【摘要】 岩质边坡稳定的可靠度分析中包含多个相关的失效模式,传统的岩质边坡体系可靠度分析方法不能有效地考虑多失效模式相关的体系可靠度问题。为此,提出考虑多失效模式相关的岩质边坡平面滑动的体系可靠度分析方法。建立考虑多失效模式相关的岩质边坡平面滑动体系可靠度分析的概率故障树模型。采用β分布描述岩质边坡稳定分析中张裂缝的位置、岩体的黏聚力和内摩擦角。张裂缝中充水深度用截尾指数分布来描述。采用自适应重要抽样方法计算岩质边坡平面滑动的体系可靠度,并进行随机变量分布参数的敏感性分析。算例结果表明,概率故障树模型能够有效地分析岩质边坡多失效模式相关的体系可靠度问题,如果不考虑失效模式间的相关性对边坡体系可靠度的影响,岩质边坡的体系可靠度将会被低估。岩质边坡2个块体之间不发生相互作用的可能性明显地比2个块体之间发生相互作用的可能性要高。建议在进行岩质边坡体系可靠度分析时将张裂缝中充水深度系数取为区间[0.0,1.0]内的截尾指数分布。此外,变量的均值敏感性因子和标准差敏感性因子都表明,张裂缝中充水深度和张裂缝位置对边坡的体系可靠度影响最大,因此设置良好的边坡排水系统以及进行详细的地质勘测工作是提高边坡稳定性的有效措施。变量的均值和标准差敏感性因子之间是高度相关的,它们都可以用来识别最敏感的随机变量。更多还原

【Abstract】 It is aimed to propose a systematic quantitative method for system reliability analysis of rock slope with plane failure considering multiple correlated failure modes.A probabilistic fault tree approach is presented to model system reliability of rock slope considering multiple correlated failure modes.The versatile 4-parameter β distribution is used instead of a normal distribution or a lognormal distribution,which is adopted for describing the location of tension crack,the cohesion along the failure surface and the friction angle.The truncated exponential distribution is used for the percentage of tension crack filled with water.The adaptive importance sampling(AIS) method is employed to perform the system reliability analysis of rock slope with plane failure.System reliability sensitivity with respect to distribution parameters of random variables is performed.Results from a numerical example indicate that the system reliability of rock slope considering multiple correlated failure modes can be effectively evaluated using the probabilistic fault tree approach,which will be underestimated without considering the correlation between failure modes.The failure mode of block A failing without interaction force due to block B has the higher probability of failure than that for the failure mode of block A with interaction force due to block B.Both the mean sensitivity coefficient and the standard deviation sensitivity coefficient indicate that the percentage of tension crack filled with water and the location of tension crack are significant random variables with higher sensitivity coefficients.Therefore,to improve the slope stability effectively,a good drainage system of the slope should be designed and a detailed geological investigation of discontinuities in the rock mass should be conducted.The mean sensitivity coefficient and the standard deviation sensitivity coefficient are strongly related and both can be used to identify key contributing random variables.更多还原