基于可靠性的围岩失稳规模预测  

Prediction of Instability Scale of Surrounding Rock Block Based on Reliability

作　　者：陈武 晏鄂川[1] 崔学杰[1] 陈前 CHEN Wu;YAN E＇chuan;CUI Xuejie;CHEN Qian(Faculty of Engineering,China University of Geosciences（Wuhan）,Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉)工程学院,湖北武汉430074

出　　处：《安全与环境工程》2018年第5期36-43,共8页Safety and Environmental Engineering

基　　金：国家重点基础研究发展计划(973计划)项目(2011CB710605)

摘　　要：块体理论中,当结构面未能完全贯通所研究的岩体时,会形成无限块体。现有研究均将无限块体视作稳定的,认为其破坏的概率为零。假设结构面为薄圆盘状,考虑三组未贯通结构面和临空面切割的空间几何关系,确定岩体中形成棱台状的潜在失稳块体,并建立块体失稳的力学模型,推导出不同运动模式时块体的失稳判别式。结合构建的潜在失稳块体模型,提出了一种基于可靠性的潜在失稳块体失稳规模(即失稳体积范围)的预测方法:该方法利用Unwedge程序确定给定临空面尺寸和结构面间距下的最大三棱锥块体,其即为结构面在临空面上可能形成的最大块体;以此为基准,运用Monte-Carlo法分别求解不同线性比下结构面直径随机分布时生成块体的体积和安全系数;通过数据整合与分析,可获得不同体积的潜在失稳块体的形成概率和失效概率,并选取一目标失效概率为阈值,即可计算得到潜在失稳块体失稳体积的预测范围。以黄岛地下水封洞库为例,利用提出的预测方法,计算得到以目标失效概率为0.001时潜在失稳块体失稳体积的预测范围:巷道顶板为0~10.900m3,巷道左边墙为0~1.681m3,巷道右边墙为0~1.630m3。该预测结果可为地下工程设计与施工提供可靠的依据。In block theory,an infinite block is formed when the structural plane fails to completely penetrate the rock mass studied. Most of the previous studies treat the infinite block as stable,and consider the prob ability of its destruction as zero. Assuming that the discontinuity is a thin disk and considering the geomet rical relationship by the cutting of the three groups of non through discontinuities and the open face, this paper determines the pyramidal potentially unstable blocks formed in the rock mass and establishes the me chanical model of block instability,then deduces the criterion of block instability under different modes of motion. Combined with the above potentially unstable block model, the paper proposes an approach to pre dict the scale of the unstable block based on reliability. Via the Unwedge program, the maximum triangular pyramid block under the open face of given size and discontinuities can be determined,which is the largest block that the discontinuities might form on the open face. Based on it, the volume and factor of safety of each formed block with randomly distributed diameter under different linear ratios can be obtained by using the Monte Carlo method. Through the integration and analysis of the data obtained,the formation probability and failure probability of unstable blocks of different volume can be solved,and the target failure proba bility is selected as the threshold to get the prediction scale of the potential block volume. Taking the Huangdao water sealed underground cavern as an example, according to the proposed method, the prediction of block instability scale by taking 0. 001 as the target failure probability are as follows： on the top plate,it is 0-10. 900 m^3;on the left wall,it is 0-1. 681 m^3;and on the right wall,it is 0-1. 630 m^3. The prediction results can provide a more reliable basis tot the design and construction ot underground engineering.

关 键 词：潜在失稳块体 失稳规模预测 可靠性分析 Unwedge程序 MONTE-CARLO法 目标失效概率 

分 类 号：X45[环境科学与工程—灾害防治] TU9[建筑科学]