Geophysical and Geotechnical Evaluation of Landslide Slip Surface in a Residual Soil for Monitoring of Slope Instability

Abstract Electrical Resistivity Tomography (ERT) technique has been widely used conventionally to monitor slope instability; however, a detailed study validate ERT models with geotechnical properties for monitoring of instability is still rare. The objective this work was evaluate soil water conditions in gravelly sand that influences instability. investigation conducted on 60 m survey length 1.5 electrodes space obtain subsurface geological structures and laboratory tests, experiments were carried out engineering validation the model results. Our results revealed three zones namely: saturated, weathered granite, boulders floaters, resistivity values 1–800 Ωm, 1,200–4,000 >4,000 respectively. saturated characterized by subsidence during dry season possible collapsed floaters prolonged heavy rainfall. analyzed slip surface potential landslide may occur at boundary between granite within 3.0 depth. also confirmed result because sliding delineated depth lowest angle internal friction 30° cohesion 8 KPa, which easier destroy, silty high 33.8° 12.7 more difficult destroy. These findings are very fundamental shaping earth's surface, especially formation landscapes.