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.     

Research on Evaluation of the Slope Stability Based on the Extension Theory

The stability of rock-mass slopes is a very complicated system which is controlled by lots of factors. It is always a very important research subject to evaluate the slope stability reasonably through some evaluation methods. Based on matter-element theory and dependent function,the extension theory is applied to evaluate the stability of rock mass slope,and the extension method for the stability of rock mass slopes is proposed. Taking a real slope project for example,based on the reasonable selection of evaluation factors of slope stability,an extension model for evaluation of slope stability is built,whose result is contrasted with the fuzzy evaluating one. As a result, it is practical and feasible to apply the extension method to estimate the rock slope stability.     

Deformation and Failure Model Test of Steep Dip Excavation Bedding Slope under the Action of Seismic Load

In the Wenchuan earthquake, steep dip bedding slope is a kind of slope that seismic mountain disaster very development and the slope earthquake disaster is often exacerbated by the excavation. In order to reproduce the process and analysis regularity of slope deformation and failure under the action of seismic load. The author chooses San Shuping landslide located Pingwu County as the typical examples of steep dip excavation damage bedding slope, and the indoor physical model test of slope deformation and failure under the action of seismic load are carried out. The results show that slope deformation and failure is intensified by the excavation. Collapse and sliding is the main form of failure and the results consistent with the field investigation. From the whole process of deformation and failure of view, it can be divided into the four stages. First, the initial phase of the earthquake. A wedge rock by excavation small slides along the rock layers and the slope toe stress increase sharply under the action of seismic load in this stage. Second, rock layers by excavation break-bend at slope toe. Third, the rock layers by excavation overall decline stage. Last, the rock slide blocked and dumping.     

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.     

高陡边坡整体与局部失稳的强度折减及安全度判别分析

为了实现从整体和局部都能较为准确地分析弧状高陡边坡安全稳定性,指导露天采矿高陡边坡设计,采用有限差分强度折减法分析边坡稳定性,获得边坡整体的安全系数。对每个计算单元引入安全度进行分析,获得边坡局部安全系数;将最大节点位移时步曲线收敛性作为边坡失稳的判定准则,弥补了采用其他准则时由于人为指定容差而引起的较大误差;以某铁矿西南边坡为例,运用FISH语言编制强度折减法、失稳准则和安全度相关程序进行计算。研究表明：有限差分强度折减法、基于最大节点位移时步曲线收敛性的失稳准则和计算单元安全度相结合的边坡稳定性分析方法适合于弧状边坡稳定性分析,研究为弧状高陡边坡设计提出了新的思路。     

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     

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.     

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.     

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.     

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.     

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.     

生物炭对山坡地烟叶产量和氮肥利用效率的影响效果评价

山坡地土壤有机质含量低和保水保肥能力差是导致烤烟产量普遍低于山间平地的重要原因之一。生物炭可以改善土壤物理化学性质,提升土壤保水保肥能力,本试验研究其对烤烟产量和氮肥利用效率的影响。通过二因素两种地形（山坡地、山间平地）和6个生物炭施用量处理（0、4.5、9.0、13.5、18.0、22.5t/hm ²）的大田试验,评价生物炭对烟叶产量和产值、烟株农艺性状、氮肥利用效率和氮素表观损失量的影响。结果表明,山坡地烤烟产量和产值显著低于山间平地。同一生物炭施用量条件下,山坡地烟叶产量和产值相对增幅显著高于山间平地。当生物炭施用量介于0~13.5t/hm ²时,山坡地烟叶产量和产值均随生物炭施用量增加而显著增加;而进一步提高生物炭施用量,烟叶产量和产值增加不显著。山间平地烟株氮素吸收量、氮肥农学利用率和氮肥回收利用率均显著高于山坡地烟株。与不施生物炭的对照相比,山坡地烟株氮肥农学利用率和氮肥回收利用率相对增幅均显著高于山间平地烟株。随着生物炭施用量增加,氮素表观损失量显著降低。相对于山间平地而言,山坡地植烟区应用生物炭的增产增收和提高氮肥利用效率的效果更加显著,其适宜生物炭施用量为13.5t/hm ²。     

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。     

农业灌溉作用下黄土边坡失稳引起耕地流失分析

为了明确在大面积农业灌溉作用下，水分入渗土壤进而渗入下部黄土体，改变临空耕地黄土边坡的稳定性状态，造成边坡失稳引起耕地流失的过程。在统计分析甘肃天水耕地流失面积、农田灌溉面积、地质灾害数量和由地质灾害造成耕地流失比例的基础上，在典型地层剖面上采集原状土壤和黄土试样，进行天然状态和灌溉作用下土体的物理力学性质和抗剪强度试验，采用理正岩土边坡稳定性分析系统，利用基于极限平衡条分法的瑞典法进行边坡稳定性定量分析。结果表明：在天然状态下，该边坡稳定性系数为1.074，处于基本稳定状态；而在灌溉作用下，随着水分入渗深度的增加，稳定性系数逐步降低，最后失稳。因农田灌溉仅使土壤层饱和，对该边坡稳定性影响不大；当灌溉水持续入渗使饱和层土体厚度大于2 m时，该边坡稳定性降低一个等级，处欠稳定状态；当饱和层厚度大于10 m时，该边坡失稳，发生滑坡，造成耕地流失。     

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.     

Stability Analysis of Rock Cave Ground under High-rise Buildings

This paper presents an all-side study on one successful engineering project, the Chongqing Zhourong Plaza, twenty floors high with two air raids caves just cross under it. The study includes geological investigation, rock mass parameters choice, elastic-plastic rock mass failure criteria, calculation with finite element method, results analyses, conclusions on stability analyses and construction suggestions.     

Epigenetic Reformation of Rock Mass in Dam Area of Xiluodu Hydropower Station

By investigating the space development rule of the epigenetic deformation and fracture trace and the combination pattern of epigenetic structure in dam area of Xiluodu hydropower station, the formation mechanism of epigenetic reformation is discussed in conjunction with the analysis of geologic physiological evolvement mechanism. Slaty rock mass structures which being made up of flat faults have played important role in controlling epigenetic reformation. The typical combination pattern of epigenetic structure is formed from steep dipping and flat faults. It is very important for understanding the feature of valley rockmass structure.     

基于Logistic回归方法的林芝市山洪地质灾害预警研究

为研究林芝市的山洪地质灾害的成因,针对降水、土地利用、土壤类型、坡度和植被指数等因素进行了分析。结合环境地质和降水时空分布特征,使用Logistic回归方法建立了山洪地质灾害的概率区划。依据灾害当前及前六天的日降水数据,通过Logistic回归模型建立了山洪地质灾害预警模型。研究发现,林芝市的大部分地区山洪地质灾害发生概率低于40%,概率在40%以上的区域约为1.8万平方公里,约占林芝市面积的14.8%。与实际发生情况对比印证,发现该预警模型对于山洪地质灾害预测的准确率为87.2%,而无灾害预测的准确率高达97.7%。     

A massive development mechanism and countermeasures for perilous rocks in the Three Gorges Reservoir area of P. R. China: The example of the Taibaiyan cliff at Wanzhou

Perilous rock is a dominant geological hazard in Three Gorges Reservoir area of P. R. China. The Taibaiyan cliff at Wanzhou is a representative case of massive perilous rocks in the area. Using this cliff as an example, the conditions triggering massive perilous rocks were studied and described. This included examining the following three conditions: alternating layers of mudstone and sandstone; steep landforms such as cliffs or scarps; and intense rainfall. The massive development mechanism for perilous rocks was discussed, including micro chained pattern gradual and interval evolution from the bottom to the summit of the cliffs individually as perilous rock, and a macro chained pattern evolving stage by stage from the cliff face backward up the mountain. In some respects, rock cells below sandstone in cliffs serves as the pulsating valve of the massive development mechanism for perilous rock. In any micro chained pattern, perilous rock situated on summits is the easiest to rupture due to the fissure pressure. For any single perilous rock, two load compositions were derived. In addition, methods for analyzing perilous rock stability were established in detail using the limit equilibrium principle. Two key techniques, a union scheme that both supports and anchors and a union scheme that nails and anchors, are proposed in light of the massive development mechanism for perilous rock.