Fuzzy reliability analysis for deep sliding stability of gravity dams

With regard to the fuzziness of limit state in the deep sliding stability of gravity dams, the fuzzy response surface method is put forward to analyze the reliability, including algorithm of fuzzy response surface method and determination of membership function. The concept of primary limit state and subordinate limit state is proposed for the fuzzy response surface method. The safety factor is endowed with general meaning, and the limit state equation is established with the combination of safety factor method and reliability theory. Both the traditional reliability index and fuzzy reliability index are calculated based on strength reduction method. The results show that the reliability indices and safety factor meet the design specifications, but the fuzzy reliability index is smaller than traditional reliability index. It´s proved that the results from reliability theory and strength reduction method are consistent with each other, and can make up the shortcomings for each other. It´s recommended that the safety level should be raised to take account of the fuzziness of limit state when strength reduction method is used to analyze the deep sliding stability of gravity dams.