以可靠度理论为基础,分别对以安全系数和破坏概率为目标的反算法进行讨论。根据楔形体破坏极限状态函数,运用Monte Carlo方法对一核电工程基坑边坡楔形体破坏进行反分析,用破坏概率表征破坏边坡的临界状态,指出以临界安全系数为目标的反分析法存在的不足,认为直接以破坏概率作为反算目标更为简单合理,并结合工程实例讨论黏聚力和内摩擦角的变异系数、截尾位置、相关系数等参数设置对反算结果的影响。研究结果表明,采用反算法得出的结构面抗剪强度值更符合实际,对工程实践具有指导意义。
The method of back analysis targeted on factor of safety and failure probability is introduced on the basis of reliability theory. According to the limit state function of wedge failure, Monte Carlo method is applied to back analysis of wedge failure of foundation pit slope in a nuclear power engineering. The limit state of failure slope is represented by failure probability. It is found that the back analysis method targeted on failure probability is more proper and reasonable than that targeted on critical factor of safety, for the latter has some deficiencies. Combined with case study, the effects of variation factor of cohesion and internal friction angle, truncated location, and correlation coefficient on the results of back analysis are discussed. The results show that the shear strength of structural surface obtained by back analysis is more realistic, and it can guide engineering practices.