2D Resistivity Imaging and Geotechnical Investigation of Structural Collapsed Lecture Theatre in Adekunle Ajasin University, Akungba-Akoko, Southwestern, Nigeria
Keywords: geotechnical, dipole-dipole, sub-grade, basement complex, engineering structures
AbstractGeotechnical and geophysical investigation involving electrical resistivity survey and laboratory test of the samples were conducted on the samples obtained at the three different locations in the area. The study is aimed at evaluating the competence of the near surface formation building construction materials. Geophysical and geotechnical methods of investigation were adopted. The Electrical Resistivity Tomography, using Dipole-Dipole configuration and soil analysis techniques were adopted. A total of four traverses and three soil samples from different location within the study area were used for the study. The geophysical results revealed that the topsoil is within the depth of 0 to 5m and it is reflective of varying resistivity which indicates materials suspected to be composed of low resistive materials such as water and underlain with a basement complex and presence of a very low resistivity in which water accumulate and percolate which makes it inimical to foundation of engineering structures. There is an evident of geological feature such as fracture within the bedrock which might aid subsidence in the area. while geotechnical results of natural moisture content, specific gravity, liquid limits, plastic limit, plasticity index, linear shrinkage, compaction and permeability ranges from 5.3-9.2%, 2.620-2.730, 23.0-41.9%, not plastic to 21.4%, from not plastic to 22.4%, 1.4-9.3,1790-2114 kg/m3, 9.1-9.9 and very low to medium respectively. Thus, the soil formation in the study area is therefore rated as relatively poor for foundation material.
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