Application of Electrical Resistivity Method in Site Characterization along Ado – Afao Road, Southwestern Nigeria

Abstract

A geophysical study was carried out at a proposed location for the construction of a structure along Ado-Afao road, Southwestern Nigeria. The aim of the study is to evaluate the electrical properties of the soil for Founding of Engineering structures. The geophysical investigation involved the Vertical Electrical Sounding (VES) technique using the Schlumberger configuration with a total of twenty-one (21) VES within the investigated area. The electrode separation varies from 1 to 100 m. The geoelectric sections identified three to five geoelectric/geologic subsurface layers along the traverses. The topsoil comprising of clay, clayey sand and sandy clay with the resistivity values range from 28 to 800 Ω-m with its thickness varying from 0.4 to 1.9 m. The second layer was found to be lateritic with resistivity ranging between 200 to 800 Ω-m and thickness ranges from 1 to 7.5 m while the weathered layer comprising of clay, clayey sand and sandy clay with resistivity varies from 30 to 220 Ω-m and its thickness varies from 1.2 to 54 m. The fractured basement with resistivity value of 763 Ωm and thickness value of 8m while the fresh basement has a resistivity value ranging from 365 to 2964 Ωm with depth to basement ranging from 8 to 58 m. The resistivity values of the topsoil are indicative of clay, sandy clay and clayey sand. This layer may not be of any special interest since topsoil is normally excavated. Hence, foundation of the proposed structures cannot be found on this layer. Based on the investigation, the subsurface of the study area can be generally classified as incompetent. There is a presence of lateral inhomogeneity of the subsurface layers and geologic features such as fractures and faults. The construction in the area should be founded on the lateritic layer or fresh basement layer coupled with pile foundation to ensure the stability of the building. The choice of foundation material, clay content and topography elevation should be put into consideration.

Electrical Resistivity and Geotechnical Attributes and The Dynamics of Foundation Vulnerability

“…The issues concerning foundation studies have remained a burning concern in the mind of geoscientists and civil engineers (Bawallah et al, 2020). Whereas, the spates of foundation vulnerability and subsequent failures that were reported in some parts of African and especially Nigeria has assumed a worrisome dimension, hence to evaluate the factors that are responsible for this foundation vulnerability in terms of depth of investigations, nature of materials, structural trends, geodynamic factors, the relevance of Electrical Resistivity and Geotechnical attributes and their significance in evaluation of foundation sustainability (Ilugbo et al, 2018;Bawallah et al, 2019a;Bawallah et al, 2019b;Bawallah et al, 2020;Oyedele et al, 2020).…”

“…structural settings, both lateral and depth extent from the topsoil to a depth of 100 meters and sometimes beyond, whereas, civil engineering site investigation takes into account geotechnical attributes such as nature of the soil, stratification, and settings up to a maximum depth of 3 -5 meters. Therefore, it brings to mind the pertinent issues of which among these attributes is most fundamental and inevitable, which most times the civil engineers do not seem to appreciate the inevitability of Electrical resistivity attributes in foundation studies (Akintorinwa & Adesoji 2009;Adebiyi et al, 2018;Ilugbo et al, 2018;Adebo et al, 2019).…”

Application of Electrical Resistivity Method to Site Characterisation for Construction Purposes at Institute of Agriculture Research and Training Moor Plantation Ibadan

“…Geophysicists interpret these measured variations and use them to develop geologic models of different complexity (Ozegin et al, 2019a). If the subsurface depth of interest can be differentiated from the basis of contrasting physical properties, the output geologic model can be of great utility to an engineering design (Ilugbo et al, 2018a, Aigbedion et al, 2021. A direct consequence of global warming occasioned by the depletion of the ozone layer may be induced as a result of human negligence (Bawallah et al, 2019a.…”

“…The causes of foundation failure may be as a result of differential settlement within a weak subsurface layer or the presence of geologic fissures such as faults, fractures, and shear zones beneath the construction site (Oyedele et al, 2020). Despite this clear reason, site engineers sometimes fail to incorporate pre-construction investigation (Geophysical survey) in their job schedule due to cost, and the findings are not taken into consideration in the design, and construction phase (Ilugbo et al, 2018a, Adebiyi et al, 2018. Designing a stable structure that is safe, durable, and has low maintenance costs depends upon an adequate understanding of the geologic properties on which such a building is sited (Adebo et al, 2019).…”

Modeling of Subsurface Integrity Using Dar-Zarrouk Parameters: A Case Study of Ikekogbe UBE Primary School, Ekpoma, Edo State, Nigeria

“…Subsequently, the need for geophysical and geological site investigation becomes inevitable, for any civil engineering or building structure [6]. For the purpose of civil engineering, site investigation, construction and other structural engineering work, engineering geophysics offer a fast, cheap, cost effective and reliable way forward to engineering and other related problem before construction work [7]. Hence, this research work became necessary, giving the growing concern about the causes of building failures, which most people readily attribute to poor building materials, poor designs or poor construction or finishing without taking into consideration subsurface geological factors.…”