Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: Integrated Geophysical Studies for Post-Foundational Investigation in Part of Afe Babalola University, Ado Ekiti, Nigeria
by Oluwaseun S.Ogungbemi and Oladimeji L. Ademilua

Abstract:
An integrated geophysical investigation involving the Electromagnetic (EM) profiling, Vertical Electrical Sounding (VES) have been conducted as post-foundation study at the campus Afe Babalola University, Ado Ekiti, Nigeria. The area is underlain by the Precambrian basement complex rocks of southwestern Nigeria. Twenty-Seven VLF traverses were established in order to determine appropriate locations for further investigation using the VES technique. In all fifty-Nine Vertical Electrical Sounding (VES) stations were established in the study area. The VES was subsequently correlated with the EM data interpretation. An interpretation of the EM anomalies identified conductive zones, suspected to be fractures/faults across the study area. The structure-depth map generated from the EM sections enabled the classification of the study area into three zones based on the depth to top of fracture (DTF),as shallow-seated fracture zone where DTF is between 15 and 45 m, averagely-depth fracture zone having DTF between 45 and 95 m and deep-seated fracture zone where DTF is from 95 m and above. The structural depth map also delineated a major fracture which coincides with a buried river channel within the study area. The geoelectric sections delineated between three to five subsurface geoelectric layers which include the topsoil, clayey soil, weathered layer, weathered/fractured basement and the resistive basement bedrock. The basement relief map revealed subsurface geologic features such as depressions and ridges underlying the study area. The basement depression constitute water collection zone and where it is overlain by a highly conductive layers such as clay, cannot support massive engineering structures. This study advocates pre-construction foundation survey at any civil engineering site since it can reliably evaluate the geotechnical competence of the subsurface geologic materials that may pose danger or otherwise favour the design and construction of engineering structures around the campus.

Keywords: post foundation study, vlf-electromagnetic, fracture, geoelectric section, bedrock relief structures

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