SMW工法支护结构失效概率的模糊事故树分析

Fuzzy fault tree analysis of failure probability of SMW retaining structures in deep excavations

针对常规事故树不能考虑基本事件发生概率的不确定性这一现状,通过引入模糊集的概念,将常规事故树中基本事件的发生概率模糊化,用三角形模糊数代替确定性发生概率,应用模糊数截集方法,推导了模糊事故树的相关算法。采用模糊事故树方法得到深基坑工程SMW工法支护结构的模糊失效概率,并进行了敏感性分析,找出对顶事件发生概率影响较大的基本事件,确认减小SMW工法支护结构发生事故的相关措施。与常规事故树方法比较表明,模糊事故树方法不仅能达到常规方法的分析目的,而且可以得到深基坑支护工程失效可能性的分布规律。

Single probability in traditional fault tree analysis was used to represent each basic event. However, it was unrealistic to evaluate the occurrence of a top event with a crisp value without considering the inherent uncertainty and imprecision of each basic event. The fuzzy set theory could be used to deal with this kind of phenomenon. A triangular fuzzy number was introduced to represent the failure probability of a basic event. Fuzzy fault tree algorithm was developed by the cut method. The fuzzy failure probability of SMW retaining structures in deep excavations was calculated by a fuzzy fault tree. Main basic events affecting the occurrence probability of the top event were verified by a sensitivity analysis, which could be applied in the risk analysis of SMW retaining structures in deep excavations. Compared with the traditional fault tree analysis, the fuzzy fault tree method could not only reach the same goal as the traditional method but also get the failure possibility distribution of SMW retaining structures in deep excavations.