考虑承压水影响的基坑抗隆起稳定性上限分析

Analysis of stability against upheaval of deep excavation by upper bound method considering confined water

摘要:

考虑基坑底部的承压水作用效应，假定Prandtl的土体滑移破坏形式，采用极限分析的上限定理建立了基坑抗隆起稳定性分析方法及其验算公式，讨论了承压水头大小、不透水层厚度以及挡土墙插入深度等因素对于基坑抗隆起稳定性的影响。工程实例的计算结果表明，坑底承压水对于基坑抗隆起稳定性的影响不可忽视，承压水头越大，基坑抗隆起稳定性安全系数越低，将本文算法与传统算法的结果进行了对比，体现了该方法的适用性和优越性。本研究结果为软土地区基坑底部有承压水层作用时的基坑工程设计提供了一种较为合理的分析计算方法，具有一定参考价值。

Abstract:

Assuming the Prandtl soil slip failure models and considering the confined water, the upper-bound limit analysis theory is used to establish the analysis method of the basal stability against upheaval and checking formula. With the proposed formulas, the effect of the confined water head, the thickness of the impermeable soil layer and the depth of the retaining wall on the stability coefficient are discussed. Calculation results indicate that it is necessary to consider the effect of the confined water on the stability against upheaval of deep excavation; and the safety factor would be smaller with the increase of the confined water head. The comparison demonstrates the applicability of the method used in this paper. The results provide a reasonable calculation method for the design of foundation pit subjected to confined water in soft clay.