Efficacy of pile-type improvement against lateral flow of liquefied ground

Abstract

Liquefied ground loses its stiffness and strength, and it flows laterally in sloping areas and backfill areas behind collapsed quay walls. A method of installing piles such as cement-treated ones into the ground to prevent the lateral flow has been proposed and studied. The authors are investigating the most effective arrangement of piles to optimise cost-effectiveness. It is proposed to irregularly displace the piles to prevent lateral flow in various directions. In the present study, centrifuge model tests were conducted to verify the efficacy of piles against the lateral flow of liquefied ground and the effect of the pile arrangement in detail. This study first demonstrated the similarity law for the lateral flow of liquefied ground in a centrifuge, where both the Froude and Reynolds numbers can be satisfied. Numerical analyses assuming the flow of liquefied ground to be fluid-like were conducted to consider the improvement mechanism and the effect of the pile arrangement. The results of the model tests and numerical analyses indicated that the improvement by piles dramatically reduced the lateral displacement and that the average total flow velocity was small in the irregular arrangement case.