Geoelectrical Subsurface Characterization for Foundation Purposes in the College of Agricultural Sciences (CAS) Campus, Ebonyi State University, Abakaliki, Southeastern Nigeria

Abstract

The study area is underlain by shales and volcanoclastics with subordinate lenses of sandstones and sandy limestone (Abakaliki Formation) of the Albian Asu River Group, southeastern Nigeria. Geophysical investigation was carried out at the College of Agricultural Sciences (CAS) Campus, Ebonyi State University (EBSU) to determine the structural competence of the subsurface geological strata for building construction and other foundation purposes, using vertical electrical sounding (VES) survey technique of the electrical resistivity method. From the result of the survey, two major zones have been established within the study area for building construction purposes. Zone A comprises of areas around the catholic church building, EBSU primary school up to the school of post graduate studies, while zone B  is made up of areas around the EBSU secondary school, proposed student centre up to the main entrance gate which led to the Ogoja road. Zone A has been recommended for bungalows and other forms of low rising buildings, while zone B has been recommended for storey buildings and other heavy engineering structures. Overburden thickness for the two zones ranges from 1.3 m to 2.7 m, and 0.6 m to 2.7 m for zones A and B respectively. The cracks on walls of the buildings within the campus have been attributed to either the inability of the engineers to dig the foundation to the required depth or the construction of heavier structures on very weak subsurface layers which triggered off movement.

Keywords: Geoelectrical, Characterization, Foundation, Ebonyi State University, Nigeria.