Numerical simulation of foundation pit dewatering using horizontal seepage reducing body.

Groundwater level has to be lowered during deep excavation. A vertical curtain is usually adopted to control the drawdown inside and outside a foundation pit in a built-up area. However, the cost and working difficulty increases substantially with the rise in depth of vertical curtains. In the manuscript, a man-made horizontal seepage reducing body (HSRB) was introduced to shorten the vertical curtain depth and control drawdown. With the No. 4 shaft foundation pit of Guangyuan Project, Shanghai as background, HSRB was proposed in foundation pit dewatering. Microbially induced carbonate precipitation grouting technology was recommended to form an environment-friendly HSRB. Numerical method was used to simulate and understand the influence of position, thickness, and hydraulic conductivity of HSRB on groundwater level. The non-separated HSRB was better than the separate HSRB. Decreasing HSRB hydraulic conductivity was better than increasing HSRB depth. Four seepage modes were summarized considering vertical curtain penetration conditions into multi-aquifer, and the fifth seepage mode was formed for vertical curtain using man-made HSRB, which can be referred by similar engineering applications.

在深基坑开挖过程中，必须降低地下水位。在建成区，通常采用垂直帷幕来控制基坑内外的水位降。然而，随着垂直帷幕深度的增加，成本和施工难度大幅增加。在本文中，引入了一种人造水平减渗体（HSRB）来缩短垂直帷幕深度并控制水位降。以上海光源工程4号竖井基坑为背景，在基坑降水工程中提出了HSRB。推荐采用微生物诱导碳酸钙沉淀注浆技术来形成一种环境友好型的HSRB。采用数值方法模拟并了解HSRB的位置、厚度和渗透系数对地下水位的影响。非分离式HSRB优于分离式HSRB。降低HSRB的渗透系数优于增加HSRB的深度。考虑垂直帷幕穿透多层含水层的情况，总结了四种渗流模式，并针对使用人造HSRB的垂直帷幕形成了第五种渗流模式，可供类似工程应用参考。