Fault stick slip instability can easily induce fault slip rockburst. In order to further explore the stick-slip evolution characteristics of faults with different dip angles and AE and charge induction multi-source precursors，bidirectional friction tests were carried out on syenitegranite with faults with different prefabricated dip angles. The accumulated energy and spectral characteristics of acoustic emission and charge induction signals during fault stick-slip were analyzed，the AE sources were located，and the nonlinear characteristics of AE and charge induction time series were studied based on multifractal theory. Three quantitative indexes(maximum multi-fractal dimension Dqmax，spectral width Δα and multi-fractal parameter Δf(?)) with good correlation with stick slip instability were constructed，and the following conclusions were drawn：(1) With the increase of fault dip angle，the fault failure mode changes from sliding failure along the plane to sliding failure through the plane，which increases the intensity and energy of AE and charge induction signals. (2) The maximum multi-fractal dimension Dqmax and spectral width Δα of the AE and charge induction signals gradually increase with the increase of fault dip angle. The maximum multifractal dimension and spectral width of the AE and charge induction signals can reflect the difference of energy released when the fault stick slip instability or severely damaged. The multi-fractal parameters Δf(?) of AE and charge induction signals are all less than 0 when the fault is instability or severely damaged.，and the critical value of Δf(?) can be used as the prediction index of fault stick slip instability and severe failure. (3) Compared with the AE and charge induction signals generated by shear slip failure along the plane of 34°and 45°faults，the AE and charge induction signals generated by 56°faults through the plane slide failure has lower dominant frequencies. It can be considered that the dominant frequencies of the AE and charge induction signals are related to fracture scale.

Addressing the issue of rock bursts and instability in deep coal roadways with high three-way stress differences，this study employs theoretical analysis，numerical simulations，and engineering case studies to reveal the mechanisms of rock bursts and instability in such areas. Based on the Mohr-Coulomb criterion，the definition of the three-way stress difference is modified to ，providing a quantitative damage criterion for coal body units. High three-way stress differences in deep coal mines are categorized into horizontal tectonic stress type and vertical stress type based on their origins. After roadway excavation in high-stress difference areas，the coal rib experiences significant crack development and increased damage extent. Additionally，there are higher movement speeds，larger displacements，and faster destruction rates. The peak value of the three-way stress difference，distributed radially around the surrounding rock，defines the interface between the failure and non-failure zones. The failure zone suppresses the increase in three-way stress difference in the non-failure zone，while the three-way stress difference distribution in the non-failure zone plays a dominant role in controlling the stability of the coal roadway. A stability parameter，Ss，is proposed to describe the stability of the surrounding rock of coal roadways or in unexcavated coal configuration areas. When the surrounding rock's Ss is less than the critical [Ss] of the non-failure zone boundary，accumulated deformation in the non-failure zone drives coal from the failure zone towards the roadway，leading to instability. When Ss decreases sharply，the non-failure zone rapidly fails，and significant deformation accumulation drives the coal body in the failure zone to experience a rock burst. This mechanism is validated through a case study of a rock burst incident in the high three-way stress area formed by a coal pillar at the Huafeng coal mine.

Understanding the mechanism of hydraulic fracture propagation in hot-dry-rock(HDR) reservoirs，particularly under the influence of thermal stress and natural fractures，is crucial for effectively guiding hydraulic fracturing design and enhancing geothermal energy development. First，an independently developed high-temperature true triaxial hydraulic fracturing simulation experiment system is utilized to conduct high-temperature true triaxial hydraulic fracturing tests on granite samples，examining how variations in temperature influence rock fractures. And a 3D thermo-hydro-mechanical coupling model for fracture propagation simulation is created based on the continuum-discontinuum element method. The model's accuracy is verified through comparison with a 3D theoretical model of fracture propagation and high-temperature hydraulic fracturing experiments. Subsequently，numerical simulations of hydraulic fracturing in HDR reservoirs are performed to study the effects of thermal stress and natural fractures on the hydraulic fractures propagation. The results indicate that the induced thermal stress caused by the injected cold water can reduce the reservoir fracture pressure and fracture extension pressure，increase the fracture width and decrease the fracture length. As the temperature of the rock sample rises，the induced thermal stress increases considerably，leading to a significant decrease in the rock fracture pressure observed in both experiments and the numerical simulations. When accounting for the effect of induced thermal stress，hydraulic fracturing can active the natural fractures even when there are significant horizontal geostress differences and large approach angles. Compared with the HDR reservoir without natural fractures，the stimulation reservoir volume of the reservoir with 200 randomly distributed natural fractures increases by 63.8%. As the thermal expansion coefficient of the reservoir rises，the influence of thermal stress becomes increasingly pronounced，leading to the formation of secondary fractures that develop perpendicular to the main fracture surface，and the stimulation reservoir volume increases significantly.

Mineral composition is an important factor affecting the macro-micro friction mechanical properties of rock. The macro-micro friction properties of sandstone are studied based on direct shear and nano-scratch tests，the variations of mineral compositions before and after shearing are analyzed using X-ray diffraction，the macro-micro friction coefficients of the rock，different minerals and their interfaces are statistically obtained，and the friction correlation mechanism between these factors is established. The results show that the proportion of hard-phase minerals in the total amount of powder increases after shearing，the proportion of soft-phase minerals decreases. The scratch depth and friction force of hard-phase minerals remain stable，those of soft-phase minerals vary significantly. Statistical analysis of the frequency distribution curve of the friction coefficient reveals that each mineral and interface exhibit a single-peak Gaussian distribution. Combined with the analysis of macro-micro friction mechanisms，it is found that the macro friction force of sandstone is influenced by surface asperities and the wear between different minerals，the friction force of hard-phase minerals primarily depends on their inherent properties，the friction force of soft-phase minerals and interfaces is affected by their inherent properties，plastic flow and the extrusion of surrounding minerals. By further quantifying the relationship between macro-micro friction coefficients，the hard-soft phase interface is found to contribute the most to the macro friction coefficient，accounting for 52.1%. The research results of the macro-micro friction properties can provide a theoretical foundation for revealing the mechanism of cross-scale friction mechanics.

The existing advanced geological forecast methods consider the integration of multiple source information，but still face issues such as limited participation of geological information and incomplete sources of integrated data. This study proposes a multi-source data fusion method for tunnel advanced geological forecast based on the full-process construction information. It screens and establishes a full-process indicator system，containing 7 major categories and 232 indicators，and a targeted unfavorable geological problem indicator system. Besides，A mapping conversion method of ITV-IRV(indicator test value and indicator risk value)，which combine quantitative indicator segment functions，semi-qualitative indicator node interpolation，and qualitative indicator threshold classification，is proposed，as well as a data area segmentation method. Finally，Analytic Hierarchy Process and Huber Weighting method are used for weight analysis. Fuzzy Fusion Theory and so on methods are applied for data fusion and obtaining the risk probabilities of unfavorable geological problems. The results show that：(1) The full-process indicator system and unfavorable geological problem indicator system provide comprehensive advanced geological forecast indicators. (2) The ITV-IRV mapping conversion method，data area segmentation method and indicator weight analysis methods，enable data normalized across indicators and be ready for multi-source data fusion. (3) The multi-source data fusion operation，combining mathematical geological logic，Fuzzy Fusion Theory，and other fusion methods，can accurately and effectively obtain the risk probabilities of unfavorable geological problems. (4) Engineering applications demonstrate that the proposed advanced geological forecast method improves forecasting accuracy，enhances comprehensiveness，increases efficiency and effectively guides construction.

A design of cyclic loading and unloading stress path before or after strength in triaxial compression is often adopted to describe the accumulated damage in rock. Considering the sudden failure of sandstone，a design with the same stress increment as the gradient to load axial stress was adopted in pre-peak，another stress drop-based unloading path was suggested in post-peak stage. The experimental results show that there are obvious stress drop，energy density drop and accumulated damage surges in the cyclic process after the peak strength，which are all strongly correlated to the generation of macro fracture surfaces separating the intact sandstone into discrete parts. Then，according to the correlation of volumetric strain and axial strain，an accurate division of the post-peak stress drop into two parts is effectively made by defining the ductile soften behavior and the macro surfaces-fracturing behavior. Three correlation modes are summarized to characterize the variation of volumetric strain with deviator stress during the whole loading-unloading stage，which are compression at the full process，compression after expansion, and expansion at full process. A new definition of post-peak fracture strength is made as stress boundary of ductile soften behavior and macro fracturing behavior，which is determined based on recognizing the critical transition of post-peak volumetric-axial strain relationship or the maximum drop of energy density. In addition， the non-linear evolution of elastic energy density is effectively described in the pre- and post-peak stages of sand rock under tri-axial cyclic loading and unloading stress. A new damage variable considering the accumulation of energy lost in each cyclic is defined. The results show that there is a liner relationship between the new damage variable and fracture volumetric strain in the ductile softening stage after post-peak and a clear surge of accumulated damage occurs in the macro surface-fracturing stage，as well as the corresponding damage increment linearly decreases with the confining pressure. The research results indicate that the design of tri-axial cyclic loading and unloading tests provides a feasible way to gradually reveal the critical mechanics of sand rock.

The dynamic loads induced by excavation disturbance and earthquake significantly influence the deformation and instability of jointed rock masses. To investigate the shear mechanical properties of rock joints under dynamic normal load，a series of shear tests were conducted on red sandstones under both dynamic normal load(DNL) and constant normal load(CNL) boundary conditions. The test results，i.e.，shear strengths，failure modes，acoustic emission characteristics and failure pattern obtained under the two boundary conditions were comparatively analyzed. The analysis shows that the shear stress reflects was lagged the dynamic normal stress and the phase offset was positively correlated with the initial normal stress and joints roughness. The influence of dynamic normal load on peak shear strength depended on the failure mode. When the primary failure mode was climbing and dilation，the peak shear strength was increased by the dynamic normal load；conversely，when the failure mode was dominated by shearing and fracturing of asperities，the peak shear strength was decreased. The dilation was significantly confined by the dynamic normal load，which exacerbated the wear on joints surface and the degradation of asperities. The acoustic emission monitoring results indicated that the dynamic normal load intensified the damage degree at the initial shear stage. It increased the proportion of shear fractures whereas decreased the proportion of tensile fractures. Based on obtained test results and revealed shear mechanism，a dilatancy model was deduced considering the influence of the dynamic normal load. Finally，a model for predicting the peak shear strength of joints under DNL conditions was proposed and it was validated to have a satisfactory prediction accuracy.

To analyze the impact of excavation unloading on the stability of the surrounding rock in existing deeply buried tunnels，the study utilized conventional triaxial compression tests and lateral unloading tests on hollow-cylinder sandstone specimens，simulating the mechanical behavior and fracture mechanisms of circular tunnels under complex stress conditions. Initially，stress-strain curves of hollow-cylinder sandstone under various confining pressures obtained from indoor mechanical tests were analyzed to assess the impact of confining pressure on mechanical properties. Subsequently，the effects of unloading rate and stress level on the strength deformation characteristics and energy evolution laws of hollow-cylinder sandstone were detailed，based on the stress-strain curves of rock samples under lateral unloading. Finally，the multi-scale fracture mechanisms of hollow-cylinder sandstone under lateral unloading were discussed through observations using cameras and micron-scale industrial CT on the failed specimens. The results showed that both the peak strength and elastic modulus of hollow-cylinder sandstone increased with confining pressure，with peak strength being more sensitive to confining pressure than the elastic modulus. As the unloading rate increased，the peak strength and damage threshold of hollow-cylinder sandstone showed a non-linear decreasing trend，while the Young?s modulus remained essentially unchanged，and the elastic energy and dissipated energy at the peak stress decreased. With increasing unloading stress levels，the peak strength and damage threshold of hollow-cylinder sandstone showed non-linear and linear growth，respectively，with no significant change in Young?s modulus，but an increase in elastic energy and dissipated energy at the peak stress. Under conventional triaxial compression，hollow-cylinder sandstone exhibited shear failure，and with increased confining pressure，the fracture angle decreased while the degree of fracturing for internal wall increased. Under the same confining pressure，as the unloading rate increased or the unloading stress level decreased，the surface fracturing of the hollow-cylinder sandstone was severe while the fracturing damage of internal wall weakened. The crack rate in the failed hollow-cylinder sandstone was directly proportional to both the unloading rate and the stress level. The study’s conclusions provide insights into the failure and instability mechanisms of the surrounding rock in deeply buried tunnels/roadways under lateral unloading conditions.

In search of a safe and efficient method for fracturing coal and rock masses without using explosives and with controllable crack propagation direction，this study proposed an efficient directional rock-breaking technology utilizing a coal-based solid waste non-explosive expanding agent，i.e.，instantaneous expander with a single fracture surface(IESFS). First，directional rock-breaking experiments with an IESFS were performed with the aid of a self-developed experimental system. Besides，the damage-displacement evolution in the rock-breaking process of the IESFS was studied through numerical simulation. Furthermore，the IESFS was applied to directional roof fracturing in an underground coal mine. The research findings are as follows：(1) The IESFS utilizes an electrical current to activate the fuse，which in turn triggers the coal-based solid waste expanding agent to generate high-pressure gas within 0.05–0.5 seconds. Such high-pressure gas serves to efficiently break the rock. (2) Conventional blasting generally induces rock fracturing in a “line-to-plane-to-solid” pattern. In contrast，the IESFS fractures the rock in a “point-to-line-to-plane” pattern，that is，it exerts forces at a point，initiates rock fracturing on a line，and complete rock fracturing on a plane. (3) When used to fracture concrete specimens，the IESFS induces the formation of a high-pressure gas jet with concentrated energy at points，enabling precise control over the direction of fracture propagation and the number of fractures. (4) The damage in the cutting direction is significantly greater than that in the non-cutting direction，the former being 7.92 times greater than the latter. (5) After the IESFS is applied to in-situ fracturing of the roof，the directional roof cutting effect was superior. Additionally，its cutting rate is 11% higher than that of conventional shaped charge blasting，which is indicative of its more powerful performance. The research findings are expected to provide valuable insights and references for exploring novel non-explosive directional rock-breaking methods.

The dynamic mechanical properties of anchored bodies，which determine the stability of anchor bearing structures，is the scientific basis for further revealing the deformation and failure mechanism of anchor bearing structures under impact dynamic loads. In this study，the dynamic mechanical properties and deformation failure processes of three types(unanchored，end-anchored，and fully-anchored) of specimens subjected to dynamic impact loads under varying pre-tightening forces were investigated with the aid of the split Hopkinson pressure bar(SHPB) technique. Based on the test results，the dynamic stress-strain curves，dynamic strain field evolution characteristics，and anchor rod axial force characteristics of anchored coal specimens were yielded. Furthermore，the interactions among anchor rods，anchoring agents，and pre-tightening forces during impact failure of anchored coal specimens were analyzed，and the dynamic deformation and failure mechanism of anchored coal specimens was disclosed. The following beneficial results were obtained：(1) Under dynamic impact loads，the stress-strain curves of anchored coal specimens exhibit significant elastic-plastic behaviors，and their dynamic strength and average peak strain values both grow with the rise of pre-tightening force. Among the three types of specimens，the dynamic strength values of end-anchored specimens are 3.7%–7.9% lower than those of fully-anchored specimens. (2) Affected by anchor rods and pre-tightening forces，crack development and propagation in the specimens slows down，and the position of crack initiation shifts towards both sides. An increase in the pre-tightening force and anchorage length brings about a decrease in the fragmentation degree of specimens，and these two factors exert a stronger influence on fully-anchored specimens than end-anchored specimens. (3) The deformation compatibility process between specimens and anchor rods is divided into two stages，i.e.，“advance response” and “delayed response”. For end-anchored specimens，the strain response of anchor rods precedes that of the specimens. In contrast，for fully-anchored specimens，it lags behind that of the specimens. (4) Under dynamic impact loads，a larger anchoring length and pre-tightening force correspond to a higher support stiffness and sensitivity of specimens and a smaller peak axial force of anchor rods. The pre-tightening force should be controlled below a value that neither diminishes the strength of surrounding rock nor exceeds the yield load of the rod body，as an excessively high pre-tightening force is inconducive to the overall impact resistance of the anchored coal body. These findings are expected to offer guidance and reference for grasping the anchoring mechanism of roadway support under dynamic impact loads and the degradation mechanism of anchored bearing structures in surrounding rock.

At present，the academic community has not yet been able to condense the applicable conditions of the unified rock burst inoculation mechanism. Through the self-developed multi field coupling test system for deep coal and rock dynamic disasters，the“stress-temperature-seepage-disturbance” multi physical field coupling analysis method is applied to the study of the influencing factors of rock burst. The single physical field(uniaxial test and conventional triaxial test) and the double physical field(confining pressure-seepage and confining pressure-disturbance) comparative test. This not only verifies the reliability of the self-developed equipment，but also provides a strong theoretical basis for the accurate picking and reliable identification of the induced factors of rock burst under multi physical fields. The test results show that：(1) The multi-field coupling test system of deep coal-rock dynamic disaster can carry out uniaxial and triaxial compression tests，cyclic loading and unloading tests and permeability tests under three-way coupling conditions under normal temperature，high temperature environment and low frequency dynamic disturbance. It can meet the test requirements of different engineering rock masses under complex stress paths and the test results are reliable. (2) The energy index in the loading process is analyzed by the multi-field coupling test of related dynamic disturbance to characterize the damage process of coal samples. It is found that when the confining pressure of coal sample is increased from 0 MPa to 4 MPa，the average peak strength is 14.75 MPa and 62.67 MPa respectively. The cumulative energy of single physical field is 24.3×105 mV•ms，and the cumulative energy of double physical field is 52.0×105 mV•ms. This further indicates that the disturbance strengthens the strength of the coal body and aggravates the degree of damage. (3) The failure types of coal samples are divided by RA/AF index. It is found that the complexity of different physical field failure types is aggravated under triaxial stress conditions，and shear failure is still dominant. This intuitively shows that the strength of coal samples in different physical fields is obviously affected by confining pressure. The overall performance is that the discreteness of monitoring data under multi-field coupling is significantly increased. (4) Because the real occurrence environment of the site is a multi-action mode of superposition of dynamics，statics and seepage mechanics，which aggravates the difficulty of prevention and control. The above analysis results are of great significance for further establishing the prevention and control system of rock burst under complex stress conditions.

Tectonic movements and human engineering activities often cause disturbances in the stress of strata. However，it is still unclear how the frictional properties of fault gouge evolve under the disturbance of normal stress，and whether this will lead to the reactivation of faults and trigger earthquakes. This paper documents 20 direct shear experiments on simulated granite gouges(grain size＜0.25 mm) collected from Heyuan fault zone，China，to investigate frictional properties under dynamic normal stresses. All experiments were conducted，using a conventional direct shear equipment，at room temperature with a fixed shear rate of 1 ?m/s. Dynamic loading was applied by using square and triangular waves(initial normal stress of 10 Pa，amplitudes of 1–9.5 MPa and frequencies of 0.003 3–0.001 0 Hz). The results show that：(1) Shear stress exhibited a clear hysteresis effect with dynamic normal stress loading. (2) The apparent friction coefficient linearly decreases from 0.63 to 0.14 with increasing amplitude during loading and increases linearly from 0.63 to 0.91 during unloading. Microstructure analysis revealed that samples subjected to higher stress perturbation amplitudes were more intact and exhibited fewer tensile fracture zones. These hysteresis effects and the evolution of the apparent frictional coefficient align with the micromechanical model of grain contact proposed by Wang and Scholz. Additionally，a relationship between the apparent friction coefficient of fault gouge and the amplitude of normal stress perturbations was established based on experimental results. Using the Heyuan fault zone as a case study，we analyze the impact of dynamic perturbation in principal stress and pore water pressure on fault stability based on the Coulomb strength theory. It was found that increasing the disturbance amplitude of the maximum principal stress by 1 MPa reduces the fault shear strength by 0.18 MPa. This could reactivate faults，potentially causing seismic events with magnitude above 6 if the fault exceeds 10 km.

Due to the complex nonlinear characteristics often exhibited in the shear failure behavior of rock mass， existing theoretical methods face challenges in analyzing the stability of fractured rock slopes. In this study，a limit equilibrium(LE) variational method for assessing the stability of rock slopes is proposed. This method utilizes the variational method to derive the differential control functions for the slip surface and its associated stress. Additionally, the LE principle is employed to establish the calculation formulas for the factor of safety (FOS) of the slope and the unknown variable related to the slip surface stress. Furthermore，to address the interdependent relationship among the shape of the slip surface，the normal stress on the slip surface，and the instantaneous shear strength parameters under the generalized Hoek-Brown(H-B) strength criterion，a discrete calculation approach coupled with a correlational solving strategy is applied to overcome the challenges posed by the direct incorporation of the nonlinear strength criterion. Building on this foundation，the global vraiational extremum problems of the slope are considered as multiple deterministic boundary variational extremum problems. Subsequently，the slip surface parameters are treated as optimization variables, with the objective of minimizing the slope FOS while satisfying the variational extreme conditions. A multi-objective optimization genetic algorithm is introduced to achieve a precise and rapid search for the critical slip surface of the slope，ensuring the removal of movable boundary cross-sectional conditions and strict adherence to the variational control conditions. The feasibility and practicability of the proposed method are verified through comparisons with several examples. This research contributes to the advancement and refinement of the LE theory for slope stability and provides an effective computational framework for the stability analysis of fractured rock slopes under complex conditions.

This paper proposes a hierarchical Bayesian method(HBM) combined with Markov Chain Monte Carlo (MCMC) to address the challenges of large statistical uncertainty in geotechnical experimental data，inaccurate probability distribution of geotechnical parameters，and unreasonable slope reliability analysis under small sample-sized conditions. The HBM comprehensively incorporates information from multiple similar geotechnical sites and integrates it with the limited measurements from the target site. This approach enables a more reasonable characterization of the probability distribution of geotechnical parameters under small sample conditions. The proposed method is validated using real datasets from several loess sites in northern Shaanxi Province，China. Based on these datasets，a reliability analysis of a loess slope is conducted to demonstrate the practical application of the HBM. The results indicate that，compared to the independent parameter model(IPM)，which does not utilize information from similar geotechnical sites，the failure probability of the loess slope is reduced from 11.6% to 4.8% when using the HBM. Additionally，extensive numerical simulations are carried out to further verify the accuracy of the HBM compared to traditional methods. The results show that，compared to IPM，the HBM improves the accuracy of geotechnical statistics by 33% to 53% and reduces uncertainty by approximately 19% to 53%.

The position of the trailing edge crack is often the location of the boundary of the trailing edge in a soil landslide. This paper aims to explore the effect of bedrock-surface inclination on the characteristics of the trailing edge crack in a soil landslide sliding along the bedrock surface. Twelve laboratory tests on trailing edge cracks in soil landslides along the bedrock surface are first conducted. A theoretical approach for calculating the position of the trailing edge crack is then proposed. The theoretical approach is finally applied to calculate the positions of trailing edge cracks in twelve laboratory landslides and two field landslides. The results show that the inclinations of the trailing edge cracks in the twelve laboratory tests range from 63.7° to 78.1°. As the bedrock-surface inclination increases，the failure mode of the trailing edge crack transitions from predominantly tensile failure to predominantly shear failure，resulting in a corresponding decrease in the inclination of the trailing edge crack. The proposed theoretical approach treats the landslide as a stressed body，with the slip surface divided into two parts：the bottom slip surface and the steeper trailing edge crack surface. The bottom slip surface exhibits shear failure. In contrast，the trailing edge crack surface exhibits tensile failure and shear failure at positions near and far from the slope surface，respectively. For both laboratory and field landslides，the overall deviation of the trailing edge crack positions calculated by the theoretical approach from the measured positions is not significant. The results of this study help to accurately locate the trailing edge crack in the landslide.

The Smoothed Zhang-Zhu(GZZ) criterion is a three-dimensional strength criterion for rocks proposed in recent years，which can reasonably and reliably describe the nonlinear strength characteristics of rock materials. However，only a few finite element software are equipped with this criterion，and most of the existing constitutive model programs based on the GZZ criterion are carried out in the principal stress space，making it difficult to apply in ABAQUS. In addition，the current numerical simulations based on the Smoothed GZZ criterion often use the associated ideal elastoplastic model，ignoring the plastic deformation characteristics and strength nonlinearity of rocks. In this paper，the plastic potential function of the Smoothed GZZ criterion is improved，and a numerical implementation method of the constitutive model based on the Smoothed GZZ criterion in the general stress space is proposed to avoid the problem of principal stress transformation. Meanwhile，a calculation method considering the dilation characteristics and strength variation of rocks is given. Finally，the calculation of this constitutive model is implemented by writing a UMAT subroutine in ABAQUS. Verified by three calculation examples，this model can directly conduct calculations in the general stress space，can reflect the dilation characteristics and strength nonlinearity of rocks，and the numerical solutions are in good agreement with the analytical solutions and the results of model tests，showing a relatively high calculation accuracy.

The objective of the current investigation is to delineate the dynamic response mechanism of piled raft foundation supporting high-rise structures in the context of liquefiable sandy soil under the influence of intense seismic activity. Within the scope of this study，a scaled-down model representing the integrated system of saturated sand strata，piled raft foundation，and high-rise edifice has been meticulously designed and fabricated. Utilizing the centrifuge shaking table apparatus，dynamic response assessments under varying degrees of ground motion intensity have been conducted. The study primarily concentrates on the analysis of soil acceleration responses，variations in excess pore water press ratio，dynamic behavior characteristics of high-rise structural systems，and the underlying dynamic response patterns of pile-raft foundations. Furthermore，the investigation delves into the interrelation between soil liquefaction and the dynamic response of the pile-raft foundation system of high-rise buildings. The empirical findings indicate that the piled raft foundation of high-rise buildings exacerbates the depth of soil liquefaction to a certain degree，with the dissipation of pore pressure occurring at a leisurely pace amidst the pile clusters. The amplitude of acceleration response spectra diminishes with the progression of soil depth. During the occurrence of minor seismic events，the acceleration of the raft tends to escalate，whereas，in the case of major seismic events，the acceleration response of the raft exhibits an initial increase followed by a subsequent decrease. As the peak acceleration of seismic waves intensifies，the maximum bending moment experienced by the pile shafts progressively diminishes，with the upper bending moment of the central pile being more pronounced. Moreover，the maximum bending moments of corner piles，side piles，and central piles are observed at the interface between the sandy soil layers. The liquefaction of the foundation soil provides a damping effect for the superstructure to a certain extent.

Frost heave is the main factor affecting the mechanical properties of frozen soil，which will lead to more significant strain softening and dilatancy characteristics of frozen soil during the shear process. To accurately describe the mechanical characteristics of frozen soil，this paper introduces the concept of phase transition state concept to describe the dilatancy of frozen soil，solving the problem of difficult to unify the softening and dilatancy characteristic point displacement laws using only critical state theory. Furthermore，by combining the fractional order differentiation，the non-associated plastic flow law of stress-strain of frozen soil is described，avoiding the additional construction of plastic potential surfaces. The mechanical response of frozen soil is described by introducing the yield function considering the influence of temperature. Based on the hardening rule considering phase transformation and the yield condition considering temperature effect，an improved elasto-plastic constitutive model is proposed to evaluate the mechanical properties of frozen sand. The model unifies the temperature effect，phase transition state，critical state and non-associated plastic flow in the theoretical framework of elasto-plastic mechanics，and all model parameters have clear physical meaning. Finally，by simulating the stress-strain behavior of frozen sand，and comparing with the experimental data，the results show that the constitutive model can effectively capture the phase transition and strain softening law of frozen sand at different temperatures and confining pressures.

To investigate the compressive strength characteristics of fiber-reinforced loess and develop a corresponding strength estimation model，unconfined compressive strength tests were conducted to analyze the effects of varying fiber content，fiber length，fiber fineness，and moisture content on the compressive strength of reinforced loess. Combined with scanning electron microscopy(SEM) tests，the reinforcement mechanism and macro-mechanical properties of the fiber-reinforced soil were analyzed from a microscopic perspective. The test results indicate that the compressive strength of fiber-reinforced loess increases with higher fiber content，greater fiber length，and reduced fiber fineness；within the studied fiber length range of 10 to 40 mm，fiber reinforcement was effective. When fiber content is below a critical level，increasing fiber length and reducing fiber fineness further enhance soil reinforcement. Based on the test data，a reinforcing parameter Ir was developed to quantitatively evaluate the reinforcement effect，and a strength estimation model for fiber-reinforced loess was established. This model can accurately estimate the compressive strength of fiber-reinforced loess. Comparison with experimental results verifies that the model has high prediction accuracy and practical application value.

The composite foundation with multiple drains can be combined with different drainage bodies to accelerate the consolidation of foundation，and the multiple drains will clog inevitably during consolidation. However，there is no analytical consolidation theory of composite foundation with multiple drains that can consider the clogging effect. Based on this，the mathematical model with an exponentially decaying well resistance over time and four layout forms are introduced to establish the consolidation model of composite foundation with multiple drains combining stone columns with prefabricated vertical drains(PVDs). Considering the radial two-way seepage to stone columns and PVDs in the foundation soil and smear effect，based on the assumption of equal strain，the consolidation analytical solutions of composite foundation with multiple drains considering stone columns clogging and PVDs clogging are given respectively，using mathematical and physical methods such as the method of separated variables and the orthogonality of Fourier functions. The rationality and practicability of the solutions are verified by theoretical degradation and case comparison. The consolidation behavior is analyzed，and the following conclusions manifest：Considering the clogging effect will slow down the consolidation rate of the composite foundation，especially the clogging effect of the stone columns. If the final drainage capacity is reduced or the exponential attenuation factor of permeability coefficient is increased，the consolidation rate will slow down. The final drainage capacity has a great influence on the later stage of consolidation，with minimal influence on the early stages，while the influence of exponential attenuation factor on the whole stage of consolidation is relatively balanced. When the initial permeability coefficient of stone columns is low，the clogging effect exhibits a greater influence on consolidation，whereas when the initial permeability coefficient of PVDs is large，the clogging effect has a greater impact. Considering the clogging effect，the dissipation of soil pore pressure slows，and the influence of stone columns clogging on soil pore pressure is stronger than that of PVDs.