Abstract
This paper addresses the liquefaction disaster that significantly damaged houses and lifelines in Urayasu City on Tokyo Bay during the 2011 off the Pacific Coast of Tohoku Earthquake. Aiming at reconstruction and mitigation of damage during future earthquakes, subsoil investigation was carried out intensively in the city. It was found that the damaging liquefaction occurred in the reclaimed sandy layer near the ground surface as well as in the upper part of the underlying alluvial sand. The present paper provides detailed information about the liquefied ground and soil characteristics therein with special emphasis on relationship between building and sewage pipe damage extents and the locations of sand discharge during dredging works. Furthermore, undrained cyclic triaxial shear tests were conducted on undisturbed sand samples to show that the obtained liquefaction resistance is consistent with the resistance assessed by in-situ investigations and soil characteristics.
