The Fuzzy-random Reliability Analysis Of Slope Safety Of Open-pit Mine

The safety analysis of slope engineering is a hot researching spot of the geotechnical engineering field at home and abroad. Conventional analysis methods are based on determinative value(such as the limit equilibrium method). They don't consider the uncertainties of slope engineering which include slope load, physical mechanial parameters and so on. Actually, the uncertainties of slope engineering have the characteristics of randomness and fuzziness. So conventional analysis methods cannot reslove the fuzzy-random uncertain problems of slope engineering.Based on the discussion of fuzzy-random uncertain problems of slope engineering, this paper studied two methods which consider the uncertainties of slope engineering,established a fuzzy synthetical evaluation united model and fuzzy-random reliability computational model , then analysed the fuzzy-random reliability of slope safety of open-pit mine. The main contents and conclusions are as follows:(1) This paper summarized the current methods and researches of stability analysis of slope; discussed the fuzzy-random uncertain problems of slope engineering of open-pit mine; then pointed out that the method of fuzzy synthetical evaluation and fuzzy-random reliability can reslove the fuzzy-random uncertain problems of slope engineering.(2) This paper established a fuzzy-random reliability computational model. It applied fuzzy mathematics into reliability analysis, studied the fuzzy-random reliability method; put forward two computational methods, which were based on subordinate function of safety coefficient and fuzzy limit state equation; introduced three different subordinate functions of safety coefficient ; established a united fuzzy-random reliability computational model of randomness and fuzziness.(3) This paper applied Fault Tree Analysis(FTA)to analyse the slope safety of open-pit mine. Influential factors of slope accident were divided into natural disasters, artificial disasters and the destructions of human project,then a FTA model of slope accident was constructed. The possible least path leading to accident was investigated; the basic approaches for accident prevention were put forward; the structural importance of each basic event was studied by qualitative analysis. It provided a foundation for a choice of effective method of evaluating the stability of slope, reasonable and economical plan for controlling slope.(4) This paper constructed a fuzzy synthetical evaluation united model of slope stability of open-pit mine. Considering the uncertainty of slope engineering, the concept of 'subordinate degree' in fuzzy mathematics was applied to describe the transformation from 'affirmation' to 'negation' by using the figures from 0 to 1. Fourteen influential factors were chosen to analyse slope stability; according to different stability condition, state of slope stability were divided into five grades; subordinate functions of quantitative and qualitative influential factors were constructed; Analytic Hierarchy Process(AHP) method was used to decide the first weight and the second weight of influential factors. The method of two class synthesis assessment was adopted to analyse two examples. The analysis result shows that the fuzzy synthetical evaluation model constructed in this paper can be regarded as a united model of slope stability of open-pit mine.(5) It took slope plane failure as a computational model, analysed the flizzy-random reliability of slope safety. The analysis result shows that the analysis method of flizzy-random reliability, which considers the uncertainties of variable and destroy rule, is reasonable and practical. The result of using subordinate function which is based on practical experience is more accurate and closer to practice than subordinate function which is based on probability theory.