APPLICATION OF ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT) FOR SLOPE FAILURE INVESTIGATION: A CASE STUDY FROM KUALA LUMPUR

Electrical Resistivity Tomography (ERT) is a commonly used tool in near surface geophysical surveys to investigate numerous geological, environmental, and engineering problems including landslides. In this study, an electrical resistivity survey was conducted at a landslide area, located in Bukit Setiawangsa, Kuala Lumpur, Malaysia. On 29th December 2012, a luxury hilltop bungalow was split into two when a 43m retaining wall was collapsed after a continuous heavy downpour. 2-D electrical resistivity survey have been acquired along two (2) profiles on the adjacent slope in an effort to mitigate the risks of instability, especially during the rectification work of the failed slope using a Schlumberger Array. It produced useful information about the geometry and characteristics of the study area. In addition, the 2-D resistivity method was performed to determine the behaviour of electrical resistivity underlying the slope areas and estimate the location of the failure surface. Four (4) boreholes were also drilled to obtain engineering properties of the study area such as soil classification, moisture content, soil hardness and SPT N-value. In order to develop the relationship between resistivity and engineering properties, a comparison between soil hardness and the resistivity value was made. Results from the ERT indicated the presence of zones with low resistivity values identified as percolated water in permeable loose soil, which was believed to be the potential slip surface. The findings of this study also showed that the electrical resistivity imaging coupled with borehole drillings were useful tools for the characterisation of slope failure via subsurface profiles and engineering properties of soil.