地盤の複素比抵抗特性を利用した土質判別法の検討

抄録

It is very important to classify soils for investigation and evaluation of residential sites, which can be considered as the reference information for determining the necessity of soil improvement and the selection of soft ground stabilization method. In general, Screw Weight Sounding (SWS) test as a cheap and simple method or Standard Penetration Test (SPT) with high-cost boring is used for the soil classification in private residential sites. SWS testing results depend on the experience of well-trained operators, and it is difficult to accurately discriminate the soil type without individual evaluation variability. Meanwhile, subjective factors in SPT such as the geological background knowledge of the observers for core sampling and their personal characteristics (habits) often cause the differences in the appraisal results, unless the soil samples are collected and laboratory tests for physical properties of soil are conducted. In this study, the four-probe AC impedance method was applied to identify the soil classification by capturing the complex resistivity properties of soil, aiming at newly proposing a simple and quantitative soil classification technique. Specifically, focusing on the frequency characteristics of the complex resistivity for each soil, multivariate analysis that calculates the generalized Mahalanobis distance was carried out based on soil property as the criterion variable (qualitative data) with selecting two variables as explanatory variables (quantitative data). The results showed that the proposing method objectively enabled the soil classification.