Behavior of double sheet pile wall cofferdam on sand observed in centrifuge tests

Abstract

Behavior of double sheet pile wall cofferdam on sandy soil subjected to high water was studied through a series of centrifuge model tests. Model ground and fill of the cofferdam were made by fine silica sand in a rectangular model container. The model double sheet pile wall cofferdam consisted of two aluminum sheet pile walls, tie rods at the top and also at ground level. Various factors affecting stability of the cofferdam were examined. Under 70g, water was fed into the upstream of the cofferdam to simulate high floodwater until the water level reached nearly to the top of the cofferdam or large deflection of the cofferdam was observed. Test results imply that: (i) the shear deformation of the fill dominates the failure mechanism of the cofferdam, (ii) as the width of the cofferdam increases, the water height at failure increases, (iii) to a certain depth the embedment does not appreciably increase the resistance against high water, (iv) the relative density of the fill and the friction between the walls and the fill contribute to the resistance of the cofferdam against the shear deformation of the fill, (v) the sheet pile wall at the downstream is subjected to higher stresses than the sheet pile wall at the upstream and (vi) double layers of tie significantly increase the lateral resistance of the cofferdam against high water.