Abstract

An electrical resistivity investigation was carried out within the vicinity of some failed building structures at Amafor Ihuokpala through Agbani, Enugu, Southeastern Nigeria. The aim of the survey was to determine the causes of the failure of the structures. Resistivity data were acquired by using PASI (16GL) digital earth resistivity meter. Interpretation of the vertical electrical sounding results indicates the occurrence of relatively thin topsoil (<2 m) composed of sandy-clay which is underlain by clay-shale formation to about 40 m depth. The resistivity distribution map of the formation shows significant lateral facie and/or moisture changes within the topsoil. The clay-shale has vertical facies changes without any significant lateral facies changes. Synthesis of the result indicates that, due to hydrological and petrological factors, there is significant variation in the moisture regime of the soils underlying the site. This results in substantial swelling and shrinkage of the foundation soils leading to occurrence of cracks/deformation in the building structures. Improvement of the soil through stabilization and/or reinforcement is required for effective foundation design.

Key words: Electrical resistivity, vertical electrical sounding, lateral facies, and soil stabilization.