考虑空间变异特性的土坡失稳模式比较分析

Comparative analysis of failure mechanism for spatially variable slopes

用一维稳态随机场模拟了土坡不排水强度的空间变异特性,将随机场中的生成样本视为土坡强度输入参数的确定值,然后利用极限平衡分析方法与强度折减法分别进行了土坡确定性分析,并进行了安全系数与失稳模式的对比.通过30个样本结果的汇总与对比分析发现,简化Bishop法得到的安全系数与有限元强度折减法以及有限差分强度折减法所得结果一致,而基于Morgenstern-Price方法计算的安全系数与强度折减方法得到的安全系数有明显区别.在失稳模式方面,极限平衡方法无法模拟可能会出现的多重滑动面,而有限元以及有限差分强度折减方法却能很好地描述土坡的多种失稳模式.

The spatial variability of undrained shear strength of soil slopes is modeled by a one dimensional stationary random field. For each set of random samples within the generated random field, both the limit equilibrium method and strength reduction method are adopted to conduct the deterministic slope stability analysis in order to obtain the factor of safety （FoS） and the corresponding failure mechanism （FM）. Thir- ty sets of random samples are selected to demonstrate the difference in FoS and FM between the limit equi- librium method and strength reduction method. The comparison has witnessed that the FoS obtained by simplified Bishop method agrees favorably well with that provided by strength reduction method; and that significant difference in FoS has been noticed between Morgenstern-Price method and strength reduction method. For the aspect of failure mechanism, the potential multiple failure surfaces can not be simulated within the concept of limit equilibrium method, whereas this characteristic can be well recognized in strength reduction method.