Integrated geophysical investigation of foundation condition beneath a site earmarked for a civil engineering construction project

Geophysical investigation involving the electrical resistivity method was carried out at a site earmarked for construction of a Lecture Theatre at the Obafemi Awolowo University Teaching Hospital Complex (OAUTHC) in Ile-Ife, Osun State Nigeria. The aim was to generate 2-D subsurface images beneath the site which will provide the required geological information for location and design of the building foundation.

 The geophysical investigation involved the 2-D imaging technique which utilized Dipole-Dipole electrode array and Vertical Electrical Sounding (VES) technique with the Schlumberger array. Two orthogonal traverses oriented South – North and  West – East were established across the site and denoted as Traverses 1 and 2 respectively. Nine VES stations were occupied along the traverses while the Dipole – Dipole data were also collected along the two traverves. The VES curves were interpreted quantitatively by partial curve matching and computer assisted 1-D forward modelling using  WinRESIST 1.0 Software. The Dipole – Dipole data were inverted to 2-D resistivity images of the subsurface using the DIPRO for Windows Software. Two geoelectric sections were constructed from the results of the VES Interpretation. 

The study concluded that the high resistivity near surface stratum comprising the topsoil/laterite constitutes the competent material upon which a shallow foundation can be erected. 

TABLE OF CONTENTS

Title

Abstract

1Introduction 3

Geology of area6

Geophysical investigation7

Result discussion 9

Recommendation 15

References 16