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

Article Title: Post-Foundation Engineering Geophysical Investigation in Part of the Federal University of Technology, Akure, Southwestern Nigeria
by S. Bayode, G .O. Omosuyi and H. I. Abdullai

Abstract:
An integrated geophysical investigation involving the Electromagnetic (EM) profiling, Dipole-Dipole profiling and the geoelectric depth sounding have been conducted as post-foundation study at the premises of the 2500 capacity auditorium building, Federal University of Technology, Akure, Nigeria. The area is underlain by the Precambrian basement complex rocks. Three VLF-EM and Dipole - Dipole profiles plus fifteen Vertical Electrical Sounding (VES) stations were established in the study area. Measurements were taken at 5 m intervals along the three Traverses. The depth soundings (three-five) conducted along each of the profiles was subsequently correlated with the EM and Dipole - Dipole data interpretation. An interpretation of the EM anomalies identified conductive zones, suspected to be fractures/faults along three traverses. The geoelectric sections and the inverted 2-D resistivity structures delineated four subsurface geoelectric layers which include the topsoil, weathered layer, weathered/fractured basement and the resistive basement bedrock. The fractured/fresh basement constitutes the basement bedrock in the 2-D resistivity structure. This study revealed that the subsurface geologic materials underlying the investigated building is characterized by the presence of heterogeneous near surface geomaterials, and an uneven basement topography at shallow depths of < 1 - 4 m were foundations are usually placed. These, coupled with the mapped vertical discontinuity within the basement bedrock, designated as F1 (50 - 60 m wide), F2 and F3 (30 - 35 m wide) are classified as weak zones (Fractures/faults). These features constitute zone of geotechnical weakness which may precipitate subsidence-related failure and eventual collapse of the foundation of the building. This study advocates pre-construction engineering survey at any civil engineering site since it can reliably evaluate the geotechnical competence of the subsurface geomaterials and compliment routine pre-construction engineering geotechnical investigation

Keywords: geophysical investigation, post foundation study, geomaterials, fracture

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