Liquefaction damage analysis and application to emergency measures in Urayasu city using portable cone penetration test and surface wave method

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 also occurred where soil improvement had been performed. The difference of soil properties between liquefied and non-liquefied areas is interesting for assessment of liquefaction resistance against strong earthquakes. Therefore, the portable cone penetration test and the surface wave method, which are easily conducted immediately after an earthquake, were done at several locations in Urayasu city to estimate the cause of liquefaction and the effects of soil improvement. Finally, a simple ground investigation method is proposed to identify high-risk areas of liquefaction and to determine emergency measures.