Evaluation of Near-Surface Conditions for Engineering Site Characterization Using Combined Geoelectrical and Seismic Methods in the Faculty of Engineering Open Field, University of Benin, Nigeria

Abstract

At the University of Benin's Faculty of Engineering open field, integrated geophysical methods utilizing seismic refraction and electrical resistivity have been used to assess the near-surface conditions for engineering site assessment. In order to create three (3) profiles, seismic and electrical refraction methods were used. Seismic refraction within the research region was recorded using an ABEM Terraloc Mk.6 equipped with a 24-channel recording system, while electrical resistivity was measured using a PASI terrameter (model 16GL). The 2D electrical resistivity imaging was conducted using the Wenner electrode arrangement. Software called DIPROWIN was used to process the 2D resistivity data, while Seisimager/SW (version 1.0.8) was used for quality checking and processing of the seismic recorded data.Three resistivity structures—representing sandy clay, laterite, and clayey sand—were identified using 2D electrical imaging, and the seismic data display the velocities associated with different layers as well as the dip interface between the profiles' layers. The sections showed three layers, which are indicative of lateritic clay/shaly materials, with average velocities of 450–547 m/s for the first layer, 575–601 m/s for the second layer and 700–900 m/s for the third layer. The results of the study provide credence to the usefulness of seismic and electrical resistivity methods in evaluating the appropriateness of subsurface materials. When selecting the foundation materials, one must take into account the properties of the sandy clay in the soil. To establish an appropriate foundation design for structures, it is suggested that engineering soil testing procedures be applied.