Vertical Electrical Sounding was conducted
around four buildings in Federal University of Petroleum Resources Effurun
(FUPRE), Nigeria. This is to delineate the soil types and unravel the
subsurface conditions responsible for palpable cracks on these buildings.
Schlumberger electrode array was employed for data acquisition. Optimization of
measured field and calculated apparent resistivity data and interpretation of
electrical resistivity tomography (ERT) generated using RES2DINV software
revealed a variation in soil resistivity and type. Two major sub-soil types, clayey-sand
and sand, from top to bottom underlie the study area. The clayey-sand is
observed to exhibit low resistivity values ranging between 250 and 953Om while
the sand has resistivity values ranging between 1324 and 2957Om. The results
reveal that there is frequent intercalation of clay within the sands at depths
ranging from 0.1 to 2.0m where the foundations of these buildings are located.
The presence of clays in the sands is indicative of possible seasonal moisture
and volumetric expansion and shrinkage and uneven ground settlement underneath
these buildings. Thus, foundations of buildings should be reinforced by piling
to depths ≥2m (6ft) below the ground surface so as to avoid this zone,
especially underneath the foundations of multi-storey buildings.
Keywords: Cracks, Electrical Resistivity Tomography (ERT), clayey-sand, sand, expansive soil, buildings.