SUBSOIL EVALUATION FOR PRE-FOUNDATION STUDIES OF AAUA ALUMNI HOSTEL USING 2D RESISTIVITY IMAGING

A two-dimensional electrical resistivity survey was carried out at the proposed Alumni building in Adekunle Ajasin University campus, Akungba in the Precambrian Basement Complex of Southwestemn Nigeria. The study is aimed at evaluating the subsurface condition in order to assess the competence of the subsoil hosting the building structure. The resistivity datasets were acquired along three traverses within the premises in E-W azimuth of the structure. The 2D resistwin in interpretation software was used to analyze the data Results show resistivity variation from 23 to 600000m along the traverses. Resistivity variations across each transverse depicts weathered basement overlying uncomfortably on the partially weathered/fractured basement while the fresh basement is found at the depth range of 1.8m to 5m as the basal unit. Anomalous low resistivity zones sandwiched within the bedrock are interpreted as zones of weakness indicated as F1- F1, F2- F2, F3- F3 or succession of fractured/shear basement column. These zones are saturated and are preferential flow pathways for water. These are found and identified within traverse 1 and 2, while resistivity anomalous zones suitable for civil engineering structures are found within traverse 3. Therefore, we conclude that 2-D resistivity survey finds solution to civil engineering problems at planning stage. Hence, it is therefore recommended for appraisal study.