在对边坡进行可靠度分析时,通常选择强度参数均值对应的确定性临界滑面或最小可靠度指标对应的概率临界滑面作为计算滑面,前者为确定性滑面上的可靠度指标,并非最小可靠度指标,后者作为边坡体系可靠度的近似,更接近于边坡的实际破坏概率。Hassan和Wolff提出的概率临界滑面计算方法,基于强度参数的特定组合,进行几次稳定性计算确定最小可靠度指标对应滑面,简便易行,无需专用的可靠度分析软件。为证明该方法的有效性,将其运用到简单均质土坡与非均质土坡算例中,并将工程中常用的正交设计运用到可靠度计算中,进行对比分析。结果显示:2个算例均表明最小可靠度指标对应的滑面与参数组合中最小安全系数对应的滑面相一致。因此,在工程应用中,可以采用该方法确定最小可靠度指标对应滑面。

In probabilistic slope stability analysis, the selection of slip surface for calculation usually varies from critical deterministic surface to critical probabilistic surface. The reliability index for the former is not the minimum based on a deterministic surface, the latter is closer to the actual failure probability as a similarity to reliability of the slope system. In this paper, a technique put forward by Hassan and Wolff for the determination of slip surface with the minimum reliability index is presented. The critical probabilistic surface could be simply determined by several stability calculations according to specific combinations of soil parameters, which requires no special programs. The method’s validity is examined by two cases including simple homogeneous and heterogeneous soil slopes. Besides, the orthogonal design is applied to slope stability analysis for comparison. The results show that the critical probabilistic slip surface corresponding to the minimum reliability index conforms well with the surface corresponding to a minimum safety factor according to the combinations of soil parameters. Therefore, the critical probabilistic slip surface could be determined by this method in engineering applications.