angle，the slip gradient and the frictional coefficient，were obtained. The data were compared with the ones of the pure laterite and of the laterite with the built-in composite geomembrane. The interface between the geomembrane with optical fiber and the laterite was found to have enough affinity to resist shearing. The anti-slide stability of the dam slope met the specified requirement if the geomembrane with optical fiber was used in earth dam.

A working shaft enclosed by the continuous wall must be built at two ends of the tunnel to be excavated for shield starting and arriving in shield tunneling. Soil body at two ends of the tunnel may collapse along a sliding surface and pose a high risk in shield tunneling. A combined sliding mode of straight line and logarithmic spiral line was proposed for shallow shield tunnel. A formula to calculate the stability of the soil at the ends of shallow tunnel was deduced by means of limit equilibrium analysis and the factors influencing the soil stability were analyzed with the derived formula. The soil stability at tunnel ends is dependent on the soil strength，the thickness of reinforced soil body，the strength of reinforced soil body and the diameter of tunnel outlet. The greater the internal friction angle and the cohesion of the soils are，the higher the soil stability. The greater the thickness and the strength of the reinforced soils are，the higher the soil stability. The soil stability at tunnel end decreases with the increasing of the diameter of the tunnel outlet. The method was successfully used to calculate the soil stability and the thickness of the reinforcement of soil body of a shield tunnel of metro in Nanjing.

Previous studies show that the soil arching considerably affects the earth pressure distribution around the buried pipelines. However，very few studies investigated comprehensively how the soil arching effect changed with respect to the height of the backfill and the diameter of buried pipes during construction. This research presents the details of a study on the soil arching effect and earth pressures acting on the crown of the buried HDPE pipes. A series of field tests were conducted for the measurements of earth pressures acting on the HDPE pipes and of soil pressures at different elevations over HDPE pipes during construction. The results reveal that the soil arching effect activate in the backfills beside and above HDPE pipes increase remarkably with the increasing of the height of the backfill. At a given backfill height，the degree of soil arching effect increases with the decreasing of vertical distance from the crown of pipes. The earth pressures acting on the crown of pipes computed by Marston theory are 3% to 31% higher than those measured in the field tests. Based on a series of finite element analyses，an empirical equation was proposed to predict the earth pressure acting on the crown of HDPE pipes during soil backfilling. Predicted earth pressures using the proposed equation are in good agreement with the field test data reported by the previous studies.

The influence of modifiers on dispersity and tensile strength of dispersive clay were investigated using pin-hole，crumb and uniaxial tensile tests. The modifier for dispersive clay constitutes of aluminium chloride，trichloroacetic acid and polyacrylamide. The aluminium chloride and the trichloroacetic acid modify the chemically dispersive clay and the polyacrylamide modifies the physically dispersive clay. Results show that the dispersity is reduced and the tensile strength is increased with the increasing of the modifier content. The chemically dispersive clay is turned into non-dispersive when the aluminium chloride content is 0.3% and the tensile strength is increased slowly with the increasing of the aluminium chloride content. When the trichloroacetic acid content is 0.9%，the dispersive clay became non-dispersive and the tensile strength reaches the maximum value. The physically dispersive clay was changed into non-dispersive when the polyacrylamide content is 0.2%. The modifier for dispersive clay not only modify the dispersity but also raise the tensile strength 30% to 70%. The modification mechanism is a series of physical and chemical reactions of the modifiers with soil particles. The aluminium chloride increases the cationic content and reduces the alkaline pH and the trichloroacetic acid reduces the alkaline pH to modify the chemical dispersive clay. The polyacrylamide promotes the formation of granular structure and the resistance to erosion is enhanced. Besides，the tensile strength reduces with the increasing of moisture content and the reducing of the degree of compaction.