Mitigation of liquefaction-induced damage to residential houses by surface ground improvement and its cost evaluation

摘要

A large number of residential houses suffered from liquefaction-induced damage by the 2011 off Pacific coast of Tohoku earthquake. In this study, the applicability of surface ground improvement to the residential houses was investigated as an economically attractive countermeasure against liquefaction. Based on the case studies, the allowable tilt angles and the differential settlements of houses were proposed for required performance of livelihood against moderate and large earthquakes, respectively. The mitigation effect of the surface ground improvement against liquefaction-induced damage was confirmed by field surveys and centrifuge model experiments. The numerical analyses indicated that the surface layer improved by solidification of no more than three meters thick is needed in order to prevent significant damage of houses. In addition, a cost evaluation on the surface ground improvement for newly-built and existing houses was also carried out.