Effect of liquefaction duration on ground progressive failure under 2-D biased load

摘要

A series of centrifuge model tests at 30 g were conducted to clarify the mechanism of progressive failure of liquefied sandy ground. Two types of two-dimensional biased loads were applied using a model structure at either side of the contact interface between the structure and the soil underneath. The comparison between models of clean sand and clayey sand shows the effect of liquefaction duration on the progressive failure of the ground or tilting of the structure. The main findings are as follows. (1) The liquefaction duration was inversely proportional to the logarithm of the permeability coefficient of the sandy layer. (2) The structual tilting or ground progressive failure continued developing only in the state of full liquefaction. A small amount of dissipation of excess pore-water pressure will restore the ground stiffness/strength considerably. (3) A long liquefaction duration caused a larger tilting. The structure on the clayey sand layer with relatively low permeability has a likely possibility to tilt once those layers liquefy. (4) Permeability control or the use of clayey sand is an essential factor for studying the ground progressive failure after liquefaction using the model test.