A large number of reservoir-induced landslides caused disasters in the form of impulse waves in western China. If all landslides that may generate waves are prevented and controlled by current specification，the economic cost is huge. This paper taking Shuipingzi 1# landslide in Baihetan reservoir as an example to carry out application demonstration，a three-dimensional physical prototype model experiment was constructed with a geometric scale of 1∶150，and landslide energy reduction and wave descent experiments were carried out to find more economical landslide-induced impulse wave risk reduction solution. Physical test showed that under extreme conditions of the impounding water level with 825 m above sea level combined with a VIII-degree earthquake，the landslide would slide into Baihetan reservoir with the maximum speed of 7.37 m/s，and the maximum generated wave amplitude would be 7.59m. The maximum runup around Xiangbiling community was about 3.5 m above the ground，which would seriously threaten the safety of the riverway with the length of more than 4.5 km and the safety of Xiangbiling community. As the removal volume increases from 10×104 m3 to 47.9×104 m3，the effect of reducing energy and wave becomes evident. Wave making energy transmitted from landslide decreased by about 94.8%，the maximum wave amplitude and the maximum runup around the Xiangbiling decreased to 4.35 m and 1.73 m，respectively. The area with the impulse wave larger than 1 m was only distributed in the landslide course and the opposite bank of Jinsha River，and the risk of landslide-induced impulse wave decreased sharply. Based on this，this study proposes and discusses the feedback design mentality and the realization method of the safety margin of landslide-induced impulse wave risk reduction engineering design，which using the hazard degree of landslide-induce impulse wave as a measurement indicator，and recommends a risk reduction design scheme that can greatly reduce the economic cost of Shuipingzi 1 #landslide treatment. The design mentality of risk reduction prevention for landslide-induced impulse wave is a useful supplement of landslide control specification，which has yet to be further developed and promoted.

To improve the design approach of anchor plate supporting slope，the calculation formula of anchor plate size is proposed according to the internal balance of slope，and the formula of safety factor of unsaturated anchor plate supporting slope is obtained through the variational method combining limit balance method. By using transient seepage to simulate rainfall conditions，the variation rule of slope safety factor with rainfall time was obtained，and the internal mechanism of slope safety factor variation was analyzed. The results of safety factor are compared with the results of existing methods by 4 examples，and the rationality of the suggested formula is verified. The effects of rainfall intensity，seismic conditions and anchor plate supporting conditions on slope stability and sliding surface are analyzed. The results show that heavy rainfall and earthquakes will significantly reduce slope stability. Horizontal and vertical seismic forces will lead to deeper sliding surface，while vertical downward seismic forces will lead to shallower sliding surface. The proposed approach can not only calculate the safety factor of saturated and unsaturated slope，but also calculate the safety factor of slope under transient seepage and steady seepage，and has strong applicability. In order to facilitate the engineering application，by comparing the slope safety factor when the anchor plates are arranged at different vertical spacing，the vertical 3m spacing arrangement of the anchor plate is given as engineering suggestion. A simple method for the size design of anchor plate is presented. The size of anchor plate obtained by the simple design approach is much lower than the existing empirical design size.

粉煤灰是火力发电的主要废弃物，在中国西部地区广泛存在，受交通影响，处置成本高，西部宁夏甘肃地区沙漠化问题严重，基于两者供需关系开展粉煤灰改性材料固沙应用研究。文章基于固沙效果制定了参考固沙标准，针对改性粉煤灰固沙材料，通过单轴抗压强度试验、含水率试验、扫描电镜试验(SEM)、X射线衍射试验(XRD)、剪切试验等多种分析方法对改性粉煤灰材料的力学性质、水化产物和微观结构进行研究。结果表明，改性粉煤灰材料单轴抗压强度和胶结效果均得到了显著提高，改性粉煤灰材料水化后形成的水化硅酸钙凝胶是解释保水性差异的关键；10%碱激发剂改性粉煤灰胶结体黏聚力提升为原来的3倍以上，30%镁渣改性粉煤灰胶结体抗剪强度显著提高。文章建议采用低剂量碱激发剂(2.5%左右)或高剂量(大于30%)镁渣改性粉煤灰，并适当提高灰沙比，以获得更好的经济效益和固沙效果。

To investigate the lateral facing deformation characteristics and the relationship between the maximum deformation and stability of GRS wall in a tiered configuration，a validated finite difference numerical method was used to compute the maximum lateral facing deformation and the maximum tensile forces mobilized in each layer reinforcement，which were utilized to determine the factor of safety(FS) of the corresponding GRS walls，and then a parametric study was conducted to analyze the effect of properties of backfill and foundation soil，reinforcement properties，and configuration mode of tiered GRS wall on deformation and stability. The computed results showed that：(1) The other parameters of two-tiered GRS walls remain unchanged，increasing the friction angle or cohesion，the GRS wall becomes more stable，and the maximum lateral facing deformation and the maximum tensile force mobilized in reinforcement decrease and the FS increases. Increasing reinforcement length in upper or lower wall results in a reduction of lateral facing deformation and an increase of FS，and when reinforcement lengths in upper or lower wall reach the critical length，e.g. 0.7H(H，the total wall height) or 0.6H，the maximum lateral facing deformation and FS values tend to be stable. Reducing the vertical spacing of reinforcement or increasing the reinforcement stiffness caused a decrease in lateral facing deformation and an increase in FS.(2) For a multitiered GRS wall with equally individual wall height，with the increase of the offset distance，the maximum lateral deformation tends to decrease and then to be stable. The critical offset distance，beyond which the adjacent tiers wall functions independently，is 1.2 times the individual wall height for the recommended friction angle(? = 34°) by guidelines.(3) For a multitiered GRS wall with the same total wall height and normalized offset distance，increasing the number of tiers wall results in a decrease in maximum lateral deformation and FS，which then tend to be increasing when the number of tiers reaches a specified value. When the wall height ratio of the upper and lower wall is no great than 1，the change of the ratio does not affect remarkably the lateral facing deformation. Once the upper wall height is greater than the lower wall，the maximum lateral facing deformation in the upper wall increases significantly. In addition，increasing the total wall height causes an obvious increase in lateral facing deformation，and consequently，the FS decreases.(4) Based on the calculation results of two-tiered GRS walls，an empirical function is proposed to build the correlation between FS，normalized maximum lateral deformation，and normalized offset distance. It is helpful for engineers to evaluate the stability of a two-tiered GRS wall via the quantified maximum lateral deformation.

In order to accurately identify the pre-peak characteristic stress in the process of rock loading under different confining pressures，the pseudo triaxial tests with confining pressures of 0，10，30，50 and 70 MPa were carried out on the GCTS RTX-3000 testing machine using sandstone standard samples. The ultrasonic testing system and acoustic emission acquisition system were used to monitor at the same time，and the variation law of ultrasonic wave velocity and the distribution characteristics of acoustic emission location events during sandstone loading were obtained. A method that can shield ultrasonic interference signals from acoustic emission dates was proposed. The results show that the compression and shear wave velocities of the sample show a quadratic function relationship with the increase of confining pressure. With the increase of axial pressure，the compression and shear wave velocities of the sample show a law of growth，stability and decline. The shear wave velocities always show a downward trend before the compression wave velocities，and the shear wave is more sensitive to damage than the compression wave. The pre-peak characteristic stress can be accurately determined by comparing the change rules of volume strain，acoustic emission，ultrasonic and dynamic elastic parameters. The closure stress corresponds to the end of the rise of the shear wave velocity，the initiation stress corresponds to the beginning of the fall of the shear wave velocity and the inflection point of the dynamic elastic modulus，and the damage stress can be determined jointly by the beginning of the decline of the compression wave velocity，the rapid rise of the acoustic emission signal and the inflection point of the volumetric strain. Acoustic emission positioning can directly reflect the failure mode of the sample. Under low confining pressure，the sample will undergo split shear mixed failure，while under high confining pressure，the sample will undergo shear failure. This study is helpful to accurately identify the pre-peak characteristic stress of rock under load，and deeply understand the damage characteristics of rock under different stress conditions，which is of great theoretical significance to the stability evaluation of rock mass in deep underground engineering.

Determining the scope of the rock mass blasting damage zone is important for evaluating the stability of underground engineering surrounding rock under blasting and controlling bedrock damage under excavation. A method based on wave velocity field inversion was proposed to determine the rock blasting damage zone scope quantitatively. This method was based on multistencils fast marching methods(MSFM) and simultaneous iterative reconstructive technique(SIRT). The effectiveness of the proposed method was verified by comparing the inversed wave velocity field with the known one. Blasting and wave velocity measurement simulations were carried out on the self-developed finite-discrete element solver OpenFDEM. The waveform data were processed using a self-programmed post-processing program，and thus the post-blasting wave velocity field was reconstructed. Based on the relationship between the changing rate of wave velocity and the degree of rock mass damage in the current code，the areas with different wave velocity changing rates were compared with the areas of cracks. The scopes of the blasting damage zone with different damage degrees were quantified using the ratio of the equivalent radius to the blast hole radius. 10% and 15% of the wave velocity changing rate were used as the thresholds for defining slightly and completely damage of the rock mass，respectively. The ratio of the equivalent radius of the slightly damage zone and the damage zone to the radius of the blast hole is about 11.86 and 7.2，respectively. As the blast load increases，the shape of the damage zones with different damage degree becomes irregular and the equivalent radius increases. The study results are expected to provide a reference for determining the scope of the blasting damage zone in the field.

The shear behavior of the contact interface between frozen soil and pile is an important basis for establishing the frost jacking calculation model of pile in frozen soil regions. A series of negative temperature direct shear tests of frozen sand soil and concrete with different ice film thickness at the contact interface were carried out to analyze the influence of ice film thickness on the shear mechanical deformation characteristics of the interface. Combined with multiple regression method，a trilinear shear constitutive model with multiple factors was established. Based on the shear-displacement method，the trilinear shear constitutive model is introduced to establish a theoretical calculation model for the frost jacking behaviour of single pile during the process of unidirectional freezing of seasonal frozen soil，and an example is analyzed. The results show that the ice film thickness has a significant effect on the shear behavior of the interface，and the relationship between the peak shear strength and the residual shear strength and the ice film thickness can be approximated as hyperbolic functions. The shear constitutive model can better reflect the effects of interface temperature，normal stress and ice film thickness on the shear behavior of frozen soil-concrete interface. Some pile-soil interface will slip during the freezing process of the soil around pile，and the peak position of tangential frost heaving force moves downward with the development of frost depth. The thickness of ice film has significant influence on the frost jacking effect of pile foundation. The frost jacking force does not increase linearly with the increase of frost heaving ratio，which is mainly affected by the shear strength between pile and frozen soil.

Given the technical challenges of insufficient image clarity and inaccurate quantitative characterization in the in-situ detection of pore structures on low reflection rock walls，this paper proposes a quantification method of pore structure in low illuminance borehole images based on pixel spatial Information. By synchronously utilizing borehole wall images and point cloud data to obtain pixel spatial feature information of non-standard cylindrical borehole shapes，the quantification process of pore structure in low reflection characteristic rock layers under complex geological conditions is achieved. Firstly，based on the low illumination borehole wall image features with alternating light and dark textures that are often formed in the actual drilling environment and testing process，a borehole wall eccentricity image correction model that is suitable for the actual hole testing environment is constructed to form a cosine light and dark texture suppression function that can effectively weaken the hole wall light and dark texture phenomenon. Subsequently，a low illumination borehole wall image enhancement algorithm based on detail feature weighted fusion is proposed to enhance the texture information of low illumination borehole wall images. Finally，combining the division of pixel spatial cells and the calculation of horizontal and vertical scales of pixel spatial points，a pore structure quantification method utilizing pixel spatial information is formed. At the same time，combined with practical case analysis，the correctness and superiority of the method proposed in this paper are verified. The results show that the method can obtain pixel spatial feature information of borehole walls in non-standard cylindrical drilling shapes，which can provide a new technical method and means for in-situ detection of pore structures in low reflection characteristic rock layers under complex geological conditions.

To study the coupling mechanism of seepage and heat transfer in high-temperature rough rock fracture and improve the efficiency of geothermal energy extraction，based on lattice Boltzmann method the double distribution functions were applied to deal with the evolution of seepage velocity field and heat transfer temperature field separately. Considering the effects of fluid temperature on its kinematic viscosity and thermal diffusion，a numerical model was proposed to simulate the coupled process of seepage and heat transfer in rough rock fracture. And the accuracy of the model was verified according to a classic example. Based on the proposed model，the effects of rough fracture surface and dynamic evolution of fluid physical parameters on the coupling mechanism of seepage and heat transfer was analyzed，and the relationship between the roughness of fracture surface and the performance indicators of geothermal extraction was discussed. The results show that the obstruction effect of the rough fracture surface increases the inertial pressure drop and reduces its seepage velocity，which makes the heat transfer between water and rock more sufficient，and the water temperature is higher at the outlet. Neglecting the influence of fluid temperature on its kinematic viscosity seriously overestimates the flow velocity，and significantly underestimates the thermal breakthrough time. As the roughness of the fracture surface intensifies，its thermal breakthrough time gradually increases，while the heat production power shows a decreasing trend. When the fractal dimension of fracture surface is 1.079 8，its thermal breakthrough time increases by 191.49% compared to the smooth fracture，and the heat production power is only 44.36% of that of smooth fracture. In addition，when the pressure drops are the same，the smoother the fracture surface is，the higher the heat recovery rate obtained within the same time. However，due to its shorter heat breakthrough time，the heat recovery rate is significantly reduced when the thermal breakthrough occurs.

The application of Microbially Induced Calcite Precipitation (MICP) technology to improve geomaterials has become a significant research focus. However，studies on the resistance of treated soils to wet-dry cycles and the analysis of their deterioration mechanisms are still limited. Therefore，this study focuses on granite residual soil treated with microbial improvement and designs wet-dry cycle tests under typical environmental conditions. Comprehensive mechanical tests and microstructural analysis were conducted to systematically analyze the changes in mechanical properties and deterioration mechanisms of the microbially improved granite residual soil under wet-dry cycling. The results indicate that：(1) Under the influence of wet-dry cycles，the compressive strength and shear strength of the treated soil exhibit a deterioration trend that is initially rapid but gradually slows down. After 30 cycles，the compressive strength，cohesion，and internal friction angle decrease by 56.73%，38.73%，and 24.66%，respectively. The deterioration is faster during the first 12 cycles，while it significantly slows and stabilizes thereafter；(2) The porosity，density，and P-wave velocity of the treated soil exhibit a change pattern consistent with the mechanical parameters due to the dissolution of calcium carbonate cement and feldspar minerals under wet-dry cycles；(3) Microstructural analysis reveals significant improvements in the pore structure of the treated granite residual soil，with increased compaction and a marked reduction in interconnected pores. During wet-dry cycles，the dissolution of calcium carbonate cement and feldspar minerals in some interconnected pores leads to a slight increase in porosity. However，the calcium carbonate within enclosed pores remains intact，and the kaolinite produced from feldspar dissolution reacts with calcium ions to form aluminosilicate precipitates that fill and block pore channels. Consequently，the microstructural changes and the deterioration of the physical and mechanical properties of the treated soil under wet-dry cycling tend to stabilize. These research findings and insights provide valuable references for the application of MICP technology in improving granite residual soils.

In order to study the dynamic mechanical properties and crack extension law of water-saturated fractured sandstone，sandstone specimens with seven prefabricated crack inclinations(0°，15°，30°，45°，60°，75°，and 90°) were saturated with water，and impact compression tests were carried out with the SHPB test device. The results show that the dynamic stress-strain curves of prefabricated and natural sandstone samples with different inclination angles are similar，and can be roughly divided into three stages. The dynamic compressive strength，dynamic strain and dynamic elastic modulus all showed an overall trend of decreasing and then increasing with increasing fracture inclination. Compared with prefabricated natural sandstone specimens，the dynamic compressive strength and dynamic elastic modulus of the water-saturated sandstone specimens were slightly increased，while the dynamic strain was reduced，showing the Stefan effect of water action under dynamic loading conditions. With the change of fracture inclination，the failure modes of water-saturated sandstone specimens are tensile，shear and tension-shear composite failure modes. The fracture inclination is 0° and 15° for type II failure，30°～75° for I-II composite failure，and 90° for type I failure. The crack initiation position of prefabricated fractured sandstone specimens is mainly concentrated near the fracture tip，and the crack initiation angle decreases with the increase of the fracture inclination angle，and the crack initiation angle at the incident end is larger than that at the transmitted end.

To investigate the weakening mechanism of water on impact-induced rockburst，15 experiments were performed considering different water content levels on cubic sandstones. Photography and acoustic emission (AE) system were used to monitor the rockburst process. According to the photography results，impact-induced rockburst under different water content levels all experience three processes：particle ejection，debris peeling，and comprehensive rockburst. In addition，the results also show that the higher the water content level，the lower the intensity of the rockburst. This effect is reflected in the fact that the AE energy，the quality and the fractal dimension of fragment show a decreased trend with the increase in the water content level. Based on the perspective of energy and micro-crack evolution，two mechanisms are proposed to explain the weaking effects of water on rockburst intensity，including：(i) water increases the plastic deformation capacity，weakens the energy storing capacity and reduces the rockburst tendency of sandstone，resulting in a slightly intensity of rockburst；(ii) water accelerates the expansion of shear cracks，which is not conducive to the occurrence of plate cracking before rockburst，and destroys the conditions for rockburst inoculation.

This study focuses on Tamusu mudstone，an argillaceous rock from the preselected area for high-level radioactive waste(HLW) underground disposal in China. Based on the previous work on the evaluation of argillaceous rock for the HLW geological disposal repositories，a systematic experimental and theoretical study is conducted on the creep characteristics of Tamusu mudstone under complex conditions. Creep tests show a positive correlation between deviatoric stress and creep deformation under the same confining pressure. The elastic modulus shows a trend of first increasing and then decreasing during the creep process. The creep deformation of Tamusu mudstone results from the combined effect of strengthening and structural degradation. Based on the creep behavior of Tamusu mudstone，creep hardening variables and creep damage variables were introduced，and further the creep yield surface and creep potential function were constructed based on Perzyna?s overstress theory. A creep constitutive model for Tamusu mudstone was established，and it was numerically implemented and verified by the software ABAQUS and its UMAT subroutine. This study comprehensively and systematically interprets the creep deformation law and deformation mechanism of Tamusu mudstone in the HLW disposal environment，providing an important theoretical basis for the safety，feasibility，and suitability evaluation of China?s argillaceous rock HLW geological disposal repository. The research work has important practical value for the development and long-term safety of China?s nuclear industry.

Carbon storage is an effective way to reduce CO2 emissions and mitigate environmental problems such as global warming. The porosity and permeability characteristics of storage reservoir are the key factors to determine the efficiency of CO2 storage，one important mechanism among which is the weakening of calcite cementation by acid erosion，and it is therefore necessary to carry out the researches on weakly cemented sandstone sensitive to acid. This study developed a prepare method of acid-sensitive weakly cemented artificial sandstone，conducted the deformation analysis of acid-sensitive weakly cemented sandstone during acid erosion process，and investigated the change laws of sandstone permeability before and after acid erosion. Firstly，based on the response surface experimental method，the effects of different urease activity，concentration of cementing fluid and concentration of skim milk powder on the strength of acid-sensitive weakly cemented artificial sandstone were studied，and a regression model considering multiple factors was established. Secondly，the acid erosion seepage tests of acid-sensitivity weakly cemented artificial sandstone under different stresses were carried out to analyse the deformation of sandstone during acid erosion：During acid erosion，the sandstone strain increases linearly with the acid flow，and the cementation weakening induced by acid erosion seepage can make the sandstone shrinkage strain exceed 4%. Finally，the change of sandstone permeability before and after acid erosion was studied：The permeability reduced by 70% under high confining pressure. The study reveals the acid erosion characteristics of weakly cemented sandstone，which has a certain guidance on CO2 geological storage project.

The accurate determination of the boundary equation is crucial for the classification and identification of cracks in the rock fracture process using the acoustic emission RA-AF values. The granite shear acoustic emission monitoring experiment was carried out. Based on the crack classification method of acoustic emission RA-AF，the influence rule of slope k and intercept b of the boundary equation on the crack classification results was analyzed. With the help of kneedle algorithm of inflection point monitoring，a method to accurately determine the boundary equation was formed. Based on this，the results of crack classification were discussed and analyzed. The results indicate that both the slope k and the intercept b of the boundary equation have an impact on the crack classification results，and the influence depends on the size of the value of k and b. There exist critical slope ，and critical intercept . When the values are below the critical values，the classification results are greatly affected. While when they exceed the critical values，the impact on the classification results is small or almost negligible. The kneedle algorithm for inflection point detection can effectively determine the critical points of the boundary equation's slope and intercept，which provides a method and basis for accurately determining the critical slope and intercept in the boundary equation. Compared with the boundary equation without intercept，if the boundary equation has intercept b，the proportion of shear cracks will increase by about 20%. The research results provide a basis for determining the boundary equation of rock tensile-shear crack classification using acoustic emission RA and AF values，which is helpful to promote the application of this method in rock mechanics.

Hydrodynamically induced colluvial landslide is one of the main geological disasters in southwest China. It is significant to investigate the erosion differentiation mechanism of soil-rock mixtures for revealing the landslide mechanism in depth. The rock content is the most important factor affecting the erosion differentiation characteristics of soil-rock mixtures. Based on the seepage erosion tests of soil-rock mixtures with different rock content，the erosion differentiation characteristics and mechanism of soil-rock mixtures are revealed. The results show that there are four random states in the process of seepage erosion of soil-rock mixtures：erosion intensification，erosion mitigation，internal block structure reorganization and erosion stability. The rock content has a significant effect on the erosion differentiation characteristics. The permeability coefficient of soil-rock mixture increases at first，then decreases subsequently，and then increases again with the increasing rock content，and the lowest value is observed at the rock content of 60%，which was less than 1×10－2 cm/s and cause a slight fluctuation. Whereas，the permeability coefficient of soil-stone mixtures at a high rock content is nearly unchanged before and after seepage，with a change rate less than 10%. The amount of erosion increases with the increasing hydraulic gradient. On the basis of change of erosion amount，the seepage erosion is divided into three stages：violent erosion，slow erosion and stable seepage stage. The critical hydraulic gradient decreases with increasing rock content. The rock content affects the permeability of the soil-rock mixtures by affecting the filling form of the soil-rock structure，and the full-filled structure has the best impermeability，which provides ideas and references for revealing the mechanism of hydraulic instability of the colluvial slope.

Through conducting the triaxial unloading-induced slip tests of different types of rock structural planes with dry，wet and crude oil interfaces，the effect of interface types on the activation process of rock structural planes was explored，and the correlations between the microscopic characteristics and macroscopic performance of structural planes during the activation process were revealed. The results show that the activation of rock structural plane is divided into three stages，i.e.，stable stage，activation stage and dynamic slip instability stage. During shear sliding of rock structural plane，rock fragments resulting from the shearing and exfoliation of rock structural plane accumulate in the form of bedding，with greater damage observed at the edges of the structural plane compared to the interior. The JRC degradation rate of rock structural plane with dry interface is 62 % after the triaxial tests，which is greater than that of dry interface(33.6 %) and crude oil interface(30.5 %). For the structural plane with dry interface，the asperities on the structural plane are strongly self-locked，and the average slip rate is low(0.13 μm/s) in the stable stage. While in the stick-slip stage，the damage of the asperities on the structural plane is primarily brittle failure with suddenness，which leads to the average slip rate of stick slip reaching 9.7 μm/s，74 times larger than that in the stable stage. For the structural plan with wet interface，the presence of water promotes the occurrence of stick-slip events. During stick-slip，the damage of the asperities is mainly ductile failure，and the slip rate transition exhibits a sharp increase followed by a falling process. The mixing of rock fragment and water during shear slip increases the contact area between the adjacent structural plane，improves the intermolecular adsorption force，and strengthens the friction strength of the rock structural plane. For the structural plan with crude oil interface，a layer of colloidal crude oil is attached to the rock structural plane，which fills the void space on the rock structure surface as ductile gouge layer，weakens the hardness of the surface asperity and reduces the friction strength of the rock structure structural plane. The existence of crude oil also makes the friction strengthening effect of the structural plane and the self-locking effect of asperities weak，and the structural plane is more prone to undergo dynamic slip compared to structural plane with dry or wet interfaces. The interface type controls the increase of friction coefficient and the slip rate at the start of dynamic slip. The friction coefficient of dry，wet and crude oil rock structural planes increased by 5%，11.2% and 0.7% respectively during activation process，and the slip rate at the start of dynamic slip are 1.1 mm/s，0.27 mm/s and 0.023 mm/s respectively. Our research may provide a theoretical basis for evaluating the fault instability of structural plane with different interface types in the oil and gas reservoirs，and have important implications for better understanding the occurrence of extraction induced fault activation.

Currently，the research on the thermo-mechanical response of energy piles primarily focuses on vertical loads，while studies considering the influence of horizontal loads are relatively limited. To investigate the thermo-mechanical response characteristics of horizontally loaded energy piles，a model test was conducted to analyze the variations in pile top displacement，pile bending moment，pore pressure，and soil pressure in front of the pile under different temperature gradients in saturated clay. The research results showed that both heating and cooling of the pile induced additional pile top displacement，with cooling causing a larger additional displacement，reaching 0.22%D (D is the diameter of the pile)，while heating induced an additional displacement of 0.13%D. The ultimate bearing capacity of the pile increased after heating/cooling compared to the ultimate bearing capacity pile，with a greater increase observed after heating，approximately 32.7%，compared to an increase of approximately 26.1% after cooling. This was due to the significant increase in the strength of the soil caused by the thermal consolidation effect during heating. Heating and cooling did not have a significant impact on the location of the maximum bending moment，as the maximum bending moment consistently occurred at 37.5%L (L is the burial depth of the pile) before and after heating/cooling. The maximum bending moment increased after heating/cooling. During cooling，the maximum bending moment initially increased and then stabilized gradually. During heating，the maximum bending moment decreased first and then gradually increased，exceeding the pre-heating moment. Throughout heating period，the pile top displacement continued to increase，suggesting that the pile may undergo rigid rotation in the initial stage of heating. Heating and cooling have different effects on the soil pressure in front of the pile. Overall，the upper part of the soil pressure generally increased and the lower part decreased. Heating and cooling caused variations in pore pressure in the soil，resulting in positive or negative excess pore pressure.

In order to study the seismic dynamic response law of high arch dam，based on the measured seismic waveform of Dagangshan arch dam with a height of 210 m and a distance of 21 km from the epicenter in the Sichuan Luding MS 6.8 earthquake，the seismic response characteristics and laws are analyzed by time domain and spectrum analysis methods. The results show that under the main shock excitation of the Luding earthquake，the peak acceleration(PGA) of the arch dam along the river is 586.63 cm/s2(6 # dam crest)，and the PGA of the bedrock along the river is 229.18 cm/s2. The acceleration distribution is generally greater than the horizontal and vertical directions，and the dam body is greater than the resistance body on both sides. The dynamic response of the dam is the most significant along the river. As the elevation increases，the dynamic amplification effect gradually increases，and the maximum amplification factor reaches 4.2 times(6 # dam crest).The results of spectrum analysis show that the main frequency of the earthquake is about 1.73 Hz，and the main frequency of the dam above 1081 m is between 1.52 and 1.75 Hz，which is close to the modal frequency of the dam. This is one of the reasons why the dam has a strong sense of earthquake. Combined with the dynamic response analysis of typical earthquake dams in recent years，earthquakes with large magnitude and far epicenter distance are more likely to stimulate the low-frequency dynamic characteristics of dams. The relevant results can provide reference for post-earthquake dam safety assessment，seismic design and research of high arch dams.

The stratification and bedding characteristics of the coal-bearing construction make the surrounding rock more of a shear disaster. To further investigate the shear fracture behaviour of coal rock masses under cyclic loading conditions，uniaxial compression tests on sandy mudstone were carried out using constant amplitude cyclic and stepwise linear cyclic loading and unloading methods in conjunction with CT scanning. The “Domino” structure of shear rupture of rock samples and its evolutionary characteristics were analysed by means of the rupture morphology and the stress-strain curve of the whole process. The results show that：under uniaxial compression and constant amplitude cycles and stepwise linear cycles，shear failure occurs in all rock samples. Moreover，the shear fracture zone formed by the failure of rock samples under stepwise linear loading and unloading cycles includes several strain localization zones with a “Domino” structure，and the stress-strain curve corresponding to the failure process shows a special “hysteresis-reciprocation-hysteresis-reciprocation” oscillation fluctuation. The strain localization zone presents the evolution process of nucleation，cracking，expansion，decay and conduction. The rotating-gyration motion of the fragmented block with the “Domino” structure causes multi-stage dissipation of the input energy and elastic storage energy after the peak in the friction of the block，which prolongs the damage time and has a significant “slow release” effect. The shear crack morphological evolution and stress–strain concealment information cooperate with each other to divide the shear failure process into six failure stages，namely：crack initiation micropropagation(I)，crack initial propagation(II)，primary shear crack propagation(III)，Crack propagation metastable(IV)，rapid crack propagation(V)，accelerated failure(VI). The “Domino” structure is a unique form of shear failure，and the energy “slow release” effect it plays may be a new idea for coal mine roadways to use the surrounding rock structure to relieve pressure and protect the roadway.

With the continuous warming of climate，thermal and melting degradation of perennial frozen layers in the Qinghai-Tibet Plateau，Alps and other high altitude areas leads to a large number of rock mass instability disasters. To study the "softening effect" of mechanical properties of frozen ice-sandwiched rock mass upon thawing is a key premise to reveal the thermal melting instability mechanism of frozen rock mass. In this paper，a series of uniaxial compression tests were carried out on frozen rock mass with different crack angles and melting temperatures，and acoustic emission and high-speed photography methods were used to monitor the failure process. The results show that：(1) the uniaxial compressive strength of the samples decreases first and then increases with the increase of the crack angle θ.(2) The uniaxial compressive strength of the sample decreases gradually with the increase of temperature，which can be divided into three stages： rapid reduction stage(－20 ℃～－6 ℃)，fluctuation decline stage(－6 ℃～－1 ℃) and strength plunge stage(－1 ℃～0 ℃).(3) The samples with different crack angles have three failure modes：the ice layer is crushed as a whole，which is brittle failure；The obvious plastic deformation occurs after the ice is broken，which is ductile failure. Cracks in the middle of the ice layer extend to the upper and lower ice-rock interface，and relative slippage occurs along the interface of the upper and lower rocks. The whole sample is broken，which is brittle failure.(4) Under the condition of thermal melting，the failure mode of fractured ice-sandwich rock mass can be divided into two types：the cracks in the middle of the ice layer expands to the upper and lower ice-rock interface，the relative slip of the upper and lower rocks occurs along the interface，and the whole sample is broken(－20 ℃≤T≤－6 ℃ or －1 ℃≤T≤0 ℃)；Obvious plastic deformation occurred after the ice layer was broken，and no whole fracture occurred(－6 ℃＜T＜－1 ℃). Through theoretical analysis，the influence mechanism of crack Angle on the compressive strength of fractured ice-sandwich-rock mass is mainly that the failure mode of fractured ice-sandwich-rock mass changes from vertical splitting failure of ice sheet to shear failure along ice-rock interface and shear failure along ice layer with the increase of crack Angle. Based on the results of NMR one-dimensional imaging，the content of unfrozen water at the ice-rock interface increases continuously during the heating process，that is，the strength of the ice-rock interface decreases continuously，which leads to the temperature dependence of the strength variation of fractured ice-rock mass.

Rockburst proneness evaluation provides a basis for rockburst risk assessment in deep tunnels. Based on energy dissipation characteristics of the complete stress-strain curve of rocks under uniaxial compression，a new evaluation index for rockburst proneness，the maximum energy dissipation rate(the maximum value of time derivative of the dissipated energy density)，was proposed. The rationality of proposed index was explained from three perspectives：stability criteria，experience，and definition of rockburst proneness. To quantitatively calculate the proposed index，an elastic-brittle-damage constitutive model considering void compaction and initial damage was established. To verify the applicability of the proposed index and damage model，uniaxial compression and cyclic loading and unloading tests were conducted on four different rocks(basalt，granite，limestone，and sandstone) under rigid and flexible testing machines. Based on the orthogonal tests，correlation analysis，and range analysis，the internal relationship between the proposed index and other rockburst proneness indices was revealed. The major findings are as follows. (1) There exists a maximum energy dissipation rate in the post-peak stage of rock stress-strain curve，which can be used as an inherent stability indicator to evaluate rockburst proneness. The advantage of this indicator is that it can comprehensively consider the pre-peak energy storage and consumption characteristics and post-peak characteristics. (2) The proposed elastic-brittle-damage model effectively describes the nonlinear mechanical behavior and intrinsic energy evolution characteristics of brittle rock(including input energy density，elastic strain energy density，and dissipated energy density). The theoretical curve is in good agreement with the experimental values，and the proposed maximum energy dissipation rate index can be accurately calculated using proposed model. (3) The calculation results of the maximum energy dissipation rate index for different rocks are consistent with the actual rockburst intensity observed in the experiment，verifying the reliability of proposed index. (4) Among the energy-based rockburst proneness indices，the proposed index has the strongest correlation with residual elastic energy index(with a correlation coefficient of 0.940)；the proposed index considers the degree of influence of rock brittleness on rockburst proneness more reasonably. The research method adopted in this study provides a new approach for proposing rockburst proneness indices and analyzing their interrelationships，and the research results provide a scientific basis for the reasonable evaluation of rockburst proneness.

To study the hard sandstone rockburst failure characteristics under high ground stress and simulate the "damage" failure characteristics of the rock mass in that state，a Mode I/II mixed cohesive zone model based on Park-Paulino-Roesler(PPR) potential energy function was established. Through disk-shaped compact tension test and punch-through shear test，the Mode I and Mode II fracture characteristics of hard sandstone were studied，and model parameters were obtained. Then，a numerical model is established to simulate the rockburst of hard sandstone tunnel under high ground stress. The stress and energy of the elements in the process of rockburst are tracked to analyze the process and failure characteristics of rockburst in hard sandstone tunnel. The research results indicate that：(1) The shear strength and Mode II fracture energy of hard sandstone increase with the increase of confining pressure. When the confining pressure exceeds 30MPa，the Mode II fracture performance tends to stabilize. (2) When the vertical stress is much greater than the horizontal stress，the hard sandstone tunnel mainly experiences tensile-toppling rockburst in the form of layered spalling or wedge-shaped burst；On the contrary，shear-bursting rockburst characterized by penetrating shear failure in rock mass will occur. When the horizontal stress and vertical stress are both large，the unloading failure mode of rock mass mostly shows the characteristics of tensile-shear composite failure，and the tensile-stripping rockburst mainly occurs.

Tension cracks at the rear edge of a slope often have a significant impact on the stability of rock slopes，how to effectively predict the location and depth of tension cracks becomes a key prerequisite for reliable analysis of the stability of rock slopes with tension cracks. Thus，a novel method is developed to solve the location and depth of tension cracks at the rear edge of rock slopes，specifically focusing on rock slopes without joints or with four or more sets of joints，based on the formation mechanism of tension cracks. The present method begins by applying the nonlinear generalized Hoek-Brown(GHB) strength criterion，which incorporates the influence of joints into the calculation of rock mass strength. Furthermore，given the approximate vertical development of tension cracks at the rear edge of the slope，the horizontal stress state of the rock mass becomes a crucial factor in the formation and development of tension cracks. Consequently，a micro-wedge unit mechanical analysis model is introduced to determine the horizontal stresses of the rock mass at the rear edge of slope. Thereafter，based on the top-down development pattern of vertical tension cracks at the rear edge of slope and the relationship between the terminal stress level of the tension crack and the rock mass’s tensile strength，a discriminant formula is formulated to calculating the location and depth of tension cracks at the rear edge of slope. The rationality and effectiveness of the present method is verified by comparing with the numerical simulation method，laboratory test results，and engineering measured data. The research findings provide a theoretical basis for predicting the location and depth of tension cracks at the rear edge of rock slope and establish necessary conditions for a reliable stability analysis of rock slopes with tension cracks at the rear edge.

To study stress distribution and failure characteristics of floor of a longwall panel with a negative gate pillar，coupled finite and discrete element numerical modelling method was adopted to construct a FLAC-PFC coupling numerical model. Spatiotemporal evolution of floor stress distribution，failure characteristics and effect of caved rock accumulation on floor stress and failure were analyzed throughout the process from setup room excavation to compaction of caved rock in gob to roof strata settlement. Based on elastic mechanics，a mechanical floor model was established to derive failure depth. The results show that：(1) Asymmetric accumulation of caved rocks in gob and asymmetric collapse of roof result in asymmetry of stress and failure of floor. (2) A "bottleneck" structure is formed by asymmetric failure of the floor and rotary cave-in of key blocks of roof，which hinders the further asymmetric slip of gob rocks. (3) The floor stress distribution under the influence of asymmetric accumulation of gob rocks presents a spacial distribution of "large top and small bottom". And the stress concentration on both sides of the gob increases first and then decreases over time，and the floor stress experiences a transition of "compressive-tensile-compressive". (4) Numerical simulation，theoretical calculation and field measurement results verify the asymmetric characteristics of stress and failure of floor caused by asymmetric accumulation of gob rocks. The study serves to provide theoretical support and scientific basis for determining location of gob side entry and its surrounding rock control of future adjacent panel with a negative gate pillar.

In order to reveal the unloading creep failure mechanism of water-bearing mudstone，the rising axial pressure-reducing confining pressure creep tests，meso-structure tests and numerical simulation analysis were carried out for mudstone with different water contents. The results show that：(1) The water content has a significant effect on the creep deformation of mudstone，and the axial strain is significantly more affected by the water content than laterally at the same creep stress level. (2) SEM image analysis shows that the increase of moisture content leads to the increase of internal porosity of mudstone，and the mineral particles are dissolved and weakened，which is transformed from a dense and high strength to a loose porous and irregular accumulation structure with low strength. (3) Based on the real meso-structure characteristics of mudstone，a statistically equivalent meso-structure network is generated，and the corresponding GBM-PSC numerical model is established and verified. (4) The numerical simulation results show that the number of microcracks increases with the increase of moisture content，and the number of intragranular tensile cracks increases first and then stabilizes and then increases，while the number of intergranular shear cracks continues to increase with the increase of moisture content. The contact tangential force，angular deflection value and average porosity decrease first and then stabilize and then increase with the increase of unloading creep time，and the more the moisture content increases，the more significant the trend. (5) A three-stage unloading creep deterioration evolution model of dry and water-bearing mudstone is established，and the research results can provide a theoretical reference for the study of the creep deformation failure mechanism of excavation and unloading of soft rock engineering under the action of water.

In this study，drying experiments at different temperatures were conducted to study the variations in the quality，fracture，pore，microstructure and expansion of upper-Shaximiao Formation red mudstone in eastern Sichuan Province. Field emission scanning electron microscope(SEM)，N2 adsorption measurement and digital radiography(DR) were used to evolution micro-structure，meso-pore and macro-fracture of rock samples during heat treatment，aiming to obtain the mass loss and expansion rules of rock samples reveal the influence of heat treatment on the expansion mechanism of red mudstone. The results show that：(1) The mass loss of rock samples presents two patterns as "rapid water loss-slow water loss" and "slow water loss" with the increase of heat treatment temperature. The complete water loss of the red mudstone requires a heat treatment temperature greater than 130 ℃；(2) Clay minerals exhibit interlayer opening and cracks along layers after high-temperature heat treatment，while they mainly show intralayer cracks after low-temperature heat treatment. The contribution of heat treatment temperature to macro cracks after heat treatment is low less than primary fissure；(3) The fine particles (0.5～2 nm) in rock pores increase significantly with the decrease of heat treatment temperature，and the number of these particles reaches the peak at 110 ℃. Heat treatment temperature has an obvious effect on the micro-pore sizes of rocks. Compared with the "single peak" distribution of pores in natural state，the pore distribution after the high temperature heat treatment presents a bimodal type. (4) The expansion pattern under the low temperature treatment is mainly controlled by macro-fractures，while the expansion pattern under high temperature treatment is dominantly controlled by the macro-fractures and micro-pores. In addition，increasing the heat treatment temperature can significantly increase the curve slope and final expansion in the “rapid expansion” stage. The results reveal the characteristics of micro-structures and micro-pores and the development of macro-fractures under different heat treatment conditions and discuss the influence of heat treatment temperature on the expansion processes of upper-Shaximiao Formation red mudstone，which may provide a new insight into predicting the drying degree of mudstone and provide a reference to the correction of final expansion rate under specific heat treatment conditions.

In order to explore the influence of multi-stage cyclic loading with a constant amplitude on rock deformation，damage and permeability，a four-stage cyclic loading and unloading triaxial test was carried out on sandstone samples under different confining pressures. The permeability was measured and acoustic emission (AE) signals were monitored in real time during the test. The effects of confining pressure and cyclic loading on the characteristic stresses，permeability，b-value and RA-AF (risetime/amplitude - average frequency) value of AE signals during multi-stage cyclic loading are analyzed. The results show that：(1) Compared with the conventional triaxial compressive test，the volume strain of the sandstone crack under each stage of the multi-stage cyclic loading test is expanded，and the peak stress decreases. With the increase of confining pressure，the difference between the two peak stresses decreases，and the cyclic loading effect is weakened. (2) Under both the conventional triaxial loading and multi-stage cyclic loading conditions，the permeability decrease first and then increase. After cyclic loading，the permeability strain-based loss rate(PSL) of the rock sample is smaller，and the macroscopic deformation of the rock is aggravated. When the confining pressure increases，the PSL increases and the macroscopic deformation decreases. Under low confining pressure，the stress-based irrecoverable permeability coefficient(EIP) in each cycle is negative or small，and the permeability increases. Under high confining pressure，EIP value in the fourth cycle is positive，and the formation of seepage channel is affected by confining pressure constraints. (3) Compared with the conventional triaxial test，the b-value of AE signals under multi-stage cyclic loading fluctuates more. Under the two loading modes，the rock samples are dominated by tensile cracks. Under the condition of multi-stage cyclic loading，there are more shear cracks in the rock sample，and with the increase of confining pressure，the proportion of rock tensile cracks gradually decreases，and the proportion of shear cracks increases.

The existence of faults in high-intensity earthquake areas has a serious impact on engineering structures and the longitudinal response of tunnel crossing faults needs to be studied further. An analytical solution for longitudinal response of tunnels crossing faults is presented. For the derivation，the tangential foundation springs are used to analyze the tangential contact effect of surrounding rock-lining and axial deformation characteristics of tunnel. Firstly，the elastic foundation beam model is used to simulate the surrounding rock-tunnel structure interaction. Wherein，the displacement of free field is applied on the distal end of normal foundation spring and the tangential interaction is transformed into tangential foundation springs. The analytical solution of the tunnel?s response is gotten based on the model by using Green?s function. Secondly，the numerical solution from finite difference model of 3D is used to verify the validity of the proposed analytical solutions. The results show that the tangential contact effect of surrounding rock-lining has a significant impact on the longitudinal response of tunnel. Ignoring it，the peak bending moment error of structure reaches 35.33%. Finally，the effects of fault zone width，fault elastic modulus and lining concrete grade on the longitudinal response of tunnel are explored. As the fault zone width increases，the internal force of the tunnel structure decreases；increasing the lining concrete grade results in unfavorable effect on the structure；the increase in the elastic modulus of the surrounding rock in fault zone reduces the bending moment and shear force of structure，and increases the axial force，respectively. The research results can provide a theoretical basis for the anti-offset design of tunnels crossing faults.

Fouled ballast can commonly cause severe defects of ballasted trackbed including mud pumping and uneven settlement，thus further endangering stable and safe operations of trains. To address this engineering challenge，ballast specimens with different fouling levels were prepared in the laboratory by adopting the classic fouling index(FI)，and subsequently subjected to monotonic triaxial compression tests. The newly-invented wireless，self-powered，and smart sensors(SmartRock) were placed at different positions inside ballast specimens to measure real-time particle rotation data. The macroscopic shear strength behavior of ballast specimens with different fouling levels were analyzed comparatively and linked to meso-scale ballast particle movement. The results show that increasing coal dust fouling level could cause gradual transition of macroscopic behavior from strain hardening to strain softening. When the fouling index(FI) value ranged from 10% to 15%，both peak deviator stress at failure and apparent cohesion reached their minimums，respectively. The rotation of ballast particles inside the triaxial specimens mainly occurred in the vertical planes，whereas the vertical-plane rotations of ballast particles located closer to the bottom of clean ballast triaxial specimens increasingly attenuated due to the increasing restraint of lateral boundaries on particle movement. When the FI value reached 15%，no discernible rotation patterns were observed for ballast particles inside triaxial specimens，which may be attributable to the loss of inter-particle force-transferring skeleton. When the FI value further exceeded beyond 15%，ballast particle rotations exhibited significantly increasing differences，probably resulting in macroscopic mechanical instability. The uniformity of ballast particle rotations determines macroscopic shear strength behavior to a certain extent. Therefore，the coefficient of variation of the vertical-plane peak Euler angle of ballast particles could be potentially used as a meso-scale indicator of the actual fouling level of ballast beds. The findings are expected to provide theoretical basis and technical reference for Non-destructive evaluation of fouling degree，optimizing ballast-cleaning schedules and implementing intelligent maintenance of ballasted trackbeds.