This research showed the significance of electrical resistivity method for road construction along Shake road, Irrua, Edo State, Nigeria. The aim of the study is to establish the near surface geological features that are predisposed to incessant case(s) of road failures few months or years after construction. The geophysical investigation involved three techniques; Vertical Electrical Sounding (VES), 2-D Electrical Resistivity Tomography (ERT) and Horizontal Profiling (HP) which covers a pilot test of 220 meters. Ten (10) VES were carried out using Schlumberger array with current electrode spacing varying from 1.00 to 100.00 m, with 2-D ERT using Dipole-Dipole electrode array with inter-station separation of 10 m and an expansion factor that varied from 1 to 5 and HP using Wenner array with an electrode spacing of 5 m interval. The VES interpretation results were used to determine the second order parameters for determination of integrity and susceptibility test of failure. The result obtained from the VES delineated three geoelectric units which Comprise of topsoil, clay layer, sand layer/shale horizon units. The 2 D imaging (Dipole-Dipole) gave information on the subsurface characteristic which indicates high, moderately high integrity and low integrity/a low competence material. The Wenner profile is characterised by low resistivity.
for road construction along Shake road, Irrua, Edo State, Nigeria. The aim of the study is to establish the near surface geological dynamics that may be responsible for this increscent case of road failures few months and years after construction. The geophysical investigation involved Vertical Electrical Sounding (VES) technique using Schlumberger configuration, Dipole-Dipole Horizontal Profiling and wenner profiling investigation which covers a pilot test of 220 meters. A total of Ten (10) vertical electrical sounding (VES) was acquired, with 2D Imaging using Dipole – Dipole horizontal and wenner profiling with electrode spacing of 5m interval. The VES interpretation results were used to determine the second order parameter for determination of integrity and susceptibility test of failure. The result obtained from the VES delineated three geoelectric units which Comprises of topsoil, clay layer, sand layer / weathered layer / shale horizon units. The 2 D imaging (Dipole – Dipole) gave information on the subsurface characteristic which indicates high, moderately high integrity and low integrity / a low competence material. The wenner profile is characterized by low resistivity. All the results correlate well with each other showing that all the techniques used were complimented. The result obtained from the pilot test of 220m reveals that only 10% of the road survived susceptibility test, with a longitudinal conductance value of 1.099, and 30% of the class distribution were moderately susceptible to failure with longitudinal conductance values between 0.1000 to 0.999, while the rest of the study location with total longitudinal conductance values of 0.010 to 0.099, implying 60% susceptibility chance of failure.