Altered rock masses often lead to deterioration of physical and mechanical properties obviously. The associated distribution of alteration along the structural plane is a common geological phenomenon in altered rock strata，which will have an important impact on the stability of surrounding rock of underground engineering. The natural altered structural planes with the same degree of alteration，filling thickness and rock disk roughness，existing in the surrounding rocks of the underground powerhouse cavern groups of Fengning Pumped Storage Power Station in Hebei Province China，were selected to carry out the shear characteristics test and acoustic emission(AE) monitoring. The shear deformation and strength characteristics，failure mode and AE energy evolution law of natural moderate altered structural planes were analyzed. A shear statistical damage model based on the AE energy law of the natural structural planes was established，and the effects of model parameters on shear deformation and strength were analyzed. The results show that：(1) Shear stress has an effect on both normal and tangential deformation，and dilatancy effect occurs at the late shear stage before the specimen is about to fail；the failure mode of the structural planes is mainly manifested as failure along the filling material，dissociating and crushing of massive particles，and finally shear sliding；(2) AE is released in the whole shear process of natural altered structural planes，it bursts when stress changes and tends to be calm after stress balanced，and active suddenly before shear failure. The whole test process can be divided into compaction stage，dissociation stage，crushing stage and slip stage；(3) With the AE energy sequence of natural structural planes? shear process to define the damage variable and assuming the micro elements among the structural plane obey Weibull distribution，a shear statistical damage model of natural structural planes was derived，which is in good rationality and adaptability with the experimental results.

A shaking table model test was designed and completed to study the dynamic response and damage mechanism of counter-bedding slopes with thin and thick rock combination，taking the pre-slide slope of the “Gongzha” landslide in the Xuelongnang area of the Jinsha River basin on the Qinghai—Tibet Plateau as a prototype. The test results show that the PGA amplification coefficient increases significantly above 1/2 slope height of the slope，that the PGA amplification coefficient changes differently from inside to surface at different elevations of the slope，and that the PGA amplification coefficient increases in the high-steep area but decreases at the foot of the slope. The input seismic wave frequency，amplitude and time compression ratio all have a relatively large effect on the slope dynamic response. When the input wave amplitude is relatively large，the PGA amplification coefficient increases significantly under high-frequency wave excitation. When the input wave frequency is less than the slope natural frequency，the PGA amplification coefficient increases with increasing the input wave frequency，and after exceeding the slope natural frequency，the PGA amplification coefficient decreases at the surface while decreases first and then increases at the inside of the slope with the input wave frequency. The effect of input wave amplitude on the slope dynamic response is related to the type of input wave，and the slope dynamic response law is different under different types of input wave excitation. Comprehensive analysis of the slope dynamic response and high-speed camera photo records indicates that the PGA amplification coefficient in the high-steep area of the slope surface is the largest while that the variation law of PGA amplification coefficient along the elevation inside the slope basically follows the elevation effect. The natural frequency of the slope drops significantly at 0.2 g amplitude seismic wave excitation，and at this time the slope structure changes under seismic action. The damage mode is：cracks initiating in the upper shoulder of the high-steep area→the crack area expanding downward→local instability of the upper right side of the high-steep area→the instability zone expanding to the whole high-steep area→the rock in the high-steep area being shaken down from top to bottom along with part of the lower thin rock block，and the damage process is accompanied by a slight uplift of the lower part of the slope. The test reveals the dynamic response law and damage mechanism of counter-bedding slope with thin and thick rock combination under the action of earthquake，which provides a basis for the prevention and control of such slopes.

With the rapid development of underground rock mass engineering，the quantitative assessment of surrounding rock stability of underground caverns has become a major concern in the current academic and engineering communities. However，there is no quantitative standard for the assessment and classification of the global stability of surrounding rock in underground caverns. Therefore，this paper proposes a quantitative assessment approach for the global stability of the hard surrounding rock in underground caverns. The quantitative assessment approach integrates the results of engineering geological investigation，numerical simulation and field monitoring and takes the rating system as the basic framework. The quantitative assessment approach incorporates the influence of basic quality of surrounding rock，in situ stress，unfavourable geological structures，cavern dimension and layout，construction factors and groundwater on the global stability of surrounding rock. Based on the basic principle and the flow chart of this assessment approach，a cloud assessment system for the stability of surrounding rock in underground caverns is developed. The assessment system helps users to quickly and effectively determine the global stability of the surrounding rock in underground caverns and guides engineering practice. The quantitative assessment approach and cloud system are applied to assess the global stability of surrounding rocks in numerous underground caverns within many industries. The reliability and applicability of the approach and system are verified.

针对日益严峻的煤矿大巷群冲击问题，以某矿中央大巷复合构造区为工程背景，采用理论分析、数值模拟、现场监测与工程实践相结合的方法，研究大巷群重复冲击致灾机制及防治方法，得到如下结论：(1) 中央大巷复合构造区冲击地压是在特定地质环境和工程结构叠加作用下，以静载为绝对主导的自发型冲击；(2) 冲击后巷道围岩抗冲击能力下降和煤体应力恢复性增长是冲击地压重复发生的根本原因，没有支护的厚底煤承受高集中应力，成为能量释放的突破口，表现为底煤冲击；(3) 采用顶板超长孔水平分段压裂技术对中央大巷复合构造区进行区域卸压，通过压裂，使原本完整较好的坚硬目标岩层内形成数量众多、方位和长度不一的网状裂缝，大幅减弱岩层的整体强度，破碎后的岩层可视为塑性垫层，能起到吸收部分能量和减弱上覆顶板应力传递的作用，使应力由“硬传递”转化为“软传递”，进而降低压裂区域下方煤层的整体静载水平，使其无法恢复到冲击地压发生所需临界载荷，实现了降低冲击致灾风险的目的。

In order to study the anisotropic characteristics of argillaceous slate with structural planes during swelling in water-rich environment，the remolded argillaceous slate samples with different dips of structural planes were prepared to carry out swelling characteristics test，nuclear magnetic resonance test and scanning electron microscope test to analyze the macroscopic evolution law and microstructure change characteristics of argillaceous slate swelling anisotropy. Based on the tests results，the three-dimensional swelling constitutive model and the meso expression of swelling stress of argillaceous slate with structural plane dig are established. The results show that under the influence of the dip of the structural plane in water-rich environment，the swelling rate-swelling load of remolded argillaceous slate shows a nonlinear relationship，which is consistent with the natural argillaceous slate. Under the same axial load，the axial limit swelling rate is negatively correlated with the dip of the structural plane. Due to the structural planes with different dips，argillaceous slate?s lateral limit swelling ratio and the axial limit swelling stress under constant volume show obvious anisotropy，which are negatively correlated with the dip of structural plane. The pores of argillaceous slate after swelling are mainly small and medium pores；The microscopic basic unit of argillaceous slate is mainly composed of flake particles，and the part of the particles is massive particles. The orientation of spatial arrangement of particles is obvious. The contact mode between particles is mainly surface-surface contact and they are stacked in tower shape. With the increase of dip of structural plane，the number of pores，pore area and surface porosity gradually decrease，and the edge of pores tends to be complicated. The three-dimensional swelling constitutive model and meso expression of swelling stress of argillaceous slate with structural plane dip quantitatively characterize the anisotropic characteristics of swelling evolution of argillaceous slate in water-rich environment from macro-meso-micro scale. The research results can provide reference for the study of soft rock swelling mechanism and the treatment of soft rock swelling problem.

Coal seam water injection has a significant effect on preventing coal and gas outburst，reducing dust and cooling，softening coal seam pressure relief and anti-scour. Monitoring the migration law of water in the coal seam and obtaining an effective hydraulic wetting range are very necessary to evaluate the wetting effect of coal water injection. Therefore，in this paper，the water injection experiment is carried out on the coal body under the true triaxial state，and the ultrasonic self-excitation is supplemented. Technical monitoring records the characteristic parameters of coal transmission ultrasonic wave under different water injection conditions，and analysis of the relationship between water injection conditions and characteristic parameters such as longitudinal wave velocity，amplitude and attenuation coefficient is carried out. The results show that：(1) The amount of water injection increases with the water injection pressure and presents a linear stable state，but as the water injection time increases，the growth rate of the water injection gradually decreases and tends to zero. (2) The ultrasonic wave velocity has a linear positive correlation with the water injection pressure，and the wave velocity increment is basically stable with the increase of the water injection pressure；the wave velocity has an exponential positive correlation with the water injection time，but the sensitivity to the water injection time is gradually weakened；Wave velocity characterization of bulk modulus. (3) With the increase of water injection pressure，the ultrasonic amplitude increases as a whole，and the attenuation coefficient decreases as a whole；the sensitivity of ultrasonic amplitude and attenuation coefficient to water injection time is low-high-low. (4) The ringing count and the like are linearly positively correlated with the water injection pressure，and have an exponential positive correlation with the water injection time，and have a good consistency with the changing trend of the water injection amount.

为探讨不同含水状态红砂岩试样在动静组合状态下的失稳破裂特征，采用QKX-YB200真三轴岩爆试验系统、声发射监测系统以及高速摄像仪对自然和饱水状态下的红砂岩立方体试样开展真三轴卸载–动力扰动试验。研究结果表明：在真三轴卸载–动力扰动条件下，自然状态砂岩破坏模式为张拉–剪切混合型破坏，而饱水状态砂岩的破坏模式为张拉型破坏，不同含水状态砂岩的裂纹扩展程度与初始轴向静应力和动力扰动频率密切相关；相比于饱水状态砂岩，自然状态砂岩试样在动力扰动阶段出现了不同程度的块片弹射和飞溅现象，体现为典型的应变型岩爆特征；轴向静应力以及动力扰动频率对于不同含水状态砂岩的力学响应特征具有显著的差异性，其对于自然状态砂岩的力学响应主要体现为岩样的破坏剧烈程度，而对于饱水状态砂岩的力学响应则主要体现为岩样的破碎程度；对含水砂岩试样建立了真三轴卸载–动力扰动下裂纹扩展模型，认为水楔效应、中间主应力效应以及开挖卸荷效应是诱发饱水砂岩产生张拉型破坏的本质原因；基于室内试验结果，从能量转化、力学、物理以及化学的角度初步揭示了真三轴卸载–动力扰动下水弱化岩爆机制。

In order to study the influence of the micromechanical property and microstructure on the macroscopic mechanical properties of granite，the composition and proportion of each mineral as well as the morphology of the granite are firstly obtained by the X-ray diffraction and the polarizing microscope tests. Then，the mechanical properties of each mineral are qualitatively analyzed by nanoindentation test and the micromechanical parameters are calculated. In order to overcome the difficulty of considering the internal microstructure characteristics of rocks by the traditional homogenization methods，a DIP-FFT numerical method is proposed based on the combination of the digital image processing(DIP) and the fast Fourier transforms(FFT) method which can directly use the actual image of rocks to generate the numerical model. The proposed method is applied to calculate the effective elastic modulus and Poisson?s ratio which are compared with the analytical homogenization solution and the triaxial compression tests. The research results show that the mineral phases are obviously heterogeneous at the microscopic scale. It is noted that the phase of quartz possesses high strength with stable mechanical properties，and followed by the feldspar. The phase of mica performs large deformation with internal pore structure. The macroscopic elastic modulus of granite increases with the growth of the confining pressure and tends to be stable. The proposed DIP-FFT method reasonably considers the influence of microstructure characteristics and establishes the relationship between the microscopic and macroscopic properties of the studied granite. The predicted effective elastic modulus and Poisson’s ratio are well consistent with the experimental results under medium confining pressure. The results of this research provide a reasonable and efficient approach to determine the macroscopic mechanical properties of rock materials from the microscopic level. It is also important in engineering practice for evaluating the mechanical properties of surrounding rocks especially in complex engineering applications.

In order to study the unloading mechanical characteristics of cemented backfill in the high geothermal environment of deep coal mine，RTX–4000 rock dynamic triaxial apparatus was used to carry out the conventional triaxial unloading confining pressure test under different initial unloading confining pressures on cemented backfill after cured at different temperatures(20 ℃，35 ℃ and 50 ℃). The deviatoric stress-strain curve of cemented backfill during the whole triaxial unloading process was obtained，and its deformation，failure characteristics and strength criterion were analyzed. The results show that the harmful thermal stress inside cemented backfill after cured at 50 ℃ is easy to cause the stress-strain curve of cemented backfill under unloading to appear micro-rupture phenomenon in the post-peak stage，and then makes the deformation modulus drop suddenly and increase reversely in the process of unloading confining pressure. The unloading failure forms of cemented backfill are mainly local tension cracks，shear cracks and dislocation cracks，in which the dislocation cracks are caused by thermal damage and mechanical damage. Mogi-Coulomb strength criterion can better characterize the unloading failure strength characteristics of cemented backfill under the condition of increasing axial pressure and unloading confining pressure. With the increase of curing temperature，the cohesive force of cemented backfill decreases first and then increases，and the internal friction angle increases first and then decreases. The change of cohesive force is consistent with the change law of unloading peak strength. The greater the cohesive force，the higher the unloading peak strength，indicating that cohesive force is the main factor affecting the unloading peak strength of cemented backfill.

Key issues still remain in revealing the effect of hydrate formation on coal permeability，as well as the permeability variation subjected to mining exploitation，concerning to the application of the hydrate method. Using steady-state method based on outlet flow，the permeability tests of gas-bearing coal(three water contents and three particle sizes) and subsequently the tests of mine gas hydrate bonded coal for against loading-unloading of axial stresses were conducted，by triaxial testing machine for coupled seepage，chemical and triaxial stress measurements in mine gas hydrate bonded coal. Then，the rule and mechanism are revealed relating to the effect of hydrate formation，effective stress and hydrate saturation on coal permeability. The results show that the coal permeability decreases after hydrate formation by a reduction between 79% and 99%. The permeability varies exponentially with the effective stress under loading-unloading of axial stresses. The variation of the permeability under unloading can be divided into three patterns，including a small amount of permeability recovery，partial permeability recovery and permeability increase. In the process of loading-unloading of axial stress，the permeability loss rate and damage rate increase with the growth in the hydrate saturation for mine gas hydrate bonded coal. As a result，the formation of gas hydrate blocks the coal penetration channel and restricts the coal mine gas migration，which makes it a possible solution to shortening the construction period of rock cross- cut coal，accompanied by gas pressure decrease in a short time.

The key to the accuracy of the numerical results of the fracture evolution of mining overburden is to establish the mechanical constitutive model and numerical method reflecting the continuous-discrete medium transformation of mining rock. The yield function and plastic potential function with deviatoric stress and spherical stress as basic variables were constructed，and the elastic-plastic constitutive model of complete rock block was obtained by combining with generalized Hooke?s law. By introducing the elastic-plastic damage theory，taking the square tensile-shear stress criterion as the initial damage criterion and combined with the Benzeggagh-Kenane fracture criterion，the constitutive model of tensile-shear mixed mode fracture was obtained. The discrete block compression constitutive model was constructed，and the Sargin?s shear friction constitutive model of rough discontinuities was modified based on the direct shear experimental data. Therefore，a continuous-discrete coupling simulation program reflecting the progressive failure of rock was compiled. On the basis of verifying the constitutive model，the numerical calculation model was established according to the engineering geological conditions of the DaTong mine. The results show that：(1) The progressive failure constitutive model of rock and the corresponding continuous-discrete coupling simulation method can numerically realize the transformation process of rock from continuum to discrete body. (2) Under the disturbance of repeated mining in multiple coal seams，the distribution of overburden fractures in Carboniferous coal seams is complex，and its height is about 21 times of the mining height，far exceeding the results obtained by empirical formula. (3) Under the coupling action of concentrated stress and mining stress of Jurassic coal pillar，the peak value of advanced support pressure of Carboniferous mining face reaches 42 MPa，which is about 8–10 MPa higher than that in the area without coal pillar，and the ground pressure shows strongly. The above results have been preliminarily applied in Datong mining area，which provides theoretical support for further water retaining mining，fracturing and pressure relief.

Through field test and numerical simulation，the stress field distribution characteristics of high embankment slab-culvert and the surrounding soil are studied. The results show that the earth pressure at each point of the culvert is approximately linearly related to the self-weight of the filling soils over it，The linear coefficient is the unimodal curve with the width to height ratio of the slab-culvert，Based on this，an empirical formula for the midpoint pressure at the top of culvert is established，and compared with the standard method，the calculation accuracy is improved greatly. Under the influence of stress concentration at the top of culvert，the earth pressure on the plane of the culvert top presents M distribution，and the non-uniform distribution is about 1.5 times of the width of the culvert. The culvert has an effect on the distribution of soil pressure in the upper 1.5 times of the embankment?s height，and the profile shape of the affected area is inverted trapezoid. According to the distribution characteristics of earth pressure in the soil on both sides and above the culvert，the range of unequal compaction to reduce the pressure at the top of culvert is proposed. The horizontal pressure at each point on both sides of the slab-culvert is less than the static earth pressure，according to this design slab-culvert is biased to safety.

A series of base frictional tests were conducted to study the failure process of mine waste dump reinforced with geogrid under various conditions. By the image speckle analysis and point-tracking technology，the displacements and strains of mine waste dump were obtained，and the failure mode，stability of the dump and mechanism of the geogrid were analyzed. The results show：(1) When there is no geogrid or the length of the grogrid is insufficient，the mine waste dump will suffer deep failure，showing an integral arc sliding from bottom to top. When the full-length geogrid is used，the failure mode of the dump changes from the overall failure to local failure，and the shear effect of the shallow layer of the slope becomes more significant when the bench slope is steeper. (2) The deformation process of the dump can be divided into three stages. The first stage is the uniform deformation stage，and the displacement of the measuring points is small. The second stage is the deformation localization stage，in which some measuring points produce displacement acceleration and slip crack forms inside the model. The third stage is the failure stage，where the displacement of the measuring point shows a bifurcation phenomenon. To be specific，the displacement of the measuring point of the sliding body continues to increase，while the displacement of the measuring point in the stable body tends to be constant. The geogrid has a significant control effect on the deformation of the dump. (3) The initial cracking time and local failure time are taken as the evaluation index to study the stability of geogrid-reinforced dump. The geogrid can be used not only to improve the dump stability，but also to expand the volume of the dump. Taking Model A1 and B1 in this study as examples，the dump expands the volume by about 6.33% with geogrid reinforcement under the promise of ensuring stability. (4) For high and steep dumps with weak foundations，we recommend using full-length geogrid；however，for dumps with fine foundations and smaller heights，the length of geogrid can be reduced to save costs according to the practice. The results have guiding significance for the stability and expansion of the dump and saving the land area of the mining area.

Resilient modulus(MR) is an important mechanical performance indicator of unbound granular pavement materials subjected to repeated traffic loads，as well as a key input parameter of mechanistic pavement analysis and design. In order to investigate MR characteristics of unbound aggregate materials(UAMs) recycled from construction & demolition waste(CDW) under different combinations of influencing index properties and stress states，laboratory repeated load triaxial tests were conducted on UAMs recycled from single-source CDW，of which five different gradations，three different moisture content levels，three different compaction levels，and 15 different loading sequences were properly designed. The effects of index properties and stress states on MR were analyzed，and a unified MR prediction model was developed and further validated by using the shift factor and master curve concepts to incorporate multiple influencing factors. The laboratory testing results show that resilient modulus of UAMs recycled from CDW gradually decreased with decreasing degree of compaction or increasing moisture content and increased with increasing relative content of coarse particles. Both deviator stress and confining pressure affected resilient modulus of UAMs with the effect of confining pressure being relatively more significant. The unified MR prediction model developed can consider all the influencing factor while yielding satisfactory accuracy. The findings could provide theoretical basis and lay solid foundation for resource-conserving and value-added engineering applications of UAMs recycled from CDW in unbound granular pavement layers.

In order to intensively study the influence of different subsoil properties on the seismic performance of soil-pile-nuclear island structure system and the related seismic damage mechanism of pile foundations，three kinds of subsoil models with different stiffness were prepared for shaking table test，and the macro phenomena and test data were analysed and compared. The test results show that subsoil stiffness has a great influence on the seismic-soil-pile-superstructure interaction system. With the decrease of the subsoil stiffness，the phenomenon of soil-structure separation is more obvious，and the seismic damage of pile foundation is more serious. Due to large inertia force of the superstructure and compliance of the subsoil，the foundation pile is damaged not only at the pile head，but also at the depth of 5–6 times the pile diameter. In order to ensure the seismic safety of nuclear power engineering foundation，it is recommended to strengthen or select the soil layer with shear wave velocity greater than 300 m/s as the foundation subsoil.

In order to elucidate the phenomenon of freeze-thaw hysteresis and uneven frost heave in soil/rock mass during the freeze-thaw process，the mechanism of freeze-thaw hysteresis and freeze-thaw water migration was studied. Firstly，according to the generalized Clapeyron equation and Gibbs-Thomson equation，the freezing temperature equation of liquid water at any curved interface is given，and the freezing and thawing model of capillary is constructed. Based on this，by introducing the “main-branch type” pore structure with poor freeze resistance，the freeze-thaw hysteresis triangle model of capillary-film water is constructed. Finally，the correctness of the model is verified by low-field nuclear magnetic resonance experiments. The research shows that：(1) due to the difference in the curvature of the freeze-thaw boundary，the capillary pressure is twice the interface pressure，resulting in the melting temperature being only 1/2 of the freezing temperature；(2) the interface pressure is only related to the boundary conditions and has nothing to do with the freeze-thaw process. (3) The interface pressure has nothing to do with the theoretical ice pressure，theoretical suction，migration driving force and surface adsorption force，but is inversely proportional to the theoretical liquid pressure and the net suction；(4) Under the action of the interface pressure，the net suction is always maintained during the freezing and thawing process：PSuhi，1＜PSuhi，2＜PSuhi，3，thereby driving the migration，aggregation and phase transition of unfrozen water from micropores→secondary pores→main pores. In conclusion，the interface effect is the main cause of freeze-thaw hysteresis and freeze-thaw moisture migration.