A Hybrid Simplified Method to Predict Liquefaction in Urayasu City during the Great East 2011 Earthquake

This paper presents a semi-coupled method to predict the occurrence of liquefaction in the city of Urayasu caused by the 2011 Tohoku-Pacific Ocean earthquake (Mw=9.0). The presented method is a combination of a linear equivalent computation and a formulation for computing plastic volumetric strain based on the works of Byrne (1991) and Wu (1996). Further, this approach was conducted to simulate the seismically induced soil liquefaction and volumetric settlements before triggering of two representative soil models: one representing a non-liquefied ground model chosen from the old town of Urayasu and another a liquefaction-prone ground at the reclaimed area of the city. Fully undrained behavior was assumed during calculation, so the effect of seepage are not taken into account and then results are restricted to the shaking duration before triggering liquefaction. The computed zones of liquefaction or non-liquefaction were compared and in a good agreement with observations. Predicted values of settlements are in a good agreement with in-situ measured values at non-liquefied locations.