基坑工程地下水三维渗流与土体沉降数值模拟分析

Numerical Simulation Analysis of Three-Dimensional Groundwater Seepageand Soil Settlement in Foundation Pit Engineering

深基坑下伏承压含水层制约着基坑工程的安全施工,常需通过基坑降水进行减压处理,制定基坑降水方案的同时,实现按需降水的设计理念亦是较为重要。选取上海某深基坑工程为研究对象,基于现场抽水试验数据及建立的地下水三维渗流与土体沉降耦合模型,利用地下水数值模型软件进行数值模拟研究,对基坑降水方案可行性进行了预测分析。结果显示:单井抽水试验获取的水文地质参数较为可靠,与数值模型反演的参数(水平渗透系数为5.12 m/d,贮水系数为1.8×10^(-4),弹性释水系数3.0×10^(-4),非弹性释水系数7.0×10^(-4))相近;经群井抽水试验数据校核后,模拟水位与实测水位误差不超过0.5 m,数值模型符合场地水文地质条件,可靠性高;利用数值模拟预测分析基坑降水期间地下水流场与土体沉降的变化特征,验证了降水方案可将承压水位降至标高-6.13 m的同时,体现了按需降水的设计理念,保护了周边环境。

The confined aquifer under the deep foundation pit restricts the safe construction of the foundation pit project.It is often necessary to reduce the confined water level by foundation pit dewatering.How to realize the design concept of on-demand precipitation is particularly important.A deep foundation pit project in Shanghai is selected as the research object.Based on the field pumping test data and the established three-dimensional groundwater seepage and soil settlement coupling model,the groundwater numerical model software GMS is used for numerical simulation research,and the feasibility of foundation pit dewatering scheme is predicted and analyzed.The results show that the hydrogeological parameters obtained by single well pumping test are reliable and similar to the parameters of numerical model inversion.The horizontal permeability coefficient is 5.12 m/d;the water storage coefficient is 1.8×10^(-4);the elastic water release coefficient is 3.0×10^(-4),and the inelastic water release coefficient is 7.0×10^(-4).The numerical model checked by the group well pumping test data conforms to the hydrogeological conditions of the site with high reliability,and the error between the simulated water level and the measured water level is less than 0.5 m.Using numerical simulation to predict and analyze the variation characteristics of groundwater flow field and soil settlement during foundation pit dewatering,the feasibility of dewatering scheme is verified,and the design concept of on-demand dewatering is realized,which can protect the surrounding environment.