考虑参数空间变异的高风化岩质边坡可靠性分析

为探讨高风化岩质边坡参数的内在变异性,结合一阶可靠性理论(FORM)、改进拉丁超重要立方采样法(LHIS)的数值分析方法,对实际工程中的高风化岩质边坡进行概率稳定性分析。充分考虑高风化岩质边坡的岩石参数的空间变异性对边坡稳定性的影响,利用LHIS模拟计算得到安全系数的概率分布,同时利用FORM确定临界失稳破坏面的概率进行初步的敏感性分析,从而确定模型输入参数对边坡稳定性的影响;利用Spencer极限平衡法求出失稳破坏面的F_s来评价功能函数G(X)的值,并计算可靠性指标。结果表明:考虑岩石参数的空间变异性比传统单一变量更能真实反映高风化岩质边坡的特征;利用LHIS能比传统的抽样方法明显减少模拟次数,提高效率;可靠性理论及概率稳定性分析方法比传统的极限平衡法更适用于评价岩土参数空间变异的高风化岩质边坡的安全性。

Reliability Analysis of Influence of Spatial Variability of Parameters on Highly-weathered Rock Slope

In this paper,a numerical analysis procedure which integrates the first-order reliability method (FORM) and the modified Latin hypercube sampling technique (LHIS)is adopted in the probabilistic stability analysis to ex-plore the inherent variability of parameters of a highly weathered rock slope in practical engineering.Effects of spa-tial variability of parameters on the slope stability are taken into consideration.The LHIS technique is employed to calculate the probability distribution of safety factor,and meanwhile the FORMis used to determine the critical fail-ure surface and conduct preliminary sensitivity analysis,then the influence of model input parameters on slope sta-bility is obtained.Moreover,Spencer’s limit equilibrium method is employed to calculate the value of Fs of the in-stability failure surface and to evaluate the function G(X)and then to calculate the reliability index.Results reveal that the characteristics of highly weathered rock slope can be more truly reflected by considering the spatial variabil-ity of parameters rather than traditional single parameters;the number of simulation is apparently reduced and the efficiency is improved by using LHIS rather than using traditional sampling method;the reliability theory and proba-bilistic stability analysis method are more suitable to analyze the effect of parameter’s spatial variability on the safe-ty of highly weathered slope than traditional limit balance method.