岩质边坡稳定的体系可靠度分析及工程应用

Systematic Reliability Analysis of Rock Slope Stability and Its Engineering Application

对岩质边坡存在多个滑动面时的体系可靠度进行分析,可以对边坡的稳定性作出更加合理的评价。采用非线性有限单元法,通过降低岩体的强度参数,寻找边坡的潜在滑动面,并定义滑动面上所有单元同时破坏时,作为边坡的失稳模式;针对岩体破坏的特点,按Druker-Prager屈服准则和单轴抗拉强度准则构建失稳模式中单元的功能函数,再采用响应面法和蒙特卡罗法计算单元的可靠指标和相关系数;单一失稳模式是由滑动面上的单元组成的并联体系,为此,研究了一种逐步等效线性化求交法用于计算单一失稳模式的可靠指标;最后,用Ditlevsen窄界限公式估算由各失稳模式组成的串联体系的可靠指标。上述方法得到的可靠指标可用于边坡的稳定性评价。作为工程实例,对某水电站左岸坝肩边坡的体系可靠度进行了分析和评价,验证了本方法的合理性和可行性。

Stability can be evaluated more reasonably by analysis of systematic reliability of rock slope with various sliding surfaces. Using nonlinear FEM, the possible sliding surfaces could be found by reducing rock strength, and a failure mode is defined that all the elements of the sliding surface are destroyed synchronously; According to Druker-Prager yield rule and uniaxial tensile rule, the performance functions of elements are built, the reliability indexes and correlation coefficients are computed by response surface method and Monte-Carlo method; Each failure mode is a parallel system consist of the elements of each sliding surface, so a stepping equivalent linear method was researched to calculate the reliability index of each failure mode. Finally, the reliability index of the series system composed by all failure modes can be estimated by Ditlevsen narrow-bound method. The reliability index gained from the above method can be applied to appraise slope stability. For example, the systematic reliability of a slope was analyzed, which shows the method is rational and feasible.