断续结构面控制的危岩稳定可靠度分析方法

Reliability analysis method on unstable rock mass controlled by discontinuous structure

滑动破坏模式下的危岩体稳定可靠度多受断续结构面控制,结构面连通率、分段强度与危岩所受作用力参数的变异性使得危岩可靠度存在不确定性,为此,提出断续结构面控制的危岩稳定可靠度分析方法.基于蒙特卡罗法建立考虑结构面与危岩所受作用力参数不确定性的危岩体可靠度计算方法,结合正交试验分析各因素对应失稳概率的敏感性并确立主导因素,最终通过响应面设计,分析主导因素参数变异性对可靠度的影响规律.南门湾危岩带研究表明,连通率与未贯通段黏聚力为影响危岩体可靠度的主导因素,二者参数的变异性对危岩体可靠度的影响规律受其均值大小控制,当参数均值的取值使得危岩体趋于失稳状态时,其失稳概率随变异系数减小而升高,低变异性参数可能导致可靠度评估过于保守;当参数均值的取值使得危岩体偏向稳定状态时,变异系数同失稳概率呈正相关,低变异性参数可能造成危岩体可靠度的非保守估计.所得结论可为该类危岩体可靠性评价工作提供参考.

The stability and reliability of unstable rock in the sliding failure mode are controlled by the discontinuous structure.The variability of the connection rate of the structural plane,the section intensity parameters,and the force on unstable rock exerts high degree of uncertainty on the reliability of unstable rock.This paper presents a method for the reliability analysis of unstable rock controlled by discontinuous structure.Based on Monte Carlo method,the reliability calculation method of unstable rock mass with uncertain structure and uncertain force parameter was established.The sensitivity of each factor corresponding to the instability probability was analyzed and the dominant factor was determined by orthogonal test.Through the response surface design method,the influence of the dominant factor parameter variability on reliability was analyzed.The study on the Nanmenwan unstable rock belt shows that the connection rate and cohesion of unbroken segment are the main factors that influence the reliability of the rock mass,and the influence of variation of the two parameters on the reliability of unstable rock mass is controlled by their mean size.When the selected mean value causes the unstable rock mass to become unstable,the probability of instability will increase with the decrease of the coefficient of variation and the low variability will lead to an overly conservative assessment of reliability.The coefficient of variation is positively correlated with the probability of instability as the mean tends to be the stable segment of the unstable rock mass,and low variability parameters may result in a non-conservative estimate of the reliability of hazardous rocks.The study provides references for the reliability evaluation of this kind of unstable rock.