Application of electrical resistivity tomography to investigating geological causes of road failure in Taraba State, Nigeria

Abstract

The adverse effect of road failure in many parts of Nigeria has led to intense research on the possible causes of the persistent widespread road failures. In contribution to these investigations, a study was conducted in some failed portions of the Jalingo – Zing roads, located in Taraba State, Nigeria. The main purpose was to investigate the cause (s) of the perennial road failures on this road. The 2D electrical resistivity method, utilizing Electrical Resistivity Tomography (ERT) technique was adopted for the investigation. The ERT measurements were carried out on eleven profiles (two control and nine failed segments) of the roads using SSR-MP-ATS resistivity meter (IGIS, India). Results obtained revealed that the resistivity values in the top layers of all the eleven profiles were between 0 and 61.6 Ωm (i.e. < 100 Ωm). This clearly indicated the abundance of clay/shale materials on the top segments of the road, revealing the incompetence of top soils for road construction. It is recommended that the clay/shale deposits that exist below the pavement must be dug out to about four metres depth and replaced with more competent materials such as sandstone, granite and laterite before asphalt is laid. Geotechnical study is also recommended for a comprehensive result to be achieved.