Engineering and Geological Investigation of Afe-Babalola Matthew Junction in Ado

Abstract

Integrated geophysical investigation, involving the electrical resistivity and magnetic methods was carried out along ABUAD-Matthew roadway in Ekiti State. This was with a view to investigating the cause(s) of the persistent pavement failure recorded over the years along the road. The resistivity survey utilized 1-D Vertical Electrical Sounding (VES) with the Schlumberger array was employed for this research. Total field data were acquired along the identified segments of the road at 5 m intervals. The data were inverted into resistivity structures and were used to constrain the location of the five (5) VES stations. The VES curves were interpreted quantitatively and the results were used to generate 3-D geoelectric sections. The geoelectric sections were characterized by the presence of sedimentary rocks whose materials can either be sandstone, Shale or Limestone with a resistivity value of 41.7-354.1 Ωm, the hardpan layer has a resistivity value of 41.7Ωm which indicates the presence of clay at 4.7 m depth. The fractured basement has a resistivity value of 354.1 Ωm which indicates the presence of rocks which can either be sandstone, Shale or Limestone for VES 1. Also, Alluivium, soils and water at 80 Ωm and 126.8 Ωm at VES 2. VES 3 indicates the presence of metamorphic rocks which can either be basalt, marble, quartzite at a resistivity value of 4815.3 Ωm. It can be seen from the research that clay was found at every depth ranging from 1.4 to 3m which isnt a good material for construction. Geophysical survey should not be neglected as it gelps us to know the geological properties of the underlying soil structure.