The yield surface of the double-shear unified strength theory considering the influence of the intermediate principal stress is not smooth and hence，is not conducive to numerical analysis. In order to solve the problem of the singularity of the Mohr-Coulomb yield surface，some scholars derived a series of D-P yield criteria that have a special positional relationship with the Mohr-Coulomb yield surface. In order to solve the corner singularity problem of the double-shear unified strength theory，this paper refers to the derivation process of the traditional D-P series yield criterion and derives the D-P series yield criterion considering the influence coefficient  of the intermediate principal stress. According to the double-shear unified strength theory，there are 12 limit lines on the  plane，which intersect in pairs on the  plane to form a dodecagon that is symmetric about the three principal stress axes. There are six circles that have a special relationship with these limit lines，and these circles are cones in space that have a special positional relationship with the yield surface of the double-shear unified strength theory. According to theoretical analysis and mathematical derivation，the yield function expressions of the six cone surfaces are obtained，namely DDP1，DDP2，DDP3，DDP4，DDP5 and DDP6. Using the classic strength reduction method，the stability coefficients of a homogeneous slope and a non-homogeneous slope under the D-P yield criterion considering b are calculated separately. The results show that the D-P yield criterion considering b can be applied to slope stability analysis and compared with the traditional D-P series yield，can give full play to the strength potential of the material.

In this study，the effects of the normal stiffness(0–7 GPa/m) and the number of cyclic shearing(1–10) on the shear stress，normal deformation，normal stress，shear stress path，surface resistance index，acoustic emission responses and surface wear characteristics of joint surfaces were revealed through conducting cyclic shear tests on 3D rough joint surfaces under constant normal stiffness(CNS) boundary conditions. The experimental results indicate that the shear stress-shear displacement path exhibits typical normal stiffness-dependent characteristics. When the normal stiffness is small，the shear stress declines gradually after the initial peak value，showing a stress softening behavior. With increasing the normal stiffness，the increase extent of the normal displacement declines gradually，while the increase extents of both shear-induced shear stress and normal stress present a gradual increase，characterized by a stress hardening behavior. When the number of cyclic shearing is 1，with an increase of the normal stiffness from 3 GPa/m to 7 GPa/m，the apparent cohesion and apparent internal friction angle of the joint surfaces increase by 22.40% and 26.84%，respectively，while the surface resistance index remains generally stable. With continuous increasing the number of cyclic shearing，the initial peak shear stress declines gradually，while the decrease extent becomes slow down and gradually stabilizes. Especially，the decrease extent of the initial peak shear stress experiences the largest reduction(24.93%–60.91%) with increasing the number of cyclic shearing from 1 to 2. During the cyclic shear process，due to cutting and wearing of the asperities，the joint surfaces tend to be smooth，resulting in gradual reduction of the increase extents of both the dilatancy deformation and the normal stress. When the shear displacement is larger，compared with the normal stress，the attenuation of the increase extent of the shear stress is more sensitive and the surface resistance index increases gradually. The cumulative acoustic emission energy declines with the number of cyclic shearing. However，while the normal stiffness increases from 0.5 GPa/m to 7 GPa/m，the cumulative acoustic emission energy in the stable stage shows an increase by a factor of 2.298，and the ratio of the shear area increases by 72.02%–97.11%.

To study the influence of true triaxial cyclic disturbance stresses on the mechanical characteristics of coal in the process of mining and excavation，the coal mechanical experiment under the intermediate principal stress() of tiered cycle is carried out based on GCTS true triaxial mechanical experiment system，and the influence of  on deformation，energy consumption and damage characteristics of coal is analyzed. The results show that the effect of tiered cyclic  on  and  is greater than that on . With increasing ，both  and  decrease significantly. Cyclic loading or unloading of  can cause instability and failure of coal. When σ3 is small，coal tends to be destroyed in the process of  unloading to close to ，and when  is large，coal tends to be destroyed in the process of  loading close to . However，the approximation rate of  corresponding to failure is similar，all around 70%. The loading or unloading of  has equivalent effect on the residual deformation and even failure of coal. With increasing the amplitude of tiered cyclic ，the total dissipation energy of coal increases exponentially，and the damage variable of coal presents an obvious S-type change trend of deceleration, acceleration and re-deceleration. The threshold value of the average safety damage variable of coal and rock is 0.9 in the process of tiered cyclic.

To study the influence of meso-structural heterogeneity on macroscopic mechanical properties and crack propagation behaviors of fractured rocks，based on laboratory test and mineral composition analysis，the grain based models(GBM) of two types of granites were established using a discrete element numerical code PFC. The reliability and precision of the established GBM were verified against unconfined compression testing results of single flaw rock samples. Unconfined and biaxial compression numerical tests were carried out on double-flaw rock samples，and the stress-strain curve，the failure mode，and the development and evolution of microcracks were analyzed. The results show that intra-grain and inter-grain tensile cracks are primarily cracks and that the development of the cracks can be divided into initial stage，stably developing stage，rapidly developing stage and post peak stage during an entirely loading process. Compared with the unconfined compression，the morphology of crack growth under 10 MPa biaxial compression has two obvious characteristics such as center symmetry and edge extension. At the peak stress，the number of various types of cracks increases with increasing the confining pressure. In contrast，from the perspective of strain-crack number， the confining pressure has different degrees of inhibition effects on the early development of cracks except for inter-grain shear cracks. A rock with a greater heterogeneity coefficient is more prone to stress concentration in the loading process，and the failure mode can more easily transform from tensile failure to shear failure under biaxial compressions.

The surface roughness and matching state of joints have an important influence on the dynamic mechanical properties of rock masses. This paper used cement mortar materials to make fully-matched and mismatched jointed samples with different roughness，and carried out impact tests on the samples by using the split Hopkinson pressure bar system(SHPB). At the same time，a high-speed camera and the digital image correlation method were used to explore the dynamic failure process of rock masses. The results show that，under a given impact load，the jointed roughness has little effect on the dynamic compressive strength and the average modulus of the fully-matched jointed rock-like specimens but has a greater influence on the mismatched jointed rock-like specimens. Mismatched joints exhibit nonlinear closure characteristics under stress wave，which is not only affected by the joint roughness but also related to joint specific morphological characteristics. With increasing the joint roughness，the ability of the stress wave to through the mismatched jointed rock mass increases，while the fully-matched jointed rock mass showed little effect. The failure of jointed rock mass is related to the irregular bulge of the joint surface. Specifically，The interaction between the stress waves and the bulge on the joint walls leads to the stress concentration in the vicinity of the bulge. The dramatical tensile stress initiates cracks，then these cracks develop，and splitting failure occurred.

Failure modes and landslide mechanisms of rock slopes with weak layers are of great significance to the study of the stability of open-pit mine slopes. Based on limit equilibrium theory，a regional sliding mechanical model of rock slopes with weak layers is established. The slope above the weak layer is divided into stable region，understable region and unstable region. Mechanical equilibrium equations of the three regions and the stability difference function of the slope are derived. Influence factors of the slope regional stability with a weak layer are studied，and it is revealed that the understable region is the key area of large landslides. The base friction model test of sliding failure process is carried out，and theoretical results are verified. The study shows that regional sliding failure is a typical failure mode of rock slopes with a weak layer，and that the dip angle of the weak layer is the decisive factor affecting the distribution of the stable，understable and unstable regions and that the back end of the understable region of the slope is more sensitive to the dip angle. The slope with a smaller dip angle is more evenly distributed in the three regions，and the slope with a larger dip angle is less stable at the corner. Finally，taking the north landslide in Hejia mining area of Gongchangling open-pit iron mine as the background，the accuracy of the regional sliding failure mode is verified. The research results can provide reference for the research and treatment of similar rock slopes with weak layers.

It is of great significance to explore the influences of the spatial resolution and the proportion of model training and testing dataset on the uncertainties of landslide susceptibility prediction(LSP). Taking the landslides in Ningdu County of Jiangxi Province as examples，the frequency ratios of various environmental factors under different spatial resolutions(15，30，60，90 and 120 m) are firstly calculated. Then，the landslide and non-landslide samples are divided into different model training and testing datasets with the proportions of 9/1，8/2，7/3，6/4 and 5/5，and the model input and output variables under 25 combined conditions are obtained. Furthermore，these input and output variables are imported into the Support Vector Machine(SVM) and Random Forest(RF) models to carry out LSP. Finally，the uncertainties of LSP modeling under the 25 combined conditions are discussed using the accuracy assessment as well as the distribution characteristics of landslide susceptibility indexes. The results show that the landslide susceptibility accuracy predicted by the RF model under the spatial resolution of 15 m and training and testing dataset proportion of 9∶1 is the highest，and that the more important environmental factors under each condition are elevation，slope and topographic relief，etc. With decreasing the spatial resolution and/or the proportion of training and testing dataset，the LSP accuracies of both SVM and RF models decrease gradually，and the mean values of landslide susceptibility indexes increase with a decrease of the corresponding standard deviation value. For all combined conditions，as the spatial resolutions and the proportions of training and testing dataset decrease，the LSP accuracies decrease gradually while the corresponding uncertainties increase. It is also indicated that the LSP accuracy of the RF model is better than that of the SVM model under various combined conditions，and that the influence of the spatial resolution on the RF model is significantly greater than that of the proportion of training and testing dataset while there is little difference between the effects of the two factors on the SVM model.

The deformation and failure process of deep rock masses is affected by excavation unloading or other disturbing loads. In order to explore the propagation law of spatial micro-cracks in rock masses and the non-linear mechanism of the progressive failure process，a three-dimensional positioning acoustic emission experiment of limestone under pre-static low-frequency unequal amplitude loading and unloading cycles was carried out. The results show that the ratios of the elastic energy and the dissipated energy to the total energy all have corresponding stage characteristics. The change of the dissipated energy is related to the distribution of the prefabricated cracks as well as the location and the expansion speed of the micro-cracks. The changes in the dissipated energy and the number of impacts satisfy the critical power law of limestone catastrophe. The peak strengths of the intact limestone specimen and the prefabricated limestone specimen with different inclination angles decrease with increasing the number of the prefabricated cracks and are affected by the position of the prefabricated cracks. The stress-strain curves of different specimens present different degrees of transition after the peak and appear type I curve and type II curve. It is also shown that the multiplicity and local propagation of three-dimensional cracks in limestone samples are affected by the prefabricated cracks，and that the failure processes of the intact samples and the samples with different prefabricated fractures are dominated by different mechanical mechanisms and show different failure modes macroscopically. On the basis of in-depth study on the rock degradation process，the calculus in the field of mathematics，the principle of thermodynamics in the field of physics and the specific problems in the field of rock mechanics and engineering are combined to reveal the nonlinear mechanism of the energy evolution process. The research results expand the depth of thermodynamic research and facilitate the understanding of the transient state thermodynamic mechanism and the non-linear breakage mechanism of the engineering rock mass degradation process.

In order to solve low accuracy of strong rock burst prediction resulted from outliers in the rock burst data set and the small number of strong rock bursts. Combination of local outlier factor(LOF) and improved synthetic minority oversampling technique(SMOTE) algorithm is proposed. Firstly，305 groups of rock burst cases collected at home and abroad are used to construct the original rock burst data set，and the averaging method is adopted for non-dimension of the data set. Secondly，the data set structure during data preprocessing stage is improved by using LOF algorithm to eliminate outliers in each rock burst level and through improved SMOTE algorithm to increasing the number of strong rock burst samples at the boundary between strong rock burst samples and medium rock burst samples. Finally，the original rock burst data set and the preprocessed rock burst data set are respectively predicted by six commonly used machine learning models to verify the effectiveness of the preprocessing stage. The results show that the pre-processed rock burst data set has an average increase of 18.35% in the prediction accuracy of the overall rock burst and an average increase of 44.55% in the prediction accuracy of strong rock burst, indicating that combination of LOF and improved SMOTE can effectively improve the accuracy of strong rock burst prediction.

Surrounding rock control of deep mining roadways is a key research direction of bolt support in the future. Taking the coal roadways of Hulusu coal mine in three different periods as the engineering background，this paper analyzes the characteristics of roof progressive failure through drilling imaging，and points out the problems of insufficient coordination and low construction efficiency of combined support. To better study these problems，a single thick layer support system is proposed. Discrete element numerical simulation is used to study the evolution law of roadway displacement and surrounding rock fractures supported by bolts of different lengths and to clarify the correlation mechanism between the bolt length and the surrounding rock damage. The study reveals the principle of thick-layer transboundary anchoring in which the damage area near the bolt tip moves upward and gradually weakens with increasing the bolt length. A thick layer anchoring system and cross-boundary long anchoring technology are developed to realize continuous stress transmission in both horizontal and vertical directions by using long bolts on the roof in time. The results were applied in the 21205 working face of Hulusu coal mine. As is proved，the new technology significantly improves the driving speed of coal roadways，and reduces the development depth of roof fractures to within 0.61 m of the shallow anchorage zone. Meanwhile，the technology can also effectively curb the long-term large-scale“V”type rib spalling problem and control the large deformation of surrounding rock of coal roadways with deep composite roof.

The boundary of rock landslides is controlled by the rock mass structure，and the rock mass structure information can be quickly obtained by three-dimensional laser point cloud，which provides basic data for landslide genesis analysis. The 2008 Wenchuan Ms 8.0 earthquake triggered numerous landslides in the carbonate area of Huangdongzi gully，Anzhou district，Mianyang. In this paper，the Zhaobiyan(ZBY) landslide in the area is selected as an example，and the landslide boundary point clouds are obtained by three-dimensional laser scanning. Based on HSV-colored reconstruction technology and DBSCAN clustering algorithm，more than 420 000 structural data(attitude，spacing，persistence and roughness(JRC)) are identified，and the structural characteristics of the rock mass are analyzed. The results show that the ZBY landslide is a wedge failure composed of overall flat north and south boundaries and a steep back wall. Eight groups of rock mass structural planes(J1–J8) are developed on the ZBY landslide boundary，among which, by comparing with the structural planes of Huangdongzigou gully，J5 and J8 are new structural planes related to the initiation of the landslide. The average spacing of 8 groups of structural planes ranges from 0.42 to 5.97 m，showing uneven development. The structural planes with a small spacing (J2，J3，J5，J6) contribute more to the formation of the landslide boundary. The boundaries on the both sides of the landslide are controlled by the structural planes J1 and J2 with a higher persistence of 10.9 m and 9.37 m respectively，while the back wall is controlled by the structural planes of J3，J4，J6，J7 and J8 with a lower persistence ranging from 2.63 m to 7.22 m. The JRC value(2–12) of the north boundary of the landslide is the smallest，and the JRC values(6–16，2–12) of the two sides of the landslide are smaller than that of the back wall(15–35). Based on the characteristic data of the rock mass structure，it is believed that the landslide boundary has significant tectonic origin. The section steps depending on the persistence and spacing of structural joints and the section scratches depending on the sliding direction of the landslide affect the roughness of the failure boundary on both sides of the landslide. The trailing edge boundary is the result of the main damage caused by tensile fracture under the control of multiple structural planes. The research results provide a reference for the study of morphology and structure of similar landslide failure boundary.

The landslides induced by strong earthquakes are wide in distribution and large in quantity，showing obvious regional characteristic. Besides intense ground motion，earthquake-triggered landslides are also affected by environmental conditions such as rainfall，regional hydrogeology and other complex factors. Reasonable index selection strategy can fundamentally improve the accuracy and efficiency of the susceptibility evaluation of seismic landslides. The present research takes 3307 landslides triggered by Mj 6.7 Hokkaido Eastern Iburi earthquake on September 6，2018，as the study object to analyze the construction of evaluation indicator system. First，based on the comprehensive consideration of seismic characteristics，17 original evaluation indicators are selected according to the earthquake disaster investigation and data analysis. Then，rough set theory is introduced as the index selection strategy，and the reduction ability of the rough set is adopted to delete 9 factors with less relevance to landslides. Finally，the input layer of BP neural network is constructed with the optimized indicator system，and a rough set-BP neural network model for evaluating the susceptibility of seismic landslides is established. The results show that the prediction accuracy of the model is improved from 63.8% to 94.4%，indicating that the rough set-BP neural network model can effectively improve the accuracy of seismic landslide susceptibility evaluation.

Dry-wet and chemical damages are important reasons that lead to the quickly weathering process of metamorphic sandstone carrying Helan mouth¢s rock paintings following freeze-thaw and chemical damages. The research conducted 15，30，45，60，90，120，150 and 180 dry-wet cycles of rock paintings carrier in different solutions to explore the damage characteristics of rock paintings carrier under the combined action of dry-wet and chemical solutions. The results show that the mass，the longitudinal wave velocity，the uniaxial compressive strength and the stress-strain characteristics of the samples generally present gradual and differential attenuation as the number of dry-wet cycles increases，and the rate of change presents three stages with two obvious inflection points of 15 times and 60 times. SEM and XRD analysis tests were performed to qualitatively analyze the microstructure and composition of the samples，and the quantitative relation between damage variables and macroscopic test indicators was established based on the porosity. Finally，by analyzing the internal damage mechanism，it is found that the differential combination of hydrolysis，chemical corrosion，salt crystallization and dissolution result in the formation of the different number and connection of linear pores and pores in the rock due to different dry-wet conditions，which provides the necessary theory and support for the scientific protection of rock paintings.

In practical engineering，reinforced earth retaining walls bear not only vertical load but also horizontal static load and impact load. In this paper，indoor model tests of reinforced earth retaining walls subjected to horizontal static and dynamic loads were carried out. The deformation，horizontal earth pressure，reinforcement strain and potential failure surface were analyzed and summarized respectively to explore the deformation and failure mechanisms. The results show that the stability of reinforced earth retaining walls can be enhanced by reducing the reinforcement spacing and increasing the length of reinforcement material，which are also beneficial to control the deformation，and that it is more effective to increase the reinforcement length to resist the impact load. The deformation and the earth pressure develop gradually under the action of the horizontal static load，but have obvious“stepped”sudden changes under the action of the impact load. The reinforcement strain under both static and dynamic loads presents a single peak state，and the peak strain at each reinforcement layer decreases from top to bottom，which is consistent with the deformation of the retaining walls. The failure mode of the retaining walls under the horizontal load is different from that under the vertical load. When the length of the reinforcement is 0.75 times the wall height H，the reinforced soil retaining walls under static and dynamic loads will be damaged at the end of the reinforced area，but when the length is increased to 1.5H，the failure modes under static and dynamic loads are different. The results of this research can not only provide basis and reference for the design and research of reinforced soil retaining walls under the horizontal load，but also enrich the theory of reinforced soils.

To investigate the influence of the temperature and the relative humidity on the mechanical behaviour of coarse granular materials，a large-scale triaxial apparatus，which can accurately control the temperature and the relative humidity of coarse granular materials，was developed. Temperature control was achieved by controlling water temperature in the pressure chamber and relative humidity control was achieved by circulating water vapor in the sample. A set of methods for controlling the temperature and humidity of coarse granule materials in triaxial test were proposed，including the rapid relative humidity control method for coarse granular materials，the method to modify the external volume change measurement considering the influence of varying temperature and confining pressure，and the reliability detection method for sample temperature control. A series of triaxial shear and creep tests by controlling the temperature and the relative humidity were performed for phyllite coarse granular materials，meanwhile the internal mechanism of temperature and humidity effect on the mechanical properties of coarse granular materials was discussed. The results show that the new apparatus can accurately control the temperature and the relative humidity of coarse granular materials and that the increase of the temperature or the relative humidity would weaken the mechanical properties of coarse granular materials.

The temperature field and the surface deformation of a cross passage constructed in water rich silty clay layers using freezing method were studied based on field test. The results show that the temperature drop trend of each temperature measuring hole is approximately same，but the development rate from the freezing wall to the outside of the freezing pipe is 1.35 times larger than that to the inside during the freezing period. Due to excavation construction，the temperature of each measuring point far away from the excavation boundary decreases faster than that near the excavation boundary，and the influence of excavation on the temperature of soil mass at the freezing main surface is stronger than that at the freezing auxiliary surface. During freezing construction，the vertical displacement change of the ground surface could be divided into small uplift stage，accelerated frost heaving stage，freeze-thaw fluctuation stage，surface subsidence stage and thaw settlement grouting stage. In the early freezing stage，the vertical displacement increases quickly after the intersection of frozen pipes，the excavation of the connecting passage leads to the fluctuation of the vertical displacement which rises as a whole，and 3 months are needed for silty clay reaching the complete thaw state. During excavation，the maximum frost heaving curve and the maximum settlement curve show inverted“V”and“W”shapes respectively. The frost heaving and the settlement of the measuring points above the central axis of the connecting channel are respectively larger and smaller，and the farther away from the central axis，the smaller the frost heaving. It is proposed that the construction time of freezing construction in silty clay layer should not be less than 40 days and the average temperature of freezing wall should be －10 ℃.

At present，most studies in the field of foundation pits ignore the wall deflection caused by pre-excavation dewatering(PED). How to effectively control such deformation is of great significance to the construction of deep foundation pits in soft soils. In this study，an idea of rationally arranging cross walls for deformation control is proposed. Through laboratory-scale tests and numerical simulations，the effectiveness of the cross wall in reducing the foundation pit deformation induced by PED is investigated，and the influence of the cross wall spacing on the deformation control effect is discussed. Results show that the deformation control of a single cross wall has a certain range of influence，about 30 m apart from both sides of the cross wall in this paper. The deformation control effect is strongest at the cross wall location and gradually weakens with increasing the distance from the cross wall. It is also indicated that，when the cross wall spacing d is smaller than 5 times the width of the foundation pit B，the restraint effect of the cross walls on the overall pit deformation begins to appear，and that，when d is smaller than 3B，the cross walls will show apparent effect in restraining pit deformation induced by PED. It is suggested that the overall deformation of the foundation pit can be controlled through the superimposition effect of the deformation restraint of adjacent cross walls by setting a reasonable cross wall spacing.

The evolution of suffusion initiating and progressing within internally unstable soil has the characteristics of high concealment and tremendous harmfulness. Conventional laboratory tests can only observe the migration of fine particles nearby the transparent wall or the motion trail of trace particles but cannot directly monitor the migration of fine particles within the soil，which significantly hinders the understanding of suffusion mechanisms. This paper developed a new suffusion visualization apparatus based on planar laser induced fluorescence technology(PLIF)，which consists of a permeameter，a PLIF system，a high speed camera and an image processing system，and produced transparent soil specimens by adopting melted quartz sand，#15 white oil and D80 Solvent oil with the same refractive index. A testing method for preparing high transparency internally unstable specimens was proposed，and a list of transparent soil suffusion tests were performed. The results indicate that the newly designed apparatus can continuously monitor the migration of fine particles within the specimens. Temperature has significant influence on the refractive index of liquid and the transparency specimens and hence，should seriously be controlled no more than 25 ℃. Fine particle content and minimum particle size also have significant effect on the specimen transparency，and it is suggested that the fine particle content should be less than 35% and the minimum particle size should be smaller than 0.2 mm. It is revealed that suffusion will progress along to the weak zones within the specimen，then form a concentrated leakage path and eventually result in damage of soil structure. The new apparatus based on PLIF will provide an effective tool for investigating the mesoscopic mechanisms of suffusion.