The simplicity form and clear physical meaning of parameters are possessed by the cohesion weakening and friction strengthening(CWFS) model. However，the accuracy and applicability of the traditional CWFS model are not satisfactory. In this study，triaxial graded cyclic loading and unloading damage control tests of granite(tight crystalline hard rock) and siltstone(porous weak cemented rock) were performed. The traditional CWFS model was improved in three aspects：cohesion and friction angle equation，dilation angle equation，lateral to axial strain ratio equation. Firstly，the quantitative characterization points of the model stress level were optimized and the plastic parameters were unified to accurately obtain the quantitative results of the model parameters. Secondly，in response to the characteristic results of weakening cohesion and strengthening and then weakening friction，the strengthening and weakening control coefficients were introduced to construct nonlinear cohesion and friction angle equations. Finally，nonlinear dilation angle equations were established to account for the nonlinear dilation during the yield stage，and nonlinear lateral to axial strain ratio equations were developed to capture the significant nonlinear lateral deformation during the elastic stage before yield. Applicability verification shows that the improved CWFS model can be accurately applied to granite and siltstone，as well as Beishan granite and sandstone. The improved CWFS model reasonably describes the evolution phenomena of strain softening，dilatancy，elastic strain and plastic strain during the complete stress-strain process of rocks. Importantly，the improved CWFS model has significantly improved accuracy and applicability compared to traditional CWFS models.

To reveal the influence mechanism of hydraulic shear on the permeability characteristics of hot dry rock under three-dimensional stress. The self-made high temperature true triaxial hydraulic shear test device and permeability test system were used. The granite in Daqing area of Songliao Basin is taken as the research object. Prefabricated fractured granite is treated at high temperature. The geological characteristics of different thermal reservoirs are simulated by changing the three-dimensional stress，water injection pressure，flow rate and time. The roughness coefficient of fracture surface is used to describe the variation characteristics of fracture before and after hydraulic shear. The influence of water injection parameters on fracture permeability after hydraulic shear of granite under different three-dimensional stresses was tested. The results show that：(1) the mass loss rate and porosity of granite increase with the increase of temperature，and the tensile-compressive strength decreases with the increase of temperature. (2) The fracture permeability decreases with the increase of volume stress under different pore pressure and temperature. The fracture permeability increases from 10－17 m2 to 10－16 m2 at 150 ℃–350 ℃. (3) The relationship between the maximum water injection pressure and the volumetric stress obeys the quadratic polynomial distribution. The maximum water injection pressure is 4.78 MPa when the volumetric stress is 18.5 MPa. (4) After hydraulic shearing，the fracture permeability of granite increases with the increase of water injection flow rate，and increases first and then stabilizes or decreases with the increase of water injection time. (5) The roughness coefficient of fracture surface decreases after hydraulic shear with different volume stress，water injection flow rate and time，which indicates that the seepage capacity of granite fracture surface is improved after hydraulic shear.

The stepped failure path of the rock slope consists of joints and fractured rock bridges. To study the failure mechanism by geomechanical model testing，bottom friction tests were conducted. The fracture mechanism of the rock bridge was emphatically analyzed. Three slope models were examined including one with a stepped arrangement of low-inclination joints，one with a stepped arrangement of low-inclination and high-inclination joints，and one with a parallel arrangement of low-inclination joints. The stepped failure mechanism was revealed by analyzing the fracture evolution process of rock bridges and the displacement field characteristics. The fracture modes of the rock bridge were determined through the mechanical mechanism analysis. These modes were verified through in-situ rock mass failure，model test results，and PFC2D numerical analysis. The slope failure occurs in two modes：the multistage locking tensile type and the interlayer block tensile type. Local rock bridges undergo tensile fracture under compressive shear stress or tensile shear stress. The displacement-increasing area of the former failure mode appears in strips and expands towards the slope surface. The displacement-increasing area of the latter failure mode is flake-like and connected. The process of rock bridge tensile fracture and block splitting is shown in these two failure models. Compared to planar rockslides，different fracture paths，fracture properties，and extension directions in the rock bridge are exhibited in the stepped failure. The research results provide theoretical support for the stability analysis of rock slopes with stepped failure.

In the horizontal sublevel top coal caving of steeply inclined extra-thick coal seam groups，the segmented mining is prone to induce roof collapses with time delayed characteristics. The understanding of the collapse height and characteristics of the overlying strata is crucial for monitoring roof disasters，crack development，and surface collapses. To address this，a combination of similar simulation experiments，machine learning，and grey theory methods were utilized to explore the collapse characteristics of overlying strata and the laws governing surface collapses. Data indicators associated with collapse height were obtained，and the dimensionality of input data was reduced using Principal Component Analysis(PCA). A collapse height prediction model(PCA-GA-LSSVR) based on the least squares support vector regression(LSSVR) network was established through the optimization of training using genetic algorithms(GA) and leave-one-out cross-validation. Various combinations of mining parameters and monitoring indicators were employed for training and testing，facilitating the evaluation and selection of the optimal prediction model. The selected model was further validated through engineering inspections. Results indicate that with increasing mining depth in the experimental mining of steeply inclined extra-thick coal seam groups，continuous collapse of rock strata generates and expands V-shaped subsidence. There are high correlations between mining depth，single caving height，model section height，and collapse height. Additionally，the collapse of the roof in experimental mining exhibits a time delayed characteristic. Dimensionality reduction of data effectively addresses the issue of high dimensionality and information overlap，enhancing the accuracy of prediction models. The PCA-GA-LSSVR model demonstrates superior accuracy in predicting test data，with lower error rates，average absolute errors，and average absolute percentage errors(5.146，4.819，and 0.087 respectively) compared to other models. The established grey time delayed OBGM model exhibits good fitting and predictive capabilities for roof collapse height in the #45 coal seam scenario. During engineering inspection，the maximum error fluctuation range of the established collapse height prediction model is within 3.36 m. In scenarios with limited sample data availability，gradually increasing learning samples reduces model prediction errors. This research provides valuable insights for studying collapse height in steeply inclined extra-thick coal seam groups during horizontal sublevel top coal caving mining.

Efficient mapping of rainfall-induced landslide susceptibility is crucial to the success of regional-scale landslide prediction and the early warning of geological hazards. In this paper，a physically-based probabilistic modelling tool，herein named the probabilistic rainfall-induced landslide using simplified transient infiltration model (PRL-STIM)，was proposed to deal with the fast mapping of landslide susceptibility at regional scales. This modelling tool integrates the infinite slope model with considerations of rainfall-induced pore water pressure(PWP) and surface runoff. The first-order reliability method(FORM) for efficiently performing probabilistic computations is employed to simulate the geotechnical and geological uncertainties. The proposed PRL-STIM v1.0 tool is developed based on the Python programming language integrating with the Geographic Information System(GIS) framework. Validation of the proposed model is illustrated by an engineering case study of the rainfall-induced regional shallow landslides that occurred in July 2013 in Niangniangba，Gansu Province，China. The analysis results demonstrate that the adoption of the 50% failure probability threshold can effectively characterize the region?s landslide hazard susceptibility distribution. High-risk landslide areas can be well identified, with deterministic and probabilistic prediction accuracies reaching 79% and 81%，respectively，when a 20m buffer zone is used. Furthermore, it is shown that the probabilistic prediction accuracy of the rainfall-induced landslide susceptibility by PRL-STIM achieves 75%，surpassing the 72% prediction accuracy of the TRIGRS model based on the Richards equation, and it is worth noting that non-normal distributions of random geotechnical parameters may exert a significant influence on the predicted landslide susceptibility.

To reveal the influence mechanism of coal-rock interface roughness on ultra-low friction rock burst under dynamic load disturbance，a self-designed ultra-low friction test device for coal-rock interface is used. The coal rock block of 1 082 m mining depth in Shenyang Hongyang Three Mine is used as the research object. The coal block is used as the working block，different roughness characteristics of coal-rock interface is simulated by changing the surface roughness of coal blocks. The horizontal displacement of the working block is used to characterize the ultra-low friction effect strength during the impact process. The influence of different roughnesses of coal-rock interface on ultra-low friction effect of coal-rock block under stress wave disturbance is tested. The results show that：(1) under different coal-rock interface roughnesses，the ultra-low friction effect has a frequency sensitivity value. When the disturbance frequency is 2 Hz，the coal-rock interface is more prone to ultra-low friction effects. (2) The disturbance amplitude is linearly positively correlated with the ultra-low friction effect strength. The smaller the coal-rock interface roughness，the greater the horizontal displacement and horizontal acceleration of the working block，and the greater the ultra-low friction effect strength. The greater the coal-rock interface roughness，the greater the increase of the horizontal displacement and acceleration of the working block，and the greater the influence of the disturbance amplitude on the ultra-low friction effect. (3) The roughness only affects the ultra-low friction effect within a certain range，and JRC = 3.81 is the critical value affecting the ultra-low friction effect. (4) The greater the horizontal impact force，the greater the horizontal displacement and horizontal acceleration of the working block，and the greater the ultra-low friction effect strength.

For the study of shear cracking in red sandstone and the mechanical and seepage behaviours before and after shear failure，standard cylindrical specimens underwent shear tests in a triaxial stress environment. The tests utilized the Rock Top multi-field coupling test system and a self-made shear diversion component. Different confining pressures and permeability pressure differentials were applied to investigate red sandstone's triaxial shear-seepage behaviour. Additionally，discrete element particle methods were employed to study the shear cracking process in models of different sizes and shapes. The research findings indicate: The pre-peak shear stress exhibits a linear increase with shear deformation. Post-peak shear and circumferential deformation rates accelerate，with 1 to 3 stress drops observed. Higher confining pressure leads to a steeper pre-peak deformation curve，increased final shear deformation，and a smoother circumferential deformation-shear displacement curve，with concentrated peak circumferential deformation. The shear-seepage process is categorized into stages of seepage interruption，seepage state transition，and increasing seepage velocity. Characteristic values of shear stress demonstrate a linear relationship with confining pressure. Rock samples display macroscopic single shear plane failure. Increased confining pressure results in more severe fragmentation of the fracture edge and larger shear cracks at the ends. Seepage rates before and after shear failure follow a power-law decrease with confining pressure. Seepage rates exhibit a strong linear relationship with permeability pressure differential. The slope of the flow rate-permeability pressure differential fitting curve decreases with increasing confining pressure. Post-unloading seepage rate is one order of magnitude lower than the pre-unloading rate，with the difference gradually decreasing with increasing confining pressure. Simulation results align with experiments，revealing oblique shear cracks under both confining and normal constraints. The angle and density of oblique shear cracks are influenced by the length-to-diameter ratio and volume，with the least impact at a three-dimensional size ratio of 1. Under equal size ratios，triaxial shear strength is weaker than direct shear strength. The results of this triaxial shear test demonstrate reliability in both methods and outcomes.

To study the slurry seepage-rock mass deformation coupling effect during grouting in fractured rock mass，a visual fracture grouting simulation test system with variable fracture aperture was developed independently. This system included slurry supply equipment，grouting simulation equipment and data monitoring equipment. It had good sealing performance and achieved fracture aperture change under grouting pressure，and can simulate the slurry flow process under the influence of multi-source factors such as grouting flowrate，water-cement ratio，lateral pressure and so on. It was also can be used to study the mechanism of gas seepage-rock mass deformation coupling effect. A grouting simulation experiment was conducted using the system to investigate the slurry seepage-rock mass deformation coupling effect. The results showed that：the increase in fracture aperture weakened the expansion effect of grouting pressure on fracture plate，reducing energy loss during slurry flow，the decrease in water-cement ratio significantly enhanced the slurry seepage-rock mass deformation coupling effect，and the increase in lateral pressure weakened the degree of slurry seepage-rock mass deformation coupling effect. The results of grey correlation analysis showed that the order of factors affecting the sensitivity of slurry seepage-rock deformation coupling effect was grouting flow＞lateral pressure＞slurry water-cement ratio＞fracture aperture. The development of this test system provides a new method for studying fluid-structure interaction and engineering applications of rock mass deformation induced by grouting in fractured aquifers.

Rock strength criterion plays an important role in the multi-scale stability analysis for rock engineering in the theoretical and practical sense. The research progress on this topic depends on the experimental investigations of rock strengths subjected to different tensile-compressive stress states to a large extent. Despite the large strength differences under the tensile and compressive stresses，theoretical and experimental research efforts on rock strengths subjected to different stress states tremendously focused on triaxial compressive stress states. This paper provides a comprehensive review with respect to the following. The development history and research achievements of rock strength criterion were overviewed since the related work for metal and soil. The state of the art of the rock strength tests were summarized under different tensile-compressive stress states compatible with the development of rock strength criterion. The stress states covered by the current rock strength tests were further analyzed. The three characteristic tensile strengths defined by nine different rock strength criteria were also compared. Finally，the problems remaining to be solved were discussed and summarized on the theoretical and experimental researches of the rock strengths under different tensile-compressive stress states followed by the prospect of future research.

To investigate the effects of stress and water content on the creep characteristics of fractured granite，a series of creep tests were carried out using the high temperature triaxial rheological test system for rock. The experiment mainly consists of the multi-stress creep tests under different confining pressures，and uniaxial creep tests under different water content. The test samples were intact granite and granite with different inclinational fractures，which were taken from Beishan pre-selected area of Gansu Province for geological disposal of high-level radioactive waste in China. The experimental results indicates that, the lateral deformation of fractured granite presents more significant creep characteristics，and the lateral steady creep strain rate is slightly higher than axial steady creep strain rate. With the increase of the stress level，the axial strain presents a linear growth relationship，while the lateral strain and the axial and lateral steady creep strain rates all show an exponential function growth relationship. Under the condition of the same confining pressure and the same deviatoric stress，the larger the fracture inclination angle is，the larger the axial and lateral strains are，and the higher the axial and lateral steady creep rates are. Under saturated state，the steady creep rate of granite is significantly increased，and the rock mass is more prone to deformation under the same stress，resulting in the failure of granite under lower creep load or shorter creep duration. When the inclination angle θ is 45° or 60°，the failure time of saturated sample is only 1.05‰ or 0.84‰ of the failure time of dry sample. The failure modes of fractured granite can be divided into three types：causing new fractures which cut across the pre-made fracture(θ = 30°)，slipping of the pre-made fracture(θ = 60°) and the compound failure of the first two forms(θ = 45°). The confining pressure of 10 MPa，and the dry or saturated state have no significant influence on the creep failure form of fractured granite.

Water-rock interaction is an essential factor in the weakening of coal rock masses. Long-term immersion as a type of water-rock interaction is widespread in mining engineering and shaft engineering. The progressive damage characterization of coal samples during long-term immersion is obtained by a uniaxial compression experiment. The relationship between mechanical parameters and saturation and immersion time is established，and the macroscopic fracture extension characteristic of coal samples are analyzed. The results show that the soaking process of coal samples can be divided into two stages：unsaturated immersion and long-term(saturated) immersion. The peak stress in coal samples decreases by 46.3% and 34.5% in the unsaturated stage and long-term immersion stage，respectively，which conforms to the exponentially decreasing trend. During long-term immersion，the number of macroscopic cracks produced in coal samples after loading gradually decreases from 6–8 in a dry to 2–3 in a 360 d soaked. The damage mode changes from combined tensile and shear damage for unsaturated coal samples to single shear damage for 360 d soaked coal samples. Based on initial compression characteristics and critical damage strength characteristics in a coal sample，a damage constitutive model describing the whole deformation process of a coal sample under long-term immersion is proposed using continuous damage mechanics and statistical damage theory. According to this model，it can be found that the initial damage increases gradually from 0 in a dry sample to 0.773 for a soaked 360 d sample with the increase of soaking time. In addition，the error and fit between model curves and the experimental data are evaluated by introducing the root mean square error(RMSE) and the coefficient of determination(R2). The theoretical curves of the improved model are found to be the highest matching with the experimental data. The maximum value of RMSE and the minimum value of R2 for the improved model are 1.81 and 0.76，respectively，which are better than the models proposed in existing papers.

To investigate the evolution law of principal stress rotation path caused by tunnel excavation and the resulting deformation in rock masses，a numerical model has been developed to explore the evolution of principal stress rotation paths and resultant rock mass deformations due to tunnel excavation，with a focus on weakly cemented soft rock tunnels. This model examines the changes in magnitude and direction of principal stresses surrounding the tunnel, induced by the excavation process. Parameters for loading states in excavation-disturbed rotational stress path experiments are determined through this investigation. Nine kinds of excavation disturbance stress rotation paths tests were conduct by using hollow torsional shear tests on weakly cemented soft rock. The spatial curve characteristics of shear stress-strain excavation distance law and non-coaxial angle variation in the stress(?z－?θ)-2τzθ plane was researched. Significant changes were observed in the magnitude and direction of principal stresses in the surrounding rock of the tunnel，including its floor，roof，and sidewalls，as excavation progressed. Particularly within the 2D range of the tunnel，strong stress rotation and abrupt stress magnitude changes occurred. Shear stress-strain curves at monitoring points in the surrounding rock，influenced by excavation disturbance stress，were observed to develop in patterns resembling V，Z or N shapes. Excavation disturbance in weakly cemented soft rock induced principal stress rotation，resulting in a non-coaxial angle between strain increment and stress directions. The non-coaxial angles peaked at 52.8°，－22.3° and 30.6° for the tunnel floor，roof and sidewalls，respectively，influenced by stress path variations. This research results light on the non-coaxial plastic deformation in rock masses，a result of principal stress rotation from tunnel excavation. The design level and disaster prevention capability of underground engineering are enhanced.

In order to investigate the impact of variations in gas injection and extraction rates on the fatigue mechanical properties and fine-scale mechanism of the surrounding rock in compressed air energy storage salt caverns(CAES). Four groups of variable cyclic rate fatigue tests on salt rock were conducted using acoustic emission monitoring(loading and unloading rates are consistent)，with varying upper limit stress and stress routes. The correlations of residual strain，cyclic acoustic emission cumulative ring counts(AE counts) and peak frequency with cyclic rate were analyzed. The results showed that：(1) Cyclic residual strain and cumulative AE counts have an obvious rate correlation(obvious power law relationship with the cyclic rate， ， )，and a positive correlation has been observed between stress level and stress factor(coefficient terms of power functions m，m'). The rate dependence of creep plasticity is positively correlated with stress level(power function exponential term b)，while the rate dependence of cyclic cumulative AE counts is opposite(power function exponential term b? decreases). The rate correlation parameters(b，b?) are all able to predict the onset of the accelerated damage stage differently in advance of the cyclic residual strain. (2) Accelerated rise of cyclic cumulative AE counts occurs at the transition point between phases I and II of the cyclic residual strain development trend. This corresponds to 2.382%，3.464% and 4.297% cumulative residual strains in tests of 19，23，27 MPa upper limit stress, respectively. (3) The proportion of low-frequency signals reduces with increasing cyclic rate，while high-frequency signals rise with lowering cyclic rate. Mid-frequency signals only increase with increasing stress level. (4) Fast and slow cycling operate as hardening and softening，respectively，with the softening effect resulting in lower fracture initiation stresses and stronger plastic deformability(and vice versa for hardening) in the latter cycle. This mechanism can be linked to increased small-scale crack sprouting and expansion during slow cycling，as well as the full release of internal stress during slow unloading. This work provides valuable insights into the control of gas injection and extraction frequency in CAES salt caverns，as well as the analysis of damage progression.

Because the generalized nonlinear Hoek-Brown(H-B) strength criterion can exhibit the complex shear failure behavior of rock mass，it is widely used in the stability analysis of rock slope. However，the traditional limit equilibrium(LE) methods based on the slice division and assumption of inter-slice forces is not easy to directly introduce the nonlinear strength criterion，which makes the LE methods have some shortcomings in analyzing the stability of rock slopes. In addition，the local factor of safety(FOS) of slip surface is usually assumed as a single variable independent of its position in the analysis of slope stability. In fact，before the slope reaches the critical failure state，the distribution of the local FOS of the slip surface is different. Here，the Taylor series expansion is applied to construct the function of the normal stress on the slip surface，and the function of the shear stress on the slip surface under the linear distribution characteristics of the reciprocal of the local FOS of the slip surface is established to consider the difference of the local FOS of the slip surface. Thereby，the generalized nonlinear H-B strength criterion is integrated with the calculation mode of the stresses on the slip surface and the difference distribution characteristics of the local FOS of slip surface. Thereafter，the stress constraint conditions at both ends of the slip surface is introduced，and then the LE solution of rock slope stability is derived according to the mechanical equilibrium conditions of the sliding body. Through the comparison and analysis of examples，it can be verified that the proposed method can not only accurately evaluate the stability of rock slope under the generalized nonlinear H-B strength criterion，but also reasonably simulate the tension-shear stress zone of the slip surface near the slope top，objectively describe the compression-shear phenomenon of slip surface near slope toe under the stress concentration effect，and effectively distinguish the difference distribution characteristics of the local FOS of the slip surface. Furthermore，in order to facilitate the guidance of design and reinforcement of engineering rock slope，the equivalent curves of the minimum FOS of homogeneous rock slope and the partition diagrams of the difference distribution characteristics of the local FOS of the critical slip surface are drawn.

Landslide hazard assessment is an important step in disaster prevention and mitigation in mountainous areas. However，most of the previous studies focused on the risk analysis at the current stage，and there are very few effective methods for landslide risk prediction on a regional scale. Aiming at this problem，this study proposed a new framework by considering physical model and effective rainfall infiltration to predict the landslide hazard under the condition of a given rainfall return period in the future for the first time. Taking the Yarlung Zangbo River catchment in Shannan City of the Tibetan Plateau as an example，the average effective infiltration rate and the previous effective rainfall Pa from 1998 to 2017 were calculated by using the Easy_Balance software. The 95% quantile of the maximum rainfall for three consecutive days in each month in summer was used as the critical rainfall Pe，and the calibration of soil parameters and land use parameters was completed based on the physical model FSLAM. The extreme values of Pa and Pe at different return periods were obtained using the Gumbel method，and the response of probability of failure(PoF) of each grid to Pa and Pe was calculated. Then the study area was reclassified according to the sensitivity of the grid response，and the hazard assessment matrix was used to predict the landslide hazard in the whole area. The calculation results showed that when the rainfall return period reached 50 years and 100 years，92.1% of the landslide points fell into the very high and high hazard areas. Compared with the traditional TRIGRS model which didn?t consider the effect extent of rainfall on grid PoF，the AUC accuracy of the proposed method increased by 7.6%–9.0%. The current method can effectively predict the occurrence of landslides under extreme rainfall conditions in the future，and the influence of rainfall infiltration and extreme rainfall are considered at the same time，which can further improve the rationality of regional landslide hazard prediction.

To explore the shear characteristic of energy-absorbing-bolt anchored rock joints and corresponding bolt performance under constant normal stiffness(CNS) boundary conditions(the condition is associated with deep buried rock mass engineering). We conducted direct shear tests on energy-absorbing bolted rock-like joints. In particular，the tests were performed under diverse joint roughness coefficient(JRC) and anchorage depth(h) to investigate their influence on the deformation characteristics of anchor bolt and mechanical properties of rock joints，such as shear stress(τ)，normal displacement(?n)，normal stress(?n) and failure characteristics of joint surfaces. The test results revealed that energy-absorbing bolt effectively enhance the yield strength and shear strength of deep rock joints. The improvement degree progressively increases with a higher JRC value，in which the shear stress first undergoes the elastic period，followed by the stress hardening period. Besides，the shear-induced damage area on the joint surface grows with increased JRC，and it grows by 20.88%–109.21% under energy-absorbing bolt anchored conditions. Moreover，an increase in anchorage depth initially leads to an increase in shear stress，normal displacement，normal stress，and the shear-induced damage area of the joint surface，followed by a subsequent decrease. The optimal values for these properties were observed at an anchorage depth of 80 mm，allowing for the full utilization of the anchorage effect during the plastic deformation stage of the anchor bolt. These findings provide significant theoretical support for reducing cost and improving efficiency in the support of deep rock joints.

The clogging effect caused by installing stone columns is depth-dependent. The movement of soil particles into the stone column caused by consolidation further contributes to the clogging effect of the column，which leads to the column permeability decaying temporally. Considering the temporal and spatial variation of the well resistance of stone columns as well as the nonlinear compressibility and the permeability of soils around the stone column，a nonlinear consolidation model of stone column composite foundation under multi-stage loading is established. The solution of the model is solved by the finite difference method，whose reliability is verified by comparing with the existing solutions under specific conditions. Extensive computations are analyzed to investigate the effect of variable well resistance parameters on the consolidation of stone column composite foundation. The results indicate that：the consolidation rate of the stone column composite foundation decreases as the temporally or spatially dependent well resistance parameter increases. Moreover，the consolidation rate accelerates as the final drainage capacity of the stone column increases. Among these factors，the effect of the temporal parameter on the consolidation rate of the composite foundation is more significant. Finally，the consolidation model of the stone column composite foundation considering variable well resistance is applied to the settlement calculation for an actual project in Malaysia. Compared to the existing solution，the theoretical result of the proposed model shows a better agreement with field measurement，indicating that the proposed consolidation model possesses a certain engineering practicability.

Interlayer protection significantly influences the anti-seepage strength of deep overburden soil，and it should be considered in the evaluation of seepage stability，however this influence can?t be quantified now. Aiming at a typical strata structure of “②–2，③–1，④” in Luding hydropower station，a list of single-layered and three-layered seepage tests were performed to investigate the influence of interlayer protection. The results indicate that there are two different interlayer protection mechanisms between base soil and overlying strata. When the retention ratio meets the needs of filter and drainage，the overlying strata is the same as the artificially designed filter，and a continuous hydraulic transition is formed to give full play to the anti-seepage ability of the base soil. When the retention ratio only meets the need of filter，the overlying strata mainly undertake the pressure to protect the base soil. Based on the experimental results，the influence of interlayer protection on the allowable gradient was quantified，and then a method determining the allowable gradient was established. Under the protection of strata of ③–1 and ④，the allowable gradient of stratum ②–2 can increase to two times as the initial allowable gradient；Under the protection of stratum of ④，the allowable gradient of stratum ③–1 can increase to 2.3 times as the initial value. The results provide important supports for the solution of abnormal leakage and safety evaluation of Luding hydropower station，and they will provide reference for other similar projects.