Integrated Geophysical and Geotechnical Pre-foundation Assessment of Proposed Baze University Teaching Hospital Abuja, Nigeria

Abstract

This paper presents the result of the geophysical and geotechnical assessment of the proposed site of Baze University Teaching Hospital in Abuja, Nigeria. The geophysical investigationwas carried out using Vertical Electrical Sounding (VES) Resistivity method with Schlumberger array. The geophysical results revealed four distinct subsurface geological layers that are made up of lateritic topsoil, weathered layer, fractured basement and fresh basement.The natural moisture contents of the soil samples are found to range from 10.8% to 12.6%. The results of compaction test give a maximum dry density between 1.8 mg/m³ to 1.97 mg/m³ while its optimum moisture contents are between 10.3% and 18.3%. The Atterberg limit and plasticity index are also estimated along with analysis of grain size.The grain size analysis showed that for a sieve size of 200B/S or 0.075mm, the percentage passing ranged from 41% to 52%, while the linear shrinkage is found between 18.6% and 23.3%.The results were compared with the 1997 Federal Ministry of Works and Housing (FMWH) construction standards, which are then used as guidelines for thorough engineering foundation. The geophysical result shows that the study area has a shallow depth to basement which makes the site suitable for the proposed Baze University Teaching Hospital while the geotechnical result shows the lateritic topsoil contains high clay content which must be excavated and replaced with a good fill material before the construction take place to avoid swelling of the foundation material.