In order to study the dependence of the mechanical properties of fractured hard rocks，including their strength，deformability，failure mode，characteristic of energy dissipation and bursting liability，on fracture distribution and volumetric or areal damage variable，uniaxial compression tests were carried out on limestone specimens with a single fracture，three coplanar and non-coplanar fractures at different inclination angles. The results show that：(1) the elastic deformation is mainly affected by the volumetric damage variable，while the strength is mainly affected by the areal damage variable. For the specimens with a single fracture，the unified Young?s modulus and peak strength increase monotonically with the fracture inclination angle，and the relation between the unified Young?s modulus or peak strength and the component of Oda?s second-order volumetric damage tensor or areal damage vector along the loading direction，can be well fitted with an inverse proportional power function. For the specimens with three coplanar or non-coplanar fractures，both the curves of the unified Young?s modulus and peak strength with the fracture inclination angle are W and V shapes respectively，and prediction for their upper limit and average can be given by the above relations with the component of volumetric and areal damage tensors obtained from the specimens with a single fracture respectively. (2) In general，the fractured limestone specimen may undergone three damage evolution stages，i.e.，initiation and propagation of cracks，formation of macroscopic failure surface(zone) and residual deformation. There are three basic failure modes：split，stepped and blocky failure. (3) Some of the limestone specimens show certain degree ductile characteristics due to the existence of the fractures，namely，their stress-strain curves change from single peak to multi-peaks. For the specimens with single peak stress-strain curve(type I)，the elastic energy accumulated before the peak stress is rapidly transformed into dissipated energy. For the specimens with multi-peaks stress-strain curves(type II and III，multi-peaks during softening and hardening stages，respectively)，the elastic energy accumulated before each peak stress is released and transformed into dissipated energy step by step. Both the unified total strain energy and energy storage limit of the specimen may increase linearly with the unified peak strength，and therefore is inversely proportional to the component of the two damage tensors. and (4) Both the intact and fractured limestone specimens at failure appeared different degrees of bursting phenomena such as particle ejection and making sound. Compared with the elastic strain energy index and bursting energy index，the comprehensive index of elastic strain and bursting energy(the ratio of the elastic strain energy before the peak strength to the total strain energy)，can more reasonably represent the bursting liability of the fractured specimens with multi-peaks stress-strain curve，and coincide very well with the degrees of bursting intensity observed in the test.

The operating pressure range of lined underground gas storage facilities is an important design parameter，which is related to its long-term satiability and cost. Currently，the operating pressure range is mostly determined from the perspective of anti-uplift stability. The plastic state of the surrounding rock，which threatens the long-term stability of the CAES system，is not taken into consideration. Therefore，starting from the force characteristics of the gas storage structure，the elastoplastic state of the gas storage structure is analyzed according to the elastic design concept. A method to determine the operating pressure is proposed and its physical meanings are explained. When the operating pressure range during gas injection and withdrawal cycles is in this range，the structures of the gas storage remain in an elastic state，avoiding continuous accumulation of plastic deformation and structural damage. It is helpful for the long-term operation of the gas storage facility. Furthermore，the influences of factors such as the radius of the gas storage facility，the grade and thickness of the concrete lining，the strength of the surrounding rock mass，the crustal stress and the lateral pressure coefficient on operating pressure range are analyzed. The results show that the physical meaning of the operating pressure range is to use the crustal stress typical points as the center，draw a circle tangent to the surrounding rock strength curve，and the two points where this circle intersects with the axis of normal stress are the upper and lower limits of the operating pressure；the crustal stress，the lateral pressure coefficient and the strength of the surrounding rock mass are the main factors that affecting the operating pressure range；factors such as the radius of the gas storage facility，the grade and thickness of the concrete lining can be neglected；When the grade of the surrounding rock mass is unknown during the survey stage，the operating pressure range is generally between 0.5 to 1.5 times the crustal stress and this range should be further reduced if the crustal stress is far away from the isotropic state. These findings can provide theoretical support for determining the operating pressure range of the LRC in a CAES system.

To address engineering issues such as the brittle failure at the rigid connection of the crossbeam in h-shaped anti-sliding piles under seismic action，a new type of h-shaped anti-sliding pile structure with inclined crossbeam supports was developed. A series of indoor shaking table model tests were conducted to compare the traditional and optimized h-shaped anti-sliding piles in terms of acceleration，dynamic soil pressure，Fourier spectrum response，and slope deformation characteristics，revealing the improved seismic performance of the optimized structure. The results show that：(1) In terms of slope deformation，as the seismic intensity increases，cracks in the entire slope propagate from the side of the traditional pile to that of the optimized pile. The optimized h-shaped anti-sliding pile demonstrates delayed deformation characteristics compared to the traditional pile，with significantly smaller pile displacement and slope crack deformation dimensions. (2) From the perspective of acceleration response and peak characteristics，the acceleration response in the anchoring section of both pile types is weak，while the response in the loaded section from the sliding surface to the pile top gradually increases，with the optimized pile showing a marked reduction. The acceleration amplification factor of the optimized pile is lower than that of the traditional pile. (3) Analyzing the Fourier spectrum response characteristics and amplitude peaks，the optimized h-shaped anti-sliding pile with inclined crossbeam supports and damping rubber bearings shows a significantly weaker Peak Fourier Spectral Acceleration(PFSA) response amplitude in the f1 low-frequency band compared to the traditional pile. Additionally，in the f2 and f3 mid-frequency to high-frequency bands，the vibration amplitude near the pile top of the loaded section of the optimized pile is notably reduced，enhancing the overall vibration characteristics of the pile. (4) Regarding dynamic soil pressure response and peak values，the dynamic response of the soil for the optimized pile is significantly reduced compared to the traditional pile. Under seismic intensities ranging from 0.3 g to 0.8 g，the peak soil pressure behind the optimized pile decreased by 30.6%–58.4% compared to the traditional pile，and by 40.7%–41.7% in front of the pile，effectively improving the dynamic soil pressure response under seismic action. These findings indicate that the optimized h-shaped anti-sliding pile with inclined crossbeam supports has excellent seismic and damping performance. The results provide new perspectives and technical support for the treatment of large and medium-sized landslides in seismically active regions.

Under roadway excavation and unloading，the deterioration and failure characteristics of surrounding rock in different regions and their stiffness present different characteristics. In order to explore the influence of rock mass mechanical characteristics on the stability of roadway surrounding rock under different stiffness conditions，the ZS-B two-dimensional variable stiffness dynamic failure simulation experiment system is adopted to carry out loading tests on sandstone，and the failure characteristics of sandstone under uniaxial variable stiffness loading conditions are analyzed. The failure characteristics and energy evolution law of sandstone under variable stiffness loading are obtained. The results show that：(1) the loading stiffness has little effect on the stress-strain curve and the peak state of the rock before the peak，which are closely related to the material properties of the rock itself. (2) The elastic deformation energy stored by the pre-peak test machine is converted into residual energy after the peak. When the loading stiffness is low，more residual energy will be converted，and the rock will be damaged rapidly. Otherwise，the residual energy will be less，and the rock will be damaged in a continuous stage. (3) When the loading stiffness is 0.1 GN/m，the rock presents a tension-shear composite failure. With increasing the loading stiffness，it gradually evolves into a tension-shear failure，and the integrity of the sandstone gradually decreases. The data points of the RA-AF parameter diagram of the rock gradually change from being distributed on both sides of the tension crack and the shear crack to being mainly distributed in the tension crack region. (4) The pre-peak AE event ringing number is stable at a low level. With increasing the loading stiffness of the experimental machine，the peak value of the AE event number changes from a single peak to a multiple peak value，and the peak value gradually decreases. The increase in the loading stiffness promotes the development of cracks in the rock，while excessive stiffness inhibits it. The research results provide a research method for the stability of roadway surrounding rock，and corresponding measures(support，modification and pressure relief) can be taken to improve the stability of roadway surrounding rock from the perspectives of improving rock strength，increasing rock energy storage and weakening rock failure degree in the environment of stiffness.

In order to study the influence of mine water on the stability of backfill paste，chloride salt solutions with concentrations of 0%，5%，10% and 15% were prepared，and 4，8，12 and 16 times of chloride salt dry-wet cycle tests for 112 days were carried out. Combined with fractal dimension，XPS spectrum and SEM monitoring system，the macro-micro characteristics of backfill paste after chloride salt erosion were analyzed，and the deterioration mechanism of backfill paste under the action of chloride salt was revealed. The results show that：(1) The mass of the backfill paste experiences a surge period，a slow increase period and a decline period with the number of chloride salt dry-wet cycles，and the increase of solution concentration will aggravate the change of the sample mass. The mass change rates of the samples in chloride-free and chloride salt solutions with concentrations of 5%，10%，15% after 16 dry-wet cycles reach 0.26%，0.79%，1.05%，and 2.15%. (2) Under the action of chloride salt，the compressive strength of backfill paste increases first and then decreases. Moderate chloride salt erosion is beneficial to optimize the bearing strength of the sample，and excessive chloride salt erosion will seriously weaken the bearing performance of the sample. The strength of the sample in 5%，10% and 15% chloride salt solution after 4 dry-wet cycles increases by 19.07%，17.57% and 14.29% compared with the original strength，and the strength after 16 dry-wet cycles decreases by 1.21%，19.81% and 25.7% compared with the original strength. (3) The damage and deformation of backfill paste in chloride salt solution are dominated by small-scale fracture development. Chloride salt erosion can significantly change the time series and precursor information of fractal dimension of backfill paste. The fractal dimension of the sample in the chloride-free salt solution is“W”type，and the fractal dimension of the sample in the chloride salt solution is“M”type. (4) The formation of Friedel's salt is the root cause of the deterioration of the backfill paste，and the structural characteristics of Friedel's salt are the direct driving mechanism of the alienation of the bearing performance of the backfill paste under the action of chloride salt. The chemical bonding between chloride salt and the internal components of the sample will inhibit the formation and accumulation of hydration products in the interfacial transition zone，resulting in a decrease in the cementation ability of the backfill paste. The crystalline swelling force of salt corrosion products will resist the internal stress of the sample，resulting in the alienation of the compaction and damage deformation properties of the backfill paste. This study is of great significance for maintaining the long-term stability of backfill paste，and provides a theoretical basis for the failure and instability of backfill paste in mine water environment.

Physical similarity simulation is one of the important methods for studying coal/rock burst problems，and the rational selection of similar materials is a crucial prerequisite to ensure the effective simulation of mining disturbance response of roadway or longwall working face. Therefore，through the comprehensive study of similarity theory and numerical simulation methods，the fracturing characteristics as well as the effect of geometric similarity ratio of different bursting-prone prototype coals and similar coal materials in physical similarity simulation of coal/rock burst were investigated. The similarity conditions for basic parameters，damping，energy and bursting liability indexes were obtained，and the geometric similarity ratio correlation of coal/rock burst failure characteristics of coal samples and coal roadway models with different coal bursting liabilities was studied using the continuous-discontinuous simulation method. The results show that the coal samples with strong bursting liability exhibit elasto-brittle dynamic failure，while those without bursting liability represent static rupture in forms of post-peak strain-softening. For the coal sample similarity model with geometric similarity ratios of 2，5，10 and 20，the simulated values of uniaxial compressive strength are basically consistent with the theoretical values. The bursting energy index decreases first and then stabilizes with the increase of geometric similarity ratio，and the fragmentation degree and debris kinetic energy of coal samples decrease with the increase of geometric similarity ratio. The excavation of prototype coal roadways with strong bursting liability reveals a dynamic failure process，and the kinetic energy of the coal ribs decreases gradually with increasing geometric similarity ratio，and the roadway eventually transforms from dynamic failure into static failure. Finally，the reasons for the correlation of geometric similarity ratio in the dynamic failure behavior of the physical similarity simulation are discussed，and some suggestions are given for the selection of materials for the physical similarity simulation of coal/rock burst and the simulation conditions of burst phenomena. This study provides guidance for the physical similarity simulation of coal/rock burst.

For the stress relief method to measure in-situ stress，the eccentricity of core samples is a common issue that leads to significant errors in the calibration of elastic modulus，severely impacting the accuracy of stress testing. This study employs a bipolar coordinate system and a generalized Hooke?s Law to derive an analytical solution for calibrating the elastic modulus of eccentric rock cores under plane stress conditions，utilizing stress and strain solutions associated with eccentric circular models. The correction coefficients for elastic modulus calibration based on the pressure application on the inner and outer sides of the eccentric core are introduced，along with the approximate correction coefficient for hollow eccentric cores. Numerical simulations have been conducted to analyze and validate the proposed methodology，yielding the following key findings：(1) The proposed elastic modulus calibration solution significantly enhances the accuracy of elastic modulus determination for eccentric rock cores. For the core with an eccentricity ratio of 0.6，the maximum calibration errors for single-strain gauges and tri-strain gauge measurements are reduced to 2.7% and 1.1%，respectively，compared to the solution for concentric cores，showing reductions of 16.5% and 11.7%. (2) The elastic modulus calibration on the thin-walled side of the eccentric core is significantly influenced by eccentricity. When the eccentricity ratio varies from 0.2 to 0.6，the calibration coefficient for the thick-walled side remains relatively stable at 2.14 to 2.15(a variation of only 0.5%)，while the thin-walled side exhibits a wide range between 2.20 to 2.47，reflecting a 12.3% variation. (3) The elastic modulus calibration coefficient tends to decrease on the thick-walled side as the radius ratio increases，while it increases on the thin-walled side. For an eccentricity ratio of 0.6，as the radius ratio increases from 0.3 to 0.7，the calibration coefficient for the thick-walled side decreases from 1.2% to 19.8%，whereas for the shin-walled side，it increases from 16.5% to 83.8%. (4) The introduced approximate correction coefficient effectively reduces calibration errors for hollow eccentric rock cores，particular when the eccentricity ratio is below 0.5，maintaining calibration errors below 2.0%. The proposed method can provide theoretical guidance to the determination of elastic modulus for the eccentric rock cores and precise stress calculation in stress relief method of geostress measurement.

Beishan underground research laboratory(URL) is the first URL in China for the research and development of geological disposal technology of high-level radioactive waste. The ramp in Beishan URL is excavated by full section tunnel boring machine(TBM)，namely“Beishan–1”. This paper takes the cores drilled from the ramp as the research object，and studies the cracking characteristics of granite surrounding rock under TBM edge cutter fragmentation，by CT scanning，electron microscope scanning and fluorescence imaging tests. The experimental results indicate that，the cracking rate induced by TBM edge cutter is very low，about 0.13%–0.35%，and most of them are microcracks with equivalent diameter less than 120 μm. The cracks induced by TBM edge cutter fragmentation are mainly distributed directly below the groove of the cutter. The central main cracks at the bottom of the adjacent grooves are almost not connected，especially the crack concentration areas under the neighboring grooves are far apart. Most of the cracks in the rock propagate through the mineral particles. However, in the vicinity of quartz particles with higher strength that are far away from the excavation surface，the fractures preferentially propagate along the direction with less energy consumption at the mineral boundary. The crushing zone and crack intensive zone induced by edge cutter are asymmetrically conical distribution，and the inclination angle of the central main crack is related to the installation angle of edge cutter. The crack propagation depth caused by edge cutter is less than 1.60 cm measured by the three methods，among which the electron microscope scanning test has the highest accuracy. The test accuracy of CT scanning and fluorescence imaging is close，but the contrast between fracture and intact rock in fluorescence imaging test is higher，which is more conducive to fracture extraction and measurement.

Compressed air energy storage in underground caverns is a feasible solution for large-scale energy storage. In studying the mechanical and deformation characteristics of surrounding rock under long-term cyclic loading in compressed air caverns，traditional models mostly adopt elastoplastic models or statistical damage models based on the Mohr-Coulomb yield criterion. However，these models do not consider scenarios where the pressure inside the cavern falls below the fatigue threshold. To address this issue，the rationality of using a cyclic hardening model to calculate the deformation modulus and displacement of the surrounding rock in the case of the cavern pressure being below the fatigue threshold is demonstrated firstly. Then the cyclic hardening model is derived using axial residual strain as the internal variable. On this basis，the influence of fatigue parameters of different rock types on the mechanical and deformation characteristics of the surrounding rock of the compressed air chamber is studied. The model?s predicted values are compared with the measured values from on-site experiments，demonstrating its ability to accurately predict the deformation of the surrounding rock.

To investigate the water sensitivity effect and mechanical damage evolution of Xiyu conglomerate subjected to complex water environment and stress state，adopting the rock multi-field coupled triaxial servo automatic testing system，a series of uniaxial compression tests under varying water contents，and triaxial compression tests under varying pore and confining pressures were carried out. The effects of water content，pore pressure and stress state on the strength，deformation parameters，damage characteristics and failure mode were analyzed. The results show that Xiyu conglomerate in Kashgar，Xinjiang has the characteristics of low mechanical strength，high deformability，low porosity and strong water sensitivity. An increase of water content results in the decrease of elastic modulus，deformation modulus and characteristic stresses of Xiyu conglomerate，and its peak strength?s softening coefficient is around 0.77. The nonlinear deformation of Xiyu conglomerate is significantly impacted by confining and pore pressures，exhibiting robust ductility mechanical behavior at elevated levels of these pressures. Compared with other strength criteria，Drucker-Prager criterion can accurately describe the evolution of mechanical properties for Xiyu conglomerate，and the damage is analyzed based on crack volume strain. In the dry natural state，the failure modes of Xiyu conglomerate are mainly tensile and fracturing failure，while in the saturated state，tensile and shear mixed failure will occur. With increasing pore and confining pressures，the macroscopic failure mode is mainly shear failure，and its shear failure angle decreases.

Multi-cycle water huff-and-puff is an effective technique for replenishing formation energy and enhancing single-well productivity in tight oil reservoirs. Existing hydro-mechanical coupling mathematical models overlook the nonlinear flow parameters，and the dynamic changes in in-situ stress and fracture morphology throughout multi-cycle water huff-and-puff processes demand urgent investigation. This study has established a mathematical model of coupled flow，geomechanics and fracture propagation，which considers nonlinear flow in tight oil reservoirs，has developed a numerical simulation methodology for multi-cycle water huff-and-puff. The CP1 horizontal well in the Changqing Oilfield，located in the Ordos Basin，is used as a case study to explore the evolution of dynamic in-situ stress and fracture propagation during multi-cycle water huff-and-puff. The research findings indicate that：(1) Prolonged depletion development of horizontal well results in a reduction of principal horizontal stresses near the wellbore and an increase in principal stress difference；(2) By the end of the water injection period in the first cycle，the principal horizontal stresses increase and the principal stress difference decreases. As the number of cycles increases，the principal horizontal stresses decrease at the end of each water injection period，while the principal stress difference increases，with a maximum directional deviation of 10°to 30°of principal stresses；(3) The water injection period extends the fractures and generates branch fractures，and the extent of fracture propagation decreases with each cycle，stabilizing in morphology after three cycles. These results provide valuable guidance for optimizing water huff-and-puff schemes and transforming development strategies in tight oil reservoirs.

In order to understand the deformation evolution characteristics of toppling deformation bodies in deep-cut river valleys of southwestern China，this paper presents a case study of the Yagong toppling deformation，located near the spillway outlet of a large hydropower station in the Upper Lancang River. Based on field investigation，the SBAS-InSAR technique was used to analyze 53 scenes of ascending Sentinel-1A SAR images from January 2021 to April 2023. Combined with high-definition satellite images，high-resolution digital elevation data，surface deformation monitoring and rainfall data，an in-depth study of the deformation characteristics and evolution mechanism of the Yagong toppling deformation was carried out. The results indicate that：(1) The Yagong toppling deformation is currently in a continuous acceleration stage，with an annual deformation rate ranging from －49.96 mm/y to －0.70 mm/y during the SAR image period，and a cumulative maximum deformation amount of －106.97 mm. The areas of extremely strong and strong deformation are primarily concentrated in regions above 2 400 m a.s.l.，accounting for as much as 42.75% of the total affected area. (2) The monthly average surface deformation during the rainy season is 1.71 times greater than that of the dry season，highlighting that continuous rainfall is one of the most prominent factors in promoting slope deformation development. (3) Controlled by the incision caused by the Lancang River and Mushui River，as well as variations in geological structures and lithology，the toppling deformation shows significant temporal and spatial differences. This primarily manifests as increasing surface deformation with altitude，and greater deformation on the flank of the Lancang River compared to the flank of the Mushui River. (4) The presence of the basalt in the middle part of the slope effectively reduces the overall deformation rate of the underlying slate and sandstone. The soft-hard-soft rock distribution in the study area plays a crucial role in enhancing slope stability.

To address the challenge of excessive over-under excavation often encountered in the excavation of small-section diversion tunnels due to frequent changes in rock grades，this research investigates quantitative damage prediction and the optimization of blasting effects. The Quanmutang Diversion Tunnel Project was chosen as the case study. Utilizing three-dimensional image reconstruction technology，a relationship between over-under excavation and GSI classification was established. A numerical model was constructed based on actual blasting hole positions，and the mechanical parameters of the surrounding rock，which change continuously，were calculated in the numerical simulation based on a quantified GSI classification method and the Hoek-Brown criterion. Blasting damage was then simulated，and the results were compared with actual over-under excavation for analysis. Subsequently，based on this method，over-under excavation was predicted，and blasting parameters were optimized. The results show that the simulated contour of blasting damage closely matches the actual excavation contour，with an average error of only 2.54% for the simulated over-excavation volume per meter and 5.20% for the field-measured over-excavation volume and shotcrete amount per meter. After predicting rock mass damage under various peripheral hole spacings，blasting parameters were optimized，resulting in no under-excavation and over-excavation was controlled within the design allowable range. By correlating the GSI value with the BQ value，the mechanical parameter ranges for surrounding rock grades II to V are calculated. Over-under excavation for each rock grade under different peripheral hole spacings is predicted，resulting in recommended peripheral hole spacings of 55 cm for grade II–III and 50 cm for grade IV–V surrounding rocks.

Understanding the behavior of gas flow within coal seams during CO2 injection for coalbed methane recovery is essential for the efficient recovery of coalbed methane and the mitigation of the greenhouse effect. Previous studies have often neglected the impacts of water and temperature in permeability modeling within coal seams. Consequently，a novel permeability model that integrates thermo-hydro-mechanical fields has been developed to investigate the gas flow in coal seams. This proposed model accommodates the gas-water two-element two-phase flow resulting from CO2 injection，incorporating the reduction in gas adsorption capacity due to the presence of water presence，non-equilibrium gas flow，and the influences of heat transfer and conduction. The established model was applied to a CO2-Enhanced Coalbed Methane(CO2-ECBM) project in the Qinshui Basin to conduct a numerical analysis of gas flow within coal seams. The results show that：(1) CH4 and water pressure experience three stages，whereas CO2 pressure consistently exhibits an increasing trend. (2) Temperatures near reservoir injection wells change at the same rate as near production wells after a certain time of recovery. (3) Permeability progresses through three stages，each governed by different controlling factors. (4) Both CH4 production and CO2 storage persist in increasing，although the rate of CH4 production declines following a peak，whereas the rate of CO2 storage continues to decline. The results have some theoretical significance for the understanding of gas flow laws within coal seams under the multi-physical fields.

In order to enhance the anchoring effect of grouted bolts，the expansive agent was added into the slurry. A comparative anchoring test was carried out between the ordinary slurry and the expansive slurry to monitor radial stress changes during grouting body development. Subsequently，a bolt pull-out test was conducted to determine the ultimate pullout force of the bolt. The study employed Abaqus numerical simulation software to construct a refined model of a rebar bolt，incorporating transverse ribs. Numerical simulation tests were conducted to analyze the mechanical characteristics and failure mechanisms of the bolt following anchoring with different grouting materials. The results indicate that：(1) Following approximately 60 hours of development，the expansion type grouting body can exhibit a maximum radial stress of 2.34 MPa while maintaining stability. In comparison with the ordinary type grouting body，the ultimate pullout force of the bolt increases by 21.3% after anchoring with the expansion type grouting body. (2) When the drawing load is low，the interfacial shear stress gradually decreases along the anchoring depth. Conversely，under high drawing loads，the interfacial shear stress initially increases before rapidly decreasing，the peak shear stress is mainly distributed near the orifice. (3) In comparison with ordinary grouting bolts，the extrusion action of expansion type grouting results in a higher degree of interface bonding and more evenly distributed interface shear stress. This leads to reduced damage to the grouting body and improved gripping performance under the same tensile load，significantly enhancing the bearing capacity of expansion type grouting bolts. To enhance the anchoring effect the anchor bolts，an expansive agent was added to the slurry，and a comparative test was conducted between the ordinary slurry and the expansive slurry. The radial stress changes during the development of the slurry was monitored，and the pull-out test and numerical simulation of the anchor bolts were carried out to investigate the mechanical properties and failure mechanism of the anchor bolts during the pull-out process. The results show that：(1) After about 60 hours of development，the expansive slurry can generate a radial stress of up to 2.34 MPa and remains stable. Compared with the ordinary slurry，the ultimate pull-out resistance of the anchor bolts increased by 21.3% after anchoring with the expansive slurry. (2) The shear stress at the anchor bolt-mortar interface decreases gradually with the depth of anchoring at low pull-out load，and the shear stress increases first and then rapidly decreases at high pull-out load. The peak shear stress is mainly distributed near the hole mouth. (3) Compared with the ordinary mortar anchor bolts，the expansive slurry has a greater compressive effect，resulting in a higher interface adhesion，higher shear stress distribution，and more uniform distribution. Under the same pull-out load，the grouting damage is less，showing better clamping performance，which greatly improves the bearing capacity of the expansive slurry anchor bolts.

The freezing-sealing pipe roof method was firstly applied in the construction of the Gongbei Tunnel. However，the long-term stability issues during the construction period were not foreseen in the design phase. These issues involve the shear creep characteristics at the interface between the frozen soil and the structure within the pipe-roof frozen soil composite structure. Currently，there is a lack of creep models that accurately describe the shear creep characteristics at this interface between the frozen soil and the structure. A theoretical model based on fractional derivatives that can simultaneously describe the mechanical behavior at the interface between frozen soil and the structure during the attenuated，steady-state，and accelerated creep stages is derived. The model replaces the viscoelastic component of the Maxwell model with the Abel dashpot element and incorporates a creep acceleration element controlled by shear stress，then the shear creep test results of the interface between frozen soil and steel are obtained through tests. A least square fitting program incorporating fractional derivative is developed using Python，which adopted multi-parameter simultaneously. This program is used to fit the shear creep curves of the interface between frozen soil and the structure under various conditions. Finally，this paper analyzes the sensitivity of the parameters affected by the stress-controlled acceleration element within the model，revealing the influence of the acceleration index N and the fractional order on the accelerated creep stage. The research findings are demonstrated as follow：(1) The fractional derivative in the fractional-order Maxwell acceleration model significantly improves the nonlinear progression of the creep curve，and the shear stress-controlled acceleration element accurately simulates the accelerated creep stage. (2) The fractional-order Maxwell acceleration model shows higher applicability and precision compared to traditional models Under different experimental conditions. (3) Sensitivity analysis indicates that a larger acceleration index N results in more noticeable acceleration effects and a faster rate. As the fractional order increases，the proportion of time in the accelerated creep stage also grows. This study provides a theoretical foundation for numerical simulations of creep mechanical behavior in analogous freezing engineering such as pipe-roof freezing projects and pile-soil interactions.

The safety of the underground space storage geologic synergistic carrier is crucial for developing energy/carbon storage engineering. Based on the indoor uniaxial compression test of the sequestered geologic synergistic carrier constructed by coal pillar-dam，the UDTensor，the UDScalar and the Ball displacement_mag in discrete element particle flow PFC are respectively used to map the stress cross，the crack hot spot field and the displacement field，to analyze and study the evolution of the stress field-crack distribution-displacement field and the microscopic damage characteristics of the carrier during the loading process. The results show that the synergistic carrier specimen is mainly damaged by oblique shear，the rupture surface is inverted “V” type，and the shear expansion characteristics are weakened with the increase of the proportion of rock. The number of cracks in the specimen overall shows the change of“emergence-slowly-accelerating”characteristics，and after entering the damage stage，the coal monomer is damaged by the cracks. After entering the destruction stage，the shear and tension of coal monomer and rock monomer almost play a role at the same time，and the shear effect of the synergistic carrier is stronger than the tension；the concentration and transfer of stress(change in the length and direction of the stress cross)，the formation of microscopic damage(crack budding，nucleation) and accumulation，and then dominate the macro rupture(crack expansion，penetration)，which intuitively reveals the process of the accumulation of microscopic damage to macro rupture. The process of the accumulation of microscopic damage to macroscopic rupture is revealed intuitively. Finally，it is a reliable method to recognize the characteristic strength of rock samples based on the changes in crack number(emergence) and crack length(extension). Among them，the change of shear crack number can recognize the initiation strength of the specimen earlier，and the extension rate of tensile crack length can realize the damage strength earlier. The results of the study provide a theoretical basis for a deeper understanding of the microscopic damage and safety and stability monitoring of geologically synergistic bearers sealed in underground space.

Considering the similarity of the mechanical behaviors of clay and sand soils，such as the strain softening and dilatancy features exhibited during the drained triaxial test，and the alternating mobility feature induced by cyclic loading under the undrained condition，a new hypoplastic Cam-clay model is established by combining the hypoplastic theory and the critical state soil mechanics. The model first adopts a linear ultimate compression curve to calculate the Hvorslev equivalent stress of sand to determine the asymptotic state boundary surface uniquely. On the other hand，the ultimate compression curve will coincide with the isotropic consolidation compression curve of clay. Second，a new density factor is defined based on the relative positional relationship between the current state point of the soil and the critical state line，which affects the evolution of the normalized stress path of the soil inside the asymptotic state boundary surface. The initial value of the density factor depends on the overconsolidation ratio of the clay or the initial void ratio of the sand，which can be used as a state parameter to describe the effects of factors including stress history，relative density，and loading path on soil behaviors. The proposed model has parameters similar to those of the Cam-clay model，which can be calibrated through conventional laboratory tests. The calculation results indicate that the proposed model can reasonably describe the complex behaviors of clay and sand under drained and undrained shearing conditions，which can also capture the alternating mobility feature during cyclic loading. The validity of the proposed model is further verified by comparing the model predictions with the triaxial test results of Kaolin clay，Karlsruhe fine sand，and Toyoura sand.

The configuration and number of tiers are critical issues in the structural design of reinforced soil retaining walls. Through shaking table scaled model tests，comparative analyses were conducted on the seismic responses of single-tiered，two-tiered，and three-tiered modular geogrid-reinforced soil retaining walls with the same total height，aiming to investigate the tier effect in reinforced soil retaining walls. The test results show that the setting of tiers has a positive role in enhancing the overall stability of the retaining wall. However，the increase in the number of tiers contributes relatively little to this effect. The natural frequency and pre-vibration damping ratio of the retaining wall did not change significantly due to the setting of tiers and their quantity，but the presence of tiers significantly reduced key parameters such as the wall's acceleration amplification factor，horizontal displacement of the wall face，settlement at the top of the backfilled soil，earthquake-induced active soil pressure，and reinforcement strain. Additionally，the acceleration amplification factor of the three models increased nonlinearly along the wall height and reached a peak at the top of the wall. The active soil pressure under seismic action also exhibited a nonlinear distribution along the wall height，with peaks mostly occurring at the bottom of each tiered wall. As the loading acceleration increased，the incremental strain of the reinforcements in the three models also increased，showing a nonlinear trend along the wall height. The strain of the reinforcements in the lower tiers of the tiered reinforced soil retaining walls was generally higher than that in the upper tiers. The research results can provide a reference for the design and selection of reinforced soil retaining walls.