Based on detailed analysis of all available literature and technical reports in China，a comprehensive review for advancement and application of the Standard of Engineering Classification of Rock Masses(GB50218—94)，“national standard” for short herein，is conducted. Moreover，practical effects for engineering applications of the national standard are evaluated. The relations between the national standard and other rock mass classification methods，including RMR(rock mass rating) system，Q system and HC method used in surrounding rock classification of hydroelectric projects in China，are described. In addition，promotion，advancement and suggestions，for some currently-employed professional standards and rock classification method in the framework of the national standard，are also proposed. Based on the statistic analysis of more than 200 sets of measurement data，a regression formula for rock mass basic quality(BQ) associated with RMR in the national standard is given；and the reasonability of the above-mentioned classification methods for rock mass is further validated. It is shown that rock evaluation system in the national standard is reasonable with strong scientific significance and flexible operability. By using the index of rock mass BQ in the national standard，artificial disturbance during site investigation can be significantly decreased，which can improve the accuracy and effectiveness of rock mass classification，and reduce the laborious work in field. The BQ method is also proven to be convenient for engineering applications at different design stages of projects，but with various experiences accumulated in actual engineering applications，modification of the rock classification method is needed.

In order to study the failure characteristics of the deep surrounding rocks in unloading path，in-situ true triaxial unloading tests under high pressure were carried out in the field deep experimental adit. The tests have features such as large scale(50 cm ×50 cm×100 cm)，high stress( = 11.2 MPa)，unloading fracture of  . This true triaxial test can represent the real stress states of surrounding rocks of deep tunnel and the complete stress-strain curve of marbles in tunnel excavation stress path；and the triaxial strength of rock mass can be obtained. Based on the in-situ true triaxial test of marbles under high pressure in unloading path，Hoek-Brown(H-B) empirical strength criterion is adopted to study the true triaxial strength parameters of marbles in unloading path. The research results are as follows：(1) The values of true triaxial strength parameters in unloading path which are evaluated by using H-B empirical strength criterion may be relatively lower than those in in-situ true triaxial unloading test. The evaluated empirical parameter s is 0.003 951 7，  is 3.414. However，the inverse computation parameters according to the test results s = 0.095 53，  is 12.208. (2) Based on the evaluated results of rock strength by using H-B empirical strength criterion，Mohr-Coulomb criterion is used to evaluate the values of strength parameters. The true triaxial strength parameters of marbles in unloading path，tan? is 1.39，c is 6.61 MPa，while the true triaxial strength parameters of undisturbed marbles in unloading path，tan? is 1.60，c is 6.73 MPa. The former can stand for unloading damage rock mass.

In order to achieve high speed exploitation of Jinshan temple open iron mine，optimal exploitation multiple blasting techniques are proposed，which solve the technical difficulties，such as ore block degree controlling，stope slope stability controlling and sporadic veins high efficient exploitation，so as to obtain good effect. Firstly，the Kuz-Ram mathematical model is used to establish explosives consumption prediction model to control the rate of ore chunk. Combined with practical engineering geological conditions，the reasonable explosive consumption to control the blasting ore block of Jinshan temple iron mine controlled blasting is calculated. Secondly，in order to reducing explosive using，the slope pre-splitting blasting of original design is changed into buffer blasting. By adjusting the amount of explosive charge and charging structure to control production blasting damage to the adjacent end slope，reducing construction cost and satisfying the requirements of slope safety at the same time. Finally，aiming at the dispersive characteristics of ore body，the segmented blasting mining，in-situ blasting techniques are used to reduce the ore dilution and loss rate，and reduce the waste of resources. Multiple usages of various blasting techniques open a new way for the efficient exploitation of small and medium-size mines.

The strength of rock in two-phase fluids is an important parameter and is scientific problem in common of fracturing-enhanced oil recovery and safety control for projects such as CO2 geological storage，oilfield development and unconventional energy exploitation. A new hollow-cylinder cell has been developed to investigate the effects of two-phase fluids on rock failure. The hollow-cylinder cell can apply different combinations of internal and external hydrostatic pressures，axial and pore pressures to explore the rock tensile strength in state of true triaxial stress；and rock tensile failure test in two-phase fluids can be controlled. Technical problems for uniformity and constancy of testing temperature，saturation degree control and sample sealing performance under high triaxial pressure during test are solved. The failure stresses were measured for dry and water/CO2 containing fine sandstone samples. To verify the performances，repeatable verifying test，fracture test in two-phase fluids and fracture tests in different loading paths are conducted. Test results show that the apparatus exhibits performances with excellent temperature and pressure stability，high control accuracy and strong repeatability. The apparatus can serve as a new tool providing scientific data for validating failure criteria，especially in tensile regime for two-phase fluid bearing rocks.

Real rough joints profile has been rebuilt by PFC2D(particle flow code in 2 dimensions) successfully，and a series of PFC2D numerical simulation direct shear tests have been done to obtain its shear behavior. We can observe the failure process from the viewpoint of mesomechanics through PFC2D. The damage process of asperities on rough surface and the corresponding micro-fracture development can also be monitored in the numerical direct shear tests and these can be treated as a supplement of model tests. Macroscopic deformation of the sample is formed by the accumulation of mesoscopic shear cracks；and the shear failure area of rock mass mainly grows on the climbing slope of joint，where is the shear stress focus area as well. As the peak shear stress appears，the number of shear cracks is increasing quickly，when the failure of rough rock joint is most significant. According to the numerical tests，the results between model tests and numerical tests fit well；so real rock-joint model tests can be partly replaced by PFC2D numerical tests，which can become a way for forecasting the shear strength of real rock joints. The problem that the topography of real rough rock joints is hard to be restored has been solved by the numerical simulation method.

The mesoscopic numerical method for simulating unsaturated soil-rock mixture is presented based on its mesostructure features. This method includes the technique for generation of mesostructural model，master-slave contact surface algorithm，and seepage and strength theory of unsaturated soil. The feasibility and rationality of proposed method are validated by comparing the numerical results to the results obtained in laboratory experiments of unsaturated soil-rock mixture. The proposed method is then used to analyze the factors，such as the contact behaviours of soil-rock interface，rock block content and saturation degree，and their influences on the mechanical characteristics and failure mechanism of unsaturated soil-rock mixture. It is found that：(1) Under low confining pressure，unsaturated soil-rock mixture exhibits remarkable shear dilatancy，which are influenced significantly by rock block content and degree of saturation at this time. Under high confining pressure，unsaturated soil-rock mixture exhibits shear contraction. As rock block content increases，the deformation of shear contraction decreases；and the influence of saturation degree is small. (2) The peak strength and deformation modulus of soil-rock mixture increase nonlinearly as the friction coefficient of soil-rock interface increases. When friction coefficient is above 0.6，values of peak strength and deformation modulus tend to be stable. (3) The increase of rock block content will lead to the increases of peak strength and deformation modulus of unsaturated soil-rock mixture. Strain-hardening feature at this time becomes more remarkable. When rock block content exceeds 58%，values of peak strength and deformation modulus tend to be stable. Under low confining pressure，the increase of rock block content will lead to the increase of shear dilatancy deformation. Under high confining pressure，the increase of rock block content will lead to the decrease of shear contraction deformation. (4) The increase of saturation degree will lead to the decrease of matric suction and peak strength of soil-rock mixture but have little influence on deformation modulus.

The prediction of water inflow and inrush in deep tunnels is relatively difficult due to the mechanical and hydro-mechanical characteristics remarkably different from those in shallow tunnels，and the difficulty in geological exploration as well. In respect to deep and complex geological environments，such as high initial geostress，high hydraulic gradient and high rock temperature，etc.，a multifactor prediction method based on the fault-dominated water model has been proposed，in terms of the research work on West Route of South-to-North Water Transfer Project. Firstly，a macro geological model is adopted to preliminarily assess water inflow and inrush，mainly regarding large-scale faults as groundwater channels. Based on the effect laws of deep geological environment factors which have influence on water inflow and inrush，a series of coefficients are determined and utilized for the final modification of water inflow and inrush estimated by the macro geological model. The presented method can be employed for assessment of water inflow and inrush from deep long tunnels during tunnel construction and supporting.

Due to the conventional modified Cam-clay model can not describe the cohesion properties and different yield strengths in tension and compression performance (S-D effect for short) for geotechnical materials，a modified Cam-clay model with non-associated flow rule is established considering S-D effect on deviatoric plane and cohesion on meridian plane. The main contents of implicit constitutive integration algorithm for the improved model and its implementation procedure are discussed systematically. Based on the platform of software ABAQUS，the user-defined material subroutine UMAT interface is developed to generate corresponding constitutive subroutine of the modified Cam-clay model. Meanwhile，the numerical simulation of triaxial compression test on Belgium Boom clay is implemented. The study result shows that the improved constitutive model and the UMAT subroutine have higher calculation accuracy and good stability，which could effectively depict the nonlinear and plastic flow characteristics of Belgium Boom clay.

Linear Coulomb criterion can not completely describe the strength features of rock；and various revisions have been developed. The Mohr criterion on shear failure，which manifests as the envelope of failure stress circles，is studied rarely for the inconvenient to determine its parameters from the results of conventional triaxial compression test. Strength criteria with principal stresses form can be divided into explicit and implicit criteria. Implicit criteria is usually constructed with maximum shear stress and average principal stress，and has high correlation coefficient and low fitting deviation for the evaluating index. Actually，the two criteria have the same mechanical background and can be alternated after the coordinate rotation. Strengths of rocks like sandstone and marble result from cohesion and friction among grains，and can be illustrated by the normal parabolic criterion with a single parameter，which is better than the Coulomb criterion and same as the Hoek-Brown criterion in fitting the relationship between strength and confining pressure. Ideal uniaxial compression strength of intact rock can be obtained by fitting the strength with normal parabolic criterion under high confining pressure，and may be used to evaluate the initial damage after comparing the real magnitude of uniaxial compression strength.

In order to study the strength degradation law of surrounding rock in fractured zone of deep roadway，the loading-unloading tests on intact sandy mudstone samples were implemented according to the stress path simulating the changing law of stress in fractured zone of roadway by applying the MTS815 servo-controlled rock mechanics testing machine. The initial damaged rock samples for different broken levels were obtained and their triaxial strength characters under varying confining pressures were tested with single block method. The strength degradation ratio and volume expansion ratio DV were applied as damage valuables at unloading point；and the function relationships between peak strength，strength parameters of initial damaged rock samples and  ，DV were established. The study results indicate that the peak strength，cohesion and internal friction angle decrease greatly with the increasing broken level in exponential degradation law.

To deal with the toppling deformation and fracture rock-mass problem at the embankment slope in Jinping hydropower station，the whole slope surface is reinforced by shotcrete support，rock bolting and frame pier with prestressed cable. The integral stability of left slope is controlled by the potential large sliding body which is composed by fault f42–9，deep crack SL44–1 and lamprophyre dike X. Some three-layer anti-shear tunnels on the sliding body are designed；and a lot of deep perstressed cables across the faults are placed at the slope surface to reinforce the sliding body. A management system，which follows the principle of dynamic design，scientific study tracking，safety monitoring and immediate reacting analysis，and dynamic management informationization，is established. According to the geological conditions and safety monitoring data during excavation，combining with construction situation，slope stability analysis and real-time safety monitoring could be conducted；in addition to the optimization of design and strict controlling of construction procedure，excavation work of the left embankment slope finally goes on smoothly.

The maximum principal stress of Jinping II headrace tunnel is more than 70 MPa. In such a high stress condition，there must be sharp conflict between rock mass strength and geostress. Understanding the fracture characteristics of marble and grasping the damage evolution law of surrounding rock，are important to the optimization design of support and evaluation of the stability of surrounding rock. Depending on the research achievements of brittle rock fracture，the characteristic strengths of marble under different confining pressures are confirmed by inflection points of crack volume strain and marble volumetric strain matching with acoustic emission test. The characteristic strengths are expressed in principal stress space；and the stress envelope is set up，which can be used in field. The stress state in excavation damage zone(EDZ) is analyzed by crack initiation strength envelope and the scopes of different zones of EDZ are calculated. The EDZ evolution of monitoring section by tunnel face driving is described. In order to further analyze the evolution law of EDZ above，the acoustic wave and acoustic emission test are conducted. The relaxation depth by acoustic emission detection is mainly corresponding with failure zone in damage zone. The acoustic emission test can obtain the whole EDZ distribution，which is more helpful to understand the complete EDZ distribution characteristics. The results can provide scientific basis for the optimization design and timing of support.

Owing to the current measurement technical level of geostress and complexity of geological conditions for actual rock mass，validity of measured results might be suspected；and the quality and precision of measured data of geostress as basic information will directly affect the reliability of quantitative model of geostress field. A comprehensive analysis method has been put forward to study the reliability and validity of measured data of geostress. The method combines with macrotectonic geological background in project area，geostress measurement data interpretation，mechanical qualitative analysis of rock mass failure phenomenon. Firstly，influences of comprehensive geological tectonic background and local geomorphology have been considered to form overall impression and macroscopical judgment of geostress field in project area. Then，full-space stereoprojection method and typical plane stress projection method have been used to quantitatively study the characteristics of stress tensor of geostress measuring point acquired through measurements. Comparative study will be conducted on the result mentioned above and the mechanical qualitative analysis results of certain rock mass failure phenomenon at exploration adit. So，measured data，which are assumed to be representative and reliable and can reflect geostress field in project area，are selected for the regression analysis of initial geostress field. By using this method，the distribution characteristics of geostress field at dam site of a large hydropower station，located in deeply incised river valley area of Southwest China，has been analyzed. The stress concentration position predicted by the established numerical quantitative model of initial geostress field and actual stress-induced failure parts have good consistency.

Based on the composite material model of layered rockmass considering a group of rock joints，a multi-joint constitutive model of layered rockmass considering characteristics of multi-group structural plane is proposed according to the mechanical characteristics of joint planes and rock matrix；and the model can be used to describe the anisotropic characteristics of rock strength and deformation，as well as strain hardening-softening characteristics. Then，the proposed model has been successfully established and embedded to fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) by using programming language VC++，realizing its nonlinear numerical calculation. Furthermore，using the combination method of the proposed constitutive model and three-dimensional joint network model，an analysis method of synthetic rockmass model(SRMM) based on the theory of continuum mechanics is initially put forward. Based on the proposed constitutive model and SRMM above，a three-dimensional synthetic rockmass computational model for true triaixal field test is established. The comparison between field tests and numerical simulation results proves that the proposed constitutive model is suitable for the description of the above characteristics of multi-joint rock masses.

In light of the characteristics such as complicated stress variation after excavation unloading in high geostress environment，RXZJ–20000-typed computer servo-control rock mass true-triaxial site creep testing system has been developed. The main structure，function features and usage of the system are introduced in detail. Verified by the actural engineering practice，the system has the following features of high geostress，large size，complete process of stress and strain，high precision，high efficiency，multifunction and convenient for removing and installation. The system has changed the status that true-triaxial site creep test equipment has a low loading level，big pressure fluctuations，low test precision，single stress path and low degree of automation at present. The successful manufacture of the RXZJ–20000-typed rock mass true-triaxial site creep test system provides a new way to the study of the time-effect of deep rock under the condition of multiaxial stress；and it is the most advanced larger servo test instrument at home and aboard. It is suitable for long-term creep test of the hard and soft rock masses of large-scale artificial slope，deep large-span tunnel and underground caverns.

A series of conventional mechanical laboratory tests such as uniaxial compression tests and triaxial compression tests were carried out to analyze mechanical properties of green schist in Jinping II hydropower station. Based on the analysis of conventional test results，uniaxial and triaxial rheological tests of green schist were designed and completed successfully. On the basis of the testing data obtained，the long-term strength of green schist were analyzed by transition creep law. Through the analysis，we could find that the long-term strength of green schist is about 80% of instantaneous strength. Moreover，through analyzing the shortcomings of transition creep law，and combining the achievement of creep tests，a new quantitative analysis method of long-term strength was proposed and applied to the analysis of long-term strength，so as to offer a meaningful viewpoint.

In order to serve as a warning for the following mining activities，the monitoring data of rock burst，microseismic，roof breaking and stress distribution induced by mining were got；and the relating rules with each other were analyzed through field measurement method，in a strong dangerous area of rock bursting. The analysis results show that the affected area of advanced abutment pressure are the main occurring area of rockburst and microseismicity；but rock burst may occur in the area of microseismic activity where out of the affected area of advanced abutment pressure. Rock burst may occur during the period of main roof breaking，the period of high rock stratum breaking when the shape of goaf is approximate to square，and the period of microseismicity. When all the above three period are approximately synchronous，the probability of occurrence of rock burst will increase obviously in the affected area of advanced abutment pressure.

Application experiences of open-type hard rock tunnel boring machine(TBM) to diversion tunnel group of Jinping II hydropower station are summarized. Firstly，in order to determine the suitable equipment structure and boring parameters，selection of facilities and optimization of boring parameters for open-type hard rock TBM of Jinping II hydropower station under high geostresses are studied. Advanced geological prediction in front of tunnel face is carried out by adopting combined means such as BEAM，TSP and geology radar；and good prediction results are achieved；so that corresponding preparing handling measures can be established. Furthermore，the prediction and pre-warning measures of rockburst under high geostresses are investigated by firstly importing microseism monitoring system to the hydropower project in China；and the relative accurately occurrence range of rockburst have been predicted. The investigation has developed a series of experimental works on the supporting measures to prevent rockburst，which have effectively lowered the risk and harm of rockburst. Finally，a comprehensive research on how to realize safe and fast construction of TBM are also carried out，so as to provide references and suggestions to the facility selection and applications of open-type TBM in future.

Through a single fissure is being artificially prefabricated into rock-like material，strength characteristics and failure modes of deep rock mass with single fissure are studied by means of conventional triaxial compression test. The impact factors and failure conditions of shear failure along discontinuities of fissured rock mass are also discussed based on the theory of fracture mechanics. The research results show that：(1) The strength of these samples is of great concern to confining pressure，fissure inclination angle and size. (2) Fracture is external concentrated expression of damage specimens. Deformation modulus and elastic modulus are related with confining pressure，fissure inclination angle and size which has great influence on modulus. It has a lower moduli of elasticity and deformation as fissure size increases；but confining pressure and fissure inclination angle have a slight effect on the moduli. (3) The failure modes of prefabricated single fissured samples can be classified into three types，i.e. shear failure across fissured plane，sample?s own shear failure and shear failure across readjustment fissured plane when fissure size is small. (4) It has better consistency between fracture mechanics theory and the Mohr-Coulomb strength criterion if failure mode is an ideal II-type shear failure. (5) The shear failure of single fissured sample sliding across primary fissure plane depends on fissure inclination angle，size and confining pressure. Supposing fissure inclination is desired，the shear failure sliding across primary fissure plane will occur when fissure size is smaller but confining pressure is higher；and shear failure is not sensitive to confining pressure if fissure size is bigger. (6) I-type and II-type cracks of single fissured samples are found during triaxial compression test，and III-type cracks are also obtained. These conclusions can provide valuable theoretical reference for excavation，supporting design and stability analysis of underground engineering containing fissure and faults.

The instability characteristics of the fracture hinged arch for rock plates were researched experimentally with the independent researched loading device based on MTS rock mechanics test system under concentrated load condition；and vertical load-displacement-horizontal reaction force curves were obtained through the experiments. The experimental results show that rock plate fractured in beam style and formed hinged arch with the increasing vertical load；at the same time，horizontal reaction forces generated at these hinge points. There are four distinct mechanical response stages in the vertical load-displacement-horizontal reaction force curves，which are initial adjustment before loading，rock plate fracture and forming hinged arch，pre-peak hardening and post-peak softening of rock arch load bearing. Based on the engineering mechanical model of hinged arch structure of rock plate，the relationship formula for bearing capacity and horizontal reaction force of rock arch structure is deduced；and the sensitivity analysis of load bearing of rock arch structure changing with rock plate parameters is conducted.

Brittleness of gas shale reservoir is of vital significance to testing and evaluating the brittleness of shale. In view of this，through literature investigation and lab tests，20 kinds of basic methods for testing brittleness，including methods based on strength，hardness and ruggedness are summarized，focusing on discussing testing theory and lab method for shale brittleness based on complete stress-strain characteristics. Considering brittleness fracture mechanism and fracture feature，brittleness of shale is defined as a synthetic characteristic of material，affected by its heterogeneity and external testing environment. To identify brittleness of shale，complete stress-strain curve consisted of pre-peak and post-peak parts should both be considered. To improve the accuracy of brittleness evaluation，complete stress-strain testing in underground environment should be simulated. Capacity for resisting inelastic deformation before rupture and losing rate of bearing capacity after rupture are the main mechanical performance of brittleness. To improve the evaluation accuracy，existing mechanical testing schemes are also modified. Meanwhile，brittleness characteristics of black shale from South China is tested through true triaxial rock mechanics tests and then evaluated using improved methods.

Based on the research on unloading rates，the triaxial unloading confining pressure tests of deep marble under different initial damage levels and unloading paths are carried out systematically. Novel unloading mechanical parameters are proposed：increment ratio of strain increment to confining pressure increment，and uniform decreasing increment of confining pressure. Combining with the dilatational parameter and plastic internal variables，the control effect of initial damage level and unloading path on failure principle of unloading deformation of deep marble is analyzed. The origin and mechanisms of the principles obtained by the unloading and failure tests are explained through an intuitive conceptual model of unloading failure. Combining with deep tunnel projects，the major guiding significance of the initial damage level principles is discussed. The research results above can provide a theoretical basis for preventing the brittle failure of hard rock under high stress conditions，e.g. rockbursts.

Mining-induced floor failure and formation of water conducted pathway is the necessary conditions for water inrush in coal mine，which are the basis for monitoring and predicting water inrush. In order to study the formation and evolution of floor failure and water conducted pathway caused by coal mining above confined water with high pressure in Xinyi coalmine，two research means，i.e. field monitoring and numerical simulation，are introduced. Subsequently，the variations of electrical resistivity，stress and pore water pressure of floor during mining process are analyzed. The result shows that the floor failure caused by coal mining above confined water with high pressure is influenced significantly by advanced supporting stress of working face and the failure depth of floor of working face 11011 is about 25 m，which is greater than general empirical value. Based on fluid-solid coupling theory，the established numerical simulation model of mining-induced floor failure can reflect the influencing factors of floor failure more accurately and objectively；and the maximum failure depth is up to 23.75 m，which is very close to field monitoring result. The variations of electrical resistivity，stress and pore water pressure can better reflect the whole process of mining-induced floor failure formation，water inrush pathway evolution and water filling. The conclusion indicates that the above-mentioned parameters can be used as the precursor information for monitoring and short-term predicting the water inrush hazards in coalmines.

The concrete specimen coated with fireproof paints is used to simulate tunnel lining under different conditions. The mobile equipment based on line-array charge-coupled device(CCD) is designed and corresponding softwares are developed to make the model test on automatic detection of cracks in tunnel lining. Gray distribution of image and accuracy of crack detection are selected as two quantitative indices for assessing automatic detection performance. The influencing law of factors such as detection distance，light source illuminance，effective pixel and detection speed affecting automatic detection performance is summarized. The model test results are as follows：The gray distribution of image along crack width direction shows wave valley features. Detection distance and effective pixel have little influence on the gray distribution of image，but mainly affect the accuracy of crack detection. With the decreasing detection distance and increasing effective pixel，the accuracy of crack detection increases linearly. Light source illuminance and detection speed have great influence on both the gray distribution of image and the accuracy of crack detection. Too high or low light source illuminance can cause a reduction of the accuracy of crack detection. With the increasing detection speed，the accuracy of crack detection decreases linearly.

By using plane strength theory，unified strength formula based on the spatially mobiliaed plane(SMP) and Lade-Duncan criteria is derived. Combining with post-peak rock material mechanical properties of post-peak strain softening，considering post-peak internal friction angle ? as intermediate variables，residual strain ? is used to express the post-peak nonlinear elastic modulus E，and finally a unified nonlinear constitutive equation which can be also named as constitutive model of rock post-peak residual stress is established. Combining with triaxial test of typical fractured diorite porphyrite in Eastern area of Xiaoguanzhuang iron mine，simulated calculation of post-peak stress-strain relationship curves for different confining pressures by this model is conducted. The result shows that the post-peak constitutive relation of this study can simulate the experimental results well，so as to prove the rationality of the model and providing a new way to study the post-peak mechanical regular pattern of rock.

The vertical stress of underground rock mass can be evaluated by depth times the average unit weight of overlying rock mass. However，horizontal stress is difficult to estimate. Based on the fact that rock fracture toughness is a constant，two-collinear crack model is applied to establish the stability condition of fractured rock mass. From this stability condition，the range of horizontal stress can be evaluated；and the evaluation result agrees well with in-situ measurement results，so that indicating the evaluation method is effective and feasible. Through the stability condition of fractured rock mass，we can well explain the phenomenon that the ratio of horizontal stress to vertical stress in shallow zone is scattered in a wide range；but in deep zone，it is scatted in a narrow range.