ABSTRACT:

In Japan, the Swedish Weight Sounding (SWS) test is a popular and essential method for evaluating the ground bearing capacity in home site. Measurement of groundwater level using a SWS test hole is applicable only when a groundwater sensor or a rod with tapeline for eye measurement can be installed into the hole. However, the method of eye measurement using the tapeline is susceptible to inaccuracies. In this point of view, in the former paper, we introduced the new groundwater measurement technique using a SWS test hole, a foraminate pipe and an Alternating Current (AC) resistivity sensor. The excellent performance of the new technique, degree of accuracy and the short settling time of less than 30 minutes were confirmed. In this paper, based on in-situ experiments, we investigated the relationship between settling time of the groundwater level in the SWS test hole and N-value with respect to the soil classification. In addition, by carrying out the two dimensional seepage flow analysis (FEM), the groundwater flow surrounding the SWS test hole was simulated numerically, and the new technique may become an effective tool for the primary judgment of liquefaction possibilities of home sites.

INTRODUCTION

Method for evaluating the ground bearing capacity in home sites using the Swedish Weight Sounding (SWS) test has been regulated by law in Japan, and it is required in advance to check the subsidence and displacement of buildings caused by liquefaction due to earthquakes. On the other hand, by the "Recommendations for Designing of Small Buildings Foundations", the conventional method for liquefaction judgment with regard to the geographic features, grain size analysis and groundwater level has been prescribed for middle level earthquakes. Whether groundwater level exists within 3m deep from the ground surface is crucial in judging the possibility of liquefaction.

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