Energy varies during the whole process of rock deformation and failure. In order to investigate the effect of confining pressure on rock energy variation，axial loading and unloading tests under six different confining pressures were conducted for sandstone samples. The confining pressure effects on variation and allocation pattern of elastic energy and dissipated energy were revealed，and the energy path of engineering rock mass was discussed. Three characteristic energy parameters，i.e. the energy accumulation limit，the maximum dissipated energy density and the residual elastic energy density，were proposed to describe the accumulation，dissipation and releasing of energy respectively. Rock energy variation under different confining pressures was found to be similar. The energy accumulation occurred mainly before the peak stress while the energy dissipation and releasing were dominant in the deformation stage after the peak stress. As the confining pressure increased，the maximum accumulated rock energy increased exponentially，the residual elastic energy density increased linearly，and the maximum dissipated energy density risen exponentially，indicating that the confining pressure enlarged the rock energy transmission and weakened the intensity of energy release. The greater the confining pressure was，the larger the elastic energy ratio in the stage before peak stress，the less the elastic energy ratio fall at the peak point，and the more closely the elastic energy ratio approached the maximum value when it rose again after the fall，indicating that the confining pressure enhanced the efficiency of energy accumulation，and elevated the energy storing capacity of fractured rock. The energy path of rock mass leading to buckling failure is a combination of the ones of enlarging the energy accumulation level and reducing the energy accumulation limit. When the slope of energy path is large，the rock mass stored a large quantity of energy reaches the critical state，and the sudden unloading of confining pressure can lead to energy releases strongly.

In order to investigate the interaction of the hydraulic fractures and the bedding planes of shale in hydraulic fracturing，the hydraulic fracturing experiments under triaxial conditions were carried out with the acoustic emission system monitoring the process of hydraulic fracturing and the CT scanning system scanning the sections of rock samples before and after hydraulic fracturing for capturing the distribution of fractures. The initiation and propagation of the hydraulic fracture was captured experimentally. At the situation of small difference of stresses，the critical pressure for initiation was found to be differed little in different angels，the fracture grew along the direction of  after initiation. The critical pressure for the propagation of major hydraulic fractures was related to the length of fracture and  . The small sections of the bedding planes in shale were opened up when the major hydraulic fracture approached. The passage was created at the intersection of the hydraulic fracture and the bedding plane due to shearing tension. The shear zone was larger than opened one，with a ratio of 13 at maximum，functioning as the major passage for fluid flow. The length of the shear zone is sensitive to the cohesion of bedding planes, and the angle of intersection of hydraulic fracture and bedding plane.

3D digital volumetric images of red sandstone specimen during uniaxial compression were obtained in real time by using industrial computer tomography(CT) of X-ray. The digital volume correlation(DVC) method was applied to calculate the three dimensional displacement and strain fields inside of the sample. The development of strain localization and the failure process were revealed. The internal features of red sandstone were used as speckle patterns，the information carriers of deformation. The accuracy of measurement by DVC method reached 0.05 voxels. The notable strain localization inside the red sandstone specimen was observed and the zones of strain localization occurred at 68.9% of peak load and developed gradually until finally the specimen was broken. The localized strain zone is consistent with the final position of failure surface in the specimen.

In order to investigate the development of surface cracks and the intrinsic link between the surface cracks and the internal rupture in the process of rock failure，the developmental characteristics of surface cracks of rock during shear failure were quantitatively analyzed and relationships among the parameters describing the surface cracks，the stress state and the acoustic emission characteristics were established. Meanwhile，effects of water content on the parameters describing surface cracks upon shear failure were investigated. The results revealed that the echelon cracks accompanied with the formation and transfixion of surface cracks during shearing process and appeared for a very short period just before rock failure，then shear cracks penetrated through completely. The maximum rate of AE event appeared always for a very short period before the sharp drop of shear stress，and before the occurrence of the non-stable state of rapid propagation of surface cracks. The coefficient of saturation was found to affect the time and the position of occurrence of surface cracks relative to the peak shear stress. As the coefficient of saturation increased，the surface cracks occurred earlier，the maximum instantaneous transfixion velocity decreased，the transfixion time was longer and the time delay of the rapid propagation of surface cracks increased significantly.

A series of coupled hydro-mechanical triaxial tests on granite specimens were carried out in order to investigate the permeability of dense rock under triaxial compression using servo-controlled triaxial testing equipment. The variations of the permeability with the confining pressure，the seepage pressure and the volumetric strain in the complete stress-strain process of the rock were obtained. The experimental results showed that the stress-strain relation exhibited the behavior of brittle failure. The strength of granite at failure increased with the increasing of confining pressure while the seepage pressure was kept constant. The low seepage pressure had little influence on the failure strength of rock. The granite specimens experienced a stage of compaction and a stage of expansion. The maximum volumetric compressive strain increased with the increase of confining pressure. The lowest permeability appeared before the inflection point of volumetric strain and the volumetric strain corresponding to the lowest permeability was found to be about 95% of the maximum volumetric compressive strain. A relationship between the permeability and the volumetric strain was presented.

An algorithm of composite element for calculating the unsteady seepage in fractured rock masses was established according to the hydraulic properties of fractured rock masses including the discontinuity，the heterogeneity and the anisotropy. The pre-process of composite element，the method to calculate the integral over free surface boundary and the judging criterion of overflow boundary，etc. were presented. The features of the algorithm are as follows：(1) It can simulate arbitrary distributed fractures exactly. (2) The permeability of intact rock and the flow exchange between rock blocks and fractures are considered. (3) It can be integrated into conventional finite element method easily. (4) The topological information of composite elements is obtained by the calculation of intersection and incision between fractures and the finite elements. In this way，the mesh generation is not restricted by fractures and is considerably simplified. (5) The phenomenon that seepage in rock blocks and in fractures are out of sync can be simulated by using the algorithm which provides the same precision of calculation as finite element method. The validity of the algorithm was verified by a typical seepage test. Finally，the algorithm was applied to calculate the unsteady seepage behaviours in fractured rock masses and to reveal the process of pressure transfer. The calculated results show that the direction of local flow is different from the general one，which is due to the different hydraulic properties of fractures and rock blocks.

The roughness of the joint surface of rocks is notably anisotropic and size affected. To describe it quantitatively remains a difficult problem because of the complex structure of joint surface. The method of geological statistics was used to analyze the anisotropy and the size effects of structural surface of rocks. A method based on the dimensional analysis，JRCv，was proposed to describe the surface roughness of joints using the sill value and variable range of the variogram. Ten sampling sizes from 100 Pixel×100 Pixel to 1 000 Pixel×1 000 Pixel were selected from the central part of the surface to calculate JRCv values. It is found that the rougher the surface in analysis direction is，the larger the value of JRCv. JRCv is thus a good parameter to describe the anisotropy and roughness of joint surface of rock. The JRCv values decrease with increase of the size of the sampling windows. When the sampling windows are larger than a threshold value，the estimated parameters remain constant. Anisotropic properties are influenced by the surface size when the sampling windows are smaller than the threshold.    

Hydraulic fracturing is a commonly-used technique in unconventional gas rupture(such as shale gas) exploration. A theoretical framework，called FDEM-flow method，for analyzing flow-structure interaction was proposed based on FEM/DEM. Combined with the recursive algorithm of searching the fracture network formed，a complete solution was developed to simulate the hydraulic fracturing of rock under the coupled action of fluid and solid in two-dimensional condition. The results from the proposed method agree well with the analytical solutions in two seepage cases，which verifies the correctness of the proposed method. An example of hydraulic fracturing was analyzed. The results demonstrate that the proposed method has a good potential in simulating hydraulic fracturing and that the method might provide a new way to simulate the hydraulic fracturing in the exploitation of shale gas.

The TBM excavation in deep stratum is a process of smooth and quasi-static unloading of high initial confining pressure. In order to reveal the deformation and failure characteristics of soft rock at deep ground under the condition of TBM tunnelling，triaxial unloading tests on sandy mudstone with different unloading rates were carried out. The pre-peak stress-strain curves under the condition of smooth and quasi-static unloading of confining pressure were found close to the ones obtained from the conventional triaxial compression test. At the yielding stage upon unloading，the specimens exhibit damage dilatation，the lateral deformation grows accelerated，resulting in a turning of the volumetric strain from shrinkage into dilatation. After the peak strength，the specimens slide along the fracture surface already formed to display the modest brittle drop of strength once or twice. Then a linear strain softening stage accompanied by multistage micro fractures occurs on the stress-strain curve with a line segment of a small slope as the confining pressure is continuously and slowly unloaded. The complete deformation process of unloading is composed of the elastic deformation，the damage dilation，the post-peak brittle drop，the linear strain softening and the residual stress period. The specimens display composite shear-tension failure macroscopically accompanied with axial splitting cracks during the process of smooth unloading. Many split cracks link and cross each other to form a shear band of a certain width. The rock in the shear band is squeezed and wears into the fine particles and the powder as a result of the interaction of axial extrusion and the shear stress along the shear plane.

In order to reveal the pullout mechanism of tunnel-type anchorages，the deformation characteristics and the potential failure patterns of surrounding rocks and to verify the design safety factor of the tunnel-type anchorage，a field model test with the similarity ratio of 1∶25 for tunnel-type anchorage was conducted in the exploration cave of the Puli Bridge. By performing the elasto-plastic and rheological tests under different loading conditions，the load transmission，deformation distributions and rheological characteristics of the anchorage and surrounding rocks were obtained. The test results show that the distribution curves of maximum deformation at the rear surfaces of anchorage and surrounding rocks exhibit symmetrical double-peak shapes，and those of the frontal surfaces exhibit upward convex shapes. The deformations at the rear surface are bigger than those at the frontal surface. The maximum deformation under 8P load(where，P is the design load) is only 61 μm，and the maximum deformation under 50P load is 566 μm. Due to the clamping effects of the surrounding rocks，the stress in the rear end diffuses very slowly to the front under overloading conditions. Under 50P load，the strain in the front end is only 3% of that in the rear end. The stress concentration clearly occurs at the rear end of the concrete anchorage and the strain is partly irreversible，i.e. the plastic deformation occurs. Having considered that the quality of rock masses at the testing area is better than the one of the prototype tunnel-type anchorage，the overloading stability coefficient is recommend to be larger than 8. As there is no observed rheological behavior under 6P load，the long-term stability coefficient is considered to be larger than 6.

The characteristics of surface subsidence and ground pressure in recent years in No.2 mine area, Jinchuan were briefly described and the mechanism of deformation was carefully analyzed. A monitoring scheme was implemented based on the results of deformation analysis. A device was made to monitor the relative deformation of bulky backfill of 50 m in height at the altitude level of 1 150 to and 1 200 m. Bubble level was used to monitor the vertical displacement of the bulky backfill and the surrounding rock. The monitoring results shows that the rate of total deformations of measurement points is 16.00–51.44 mm/month and that the maximum accumulated deformations is 515 mm. The rate of relative deformations at measurement points is 1.953–28.585 mm/month，and the maximum accumulated relative deformations is 285.85 mm. The development trends of the total deformation，the relative deformation and the deformation of surrounding rock are also studied.

Triangular meshes together with the linearized Mohr-Coulomb criterion are commonly used in the finite element upper bound solution to form a linear programming model. In addition to higher accuracy and solution efficiency，quadrilateral meshes can adjust the velocity field of the element and converge more rapidly to the realistic upper bound solution. To overcome the shortcoming that the linear programming algorithm cannot be implemented directly for quadrilateral meshes，a weak form of compatibility equations was established based on the integration over the whole elements and the linearization of the compatibility equations was obtained for linear programming. With the hyperbolic strength reduction，the final safety factor of slope and the critical field of slipping velocity were obtained quickly. The validity of the method was verified with two examples.

Morphological characteristics of slopes determine the predominant frequency，which may amplify the incident seismic wave of the same or similar frequency range，thereby increase the slope dynamic response，and even trigger landslides. The microtremors and seismic observations were carried out in the adits along the Shiziliang slope surface in the meizoseismal area of Wenchuan earthquake(Ms 8.0). The spectral ratios of horizontal to vertical component from the microtremor and the seismic records of 3 aftershocks were analyzed and the spectral characteristic curves were obtained. It was found that the minimum predominant frequency occurred at the slope crest. The PGA amplification decreased initially and then increased with the elevation，exhibiting a concave shape. The biggest PGA amplification reached 1.25 at the slope crest. The phenomenon of the low predominant frequency corresponding to the high PGA amplification at the top of slope may be related to the ratio of slope height to the wavelength of incident wave. The ratio was 0.2 when the PGA amplification reached the maximum value. To further investigate the morphological amplification effect on spectral characteristics，dynamic analysis was performed using the finite difference software FLAC by inputting the waves of multiple frequencies from the seismic acceleration records at Wolong station during Wenchuan earthquake(Ms 8.0). 3 different angles of inclination were assumed for the slope being simulated. The calculated predominant frequencies of the slopes with different angles of inclination were found to be the same，which were verified by the results from inputting Ricker wavelets of different mono-frequencies. This indicated that the slope angle had no effect on the predominant frequency.

Combined structure of feet-lock bolt and steel arch is an effective support measure in preventing the crown settlement. An analytical model to calculate the support of joint bearing with feet-lock bolt and steel arch in weak rock tunnel was established considering the compatibility conditions of bending moment，axial force，shear force and deformations at the junction. The steel arch was taken as a fixed arch and was analyzed using the method of structural mechanics. The formulae describing the lateral and axial mechanical behaviors of feet-lock bolt were derived with the methods of elastic foundation beam and load transfer respectively. The internal forces and the deformation of feet-lock bolt were studied through an example，and the results were compared with the model given in a reference paper in which the bending moment and deformation compatibility conditions at the junction were ignored. The influence of different installation angles of feet-lock bolt on its internal force and deformations at the junction was discussed. Finally，the influencing factors for the effect in controlling the crown subsidence were studied，including the lateral pressure coefficient and stiffness of surrounding rock，and the parameters of feet-lock bolt. The results indicated that the welded part was the weakest link for feet-lock bolt and should be welded firmly. The bending moment transfer at the junction was recommended to be considered. The lateral resistance to bolt mainly concentrated in the region near the end of bolt，where the surrounding rock should be specially reinforced. Extra length of bolt had no effect to its lateral behavior. The best installation angle was found to be about 45°.：Using more feet-lock bolt(pipe) or using feet-lock bolt(pipe) of high specification enhanced support effect. A low value of the lateral pressure coefficient of surrounding rock be better considered in the design of feet-lock bolt.

Cemented backfilling technology has been increasingly used in the exploitation of mineral resources under the low temperature condition，but it has also brought about a series of difficult issues，such as the problem of poor strength of backfilling materials，the collapse and the failing. The effects of the curing temperature，the cement content and the slurry concentration on the strength of backfilling materials were thus studied experimentally to tackle the problems faced in a gold mine at cold region. The rational proportions of mixed material contents and the curing temperature of paste of cement-rock debris mixture were determined to meet the requirement of gravitational transportation. The experimental results revealed that the cemented rock debris was better than the iron ore tailings as the backfilling material and its slurry concentration reached to 75%. The low temperature was found to hinder the hydration. The higher the curing temperature was，the higher the uniaxial compressive strength (UCS). The increasing of curing temperature improved the strength of backfilling material. The curing temperature influenced more on the early strength but little on the later strength of backfilling material. The heated water for rock debris mixing and cementation was therefore proposed and applied successfully in an industrial experiment.

The deformation and the influence factors of the wrap reinforced retaining wall located on the soft soil foundation was carried out by the method of centrifugal model test and numerical simulation with FLAC2D. The centrifuge model test showed that the lateral deformation of the wrapped reinforced retaining wall was small and the wrapped reinforced retaining wall acted as a traditional panel. The effects of length and vertical spacing and stiffness of geosynthetics on the deformation of the retaining wall were analyzed in the numerical simulation with FLAC2D and the centrifugal model tests respectively. The results of the numerical and experimental study showed that the vertical spacing of geosynthetics is the most significant factor influencing the deformation of the retaining wall，and these three parameters should be controlled in a certain scale in the actual projects.

According to the site information of an offshore project of wind turbine，the dynamic characteristics and the seismic response of the supporting system of turbine were analyzed by considering the complicated interactions of water，soil，and supporting system. The fluid-structure coupling，the seepage of saturated soil and the pile-soil contact behaviour were simulated using the finite element method. Four working conditions were considered for the analysis of characteristics of natural vibration，i.e. the single-pile supporting with water and without water in consideration，the four-pile supporting with water and without water in consideration. The results from the simulations indicated that water had negligible influence on the lower-order frequencies of the structure，but led to a large reduction on the high-order frequencies. Water reduced the horizontal and the vertical displacements，the peak acceleration and the effective stress of the supporting system. The excess pore water pressure in the foundation soil fluctuated under seismic actions. The calculated structural displacements and effective stresses met the regulation requirements.

The relationship between the void ratio and compressive stress of soils under initial compression and recompression，namely e-p curve，is a key issue for the analysis of natural ground settlement. Firstly，a hyperbolic formula between the compression stress and strain for soils was introduced based on the investigation of the mechanism of initial deformation of compression and the characteristics of e-p curves for soils. The mathematical relationships to determine the parameters of the formula were derived assuming that the soils were under consolidation with lateral restraint. The difference between the e-p compression curves for initial compression and recompression soils lies in the different values of initial void ratios and initial compression modulus for each case. A method to determine the parameters，such as the initial void ratio and the compression modulus of soils at recompression，was proposed. A formula of e-p curve for recompression of soil considering the effect of stress history was put forward. The proposed formulae of e-p curve for initial compression and recompression of soils have three conventional parameters，the initial void ratio and the initial compression modulus and the compression coefficient. Results of comparisons show that the experimental data and theoretical curves are in good agreement.

The interaction between the drilling machine and the lunar soil in the special environments on lunar surface has been the key issue of sampling in lunar regolith. Direct shear tests，compression tests and triaxial tests were carried out to investigate the mechanical property of lunar regolith simulant CAS–1 under the low levels of stress. The simulant was found to have the cohesion of 2.8 to 5.0 kPa and the angle of internal friction 39.84°to 41.09°when the porosity e = 0.8–1.1 at the low stress level. The compression curve was found to have a shape of concave upward firstly and then a shape of concave downward at the low stress levels. The initial compression moduli were from 12.647 to 3.923 MPa when e = 0.9–1.1. The stress-strain curve can be divided into a harden and a soften stage. The decreasing rate of the soften stage is rather fast and the duration of the residual strength is long. When the void ratio is smaller，the ratio of peak deviator stress/stress is larger，the peak axial strain is smaller and the values of peak axial strain are between 2% and 5%，the ratio of residual strength/stress is larger and the duration is longer. The initial tangent of the stress-strain curve，the peak stress ratio and the residual stress ratio vary with the compression stress logarithmically. The initial tangent decreases slowly， the initial tangent modulus  changes little but the peak stress ratio and the residual stress ratio decrease rapidly.

The expansion of cylindrical hole in sand was analyzed based on the yielding criterion of spatially mobilized plane(SMP). A theoretical relationship among the initial radius a0，the expanded radius a and the expanding pressure p of the cylindrical hole was derived employing the boundary conditions of plastic zone and the volumetric variation of soil around the cylindrical hole. The limit pressure of expansion pu and the stress and displacement fields in the elastoplastic zone were obtained with the theoretical relationship. A theoretical relationship among the radius of the plastic zone rp and the expanding pressure and initial radius a0 was derived under the plane strain condition. The limit bearing capacity of a pile in granular material was deduced by using the stress field formula. Finally，an example was presented to illustrate the variations of the stress and displacement fields，the radius of plastic zone a0 and the expanding pressure p.

Compression tests were performed to study the AC electrical resistivity of unsaturated loess with different stresses，strains，porosities，degree of saturations and current frequencies. Considering the inhomogeneity of micro pore distribution，the tortuosity of current flow and current frequency，an electrical resistivity model of equivalent circuit for unsaturated loess was proposed. Under different current frequencies，with the increasing of the stress and strain，the electrical resistivity decreased rapidly at first，and then remained basically unchanged after the stress exceeded 200 kPa and the strain exceeded than 0.084. With the decreasing of porosity，the electrical resistivity decreased rapidly at first，and then approached a stable value when the porosity was below 0.41. With the increasing of the degree of saturation，the electrical resistivity decreased sharply at first，and then approached a stable value when the degree of saturation was above 52.7%. The electrical resistivity of unsaturated loess was found to be closely related to its micro structure and can be divided into four stages. Under different stresses，with the increasing of current frequency，the electrical resistivity decreased rapidly at first，and then approached a stable value. In order to reduce the influence of current frequency on electrical resistivity，the range of 50 kHz–1 MHz was recommended when using AC electrical resistivity method to measure and evaluate unsaturated loess.

It was shown from three years of in-situ tests of Luliang airport in Shanxi province that the expansion and collapse of hidden cavities in loess filled high embankment were harmful to the airstrip. Based on the theory of equilibrium and arch upon collapse，the expansion of hidden cavities were divided into a mode of lifting and a mode of radial expansion. The lifting mode was due to the development of the vertical fractures in loess and the radial expansion mode was due to the water sensitivity of loess. The quantitative methods of calculating the expansion process of hidden cavities were proposed. The three dimensional finite element method(3D-FEM) was used to analyze the deformation and stabilization of airstrip induced by the expansion of hidden cavities. A method of stability analysis was proposed based on the deformation limits and critical thickness. A method of predicting the stability of airstrip was also proposed when hidden cavities were expanding based on the laboratory disintegration test of compacted loess.

The difference of solar radiation on different surfaces of embankment would cause uneven transverse deformation. The calculation method based on solar incident angles without considering the shielding to sunshine of high embankment in permafrost regions produces results that have large deviation from the actual situation especially for the permafrost near the toe of slope. A mathematical model of sunshine shield considering the time，the intensity of solar radiation，the position of sun and the track of embankment shadow was established. The mathematical model of embankment sunshine shield was verified with the results from the calculation method of K.Y. Kondratyev and the field test data. The concept of the rate of direct radiation and an empirical equation of surface temperature were proposed based on the shading theory. The results showed that there were differences in solar radiation on different surfaces of embankment. The direction and slope angle of embankment were found to be the major factors of influence. The solar radiation on permafrost surfaces around the embankment were found to be affected greatly，especially when the embankment is higher and the slope angle is larger. The closer to the toe of embankment slope，the weaker radiation it received. The solar radiation on permafrost in shaded slope side is weaker than sunny slope side. The difference of solar radiation on permafrost surfaces around the embankment should be considered in the stability estimation of embankment.