Abstract:
Electrical resistivity measurement and geotechnical tests were carried out at a part of the Federal
University of Technology, Akure Campus. The apparent resistivity and geotechnical parameters
distribution at the depth of 1 and 2 m were obtained with the aim of establishing an empirical relationship
between the two parameters. The electrical resistivity data was acquired at ten (10) locations that cut
across the geology that underlay the study area. Schlumberger configuration was adopted with electrode
spreading corresponding to the depth of interest (1 and 2 m). The geotechnical analyses were carried out
on twenty (20) soil samples taken at the depth of 1 and 2 m from the ten sounding locations where
apparent resistivity (a) values were determined. The geotechnical tests conducted include; natural
moisture content, grain size analyses, specific gravity, Atterberg limits, compaction, California bearing
ratio (CBR) and unconfined compression tests. ArcGIS 10.1 software was used to generate maps showing
the iso-resistivity as well as the geotechnical parameter distribution across the study area at 1 and 2 m
depth. It was observed that they all correlate with the composition of the weathering end-product of the
geology of the study area. The apparent resistivity values obtained within the study area ranges from 45
to 487 m and 8 to 701 m at the depth of 1 and 2 m respectively. The apparent resistivity values
obtained were plotted against each of the geotechnical parameter using Microsoft Excel software, and
the trend line was used to obtain the resultant linear empirical equation as well as the coefficient of
correlation. From the correlated plots at both depths, it was observed that specific gravity, maximum dry
density and California bearing ratio exhibit a direct relationship with apparent resistivity. Other analyzed
parameters such as moisture content, clay and silt content, liquid limit, plastic limit, plasticity index, linear
shrinkage, optimum moisture content and unconfined compression shear strength exhibit an inverse
relationship with apparent resistivity. Almost all the cross plots at both depths show a relatively good
correlation with coefficient of correlation (R) ranging from 0.52 to 0.93, except for plastic limit that weakly
correlates with apparent resistivity, whose coefficient of correlation is 0.34 and 0.38 at 1 and 2 m depth
respectively, and plasticity index with coefficient of correlation of 0.44 at 1 m depth.
