基于模糊故障树的抗浮锚杆系统失效分析

Failure analysis of the anti-floating bolt system based on the fuzzy fault tree

针对抗浮锚杆系统失效分析中很难获得底事件精确概率的问题,将故障树理论与模糊数学方法相结合,对抗浮锚杆系统失效概率进行了分析。首先,通过对抗浮锚杆系统的结构破坏危险源和上浮失稳危险源进行层层分析,构建了抗浮锚杆系统故障树模型,采用上行法对该模型进行逐层展开,确定了13种最小割集。然后,采用德尔菲法获得专家对底事件失效概率的评判语言,再利用三角和梯形模糊数对这些自然语言进行表达。最后,根据模糊数学方法计算底事件和顶事件的模糊失效概率,确定抗浮锚杆系统失效事故属于可能发生级。

Aiming at overcoming the difficulty on how to obtain the accurate probability of the bottom event in the failure analysis of the anti-floating anchor system,this paper has analyzed the failure probability of such a system by combining the fault tree analysis theory with the fuzzy mathematics method.To achieve the purpose,we have analyzed the structural damage hazards and the floating instability hazards of the anti-floating anchor system layer-by-layer,step-by-step.As a result of the analysis,it would be possible to find that the structural hazards of the said system may include the following steps:the anti-floating anchor damage s,the foundation floor damage and the rock--soil destruction damage.Since the risk sources of the floating instability should include the local floating instability and that of the overall floating,we have to further determine the bottom events according to the failure mechanism of the anti-floating anchor structure and the floating instability mechanism.The above analysis results help us to build up a fault tree model of the anti-floating anchor system.The said fault tree model has been,as a matter of fact,can be expanded layer-by-layer,whose 13 minimum cut sets can be analyzed and determined with the upstream method.And,then,the paper has also established a fuzzy set of the evaluation language for the failure probability of the bottom events,which can be divided into seven grades.This is because,for the different credibility degrees of the different experts,each of them feels needed to be empowered in their data and information acknowledgement by the expertise.To achieve the purpose for the experts to own the necessary information and the factual situation,the paper has taken the Delphi method to gain the expert's own natural language to assess the failure probability of the bottomevents.Actually,the given paper has used the triangular and trapezoidal fuzzy functions and the expert weights to transform the natural languages into fuzzy numbers so as for them to represent the necessary real numbers and different membership functions by converting the expert's evaluation of natural language quantization into a fuzzy set.And,in so doing,the method of the fuzzy mathematics can be in a position to transform the fuzzy number or numbers of the bottom events into the fuzzy probability values of FPS of the bottom events included.For,only in such a manner can the paper transform the fuzzy probability value FPS into the fuzzy failure probability FFR of the bottom events.And,consequently,the given paper will be able to determine the fuzzy failure probability of the anti-floating anchor system in accordance with the probability formula of the top events in the fault tree method.Only in so doing,can the calculation results be able to show that the failure of the anti-floating anchor system belongs to a possible level of the authentic actuality.