Interpretation of existing survey results concerning liquefaction damage using soil element tests

Abstract

Large-scale liquefaction of reclaimed ground occurred in Urayasu city, Chiba prefecture during the 2011 off the Pacific coast of Tohoku Earthquake, causing severe damage to infrastructure of many kinds. However, slightly damaged areas were also existed where soil improvement had been performed. Then, the portable cone penetration test and the surface wave method were done at heavily liquefied and non-liquefied areas. However, there was not large difference in results obtained between liquefied and non-liquefied areas. Therefore, it was examined what factors were affected on shear wave velocity and liquefaction strength using triaxial tests. As a result, the stress history didn't affect the shear wave velocity of the specimen in spite of an increase of liquefaction strength. Moreover, re-liquefaction characteristics were also discussed in the paper because of a tendency that liquefaction damage expanded during the aftershock. It has been demonstrated that the increase of liquefaction strength induced by stress history vanished by liquefaction history.