Failure Likelihood And Reliability Of Key Block For Jointed Rock Mass Slope

In construction projects,such as mining engineering,communications and transport engineering,hydroelectricity and water conservancy engineering,rock mass slopes exist in bulk.The stability of them has an vital influence on project implementation,which is also hand in glove with discontinuity surface, for example,joints,fissure,fault and weak interbed etc.These discontinuity intersect vertically and horizontally ,which makes great difference in property between it and integrated rock.On that account,we should do deepgoing research on deformation failure mechanism and stability analysis for rock mass slopes.As a significant method for rock mass slope analysis,Block Theory has been used far and wide in engineering field.With embedded study,its theory and method has been broadened and developed continuously.On the basis of project geological investigation, the paper adopts Block Theory together with probability model,orthogonall sensitivity anslysis,reliability calculation of block and numerical simulation to establish computation method for stability analysis of rock mass slope.lt has been applied in the stability evaluation of rock mass slope of BeiJiGe scene zone in NanJing,the result of which contains great theory and practical value.The main achievement for this paper as follows:(1) Combined with concrete project situation of BeiJiGe rock mass slope,the paper makes use of Block Theory to determine the key block on excavation surface.and reckons the joint combination probability and the JP instability parameter for the key block,so the block failure likelihood P(B) is abtained.Then we could apply P(B) into accessing failure probability and decide which key block is the dangerous block(2) Orthogonal experiment design is used to analyze influential factor's sensitivity for dangerous block,and array sensitivity of distinct factors gradedly.The project should pay more attension to the factor of obvious effect.(3) With regard to determined dangerous block,the paper makes use of Monte-Carlo method to calculate failure probability of block of different sizes, considering the random distribution of geometry parameters and mechanics intensity of block globally,and fit the function relationship between failure probability and dividing side length.After putting distribution of joint trace length forward to analyze the formation probability,we could reckon formation probability for block of different size,and achieve density function of formation probability.Block is subregionedaccording to size,and failure and formation probability in distinct region is calculated,so the association probability distribution is abtained to evaluation block stability of different region.Then the easy-failure block region is achieved to offer reference to project design.(4) The stress-strain relationship during slope excavation is simulated by FLAC-3D,and the affection for slope stability of the block formed by weak layer and fault is discussed after excavation.This paper does research on the block stability of slope in terms of displacement,stress field and systemic imbalance force,and enrichs the deficiency research on key block by Block Theory,and evaluates slope stability globally and deeply.