Application of Electrical Resistivity in Building Foundation Study around Led School Area in Bishini, Northwestern Nigeria

Abstract

This study evaluated the structural competence of the subsurface geological materials around Led School Area in Bishini, NW Nigeria to delineate the area that is suitable for building development. Twenty Seven vertical electrical soundings (VES) points were occupied in the study area employing ABEM Terrameter SAS 300C with Schlumberger electrode configuration of maximum electrode separation AB/2=150 m. The field resistivity data were interpreted using Win RESIST software. The results from the 2-D interpretation of the VES data were used to prepare the geoelectric sections along four cross sections. The interpreted results showed that the geoelectric sections consist of three to five layers, which are: Top soil, Laterite, Lateritic clay, weathered layer and Fresh basement. The resistivity value and subsurface layer thickness for the top soil varied from 191.7 Ω m to 8146 Ωm and 0.3 m to 7.0 m respectively. The Laterite layer had resistivity values ranging from 1000 Ωm to 1627.3 Ωm and thickness between 1.8 m and 2.5 m. The weathered layer resistivity varied from 33.5 Ω m to 850 Ω m with thickness of 3.6 m to 44 m. The bedrock resistivity ranged from 1238.3 Ωm to 33438.6 Ωm. Geoelectric sections along profile 4 and 1 revealed the thinnest sequence of loose overburden materials and fresh basement at the shallowest depth. The area covered by these profiles is suitable for building development. Building development should not be located along profiles 2 and 3 due to relatively thick weathered layer. However the area may be considered for citing borehole to harness its groundwater potentials.