GEOTECHNICAL INVESTIGATION OF THE SUBSURFACE FORMATIONS, USING ELECTRICAL RESISTIVITY METHOD IN NORTHERN PART OF PAIKO TOWN, NIGER STATE, NIGERIA

Abstract

Vertical electrical sounding (VES) was carried out in northern part of Paiko town, using Abem Terrameter model SAS 4000. The study was carried out with a view to determine the subsurface layer parameters (resistivity, depth, thickness and lithologies) which were employed in delineating the sites for building construction. Six transverses with ten VES stations along each traverse, having separation of 50 m apart were investigated. It has a maximum current electrode separation (AB/2) of 100 m. Three to four distinct geoelectric layers were observed namely; Top layer which consist of gravel, sand, laterite and alluvial; weathered/fractured layer consist of clay and laterite, and fresh basement layer that consist of granite, gneiss and igneous rock. The observed frequencies in curve types include 21.6% of H, 0.6% of HA, 2.4% of K, 0.6% of A, 3.6% of KH, 6% of QA and 1.2% of HK. Sixteen VES stations were delineated for building construction, having depths to fresh basement varying between 2.18 m and 3.93 m with fresh basement resistivity ranged between 1038 Ωm and 194453 Ωm.