This study seeks to furnish theoretical support for mitigating water inrush disasters during the excavation of deep-buried tunnels using the drilling and blasting method in water-rich areas. As to the mechanism of water-bearing fracture initiation in the surrounding rock mass of the deep-buried tunnel under the disturbance of drilling and blasting，the physical excavation and the mechanical state adjustment processes of the surrounding rock in deep-buried tunnel under the dual dynamic effects of transient unloading caused by excavation and blasting were revealed，and the dynamic adjustment mechanism of the stress state in the fractured surrounding rock under the blasting load was revealed. A calculation method for the stress intensity factor at water-bearing cracks and their branch cracks, considering the dual dynamic coupling effects of transient unloading due to geostress and blasting was established. The influence of the crack inclination angle，crack water pressure，blasting intensity，and geostress on the stress intensity factor of water-bearing branch cracks were analyzed. The results indicate that the stress intensity factor of water-bearing branch cracks increases rapidly at the initial stage of the blasting load，followed by a swift decrease post-peak blasting load. Geostress unloading enhances the extension capacity of water-bearing cracks，with a significant surge in the stress intensity factor of branch cracks upon completion of the unloading process. The stress intensity factor at water-bearing branch cracks decreases significantly with an increase in crack inclination angle，increases slightly with the increase of the cracks water pressure，and increases significantly with the increase of the blasting intensity prior to geostress unloading. During the rapid increase phase of the blasting load，the stress intensity factor of branch cracks decreases with rising ground stress. As the unloading process approaches its conclusion，the stress intensity factor of branch cracks increases with higher ground stress levels. The unloading effect at high ground stress significantly promotes the initiation and expansion of aquifer fractures in the surrounding rock，intensifying hydraulic damage to the rock mass.

This study aims to propose a safe and reasonable reinforcement plan for the underpass construction of a high-speed rail by an adjacent dual-track rectangular tunnel，theoretical analysis，numerical simulation，and on-site monitoring methods were employed. Leveraging the underpassing of the Hangzhou—Shenzhen high-speed rail project by a specific dual-track rectangular tunnel，this study conducted research on the three-dimensional impact zoning and its application. The results demonstrate that：(1) Based on derived discriminative expressions for lateral and longitudinal impacts，a three-dimensional impact zoning model for the underpass construction of the dual-track rectangular tunnel adjacent to the high-speed rail can be established. (2) In areas of significant impact，employing reinforced measures such as manual bored piles and D-shaped steel beam bracings effectively controls roadbed and track settlements，ensuring the safe underpass of the dual-track rectangular tunnel beneath the existing high-speed rail. (3) After adopting the optimal reinforcement plan，on-site monitoring data closely aligned with simulated results，with errors in all monitoring indicators meeting specified control standards，thereby validating the rationality of the impact zoning model and the safety of the reinforcement measures. The research findings provide a reference for similar dual-track tunnel underpass construction projects.

In order to investigate the effect of different phases of CO2 injected into difficult-to-mining coal seams on the mechanical properties of coal bodies. Taking the mining area of Inner Mongolia Mindong I Mine as an example，coal samples were put into a homemade triaxial adsorption and permeation apparatus，and the adsorption test of different phases of CO2 on the coal samples was carried out by regulating the temperature and pressure，so as to simulate the adsorption process of different phases of CO2 on the difficult-to-explore coal seams under the complex ground stress conditions. The uniaxial compression test was carried out on adsorbed coal samples，supplemented by an acoustic emission device. Changes in compressive strength，modulus of elasticity and acoustic emission energy of the coal body were obtained. Define the degradation of compressive strength and modulus of elasticity of the coal body，and take the cumulative energy of rupture acoustic emission of coal samples without CO2 adsorption as the baseline，and divide the high-energy zone and low-energy zone to get the evolution law of rupture behaviours and damage characteristics of coal samples after CO2 adsorption in different phases. The results show that：(1) CO2 adsorption weakens the mechanical parameters of coal samples, leading to changes in the macroscopic damage characteristics of the coal body and reducing its mechanical properties，and the total deterioration of the compressive strength of the coal body under the effect of CO2 adsorption ranges from 11.72% to 70.89%. (2) The total degradation of the elastic modulus of the coal body under CO2 adsorption ranges from 8.42% to 43.07%，and the total degradation of the coal body under CO2 adsorption in different phases is as follows：supercritical state adsorption group＞liquid state adsorption group＞gas state adsorption group. (3) After CO2 adsorption，more pores and fissures were formed inside the coal samples，resulting in a longer initial compaction time，and at the same time, the elastic deformation ability of the coal samples was weakened，and the elasticity stage of the coal samples adsorbed by gaseous CO2 lasted twice as long as that of the coal samples adsorbed by liquid CO2，and four times as long as that of the coal samples adsorbed by supercritical CO2. (4) Coal samples adsorbed by CO2，without CO2 adsorption of the total acoustic emission energy of the coal samples as a baseline，the division of high-energy and low-energy areas acoustic emission cumulative energy are in the high-energy area，compared with the unadsorbed coal samples，are produced to a certain extent of the rupture.

Unlike traditional underground engineering without inner pressure，the lined rock cavern of compressed air energy storage(CAES) serves as the basis for its design and construction，bearing alternating thermal and pressure cyclic expansion loads. The interaction mechanism，deformation characteristics，and load sharing mechanism of the surrounding rock mass-support-sealing structure have not yet been established，and related research is urgently needed. Firstly，a theoretical model for the CAES under high inner pressure was established based on the multi-layer thick-walled cylinder theory，and the analytical solutions for its stress and deformation were provided. Then，under the set calculation scheme，the influences of sensitive parameters such as the radius of the CAES，maximum inner pressure，and steel lining thickness on the mechanical response and load sharing ratio of the CAES were analyzed，revealing phenomena where the radial compression of the structures，small displacement，and mainly hoop tension occur. It was clarified that the deformation modulus of the surrounding rock mass is the most significant factor influencing the mechanical response of the CAES，followed by the radius of the CAES，maximum inner pressure，and thickness of the concrete lining，while the strength of the concrete lining has a minor impact but an increase in strength may exacerbate cracking. The thickness of the steel lining has almost no effect. It was demonstrated that the surrounding rock mass bears the main load，followed by the concrete lining，while the steel lining hardly bears any load. Secondly，the mechanical response during the charging and discharging process of the CAES were discussed，revealing the phenomenon of hoop tension and compression transition，with the potential cracking zone expanding with the increase of inner pressure. Finally，the concepts of critical inner pressure of the steel lining yielding and critical inner pressure of the concrete lining cracking were proposed，and it was revealed that the deformation modulus of the surrounding rock mass and the crustal stress are the key factors controlling the deterioration and even cracking of the steel lining and concrete lining. The related achievements provide theoretical support for the design and construction of lined rock cavern for compressed air energy storage.

In view of the problem of water and mud inrush when the #5 construction branch tunnel of Xianglu Mountain in Central Yunnan passes through the fragmented powder rock，guided by the engineering geological characteristics of fragmented powder rock as the，and proposes for the first time to develop a new type of grouting material(PSCG) that integrates infiltration cementation and splitting reinforcement through organic-inorganic material composite to realize multi-mode reinforcement of fragmented powder rock stratum. By compounding sodium acrylate solution with sulphoaluminate cement，making full use of the percolation characteristics of fragmented powder rock stratum，under the grouting pressure，the sodium acrylate solution diffuses into the pores of fragmented powder rock particles with its high permeability characteristics，and the sulphoaluminate cement forms a splitting slurry vein in the fragmented powder rock stratum. The synergistic effect of organic-inorganic materials is used to overcome the engineering problem of " water can penetrate，but slurry cannot penetrate " of fragmented powder rock. In this paper，the feasibility of the above material development idea was verified through laboratory mechanical test and grouting simulation experiment，and the key indicators required for the reinforcement of fragmented powder rock were selected for physical and mechanical properties test(setting time，water holding rate，impermeability of stone body，strength and volume shrinkage)，and the grouting reinforcement mechanism of the new material was revealed by microscopic testing methods(SEM and FTIR). Finally，the reinforcement effect of PSCG on fragmented powder rock geology was studied by field test. The results show that the PSCG material has the simultaneous reinforcement effect of the combined infiltration and splitting mode. There are organic-inorganic composite effect，micro-crack filling effect and hydrodynamic anti-dispersion effect in the stone body in the splitting zone，that is，sodium acrylate polymerization generates network polymer structure，which penetrates with cement hydration products and cement particles to form three-dimensional interpenetrating spatial structure with anti-dispersion effect. In addition，the contact interface between organic-inorganic materials is improved and cracks are filled. The strength of the stone body can reach 27.01 MPa at 7 days. There are capillary adsorption，chemical bond and physical lock cooperation in the stone body of the infiltration zone，that is，the sodium acrylate solution penetrates into the pores of the fragmented powder rock particles under the action of grouting pressure and capillary action and undergoes polymerization reaction，and the fragmented powder rock particles are locked into the overall structure. At the same time，the metal in the fragmented powder rock and the carboxylic acid group in the gel form a strong coordination effect，which increases the crosslinking density of the polymer network and improves the mechanical properties of the gel. The strength of the stone body in the infiltration zone can reach 2.4 MPa in 7 days，and the permeability coefficient is as high as 5.9×10－7 cm/s. Combined with the field test results，PSCG material has the dual effects of water plugging and reinforcement on the fragmented powder rock stratum.

The complexity and variety of disaster-causing geologic bodies in the tunnel of the Central Yunnan Water Diversion Project greatly increase the difficulty of interpreting the results of advanced detection. For this reason，based on the distribution characteristics and electrical parameters of the disaster-causing geological bodies，this paper establishes the theoretical models of three typical disaster-causing geological bodies，namely，caves filled with different media，water bodies，and soft-rocks，and then carries out the numerical simulation of the ground penetrating radar wave field and the research of time-frequency characteristics by adopting time-domain finite-difference forward modeling and the generalized S-transform improved based on S-transform. The ground-penetrating-radar wave-field is characterized by the following：arc-shaped reflection at the top interface of the karst cave，and the amplitude energy of water-filled karst cave is stronger than the air-filled karst cave；in the area of the water-bearing，there are several horizontal strong amplitude reflection events；in the area of the soft-rock，there are horizontal strong amplitude reflections on the interface of the soft-rock top and bottom；and the reflected waves from the top interfaces of water-filled caves，water-bearing bodies，and soft-rocks will have the phenomenon of phase reversal. The time-frequency characteristics of the ground penetrating radar signal are as follows：when the signal passes through the areas of the karst caves and water-bearing，its central frequency is concentrated in a low-frequency range；When the signal passes through the area of the soft-rocks，its central frequency distribution is more dispersed，and it is distributed in both high-frequency and low-frequency range. Based on four successful detection cases of the Central Yunnan Water Diversion Project，the wave-field，time-frequency distribution，single-trace signal，and power spectrum attenuation characteristics of ground penetrating radar real signals are consistent with their corresponding numerical simulation results，which confirms the reliability of numerical simulation results. The results of the study provide a scientific basis for the detection，feature identification，and prevention of typical disaster-causing geological bodies in tunnels，which is of great theoretical significance and engineering application value.

In China，coal mining primarily relies on underground extraction，resulting in the annual excavation of about 12 000 kilometers of massive tunnels，with over 90% using rock bolts and cable bolts for support. This study introduces a stress diffusion model for rectangular tunnel roof rock bolts，considering finite boundary conditions and stress superposition principles. It derives formulas for additional stress from bolt pre-tension and proposes a mechanical model for rock mass reinforcement. FLAC3D simulations validate the model，which is then used to study how bolt parameters affect reinforcement. Key findings show that in bolt groups，minimum vertical additional stress occurs between bolts，anchored body strength increases linearly with pre-tension，reinforcement decreases non-linearly with increased bolt spacing，and exhibits a peak with bolt length，indicating that simply increasing length doesn?t always improve reinforcement.

In order to solve the problem of the development of coal seam mining fault structure in different rock layers of the roof and floor，the mud-sand composite rock mass with prefabricated three-dimensional fractures was taken as the research object，and the crack propagation and evolution law of the mud-sand composite rock mass was studied by uniaxial compression and triaxial compression tests combined with the method of acoustic emission monitoring. The test results show that the pre-peak stress-strain curves of the three rock masses were relatively similar，and the mud-sand composite rock mass changes due to the change of fractures during the propagation of the layer，and the failure of the upper and lower rock masses was inconsistented，and the post-peak rock mass presents different shapes. The average distribution of the peak intensity of the mud-sand composite rock mass under triaxial loading was 16–18 MPa，and in the acoustic emission monitoring，there were more acoustic emission activities at the fracture position in the middle of the precast mud-sand composite rock mass，and the amplitude reaches the maximum value after failure，which was basically above 70 dB，and then the acoustic emission activity decreases sharply，and the amplitude drops to less than 60 dB. When the mudstone or sandstone with prefabricated fractures reaches the limit，the cracks propagate through the layer，which in turn triggers a new round of acoustic emission activities. When the prefabricated fracture was at the boundary position of the sediment composite rock mass，the prefabricated fracture had broken through the penetration resistance in advance，which will guide the crack to propagate in both directions. The peak acoustic emission ringing count and peak amplitude of the rock samples at the fracture location in the upper and lower parts of the mud-sand composite rock mass were smaller than those in the rock samples at the fracture location in the middle of the mud-sand composite rock mass，and the existence of the fracture in the middle of the mud-sand composite rock mass makes the rock mass structural plane fail，and the deformation and failure are more likely to occur under stress. The research results provide new ideas for the research on the prevention and control of disasters induced by fault tectonic activation and through-bed in coal mining.

The conventional hydraulic fracturing(HF) method is greatly limited in the in situ stress measurements of inclined boreholes，especially in three-dimensional stress measurements. Moreover，the hydraulic tests on pre-existing fractures(HTPF) requires a large number of pre-existing fractures to obtain reasonable results. By optimizing the assumption of shear stresses on the primary fracture surfaces and using Monte Carlo algorithm，the three-dimensional stress tensor inversion in the inclined borehole was realized by combining the conventional HF and the HTPF tests. The reliability and accuracy of the proposed method were verified by three-dimensional stress measurements of an inclined borehole in a pumped storage power station in Jizhou，Tianjin. The results show that the proposed method can determine the three-dimensional stress tensors of the inclined borehole only by selecting 1 or more test intervals for conventional HF tests in intact rock mass and 1 or more test intervals for HTPF tests. Compared with the HTPF method that only adopts pre-existing fractures in stress determination，the proposed method greatly reduces the requirement of the number of pre-existing fractures. The inversion results have little dispersion and high stability，which are also consistent with the regional stress state. The proposed method provides a new idea and a reliable approach to determine the stress tensor using a single inclined or vertical borehole.

In order to study the influence of cross joints on rock strength and fracture characteristics，the simulation of specimens containing cross joints under uniaxial compression was carried out to explore the influence of cross angle and cross way of cross joints on the mechanics characteristics and crack coalescence behavior. A simulation model of sample was established in particle flow code PFC2D，based on the experimental results of intact specimens，a set of microscopic parameters that can reflect the mechanical properties of sample were obtained. Then，the uniaxial compression tests of the specimens with X-type，L-type and T-type cross joints. The results are as follows：(1) The uniaxial compressive strength，peak strain and elastic modulus of three cross-type specimens show a good linear negative correlation with the cross angle，especially the L-type. (2) The crack coalescence behavior of three cross-type specimens is similar，and the failure mode is basically tensile failure. The number of microcracks and the damage degree of three cross-type specimens are significantly affected by the cross angle. (3) The proportion of each microcrack is basically stable when the specimens containing cross joints are failure. The failure modes of meso-structure of the specimens containing cross joints under uniaxial compression are mainly tensile failure and shear failure. The results provide a certain theoretical basis for the penetration of the Xianglushan tunnel in Central Yunnan Water Diversion Project，and can also provide reference for similar projects.

The water saturation and distribution of rocks affect the roughness of the fracture surface，which in turn determines the seepage performance and friction effect of the fracture surface. It is crucial for analyzing the stability of the surrounding rock of the roadway and the effect of hydraulic fracturing induced permeability enhancement. In this paper，nuclear magnetic resonance analysis and Brazilian splitting experiments are performed on sandstones with different saturations(0，25%，50%，75% and 100%). Three-dimensional morphology scanning of the rock sample splitting surface are also conducted. The effect of saturation on the splitting characteristics of sandstones was studied. The results show that：(1) From dry to saturated，the tensile strength of rock sample decreased from 3.05 MPa to 0.98 MPa，which conforms to the characteristics of Exponential function. Rock hardness decreased by 56.6% from dry to saturated. Plasticity enhances in highly saturated sandstone. (2) Splitting surface fractal dimension increases logarithmically with saturation. With saturation increasing，the mean value of joint roughness coefficient(JRC) increases from 5.598 to 13.306. The unsaturated JRC exhibits significant discrete. (3) The splitting surface of sandstone with different saturations was quantified using statistical principles. It is found that the roughness height，slope mean and standard deviation increase with saturation，while the slope direction gradually tends to be concentrated at 270° from a uniform distribution in drying. The increase in saturation promotes an increase in vertical fractures，ultimately leading to a rougher splitting surface. (4) NMR analysis shows that with water saturation increasing，water is transported from the periphery to the interior of the rock sample，and the pore wetting within the rock samples gradually increases. As the saturation increases from 25% to 100%，the wetting ratio of large and medium pores and microcracks inside the rock sample increases from 3% to 17%，which promotes the formation of weak structures in rock samples. It causes the transgranular cracks gradually evolve into intergranular cracks in splitting test，resulting in a coarser macroscopic appearance of the splitting surface.

Investigating effective short-term precursor methods to identify and capture events preceding rock instability based on limited displacement information is of significant research and practical importance for successfully predicting dynamic hazards in rock masses. To explore displacement precursors preceding instability in different lithologies，this study conducted uniaxial compression tests on six types of rocks：purple sandstone，coarse-grained sandstone，bituminous coal，marble，granite，and basalt. By monitoring surface displacements and internal acoustic emission signals during sample loading，the study examined surface deformation characteristics preceding rock instability，introducing the Rock Instability Precursor-Displacement Coordination Coefficient(DCC). The results indicate that DCC can capture precursor information leading to rock instability，with a sharp increase observed as a crucial precursor feature. For various rock types，the anomalous point of DCC appears at 95%–99% of the peak stress，serving as a short-term precursor indicator for rock instability. In comparison to acoustic emission parameters，DCC utilizes surface deformation information to real-time，quantitatively capture and identify precursor information before the instability of different rock types. The findings provide valuable insights for the precursor analysis and prediction of rock instability and failure.

Toppling and flexural failure are prevalent modes of destabilization in anti-dip rock slopes，with toppling deformation potentially leading to multi-stage fractures within the slope mass. To investigate this phenomenon，a comprehensive study was conducted utilizing large-scale centrifuge model tests to analyze the catastrophic characteristics of flexural toppling and multi-stage fractures. Furthermore，a predictive model for multi-stage fractures was established based on catastrophe theory，and its rationality was validated. The research findings reveal that the process of toppling deformation in anti-dip rock slopes involves the accumulation of strain energy，which is subsequently released through fracture and failure. According to the catastrophic characteristics observed，anti-dip slopes undergoing multi-stage fractures can be categorized into distinct zones：a non-affected zone，an overlapping toppling zone，a zone influenced by gently inclined structural planes，and a deformation zone. Within the overlapping toppling zone，the depth of multi-stage fractures progressively increases，whereas in the zone influenced by gently inclined structural planes，the fracture planes generally align with these structural planes. By applying catastrophe theory to analyze the multi-stage fracture depth within the overlapping toppling zone，the computational results concurred with those obtained from the centrifuge tests. These research outcomes provide theoretical underpinnings for understanding the stability and failure mechanisms of such slopes，offering valuable insights into their behavior and potential for mitigation strategies.

Understanding the dynamic characteristics and time-dependent damage of rocks under water-rock interactions is crucial for mitigating deep-seated rock engineering hazards. To investigate the impact of water-rock interaction time on the dynamic impact compression characteristics and damage properties of granite，impact compression tests were conducted using a split Hopkinson pressure bar(SHPB) system on specimens subjected to varying immersion time. The results indicate that water immersion treatment enhances the sensitivity of granite strength to loading rates. Specifically，at lower loading rates，there is a linearly negative correlation between the strength softening factor and immersion time. Furthermore，optical microscopy，atomic force microscopy，plasma mass spectrometry and nuclear magnetic resonance techniques were employed to observe surface and internal microstructural changes in granite immersed for durations of 0，2，4，and 6 months. Optimization of the pore damage evolution model revealed that the pore damage threshold was not exceeded within the 6-month immersion period. Finally，Lastly，quantitative analysis of the temporal aspects of water-rock interactions distinguishes between chemical and pore damage mechanisms. The results indicate that physical and chemical interactions jointly promote pore development in granite，albeit with contrasting temporal behaviors: chemical interactions decelerate over time, whereas physical interactions exhibit an opposite trend.

To analyze the mechanical response of surface asperities under different shear stress conditions，the UDEC software was employed to simulate and analyze the mechanical behavior and wear characteristics of 17 groups of rock joints with various sawtooth asperities under varying normal stresses. The findings were validated through laboratory tests. The results show that the effects of the attached sawtooth number and the sawtooth height ratio on the peak shear strength of rock joints initially show a positive correlation，but the correlation weakens after reaching a certain level，and are also affected by normal stress conditions. The increase of normal stress will weaken the contribution of the attached sawtooth number and the sawtooth height ratio to the improvement of shear dilation of rock joints. The joint roughness coefficient(JRC) calculation method considering only the maximum undulating asperity is only applicable under low normal stress conditions. It is also observed that there are four main failure types in direct shear tests for the rock joints with various sawtooth asperities. By conducting response surface analysis，a JRC calculation model for the sawtooth rock joints was derived with an error of less than 10% compared to experimental results. This study reveals the mechanical responses of rock joints with various sawtooth asperities，providing a comparative reference for engineering practice and further exploration of using asperity amplitude in characterizing rock joint roughness.

To solve the stability analysis problem of the tunnel construction stage under complex geological occurrence conditions，based on the Hoek-Brown strength criterion，this paper obtains the calculation formula of the plastic zone radius of the circular tunnel under the condition of lateral pressure coefficient of 1.0. And the evolution coefficient of the surrounding rock plastic zone was proposed. The relationship between the evolution coefficient of the surrounding rock plastic zone and the buried depth of the tunnel and geological strength index GSI was studied. Taking part of the Chuxiong section of the Dianzhong Water Diversion Project as the engineering background，the uniaxial compressive strength of argillaceous siltstone in the cave section was obtained by a point load tester，and one of the key parameters of Hoek-Brown-rock material constant was determined by combination with tensile strength. Combined with the longitudinal deformation curve of the surrounding rock，the characteristic curve of the surrounding rock，and the support characteristic curve，the stability of the primary support structure of the Wuzhuangcun tunnel was analyzed，and compared with the Carranza normalization method. The results show that with the decrease in the quality of the surrounding rock and the increase of the buried depth，the range of surrounding rock that enters the plastic state after tunnel excavation also increases. The plastic zone range of surrounding rock obtained by this method is larger than that obtained by the Carranza normalization method. For this tunnel，the safety factor of the existing primary support structure is greater than 1.0，which can keep the tunnel stable，and the stability analysis using the proposed method is safer and more conservative than the normalization method using Carranza，which is beneficial for the safe construction of soft rock tunnel engineering under complex geological conditions.

In order to investigate the effect of different water-cement ratio slurry reinforcement on the slip characteristics of granite joint faces under unloading-induced slip conditions，this test was conducted on granite joint faces reinforced with various water-cement ratios of cement slurry to carry out constant axial pressure graded unloading of circumferential pressure-induced slip tests. The test results show that：(1) The three-dimensional morphology scanning of the unfilled joint surface revealed that the arithmetic mean height  ，root-mean-square height   and kurtosis coefficient   of the joint surface were 5.744，7.554 and 11.106 before slip，and 13.999，17.586 and 5.431 after slip. The height difference of the surface of the joint surface increases，and stripe cuts gradually disappears. (2) Using SEM(scanning electron microscope) to observe the microstructural damage surface of the reinforced joint surface，it was found that with the increase of water-cement ratio，the strength of the cement skeleton decreased，the fluidity of the slurry increased，and the microscopic damage form of the cement-rock structural surface was changed. (3) The peak shear stresses under the same circumferential pressure were 28.067，15.609 and 8.863 MPa for 0.5，0.7 and 1.0 slurry-reinforced joints，and the shear displacements at the induced slip stage were 0.072，0.050 and 0.061 mm in that order. the shear strength and the ability of the joints to resist slip deformations were both improved. (4) The reinforced joint surface generates energy consumption through creep-slip，which improves the stick-slip phenomenon. According to the analysis of the test results：the smaller the water-cement ratio is，the more energy is dissipated through creep in the cement-rock interlocking structure. When the water-cement ratio is 0.7，the undisturbed creep sliding speed is the lowest，and the slip stability of the formed interlocking structure is stronger.

The determination of sliding thrust force has always been the key issue in the landslide prevention and control project. In order to solve the problem of large error in calculating sliding thrust force of complex polyline sliding body whose inclination angle change of adjacent slice is greater than 10°，the vector characteristics of forces are considered，the anti-slip force vector and sliding force vector are projected to the main sliding direction respectively，and the vector sum method for calculating the sliding thrust of slope is proposed. The distribution of the sliding thrust force along the sliding body and the safety factor can be obtained simultaneously. Comparing the proposed method and transfer coefficient method，the calculation results show that: for the slope with a circular sliding surface and a slope with a polyline sliding surface，the residual sliding thrust curves by the proposed method are in good agreement with those by transfer coefficient implicit method，which verified the rationality of the proposed method. Furthermore，the analysis results of a landslide with a complex polyline sliding surface in Chongqing show that the factor of safety by transfer coefficient implicit method is remarkably bigger than that by the limit equilibrium M-P method，and the relative error is 21.7%. However，for the proposed method in this paper，the relative error is only 0.3% to the M-P method，and the sensitivity calculation results show that the elastic parameters of soil have little influence on the calculation results of the proposed method. It can be seen that vector sum method has strong applicability to the landslide with complex slip surface whose inclination angles of adjacent slices are greater than 10°. This study confirms that the proposed method could provide a reliable design basis for anti-sliding slope engineering of complex polyline sliding surface.

The rheological rock mass in the sensitive neighborhood? is prone to deformation and failure under the action of disturbance load. In order to establish the criterion of rheological rock mass entering the sensitive neighborhood from the perspective of micro-damage，the red sandstone is taken as the research object，and the RRTS-IV rock rheological disturbance effect test system is used to carry out rheological disturbance tests on rheological rock mass under different axial static load pressures. The test results show that：(1) When the rheological rock mass is under high axial static load pressure，the longitudinal cumulative disturbance strain curve will experience three stages of deceleration growth，stable growth and rapid growth，and the greater the axial static load pressure，the more prominent the rapid growth stage. (2) By analyzing the relationship between the longitudinal disturbance strain rate and the axial static load pressure，the strain response characteristics of the rheological rock mass under different axial static load pressures for dynamic disturbance are explored，and different disturbance sensitive areas are divided. (3) Under the action of dynamic disturbance，the pore expansion and crack germination of the rheological rock mass in the non-sensitive area will be restrained to a certain extent. (4) When the rheological rock mass enters the weak sensitive area and the strong sensitive area from the transition zone，the dynamic disturbance can greatly promote the initiation of micro-cracks and the expansion of original cracks in the rock mass，and the closer the dynamic disturbance is to the strong sensitive area，the more significant the increase in the number of pores.

The normal closure of rock joint is one of the key factors affecting the mechanical and seepage behaviours of rock masses，and sand particles or other gouges are often filled in natural rock joint to form an infilled rock joint. However，there are abundant researches on the normal closure deformation of clean rock joints，while few researches on the normal closure of infilled rock joints have been reported. In this study，artificial rock joints with the morphology of the 5th and 8th Barton?s standard profiles were prepared by using rock-like materials，and quartz sand was chosen as the filling material to prepare artificial sand-infilled rock joint specimens with nine filling degrees. Then laboratory normal closure tests were conducted on these artificial sand-infilled rock joint specimens and their normal closure curves were obtained. According to the experimental results，the influences of infilled material on the normal closure of sand-infilled rock joints were analysed，and the power function was used to fit the normal closure curve and the maximum normal closure of sand-infilled rock joints with different filling degrees，thus establishing the empirical normal closure model and the empirical maximum normal closure formula of the infilled rock joint，respectively.

The mountain tunnel in the slope disease area of high intensity area is faced with the difficult problem of highly nonlinear，complex time-varying and multi-uncertainty earthquake response，which is difficult to be effectively dealt with by traditional analysis methods. The“model-data”dual-drive fusion is very important for efficient evaluation of lining damage behavior. In this paper，shaking table tests are carried out on the seismic damage and dynamic response characteristics of the tunnel crossing the main sliding surface，and the boundary effect of the vibration model and the evaluation method of the system dynamic characteristics are proposed. Based on the damage state of the model site soil，a“model-data”dual-drive fusion failure mode evaluation method based on marginal spectrum entropy is proposed combined with Hilbert-Huang transform(HHT) and information entropy theory. Based on EMD decomposition and HHT band energy spectrum，a“model-data”dual-drive fusion evaluation method for EMD energy damage index of lining is proposed. The rationality of the damage model evaluation method and EMD energy damage parameters is verified by testing the damage state of the site soil and lining after the earthquake. The results show that the overall failure mode of tunnel crossing sliding surface is the trailing edge settlement，the middle slip，and the leading-edge shear bulge. The slope failure process and slide surface location based on marginal spectrum entropy are basically consistent with the characteristics of slope failure process reproduced by shaking table test，which proves the reliability of the dual-drive fusion method. The HHT energy spectrum frequency of model site soil is mainly concentrated in 0–25 Hz. The peak time of HHT energy spectrum of lining(18.07 s) lags behind that of model site soil，and the instantaneous frequency of different characteristic parts is different. The distribution of the damage index is related to the spatial location of the lining characteristic parts，and the EMD energy damage index is more than 90% under the excitation strength of 0.4 g. Verified by the lining model，it shows that the damage location can be detected based on EMD energy damage index，and the damage degree can be roughly judged according to the sudden change of damage index. It provides a new perspective and paradigm to solve the problems of monitoring analysis and damage quantitative evaluation during tunnel construction and operation in slope disease section of high intensity area.

Rainfall-induced landslides along roads towards Tibet are frequent in Gongshan County，Yunnan Province. Cluster landslides were triggered herein by the heaviest rainfall since the meteorological record in May，2020. Aiming at studying the geological features of these landslides，establishing rainfall threshold and early warning method，the distribution characteristics of cluster landslides were analyzed under the condition of different geological environment factors based on ArcGIS platform. The method for establishing rainfall threshold and cumulated probability early-warning curve based on Bayesian inference method and Kernel Density Estimation were developed. The rainfall intensity-duration threshold curves of road landslides close to Gongshan County under different shortest rainless interval times(SRIT) were established and discussed. The results demonstrate that the cluster landslides sliding in shallow layer are caused by the extreme rainfall characterized by the strongest continuity，fastest growth rate and highest peak intensity during the same period of 2004–2020. Size parameter  and shape parameter of rainfall threshold decrease with increasing of SRIT. An upper limit of SRIT for establishing rainfall threshold exists in a specified region，when its value exceeded the variability of rainfall threshold is more significant. The rainfall intensity is more important than duration for road landslide triggering in Gongshan County. The established methods for rainfall threshold and early-warning are reasonable and objective. The SRIT of 12 h(dry season)＋24 h(rainly season) is more suitable for establishing rainfall threshold of Gongshan County.

The rocky slope has obvious structural characteristics，and the deformation and failure characteristics and stability of slopes of different slope structure types are also different. The existing indexes for evaluating the stability of rock slopes are difficult to reflect the relative difference of the stability of rock slopes of different slope structure types quantitatively and objectively. Therefore，based on the concept of slope safety factor K，this paper introduces a safety index for evaluating the stability of rock slope，safety stability rate ，which is the ratio of the safety factor of rock slope when the structural characteristics of slope are considered to that of rock slope when the structural characteristics of slope are not considered，and is a relative index to characterize the stability of rock slope. Based on the finite element strength reduction method，the safety stability ratio of three types of basic structural plane rock slopes and nine types of typical slope structures is calculated and analyzed. The safety stability rate of Class I structural plane slope is the lowest，and that of Class III structural plane slope is the highest. The safety stability rate of rock slopes with different slope structures varies within a certain range，and its distribution rules are basically consistent with the actual classification results of rock slope stability. The above research results show that the safety stability rate can not only objectively reflect the influence of structure on the stability of rock slopes，but also quantitatively reflect the relative difference of the stability of rock slopes with different slope structure types. The safety stability rate can be used as a new quantitative index to reflect the influence of slope structure characteristics on the stability of rock slopes，and can be used to evaluate the stability of rock slopes of different slope structure types.

High-precision artificial boundaries are generally characterized by spatio-temporal coupling，but the lack of corresponding quantitative evaluation indexes makes the current assessment of the spatial coupling state of artificial boundaries extremely limited. For this purpose，a computational method for evaluating the spatial coupling state of high-precision artificial boundaries is proposed based on the relative gain array(RGA). The method makes up for the insufficiency of the traditional linear system theory in which the coupling degree only describes the number of fixed degrees of freedom of the system by solving the  –norm of the difference matrix of both the RGA and the identity matrix，and choosing the mean-square value about the total elements of the matrix to be defined as the mean coupling degree. The correctness of the proposed method is verified with a viscoelastic artificial boundary，and the reasonableness and applicability of the evaluation results of the method are investigated by using the Thin-Layer Method(TLM) and Scaled Boundary Finite Element(SBFEM) method. The effects of different foundation areas and near-field damping on the spatial coupling characteristics of high-precision artificial boundaries are analyzed，and the feasibility of setting a limit to and rounding off the tiny elements of the dynamic stiffness matrix as a kind of decoupling method for high-precision artificial boundaries is discussed. The results show that the spatial coupling calculation method of artificial boundary conditions proposed in this paper has reasonable applicability，and the decoupling method adopted significantly reduces the storage cost.

To explore the rainfall infiltration characteristics and the macro-micro mechanism of rainfall-induced slope instability，three centrifugal modeling tests were conducted under different rainfall intensities for two types of test slopes，respectively，which have different permeabilities(i.e.，test slopes prepared with quartz sand and fine sand). During the tests，the wetting front migration characteristics，the failure mode，and the particle movements in specific areas of the slope were observed and recorded，and the variations of pore water pressure at different positions of the slope were monitored. The test results showed that：(1) During rainfall，the wetting front in the slope migrates to the deeper regions in the form of an elliptic arc，and its migration rate is fast at the beginning but reduces thereafter. With the increase in rainfall intensity or permeability，the wetting front migration rate also increases. (2) The different failure modes of slopes with different permeability result from the different modes of fine particle migration and loss and the different locations of high-water content areas. (3) The pore water pressure growth mode is different in slopes with different permeabilities. When the permeability coefficient of the slope is small，the pore water pressure varies in type Ⅰ with a single steep rise followed by a sharp drop; When the permeability coefficient of the slope is large，the pore water pressure varies in type Ⅱ with multiple rises and drops. (4) Different pore water pressure growth modes lead to different failure modes of the slope，and the slope k of the peak point line of pore water pressure is introduced to represent the integrity of slope failure. When the pore water pressure growth mode is type I，k is larger and the slope slides as a whole. When the pore water pressure growth mode is type II，k is small and the slope slides in the progressive failure mode. The results of this study can provide an experimental basis for the prevention and control of rainfall-induced landslides.

After deep tunnel excavation，rock mass is prone to collapse and instability caused by severe deformation or rock burst disaster caused by block fragmentation，so the evaluation of disturbance characteristics of deep rock mass is of great practical significance to ensure engineering safety. The elastic modulus of rock is an important mechanical parameter that affects the degree of deformation after tunnel excavation. In this paper，through the mechanical response of peripheral rock in triaxial cyclic loading and unloading test in the established research，a nonlinear fitting method is used to construct a nonlinear drop model of rock elastic modulus，which can effectively reflect the change trend of elastic modulus under the influence of peripheral pressure and plastic strain. Based on the rock modulus drop model，the finite difference method is used to derive the numerical solution of the stress-strain field and displacement field of the strain-softened surrounding rock in deep buried tunnels. Combined with the numerical solution and according to the peripheral pressure and plastic strain on the peripheral elastic modulus or not，the influence of the critical softening coefficient and the quality of the surrounding rock on the distribution of the peripheral rock elastic modulus in the plastic region is analyzed，and the peripheral deformation law of the surrounding rock in the tunnels with different elastic modulus models is discussed. The results show that the deformation of the surrounding rock in the elastic zone is mainly affected by the peak modulus of elasticity，the modulus of elasticity changes nonlinearly in the plastic region，corresponding to the plastic softening stage of the change is faster and the amount of change is also larger，and the rate of change decreases sharply in the plastic residual stage，The modulus of elasticity tends to be stable，and reaches a minimum in the cave wall，the previous research method of elasticity of the modulus of elasticity is assumed to be the constant peak of deformation of the surrounding rock at the wall of the cave is small，and the safety of tunnel design is insufficient.

In order to study the influence of fault dip angle on the creep mechanism of surrounding rock and the mechanical response of tunnel lining structure in diversion tunnel with active fault zone，the creep physical model test of tunnel lining structure passing through active fault under different fault dip angles is carried out. On the basis of the test results，the displacement mode of active faults，the circumferential strain and longitudinal strain of lining，and the change law of contact pressure between surrounding rock and lining under different fault dip angles are analyzed. The whole process of crack initiation→expansion→failure of lining structure is observed. The results show that the displacement mode curves of the tunnel axis under different fault dip angles and different dislocation magnitudes are all S-shaped. And there is sliding between the staggered plate and the influence zone. This makes the discontinuous characteristics of the displacement mode curve in this interval obvious. The peak of the displacement gradient curve represents the speed of the displacement change. The rapid deflection area and the peak area of the  curve also correspond to the serious damage area of the lining structure. The dislocation risk assessment index is defined by the displacement gradient. It is found that with the decrease of the dip angle of the active fault zone，the tunnel lining structure is more likely to be broken in the fracture zone and the damage degree is more serious. At the same time，with the decrease of the dip angle of the active fault zone，the high fault risk area gradually runs through the whole fracture zone area. Therefore，the fault risk assessment index can be used as a quantitative index to evaluate the severity of structural damage. In terms of the appearance damage of the tunnel，the lining located at the junction of the staggered plate and the upper influence zone is more likely to be broken. With the decrease of the dip angle of the active fault zone，the damage range of the lining structure and the ratio of the damage range to the hole diameter also gradually increase. When the fault dip angle is 90°，the ratio of the failure range to the hole diameter is 1.36. When the fault dip angle is 70°，the ratio of the failure range to the hole diameter is 1.88. When the fault dip angle is 60°，the ratio of the failure range to the hole diameter is 2.64. Therefore，the risk of the tunnel lining structure crossing the active fault zone vertically is the smallest.

Based on the factors contributing to landslide occurrence，a well-designed and objective evaluation system is proposed to assess and classify the hazard of regional landslide disasters，which holds practical significance for both landslide disaster prevention and accurate forecasting. This study highlights the limitations of existing landslide hazard evaluation methods，such as incomplete evaluation indicators，subjectivity in the classification of evaluation criteria，and the inability to directly measure the current impact of different factors on the overall region and different hazard landslide areas. Taking the severely landslide-prone Wanzhou District in Chongqing as an example，under the premise of fully considering the rationality of evaluation factors，an objective division of evaluation factor levels using the weights of evidence method is applied to assess the hazard of regional landslide disasters. By combining the landslide hazard sensitivity index(SW) and the newly created landslide hazard impact index(SI)，along with the impact index(HW) for different hazardous areas，the overall sensitivity and impact of each evaluation factor on regional landslide occurrence are quantified. Moreover，the differences in impact on different hazardous areas are measured. This approach provides more accurate and targeted theoretical references for reducing the hazard of regional landslides，and holds significant importance in enhancing the effective defense capability against regional landslide disasters. The study shows that：(1) the evaluation index system for landslide hazard evaluation in Wanzhou District，after removing the topographic relief factor through the test for independence，comprehensively captures the landslide causative factors. (2) Based on the initial grading of evaluation indicators，the final grading of evaluation indicators is achieved using the weights of evidence，landslide area ratio，and grading area，with the support of the weights of evidence method. This approach enables regional landslide hazard evaluation，and the evaluation results are validated through the success rate curve method，with an accuracy of 72%. Therefore，the reliability of evaluation method in this research is reflected through the favorable evaluation precision. (3) The analysis of SW and SI indices reveals that elevation，road distance，and multi-year average rainfall are the top three factors with the highest overall sensitivity and impact on the region for landslide occurrence. However，the remaining factors show variations in their rankings in terms of sensitivity and impact. The difference in the ranking results of evaluation indicators on two indices indicates the necessity and scientificity of the SI index in this study. (4) The HW index indicates that the evaluation factors for high，medium，and low hazard areas exhibit consistent characteristics with the overall regional landslide occurrence. However，in relatively high hazard areas，the road distance factor has the greatest impact. In contrast，in relatively low hazard areas，the normalized vegetation index shows the second-highest impact，indicating the effectiveness and scientific validity of the HW index constructed in this study. (5) The low hazard areas are mainly located in high-altitude regions with higher vegetation coverage. Here，evergreen broad-leaved forests and coniferous forests play a suppressive role in the occurrence of landslides. On the other hand，the high hazard areas are primarily concentrated in the main urban areas of Wanzhou District，where human activities are significant. These areas are distributed along the Yangtze River and its tributaries，with higher precipitation levels concentrated in the low-altitude regions between 1 213 mm to 1 229 mm. For the high hazard areas，it is essential to implement appropriate measures to reduce the landslide hazard，such as undertaking proper landslide control engineering，anti-slide support measures，and slope greening. The implementation of these engineering measures will help mitigate the landslide hazard and achieve the goal of reducing the overall landslide hazard in the region.

In geotechnical engineering，upper bound finite element method with adaptive mesh refinement often evaluates the plastic failure area in a posterior manner，which may cause an excessive refinement in the buffer zone between rigid and plastic zones and lead to a high computational cost. Meanwhile，the initial mesh for the adaptive upper bound finite element method should not be too sparse to avoid the large error caused by the over-rigidity of model，as it can induce subsequent adaptive refinement to deviate from the correct direction. In this study，with a combination of six-node triangular elements and a second-order cone programming model，an upper bound finite element method with simultaneous adaptive mesh refining and coarsening algorithm is proposed. This method can automatically determine both active elements and inactive elements using plastic power dissipation-based estimators. For each adaptive step，those active elements are automatically refined and those inactive ones are thus coarsened，which can achieve the purpose of reducing the total number of elements and improving computational accuracy. The proposed method is then extended to the stability analysis in non-homogeneous soils，and numerical implementation of the proposed method is discussed. Two examples including tunnel face stability and failure of active trapdoors in non-homogeneous soils are analyzed to evaluate the validity of the proposed method through a series of parameter analysis.

In underground rock mass engineering，the dynamic disturbance propagates in the form of stress wave，and is affected by discontinuities such as joints in rock mass. In order to understand the effect of joint spatial parameters on the propagation of two-dimensional plane stress wave，the indirect stress wave separation method was extended to the case of multi-jointed rock mass，and an indoor experiment was carried out by pendulum plate tester. The results showed that the indirect stress wave separation method could be used to obtain the transmission and reflection characteristics of stress waves in oblique joints and joint sets. The incident angle of the stress wave had a significant effect on the reflected P-wave and the reflected S-wave. The increase of dimensionless joint spacing could reduce the reflection coefficient and transmission coefficient of P-wave obviously. With the increase of the joint intersection angle，the S-wave reflection coefficient and the P-wave transmission coefficient of the intersecting joint decreased，and the difference between the two increased gradually. When the joint crossing angle changed，the influence of joint spacing on the refection and transmission coefficient was dominant. The research results of this paper could deepen the understanding of the two-dimensional stress wave propagation law in jointed rock mass，and have guiding significance for geotechnical exploration and stability analysis of rock mass engineering.

Massiveness of rock mass is an important index in the field of geotechnical engineering. The most common method is using the longitudinal wave velocity of the rock mass to reflect the massiveness of rock mass. However，the integrity of the rock mass as shown by the acoustic measurements cannot take into account the impacts of axial impact due to the restriction of the longitudinal wave propagation of elastic waves. By using in-situ sonic wave testing and rock sample fracture detection，a model for calculating the massiveness of rock mass while taking into account the rock fracture orientation and length was established in this study. The influence of fractures with various orientations on the measured values of acoustic waves in situ was then analyzed by in situ testing and comparison with conventional massiveness of rock mass calculation. The findings indicate that the direction and length of the fissure have a major effect on the acoustic wave?s measured value，the extent of which depends on the angle between the fissure's growth direction and the direction in which the acoustic wave is being detected. The established model is based on the changes in the fracture parameters in the rock mass and the variation of the actual acoustic measurements to correct the acoustic measurements. The calculated intactness index of rock mass overcome the problem that the intactness index of rock mass obtained by traditional methods do not fully reflect the integrity of the rock mass.

The finite element strength reduction method is a commonly used method for slope stability analysis，but it cannot directly obtain the sliding surface. Based on the assumption that the shear direction is perpendicular to the displacement gradient when shear failure occurs on the slope，this paper proposes a sliding surface tracking method based on the displacement gradient field. After obtaining the displacement modulus gradient field of the slope at limit state，the maximum displacement modulus gradient point is taken as the starting point，and the slip surface is tracked along the shear direction by the Euler?s method. The maximum value of the gradient of the displacement modulus is obtained on the slip surface，and the position of the slip surface is corrected to accurately determine the position of the entire slip surface. Finally，the reliability of the method is verified by the calculation examples of homogeneous slope，horizontal weak intercalated slope，and inclined weak intercalated slope.

The dissociation of gas hydrate leads to the reduction of the bearing capacity of the interface between gas hydrate-bearing soil and mining well，resulting in discontinuous deformation such as dislocation and sliding，which directly affects the stability of the mining well. In order to study the weakening law of gas hydrate-bearing soil-mining well interface under dissociation conditions，based on the developed low-temperature and high-pressure gas hydrate generation and triaxial test equipment，shear tests of gas hydrate-bearing sand-mining well interface under dissociation conditions are carried out，and the statistical damage model of gas hydrate-bearing sand-mining well interface considering dissociation effect is constructed. As a result，the interface is in strain softening state before gas hydrate dissociation，and the shear strength and dilatancy increase with the increase of saturation. The interface is in strain hardening state after dissociation，and the shear strength increases with the increase of saturation，but the dilatancy is slightly affected by it. In addition，comparing with before dissociation，the shear strength，cohesion and dilatancy of the interface decreased after dissociation，showing significant weakening characteristics. Therefore，considering the strength of the interface finite micro cells obeys Mohr-Coulomb strength criterion and double-parameter Weibull random distribution，the interface statistical damage model which can better simulate the failure of gas hydrate-bearing sand-mining well interface caused by dissociation is established，the relationships of the parameters m and F0 in the model with gas hydrate saturation，effective confining pressure and dissociation are analyzed. The relevant results can promote the research on the basic theory and key technology of gas hydrate exploration and development.

 Currently，the effect of the axial force servo(compensation) system on the deformation control of soft soil foundation pits is inconsistent，and its advantages have not been fully exerted. Therefore，based on the active control method of the lateral deformation of the foundation pit，the particle swarm algorithm based on swarm intelligence is innovatively applied to solve the optimization problem of the supporting axial force，and the optimization method of the supporting axial force considering the construction process of the foundation pit is established. In addition，the calculation program of the vertical elastic foundation beam method based on the particle swarm algorithm is developed to obtain the reasonable supporting axial force that can meet the strength and stiffness requirements of the supporting structure in the dynamic and multi-condition changing foundation pit construction. The results show that the particle swarm algorithm introduced in this paper can simply and efficiently solve the optimization problem of the supporting axial force under dynamic and multiple constraint conditions involving the internal force and deformation of the retaining structure and the bearing capacity of the support，providing a reference for the design of deep foundation pits based on active control in the future.

Fines content(FC) is one of the geometric conditions determining whether suffusion occurs and has a complex influence on suffusion characteristics. Based on the computational fluid dynamics-discrete element method(CFD-DEM) coupling approach，numerical simulation tests for suffusion were conducted on gap-graded sandy gravels with two hydraulic gradients and seven FCs. The mechanism of fines content?s effect on suffusion was investigated from both macroscopic and microscopic perspectives. The results show that the pore states of the soil can be classified into four types according to the FC：underfilled，filled，partially overfilled(where coarse particles are partially separated by fines)，and completely overfilled(where coarse particles are completely separated by fines). In the underfilled state(i.e.，FC≤25%)，the erosion rate of fines increases with rising FC，but decreases during the transition from underfilled to filled states(i.e.，FC = 30%). This is primarily because the void ratio of filled soil reaches its minimum，making it hard for fine particles to migrate. Subsequently，as the FC continues to increase，the erosion rate rises again. However，the erosion type gradually shifts from suffusion to backward erosion. The erosion mechanism can be determined through a comprehensive analysis of particle migration distribution and the composition of eroded particles. Specifically，in the case of partially overfilled soil(i.e.，FC = 35%)，it displays a transitional internal stability and exhibits suffusion. Conversely，for samples in a completely overfilled state(i.e.，FC = 40%)，fines cannot migrate through the pores，leading to backward erosion during testing.

An axisymmetric consolidation model of soil around a permeable pipe pile after driving is established，where the stress-strain relationship of the soil is simulated with the Merchant viscoelastic constitutive model，the permeability of the pile-soil interface is described as a semi-semi-permeable boundary. The corresponding analytical solutions for the excess pore water pressure and consolidation degree of the soil are derived using the separation of variables and Laplace transform. Then，the rationality of present solutions is verified by comparing them with the existing solutions. Based on the present solutions，the parametric analyses are carried out to in-depth investigate the consolidation characteristics of the soil around a permeable pipe pile. The results show that a larger boundary parameter of the semi-permeable boundary results in a quicker consolidation of the soil around the pile，and leads to a smaller effect of the soil viscoelasticity on the consolidation rate of the soil；in the early stages，the effect of soil viscoelasticity on the consolidation behavior of the soil around the pile is not significant，while in the later stages，the greater the viscosity coefficient of the soil and the greater the modulus ratio of the independent spring to the paralleled spring in Kelvin body，the slower the consolidation rate of the soil around the pile.

In order to realize the resource utilization of industrial solid waste dust-based foamed lightweight soil in transportation infrastructure construction，this paper puts forward the performance improvement technology of dust-based foamed lightweight soil and develops a new material of dust-based foamed lightweight soil to evaluate the mechanical properties，water stability and durability of dust-based foamed lightweight soil under different mix ratios after composite modification. The microstructure changes and strength formation mechanism of the material is also explored before and after modification. The results show that the nonionic surfactant(AEO-9) can significantly improve the foam stability and the wettability of the dust，and the optimal dosage is 20 % of the mass of the original foaming liquid and 0.4 % of the mass of the dust，respectively. After composite modification，the content of dust ash is up to 50 %，the 28 d strength of dust ash-based foam lightweight soil reaches 2.08 MPa. The water absorption and softening coefficient are 21.4 % and 0.765 respectively. The strength losses of dry-wet cycle and freeze-thaw cycle are 13.8 % and 17.3 %，respectively，which meets the requirements of water stability and durability index. The results of scanning electron microscopy show that the microscopic pore structure of the composite modified fly ash-based foamed lightweight soil is significantly optimized，and the proportion of bubbles with a diameter of less than 200 μm increases from 32.54 % to 52.2 %.The results of XRD analysis further show that the slag powder is helpful to improve the initial strength of the material in the alkaline environment，and the Fe2O3 in the dust is helpful to form a stable hydrated tricalcium aluminosilicate C3(AF)H6 after the activation of the activity，which further improves the strength of the material. The dust-based foam lightweight soil modification method and its new materials provide a cost-reduction and efficient way for the resource utilization of industrial solid waste in the backfilling engineering.

The frozen porous media recently attract a great deal of attention in the field of the geophysical exploration as follows. Most of the studies on wave propagation in frozen soil have focused on the interface between one or two media. In order to reflect the propagation law of SH wave in frozen soil more intuitively，based on the wave theory of frozen saturated porous media，this paper establishes a free-field model of a saturated frozen soil overlying bedrock under the incidence of plane SH wave. Combined with the Helmholtz theorem，an analytical expression for the propagation velocity of SH wave in saturated frozen soil is obtained by establishing the dynamic stiffness matrix. The influence patterns of incidence angle，incidence frequency，cementation parameters，porosity，temperature and contact parameters on the propagation velocity of SH wave were analyzed. The results show that the propagation velocity of SH wave increases significantly with the increase of cementation parameters and contact parameters. The propagation velocity of SH wave gradually increasing with increasing porosity and temperature overall. The incidence angle of the SH wave has a significant effect on its propagation velocity，which varies nonlinearly with the increase of the incidence angle. There are corresponding peak velocity frequencies for different incidence angles with varying parameters. Most of the acceleration of the dynamic response is concentrated in the high incidence frequency band.

To investigate the mechanisms and calculation methods of land subsidence caused by foundation pit dewatering under the condition of variations in total stress and soil parameters，a three-dimensional numerical model of groundwater seepage in the study area is constructed in this research，with the foundation pit dewatering project in the head inverted siphon section of the Xixiayuan Water Conservancy and Irrigation Project as a case. The changes in stress，parameters and subsidence during the dewatering process of foundation pit are analyzed and compared by the method of theoretical derivation and case study. Calculation formula and methodology of seepage-subsidence coupling model in view of variation in total stress and soil parameters are proposed，and the calculation results of land subsidence under different theoretical models are compared and analyzed. The results show that the seepage-subsidence coupling model built in consideration of variation in total stress and soil parameters has the smallest calculation value and the best fitting effect with the measured value. This can reasonably explain the phenomenon that the calculated subsidence value is obviously greater than the measured value in the previous studies，which is more consistent with the actual subsidence process. The research outcomes are able to provide references and guidance for land subsidence prediction in similar projects，which is of great practical significance.

Bentonite pellets have been recognized as a new form of buffer/backfilling material in the construction of a multi-barrier system for high-level waste(HLW) disposal，which is primarily due to their cost-effectiveness in production，easy transportation and convenient installation. In this study，a series of suction-controlled hydration/unhydration tests and microscopic tests were performed on GMZ bentonite pellets using the vapor equilibrium technique. The objective was to investigate the water retention property，volume-change behavior，and micro-structural evolution of the pellets. The results demonstrated that the wetting/drying water retention curves of single bentonite pellet exhibited a hydraulic hysteresis at high-suction stage，but this phenomenon was less pronounced at low-suction stages. Bentonite pellets underwent a expansion with the absorption of water and a shrinkage with the loss of water during a wetting/drying cycle. This process led to the generation of plastic deformation at the high-suction stage. As inter-aggregate pores increased during the wetting process，the pore size distribution curve of bentonite pellets gradually transitioned from a unimodal porosity to a bimodal one. Even during the subsequent drying process，the curve continued to exhibit a bimodal porosity because the inter-aggregate pores were unable to fully recover. The BExM model effectively reproduced the swelling or shrinking behaviors of bentonite pellets during wetting and drying processes. Additionally，it was also used to analyze the changes of multi-scale pores within the bentonite pellet mixture，including the examination of intra-aggregate pores，inter-aggregate pores，and inter-pellet pores.

Compared with static load test(SLT)，high-strain dynamic test(HSDT) of pile foundation is more effective，rapid and less costly. A new HSDT method was proposed and verified，which is called the multi-point dynamic method(MPDM). The difference and influence factors of pile capacity curves between SLT and DLT were studied through theoretical analysis and model experiments in the presented paper. Based on the nonlinear soil resistance model，the dynamic discrete spring-mass model of single pile under high strain condition was established firstly；the analytical expression of impact force of free-fall hammer was derived and the discrete difference solution was given. The dynamic load curves under different pile lengths was calculated based on MPDM and compared with SLT results and results predicted by Statnamic method. On this basis，model experiments were conducted to explore the difference of dynamic and static capacity curves，and to verify the reliability of MPDM. The results have shown that the capacity curve predicted by MPDM was accurate for pile of short length；the prediction results was better than that of Statnamic method for long piles. The difference between the dynamic and static curves was related to the wave effect of pile，and the prediction accuracy of the multi-point dynamic measurement method can be improved by adjusting the excitation conditions at the pile top to attenuate the wave effect. The presented theoretical model，which can consider the soil nonlinearity，accurately predicted the dynamic response of model pile. And it is applicable for low stain and high strain dynamic load conditions. This research is helpful to study HSDT methods，dynamic theoretical model and the difference between dynamic and static capacity curves.