Identification of Soil Fracture Zone Using Waxman-Smits Model Based on ERT Survey Data.

Fracture is an early symptom of ground movement related to the physical properties of soil, including permeability, porosity, density, cohesion and internal friction angle, where these physical properties affect the stability of the soil. This research aims to identify soil fracture in landslide-prone areas using the values of water saturation and soil pressure based on electrical resistivity tomography (ERT) data. Water saturation values are obtained using the Waxman-Smits model based on the relationship between porosity and resistivity. The advantage of this model is its ability to apply correction due to clay-containing soil layers found in the research area. Another parameter used to determine soil fracture is the soil stress value. In this study, the Rankine method is used to calculate soil stress, and this method can be applied to the soil conditions that experienced deformation, caused by weathering of breccia and tuff rocks, allowing water to penetrate the rock medium. Consequently, the weathered layers of breccia and tuff act as slip planes. The presence of water on the slip planes leads to soil movement. Based on the analysis results, soil fractures are correlated with low water saturation values and contrast in soil stress values. A profound contrast in water saturation and soil stress values appears only at fractured slopes. Based on our analysis, soil fractures correlate with low water saturation values (5 - 15 %) accompanied by apparent contrast of soil stress values, i.e. the fractured soil is having lower soil stress (< 15 KN/m²) in comparison to the surrounding. Such a contrast was not found in slopes without fractures. [ABSTRACT FROM AUTHOR]

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