In this study, authors discussed a utilization of electric logging method for a liquefaction evaluation targeting a detached house ground survey. Swedish weight sounding (SWS) has been the most popular survey method for a detached house in Japan, however, it can't identify a soil classification itself so that we can't judge liquefaction potential only by the SWS date. We were able to show that it is quite possible to evaluate the liquefaction potential of residential sites by a combination of Swedish weight sounding and electric resistivity, with the liquefaction strength comparison evaluated using the standard penetration test.
More than 25,000 houses were damaged due to liquefaction of the ground in the Great East Japan Earthquake of 2011 (Yasuda et al. 2012). The ground survey of residential sites itself was one of the reasons why so many houses were damaged due to liquefaction. Swedish weight sounding (SWS) is the most commonly adopted method for the ground survey of residential sites in Japan. One reason why SWS is used is its low cost, which enables investigation of many research points. SWS is not subject to site restrictions and it enables the continuous verification of the resistance of the ground up to a depth of 10 m, which is an important factor in the case of detached houses. However, since SWS is not capable of soil classification, liquefaction resistance cannot be directly evaluated using the penetration resistance Nsw obtained from SWS.
Therefore, one of the authors has attempted the evaluation of fines content using electric resistivity (Fujii et al. 2016). Another author has been carrying out studies on the evaluation of liquefaction strength directly from Nsw by pressure chamber tests and cyclic triaxial tests (Kumada et al. 2017). In this paper, we first combine these two research results and show that liquefaction strength can be evaluated directly from SWS. We then go on to compare the evaluation of liquefaction strength using the standard penetration test (SPT), which is the established procedure in Japan, with the evaluation using the proposed SWS and enumerate the differences between the two.
