Numerical analysis on the evolutionary features of deformation and failure modes of slopes

The failure of slope is a gradual accumulation process. Under the effect of many interior and exterior factors, some parts in the slope reach yield with the increase of stress, and sliding surface forms gradually till complete transfixion. With continuous increase of the plastic strain, overall failure happens on the slope. Traditional analysis method cannot display the mechanic conditions and the whole process of deformation, transfixion of sliding surfaces and failure. Meanwhile, FEM strength reduction can quantitatively show the deformation features and the process of occurrence and development of sliding surface. Based on the previous researches, the paper classifies slopes according to the features of rock and soil and the slope structure. Through analyzing the graphs of deformation and the nephograms of plastic strain under different reduction factors or safety factors, the researchers can directly find the deformation tendency of slopes and the whole process of the extension, transfixion and failure of sliding surface with the reduction of safety factor. So, the failure mechanism of slope can be found intuitively, which can provide effective basis for the prevention and governance of slopes.     

基于随机场的岩石边坡三维稳定性分析

基于随机场理论，考虑了岩石材料属性的空间变异性对岩石边坡稳定性的影响，将边坡主滑面上的摩擦系数和粘聚力视为高斯随机变量，确定了主滑面上的摩擦系数和粘聚力的均值、方差和协方差，获得了两个随机量之间的相关系数和互相关长度。在此基础上，对岩石边坡进行了三维稳定性分析，确定了岩石边坡的稳定系数和失效概率。数值计算结果表明，摩擦系数和粘聚力的空间变异性对边坡稳定性有重要影响。     

Horizontal Slice Method for the Stability Analysis of Reinforced Slopes

Relevant national codes usually require the transmitting coefficient method to be employed for the stability analysis of slope reinforcement, in which sliding mass is usually divided into a number of vertical slices.For some support technologies, such as rock bolting and anchor cable, the intersections between the slices and the anchor bar, and the forces mobilized in the reinforcements are different from the assumptions in this method.Thus the transmitting coefficient method confronts some difficulties during practical applications, which would influence the project quality of reinforcements.A new Horizontal Slice Method was proposed based on the overseas relevant literatures to overcome these difficulties in the stability analysis of rock bolting and anchor cable slopes.     

Experimental Study on the Characteristic of Seepage with Unloading Rock Mass

The destruction of rock mass arises from opening rock possibly, the main outside-factor of influence rock slope stability is groundwater and water seepage. To analyze the relationship of unloading and permeability coefficient, the method and step of experiment of unloading rock mass are put forward. The curve relationship of the seepage-unloading of different phase is found by experiment. According to the experimental result, the equation of the seepage-stress of unloading is established, the variational rule of the unloading and permeability coefficient is discussed. The permeability coefficient is almost unchanged in the elasticity phase of unloading process. The permeability coefficient changes very much in the plastic phase of unloading process, as the unloading is 80% of ultimate unloading especially, and the permeability coefficient is increasing very much.     

Study on high and steep slope stability Based on 3D laser scanning

Dangerous mountain construction projects block of high and steep slope stability is the important issue of security and disaster prevention, investigation on the surface of the dangerous mountain high and steep slope rock mass structure is the key to the analysis of the problem. The high slope of a major project of the Lancang River, the application of 3D laser scanning technique to study the long-distance survey analysis of rock mass structure analysis method to analyze the distribution of the surface space of the high and steep slope rock mass structure, statistical analysis direction of the advantages of the structure surface and the distribution of rock blocks, as the basis for the application of limit equilibrium analysis method to study the stability of rock blocks of the high and steep slope.     

The Recent Progress of the Slope Stability Analysis Methods

The slope stability is an important research content in rock mechanics. In recent years, the great achievement has been gained for the slope stability analysis methods. The deterministic analysis methods, including limit equilibrium theory, numerical analysis method, graphic method and compound method, have been developed. The stochastic analysis method and the fuzzy analysis method come forward. The recent progress of the slope stability analysis methods is analyzed in this paper. The trend of progress of the slope stability is studied.     

Study on Cusp Catastrophe Mutation of Slope Destability

A complete theoretical model for slope destabilizing mutation has been set up by studying the geomechanical model and the influences of all circumstantial factors on slope stability,and by applying nonlinear theory.This paper analyzed the influence of controlled variables in the mutation model on the slope in causing slow or fast creeping.As the limit equilibrium stability analysis method of rigid bodies has some defects in slope stability assessment,the new theory of rigidity destabilization is helpful in forming criteria for judging slope creep destabilization.This analysis explains well the underlying causes of creeping slope destabilization and proves the feasibility of studying slope creep with a mutation model.     

Determination of an Optimum Scheme forBolting Unstable Rocks on a Rock Slope

Using basic principles of stereographic projection,block theory and rock mechanics,this paper tries to find a simple and easy method for determination of an optimum scheme for bolting unstable rocks on a rock slope in design of slope engineering.finally, examination and analysis is made of the completed project for bolting the unstable,high and steep rock slope on the campus of Chongqing University.     

Nonlinear Analysis of Unloading RockMass Related to the Shiplock High Slopeof Three- Gorges Project

According to the characteristics of the shiplock high slope of Three- Gorges Project, this paper simplified the rock mass of the high slope as orthogonally anisotropical media.On the basis of recongnizing the nonlinear mechanics of excavation unloading,the paper prsents the nonlinear mechanics calculating method ,the theory of changing stiffen analysis. The calculating results agree fairly close to the measured one.By the excavating calculation of shiplock high slope, the paper shows that the rock mass will produce the large deformations,which have the large difference with the results of the old studies     

Types of Bank Slope and Its Stability form Yibin to Baihetan on Jinsha Rive

By researching the locale and studying geologic background and rock-mechanics surroundings on hyroeijectric zone of Jinsha river(Yibing-Baihetan),the authors divide bank slopes into 9 types according to structure of rock and soil and terrain,and expatiate the distributing character and stability of each bank slope types,which serves as scientific geo-accordings in forecasting and controlling of bank slope's unsteady on hyroeijectric zone of Jinsha river.     

Couple Analysis of the Slice and Gravity Increasing Methods of Slope Stability

The finite element or finite difference method and the limit equilibrium method, with their respective merits, were used to analyze soil slope stability in detail. On the basis of the slice and gravity increase methods, a fundamental principle of couple analysis, and a procedure for calculating the slope safety factor were put forward. ANSYS finite element software and finite difference software FLAC were used to determine the most dangerous sliding face and the stress-stain in slopes. The slope safety factor was determined using the slices limit equilibrium method. The calculation shows that the result obtained using couple analysis is close to the results produced using other methods in the example, and the analysis of the effects of the intensity indices is more precise. The results can provide a basis for consolidating design of the sliding slope.     

Laboratory similar model test investigation of prestressed anchor rope strengthened slope fractured rock mass

Now in the highway construction of the mountain area, fractured rock mass slope always strengthened by the anchor rope. In order to investigate the strengthen effect of the slope fractured rock mass strengthened by the prestressed anchor rope, laboratory similar model test was designed and preceded. By the self-made facilities, a new method of modeling prestressed anchor rope was used in the test. Nylon ropes and the aluminum flakes were used to model the anchor rope and discrete rock mass joints. Gypsum based mix material was used to model rock. According to the real slope engineering site circumstances, six sorts of different disposed prestressed nylon rope strengthened model specimens and the specimens without prestressed nylon rope were made by the similar theory. With the test results, the strength and deformation properties of different model specimens were investigated. Comparison to different anchor effects of the different model specimens was made. The final analysis shows that in order to make full use of the anchor rope's strengthen ability, anchor rope should be disposed perpendicularly to the fracture structure rock mass's main joint direction and should be placed in the upper or top area of the fractured rock mass slope.     

降雨入渗对宁南山区黄土梯田边坡稳定性的影响

为了研究降雨入渗对宁南山区黄土梯田边坡稳定性的影响。采用ABAQUS软件建立降雨入渗下的宁南山区黄土梯田边坡稳定性有限元模型,研究了水平梯田、隔坡梯田、原始边坡（对照）3种边坡类型,在降雨入渗强度(28~38 mm/h)和边坡坡度(15°—30°)下的破坏时间和安全系数的变化规律。结果表明:降雨入渗下,黄土梯田边坡的破坏时间随降雨入渗强度的增大而减小,且呈幂函数关系,水平梯田的破坏时间显著高于隔坡梯田和原始边坡;安全系数也随降雨入渗强度的增大而减小,但呈线性关系,水平梯田的安全系数与隔坡梯田和原始边坡并无显著差异。降雨条件下,修筑梯田能增加浅层梯田边坡的稳定性,而对于深层梯田边坡的稳定性影响不大。     

Study on Analysis Methods for Rock Slope FoundationStability of the Highrise Building

Based on the practical project a study on analysis methods for rock slope foundation stability of highrise-building project criterion transfer coefficient method, rotation limit equilibrium method (Sweden slices method) and finite element method was carried out.The authors found that safety factor of criterion transfer coefficient method is larger than that of rotation limit equilibrium method, but is similar to the results of finite element method. So, when rockslope foundation stability of highrise building is to be analysed,the rotation limit equilibrium method is suggested to use.     

Simulation Study of Water Quality for the Three Gorges Reservoir in Chongqing

In order to survey the degree of stability of dangerous rock slope and get reliable theoretical foundation about the slope restoration, earth stress measuring is performed in the engineering project through drilling on the slope surface. The survey is conducted by means of complete temperature compensation and automatic recording. In terms of experimental data, the computing ram of earth stress works out the magnitude, direction, inclination of the earth stress and their distribution. The result supplies theoretical base for the design and working of slope and dangerous rock control engineering, which has been proved to fine effects in the fields of society, security,environment, and economy in its practice.     

Numerical Simulation Research on Stabilityof Dissolving Cavityfor the Low-depth-thin-layer Rock Salt

In order to extend life of salt well, avoid sinking and use the formed cavity reasonably, the factors of effecton cavity stability must be researched during the process of water mining of rock salt, so that the effective prevention measures can be put. The stability of dissolving cavity for the low depth thin layer rock salt has been researched by the ADINA non linear finite element method.The results show that the stability of dissolving cavity obviously becomes strengthened with the decrease of its height, and has a decreasing trendas with the span increase of the cavity . The effect of incidence on stability of the cavity is very little. The stability of cylindroid cavity is higher than that of converse taper cavity. The assorted model is a kind of transition shape. The influencing order of cavity stability is the ffollows, height>geometrical shape>span>incidence.     

Finite Element Reliability Analysis of the Stability of a Slope

The whole reliability index of a slope is derived through using the strength reduction method in the finite element analysis, which can make use of the former finite element program and can be used to both linear and nonlinear finite element analysis. The affection of the evaluation of derivative and the selection of reliability analysis methods is discussed, which shows that it is very important to select the type of limit state function of the slope stability. A new iterafive formula, which can consider the correlation of fundamental parameters, is proposed for FORM, and the convergence is very well.     

Technology of Stress Relief by Overcoring Used in Dangerous Rock Slope

In order to survey the degree of stability of dangerous rock slope and get reliable theoretical foundation about the slope restoration, earth stress measuring is performed in the engineering project through drilling on the slope surface. The survey is conducted by means of complete temperature compensation and automatic recording. In terms of experimental data, the computing ram of earth stress works out the magnitude, direction, inclination of the earth stress and their distribution. The result supplies theoretical base for the design and working of slope and dangerous rock control engineering, which has been proved to fine effects in the fields of society, security,environment, and economy in its practice.     

Violent-slide rock avalanche and excitation effect of perilous rock

The physical model of perilous rock avalanche excitation effect is deudofed based on the effect of the main factors, such as weight and fissure water pressure. It quantizes the interaction of perilous rock masses through the energy point of fracture mechanics and wave theory, and gains the departure rate formula of landslide body at momentary avalanche. The particle displacement rate calculation method of perilous rock medium under the action of excitation waves is developed based on the formation of perilous rock avalanche excitation waves and the spread mechanism in slope rock formation. The example shows that the analysis results established are coincident with actual situation. Some scientific basis is provided for the further research of perilous rock damage and evolutionary mechanisms.     

水平与竖向加速度-时程曲线叠加效应下边坡永久位移计算的极限上限分析

实际边坡动力稳定性受地震竖向与水平方向效应共同作用,传统边坡地震永久位移计算方法较少考虑竖向地震波影响,采用实际地震的竖向与水平方向加速度-时程曲线共同效应更符合工程实际。基于极限分析上限法和Newmark刚塑性滑块模型,提出一种基于实际水平向与竖向地震加速度-时程曲线的边坡永久位移计算改进方法,以3个工程边坡为例,探讨了两组具有代表性实测典型水平和竖向地震地面运动记录对边坡地震永久位移计算的影响。研究结果表明:不考虑竖向地震加速度时程曲线时,本文方法可蜕化为与前人方法兼容;不同地震波的竖向与水平地震动时程曲线的叠加效应不同,竖向地震对边坡永久位移的影响不可忽略。