边坡稳定的模糊随机有限元可靠度分析

Fuzzy random finite element reliability analysis of slope stability

边坡工程中同时存模糊性与随机性,应进行边坡稳定的模糊随机可靠度分析。在边坡稳定的随机有限元可靠度分析的基础上,提出了边坡稳定的模糊随机有限元可靠度的敏感性分析方法,它可以利用随机有限元分析的相应程序,能同时考虑参数的模糊性与随机性,能同时求得边坡的模糊可靠指标及模糊滑面位置。该方法利用了随机有限元敏感性分析的结果,在模糊截集上只需进行两次随机有限元分析即可求得该截集上可靠指标的极值,因此计算效率较高。算例分析表明:随着参数变异系数的增加,边坡的模糊可靠指标明显减小;对于均质土坡,模糊滑面的位置相对集中,形成模糊滑带;对于非均质土坡,模糊滑面的位置受边坡破坏机理的影响,参数的微小变异可能导致滑面位置发生较大变化。

It is necessary to carry out fuzzy random reliability analysis of slopes because there are fuzziness and randomness simutaneously. Based on the stochastic finite element reliability anaylsis of slope stability, a sensitivity analysis method of fuzzy random finite element reliability analysis of slope stability is presented. It can make use of the existing codes of stochastic finite element reliability anaylsis, can consider fuzziness and randomnress of parameters at the same time, and can get both the possible distribution of fuzzy reliability index and the positions of fuzzy slip surfaces. Since the method is based on the results of sensitivity analysis of stochastic finite element, the maximum and minimum values of the reliability index on a certain fuzzy cut can be obtained by running the stochastic finite element reliability analysis only twice, which means that this method is very efficient. It is demonstrated by two examples that the reliability index will decrease when the coefficients of variation increase. For a uniform slope, the positions of fuzzy slip surfaces are relatively concentrated. Therefore, there is a fuzzy slip zone in the uniform slope. However, for a two-layer nonuniform slope, the positions of fuzzy slip surfaces arc affected by the failure mechanism, and the small variation will probably induce a relatively large change of the positions of slip surfaces.