Relevance of Electrical Resistivity Geophysical Method in Engineering Site Characterization in A Basement Complex Terrain

In this study, relevance of electrical resistivity geophysical technique in engineering site characterization had been demonstrated. The aim of the study was to establish the capability of the technique to unravel subsurface conditions through quantitative assessment/evaluation of subsurface geoelectric parameters. In order to achieve the objectives of the study, twenty (20) VES were acquired using R-50 Resistivity meter. The results obtained from both the qualitative and quantitative interpretations of the VES data were utilized in preparing geoelectric sections and some important layers parameters maps. The dominant curve types obtained suggest that the study area is largely characterized by the presence of highly weathered/fractured basement with evident of saturation. Three geologic layers were generally delineated, and these were top soil, weathered/fractured basement and the basement. The top soil was observed to be of thin thickness indicating that the foot of the foundation might inevitably be extended to the layer underlain the top soil. Series of linear features such as basement depressions and ridges, fracture, geologic contacts etc. capable of aggravating foundation failure were observed in some parts of the area. The study has consequently established the efficacy of electrical resistivity as a geophysical tool that can complement conventional geotechnical studies in engineering site characterization.

Keywords: Foundation failure; Geotechnical; Subsurface competence; Site characterization