ELECTRICAL RESISTIVITY IMAGING FOR PRELIMINARY ASSESSMENT OF ROAD FAILURES IN OGBIA LGA, BAYELSA STATE, NIGERIA

Road failure in parts of Bayelsa State Nigeria has been constituting nuisance to human and vehicular activities in the area. This study was designed to investigate the geologic features responsible for road failure in parts of Ogbia Local Government Area of Bayelsa State, Nigeria. Electrical resistivity method involving 2D imaging of the failed parts of Otuoke-Onuebum and Imiringi-Emeyal 2 Roads were conducted on four profiles normal to the strike of the affected parts. The data collected were tomographically inverted and the results predominantly showed that the failed portions of the roads are characterized with very low resistivities ranging from 0.094 Ωm to 173 Ωm. These results suggest that the formation underlying the failed portions of the roads are predominantly clays and peat, loam and mud. These suggest that clay volumetric variation due to variation in moisture content most likely caused the failure of some parts of the roads. The thicknesses of the clay formations range from 2 m to 8 m. Also, in the parts underlain by peat, loam and mud, the failure in those segments of the roads is attributed to the high moisture of the formations, which are easily compress by loads. The thicknesses of the peat, loam and mud formations range from 3 m to 10 m. It was recommended that excavation of clay and peat, loam and mud deposits be carried out and replaced with less expansive soil like sand on the affected parts of the road to minimize failure.