A non-destructive method for investigating soil layers of an individual vulnerable slope

Soil stability analysis becomes main concern in the preliminary design of new construction project. In a critical soil slope, the stability can be affected by the additional load and water infiltration significantly. This is due to additional overturning moment and decreasing of shear strength of the slope material. In such scenario, the non-destructive soil investigation method is needed to analyze the stability. This paper examines the use of Electrical Resistivity Tomography (ERT) to investigate soil layers in a critical slope and to measure parameters of soil shear strength indirectly. Two ERT methods used in this research were dipole-dipole array and square array resistivity (SAR). The results of ERT were verified using geotechnical testing (Bore-hole and Standard Penetration Test) results by investigating the presence of high porosity and water content with soil resistivity. The results of Dipole-dipole array and SAR at selected locations are consistent and suggest a possible crack at the location was reflected by the low soil resistivity value. Furthermore, the results of the SAR confirmed the existence of the deep crack as a continuance of visible cracks on the surface. The results of ERT can be used to detect deep cracks in the subsoil if ERT is conducted in the wet seasons, due to the existence of infiltrated rainwater. Due to the limitations of this technique, the ERT result should be interpreted cautiously. The study demonstrated the benefits of the use of electrical resistivity for the detection of soil layers in residual soil slope.