某地下空间承压含水层抽水试验及成果分析

Pumping Test and Result Analysis of a Confined Aquifer in Underground Space

由于地下水突涌风险,地下空间在施工作业中有必要通过抽水试验确定承压含水层的水文地质参数。依据勘察报告的初步评价,基坑开挖15.5m时,场地内第⑦1层承压含水层有可能产生突涌,为确保工程安全施工,需开挖前进行承压含水层抽水试验,取得场地承压含水层水文地质参数及降水引起的沉降特征,为地下空间设计和施工提供可靠依据。本次布设抽水井、观测井、分层沉降标组、孔隙水压力观测孔及地面沉降观测点,依据抽水试验技术要求获取渗透系数、抽水影响半径等相关水文地质参数。最后,针对工程场地内承压水情况及特点进行分析,提出基坑开挖时的承压水降压建议方案。

It is necessary to determine the hydrogeological parameters of confined aquifer by pumping test in an underground space construction due to the risk of groundwater gushing. According to the preliminary evaluation of the survey report, when the foundation pit is excavated at 15.5 m, groundwater gushing may occurs in the confined aquifer ⑦1. In order to ensure the safety of the project construction, a pumping test of the confined aquifer is carried out before excavation to obtain the hydrogeological parameters of confined aquifer and the settlement characteristics caused by precipitation, so as to provide a reliable basis for the design and construction of underground space. Pumping wells, observation wells, stratified subsidence benchmark groups, pore water pressure observation holes and ground subsidence observation points are laid out. According to the technical requirements of the pumping test, relevant hydrogeological parameters such as permeability coefficient and influencing radius of pumping are obtained. Finally, according to the characteristics of confined water in the engineering site, the results are analyzed, and the suggestions on reducing confined water pressure in foundation pit excavation are made.