Experimental study on the impact of seepage flow on pile friction resistance

Abstract

Seepage flow in deep excavations can elevate pore water pressure, reduce effective stress, and weaken soil particle cohesion, leading to a decrease in pile friction resistance. This study examines the impact of seepage on pile friction using a scaled-experimental diagram wall model. By conducting different scenarios of excavation depth and water table, friction resistance of piles was evaluated incorporating both effective stress and pore pressure measurements. The results were validated through direct friction measurements. The study reveals that seepage significantly reduces friction resistance for piles located near the diagram wall, with the effect diminishing as the distance from the wall increases. Key factors influencing this phenomenon include pile location, hydraulic gradient, excavation depth, and embedment depth. The maximum observed reduction in friction resistance was 91.23%. These findings are used to develop an empirical correlation that relates pile location, friction reduction, and safety factors against piping, providing valuable insights for the design of stable deep excavations.

Keywords: Seepage flow; pile friction resistance; effective stress; diagram wall; excavation stability.