基坑开挖及降水引起的地表沉降预测

以随机介质理论、渗流理论和土体压密理论为基础,探讨了一种新的基坑开挖及降水引起的地表沉降的计算方法。推导了基坑降水渗降漏斗曲线方程及考虑水的渗流作用的基坑周边土体中有效应力的计算公式,并由此导出了考虑渗流作用的基坑降水地表沉降计算公式,再利用叠加原理,得到最终的由开挖和降水引起的地表沉降分布计算公式。工程实例分析计算结果表明,距基坑周边8～10m范围以内,基坑开挖和降水引起的地表沉降基本相当,而距坑周20m以外的地表下沉主要由降水引起,因此基坑降水引起的地表下沉不容忽视。本文推导的计算方法能充分反映基坑降水对周边地表下沉的影响,是一种计算基坑开挖及降水引起的地表沉降的有效方法。

Ground surface settlement caused by foundation pit excavation and dewatering

Based on the stochastic medium theory,seepage theory and soil consolidation theory,a new calculation method of ground surface settlement caused by foundation pit excavation and dewatering was studied.The settlement equation due to dewatering was derived.Calculation formula for effective stress in the surrounding soils of foundation pit with seepage was investigated,and the formula of ground surface settlement caused by dewatering was thus obtained.Besides,calculation formula of ground surface settlement caused by both excavation and dewatering was derived.Numerical results indicate that: in the area less than 8~10m away from the foundation pit,surface settlement caused by excavation is equal to that by dewatering on the whole,while in the area more than 20m away from the foundation pit,surface settlement is mainly caused by dewatering.