考虑承压水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 with a Consideration of Confined Water

考虑基坑底部的承压水作用效应,假定Prandtl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.将本算法与传统算法的结果进行了对比,该方法能够体现出承压水对软土基坑稳定性所产生的风险.

Based on the assumption of the Prandtl soil slip failure models and the consideration of the effect of confined water,the upper-bound limit analysis theory is adopted to establish the analysis method of the basal stability against upheaval and check formula.With the proposed formulas,the effects 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.The results provide a reasonable calculation method for the design of foundation pit subjected to confined water in soft clay.