GEOPHYSICAL ASSESSMENT OF SUBSURFACE CONDITIONS AT PROPOSED BUILDING SITES: IMPLICATIONS FOR FOUNDATION FAILURE AND BUILDING COLLAPSE.

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Stephen Oluwafemi Ariyo
Julius Ogunmola FATOBA
Olateju O. BAYEWU
Kamadeen Olawale OMOSANYA
Muhideen A. LAWAL

Abstract

In the last two decades, building collapse has been a recurrent environmental hazard in Nigeria. This is a consequence of inadequate foundation investigation prior to construction, poor government policies, and general lack of awareness on the importance of geophysical and geotechnical investigations. In this study, geological mapping and detailed geophysical investigation using Electrical Resistivity Imaging (ERI) and Vertical Electrical Sounding (VES) were carried out to understand the suitability of  proposed building sites at the main campus of the OOU, Ago-Iwoye, Nigeria for construction. Both Wenner array and dipole-dipole were used for profiling and Schlumberger for sounding. Four transverses and VES were used in each of the three areas investigated. The results show that the subsurface of the study areas is underlain by Precambrian basement rock of Nigeria. The sounding stations across the three areas and 2D resistivity imaging revealed three principal geoelectric layers, the topsoil, the weathered layer and the fractured/fresh basement with varied resistivity values for each layers.  Our work demonstrates that some of the proposed sites are structurally incompetent for engineering or foundation purposes. Excavation of the topsoil and reinforcement are required to sustain the proposed structures.

Article Details

Section
Research Paper
Author Biographies

Stephen Oluwafemi Ariyo, Olabisi Onabanjo University, Department of Earth Sciences. Ago-Iwoye

Department of Earth Sciences and Assistant Professor

Julius Ogunmola FATOBA, Federal University of Oye, Oye Ekiti

Department of Geophysics and Associate Professor

Olateju O. BAYEWU, Olabisi Onabanjo University, Ago-Iwoye

Department of Earth Sciences and Assistant Professor

Kamadeen Olawale OMOSANYA, Norwegian University of Science and Technology

Department of Geosciences and Petroleum and Associate Professor

Muhideen A. LAWAL, University of Perugia

Department of Physics and Geology and Research fellow