EFFECTS OF GROUND SURFACE CONDITIONS ON LIQUEFACTION-INDUCED GROUND SUBSIDENCE OBSERVED THROUGH DIGITAL SURFACE MODELS

Abstract

 In the 2011 Off the Pacific Coast of Tohoku Earthquake, liquefaction-induced ground subsidence occured widely in the Tokyo Bay shore area. The aurthors extract values of ground subsidence at various locations of Urayasu from the soil-subsidence map which was obtained from Airborne LiDAR surveys before and after the earthquake. Given the extracted values of soil subsidence along streets and at open spaces and liquefaction potential index calculated using a borehole log at every borehole location surrounded by the streets and open spaces, the aurthors examine influential factors for liquefaction-induced soil subsidence. It is reaffirmed that the extent of soil subsidence correlates roughly with the liquefaction potential index (PL values). However, it turns out that the thicker the pavement is, the smaller is the ground settlement. This finding suggests that groundsurface conditions can affect significantly the extent of soil subsidence, which fact is to be taken into account for rational estimation of soil subsidence caused by a scenario earthquake.