为了对强风化岩块组成的岩石边坡的稳定性进行评价,通过一次二阶矩法、蒙特卡罗模拟和有限差分数值分析相结合的方法对其进行了可靠性分析和研究。首先,将岩石边坡等效为连续介质体,利用等效连续模型获得强风化岩石边坡的特征参数,之后,将岩石边坡的岩土材料参数定义为二维空间变异参数,并通过一次二阶矩法建立了变异参数的不确定性模型;然后,利用蒙特卡罗模拟了岩土参数的空间变异性;最后,利用有限差分的方法研究了协方差、相关距离对安全系数和可靠性指标的影响。结果表明:岩土工程参数空间变异性对特定岩石边坡的稳定性评价具有很大的影响;强风化岩石边坡的安全性评价不能仅凭单一参数值确定;随着岩石边坡参数协方差的增大,可靠性指标值逐渐减小,安全系数逐渐减小;随着自相关距离的增大,可靠性指标逐渐增大。因此,应在边坡常规分析和设计过程中充分考虑岩土工程参数空间变异性。

Reliability analysis on highly weathered rock slope stability is carried out by means of a combination of first order two moment, Monte-Carlo simulation and finite difference numerical analysis. Firstly, the rock slope is treated as a continuous medium, and the characteristic parameters of the highly weathered rock slope are obtained by using equivalent continuum model. Subsequently, the material parameters of rock slope are defined as two-dimensional variable parameters, and the uncertainty model of the variable parameters is established by employing the first order two moments method. Then the spatial variability of geotechnical parameters is simulated by Monte-Carlo method. Finally, the influence of covariance and autocorrelation distance on safety factor and reliability index is researched by using finite difference method. Results show that the spatial variability of the geotechnical parameters has great influence on the evaluation of specific rock slope stability. The safety assessment for highly weathered rock slope could not be determined by single parameter. As covariance of rock slope parameter increases, the reliability index and safety factor reduce gradually; and with the increase of autocorrelation distance, reliability index increases gradually. Therefore, the effects of spatial variability of geotechnical parameters of rock slope should be considered in conventional slope analysis and design process.