Post-Foundation Studies Using Integrated Geophysical and Geotechnical Methods at New Agbor Road, Uromi, Edo State, Nigeria

Globally, the incessant failure of buildings has drastically led to an increase in the loss of lives and properties, posing lots of concerns about the causes of these devastating effects. This research evaluates the immediate and remote causes of probable foundation failure on some buildings at Ohunyon Street, Uromi, Edo State, using integrated geophysical and geotechnical methods. By optimizing the measured field, calculating the apparent resistivity data, and interpreting the generated electrical resistivity tomography by using the SAS 1000 terrameter and RES2DINV software, a variation in soil resistivity and type was established. The geotechnical method required performing Atterberg limit-index studies on the gathered soil specimens in the region as well as geological laboratory grain size analyses. The pole-dipole results showed two weak zones and one moderately competent zone, whereas the dipole-dipole results revealed three primary layers: topsoil (sandy clay), clayey loam, and silty loam. The results also revealed regular clay permeation within the loam at depths ranging from 0.9 to 1.9 m, indicating yearly wetness, volumetric expansion, shrinkage, and uneven ground settlement. The geotechnical survey results provided useful information on both the textural soil test and the Casagrande soil analysis. All of the results were highly correlated, providing pertinent information regarding the factors responsible for the buildings’ failure and recommending that the foundations of these buildings be reinforced by piling to depths of 2 m (6.6 ft) below the ground surface in order to prevent future failures. This work has distinctly shown how integrated geophysical and geotechnical methodologies can potentially be used to evaluate subsoil competency.