APPLICATION OF VERTICAL ELECTRICAL SOUNDING TECHNIQUE IN BUILDING FOUNDATION INVESTIGATION IN ILISHAN-REMO SOUTHWESTERN NIGERIA

Abstract

This study investigates subsurface conditions to inform foundation design through geophysical surveying, specifically employing the Vertical Electrical Sounding (VES) method using a Schlumberger array with AB/2 spacing of 100 meters. Ten VES points were analyzed to determine subsurface composition, strength, and stability. Three to five separate layers, including topsoil, clayey sand, clay, and sandy layers, were identified in the interpreted geoelectric sections; the majority of the resistivity curves were categorized as HKA-type. Layer thicknesses ranged from 0.9 m to 45.9 m, and resistivity values ranged from 71.7 Ωm to 18,671.3 Ωm. More load-bearing capacity is shown by a higher resistivity in the sandy layer at traverse one, which qualifies it for heavy construction. The subsurface sequence in traverse two, on the other hand, has a clayey layer beneath the topsoil, indicating increased stability and suitability for constructions where minimal settlement is essential. The findings underscore the importance of integrating geophysical data with further geotechnical assessments to ensure optimal foundation planning.