Soil Classification and Looseness Evaluation by Rock Physics Based Cross-plot Analysis for Unsaturated Soils

Rock physics-based methodology for cross-plot analysis in the interpretation of the integrated geophysical survey is proposed to overcome an issue of the current cross-plot analysis. By using the rock physics models, we can avoid ambiguity or subjectivity associated with the determination of threshold values for discriminating the data in the cross-plot, which is the critical part to identify the vulnerable location in the survey area. In addition to the vulnerability section, the method provides more detailed soil type classification and looseness evaluation profiles by using theoretical cross-plots individually. We applied the methodology to actual field data obtained at the river levee where the levee body is supposed to be replaced with new one. After the survey, several points of the levee body are exposed so that we can observe actual soil types and conditions and verify our interpretation results. As a result, the estimated soil type and looseness are fairly consistent with actual soil type and conditions. Therefore, it is considered that the methodology is applicable and beneficial for the interpretation of the integrated geophysical survey.