Numerical simulation of foundation pit dewatering using horizontal seepage reducing body

Jianxiu Wang,Yu Zhao,Yujin Shi,Hanmei Wang,Jianxun Qu,Yanxia Long,Weiqiang Pan,Xiaotian Liu

doi:10.1038/s41598-022-05348-y

Abstract

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.

Highlights

Groundwater level has to be lowered during deep excavation
High rise building Foundation pit the verticality is not controlled in a certain value, the foot of two adjacent diaphragm wall splits leading to water leakage, which is dangerous for groundwater control
With the No 4 shaft foundation pit of the Guangyuan Project, Shanghai as background, horizontal seepage reducing body (HSRB) was suggested to combine with vertical curtain to control groundwater drawdown

Summary

Introduction

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. With the deepening of the buried depth of the horizontal curtain, the time required for the foundation pit dewatering to reach the design drawdown increased correspondingly.

Results

Conclusion