基坑土钉支护边坡有限元稳定性分析方法探讨

针对基坑土钉支护开挖边坡的稳定性，讨论了极限平衡方法的局限性，指出应用有限元方法分析评价基坑土体结构稳定性是近年来研究的新趋势。采用滑面应力分析法和强度折减法两种有限元方法对基坑边坡的稳定性进行了研究。对于无支护的基坑边坡，两种有限元方法得到的安全系数和滑动面结果一致，且滑动面形状随基坑土体强度的降低保持不变。对于采用土钉支护的基坑边坡，两种有限元方法得到的安全系数结果一致，不同阶段下滑动面形状和位置不同，这主要是由于在强度折减时，仅仅对土体强度参数进行折减，而未考虑土钉自身强度的降低。最后指出，在应用强度折减法时，是否考虑土钉自身强度的折减有待进一步研究。

Research of FEM stability analysis of soil Nailing support for foundation pit

In connection with slope stability of soil nailing support for foundation pit, the authors discuss the shortcomings of limit equilibrium method and indicate that the FEM stability analysis is new trend to evaluate the stability of foundation pit. The slip surface stress analysis method and strength reducion method are used to analyze the stability of soil nailing support for foundation pit. For the slope without supporting foundation pit, the results of safety factor and critical slip surface obtained by two finite element methods are consistent and the shapes of critical slip surface keep sameness with the reduction of strength parameters with soil. For the slope with soil nailing support for foundation pit, the safety factors by two finite element methods are consistent; but the shapes of critical slip surface are inconsistent in different stages. The reason is that only the strength of the soil and the cement deep mixing pile are reduced during the process in the calculation; and the strength parameters of the nail bar are regarded as constant. Finally, the authors indicate whether or not considering the reduction of soil in strength reducion method with FEM waits for further research.