重力坝坝基失稳模糊-随机风险率计算方法研究

Research on calculation method of fuzzy-random risk for instability of gravity dam foundation

基于重力坝坝基抗滑稳定各影响因素的随机性、模糊性以及失稳准则的模糊性,研究了坝基失稳模糊风险数学模型的求解方法,建立了基于安全系数的模糊随机极限状态方程,对设计参数的模糊采用计算简便的α水平截集法,而对失效准则的模糊采用降半梯形隶属函数。工程实例计算表明:此方法比参数与失效准则均采用α水平截集法时得到的模糊风险率区间值更趋合理,模糊风险分析计算得到的坝体安全结论也与现行规范的确定性方法一致。

Based on the randomness and fuzziness of factors influencing dam foundation stability against sliding and the fuzziness of instability criterion, a solving method of the mathematical model for fuzzy risk analysis of gravity dam foundation instability was studied. On the basis of the safety factors, fuzzy-random limit state equation was established. Further, α-level-cut method was used in the fuzzy processing of design parameters in the model and lower semi＇trapezoid membership function was used to fuzzily process the instability criterion. By analysis on an engineering example, concerning the resuhs of fuzzy risk interval value, the method given in this paper was proved more reasonable than the method in which the design parameters and the instability criterion were both fuzzily processed by α-level-eut method. As well, dam safety assessment conclusion by fuzzy risk analysis was corresponding with that by the deterministic approach in current design code.