某深基坑水文地质参数确定与降水方案设计

结合北京某商业区改造工程中站房深基坑工程,运用抽水试验水位恢复法观测资料确定场地的水文地质参数,并应用试算法验证渗透系数.研究表明:抽水试验的质量与数据的利用和抽水试验稳定时间的长短有关,表现为稳定流中测得的试验数据计算出的参数值,经试算法验证后更近似于真实值;由于场地土层的成层性,以及同一土层在垂直向和水平向的非均一性(厚度分布、土性质等),设计用的水文地质参数是由抽水试验得到的土层组合的综合值,而非各土层参数的简单平均值.基于上述成果,提出了深基坑开挖降排水的设计方案,采用管井井点进行深基坑降水.同时分析了降水对周边环境的影响程度,取得了良好的降水效果.

Determination of Hydrology Geology Parameters and Design of Ground-water Lowing Plan

This paper presents the determination of hydrology geology parameters and the design of ground-water lowing plan.Based on the station deep foundation pit project of modification works in the certain business district in Beijing,this paper utilizes the observation data of water level recovery method to determine the hydrogeology parameters in pumping test,and applied the trial and error procedure to confirmation permeability coefficient.It is shown that pumping test quality and the data utilization are related with the stabilization time in pumping test.It represents the parameter value that calculated by the test date which obtained in the stabilization flow,and it is approximate to the true value after the process trial and error procedure confirmation.Because of the stratified nature of the ground soil strata,as well as the nonhomogeneity(thickness distribution,properties of soil and so on) of identical soil stratum on the vertical and horizontal directions,the hydrogeology parameters used for the design is the comprehensive value of the soil layer combination obtained by the pumping experiment instead of the simple mean of each soil layer parameter.Based on the above achievement,a design of dewatering scheme in deep foundation pit is proposed,and uses the tube well to dewatering.At the same time,it has analyzed the influence to the peripheral environment by dewatering and obtained good dewatering effect.