Numerical simulation of foundation pit dewatering using horizontal seepage reducing body

Area of Science:

• Geotechnical Engineering
• Hydrogeology
• Environmental Engineering

Background:

• Deep excavations require groundwater level control (drawdown).
• Traditional vertical curtains are costly and difficult for deep excavations.
• Existing methods face challenges in urban, built-up areas.

Purpose of the Study:

• To introduce a man-made horizontal seepage reducing body (HSRB) to shorten vertical curtain depth.
• To investigate the effectiveness of HSRB in controlling drawdown during foundation pit dewatering.
• To propose an eco-friendly method for HSRB construction.

Main Methods:

• A case study of the No. 4 shaft foundation pit in Shanghai's Guangyuan Project.
• Application of microbially induced carbonate precipitation grouting for HSRB formation.
• Numerical simulation to analyze HSRB's influence on groundwater levels based on position, thickness, and hydraulic conductivity.

Main Results:

• Non-separated HSRB demonstrated superior performance compared to separate HSRB.
• Reducing HSRB hydraulic conductivity was more effective than increasing its depth.
• A new fifth seepage mode was identified for vertical curtains with HSRB, complementing four existing modes.

Conclusions:

• Man-made HSRB is a viable strategy to reduce vertical curtain depth and control groundwater drawdown.
• Microbially induced carbonate precipitation offers an environmentally friendly approach to HSRB construction.
• The findings provide valuable insights for similar deep excavation projects requiring groundwater control.