A GEOPHYSICAL INVESTIGATION USING SEISMIC REFRACTION METHOD TO DETERMINE THE CAUSES OF ROAD FAILURE, A CASE STUDY OF IRUEKPEN-OZALLA ROAD AXIS
This project work was carried out at Ireukpen-Ozalla Road Axis Ekpoma, Esan-West Local Government Area Edo State. Using seismic refraction prospecting method to examine the cause(s) of the persistent failure of the road. An ABEM TERRALOC MARK-6 Seismometer was used as the recording instrument and twelve geophones as wave detectors in series with one another. The geophones were spread at predetermined distances and the impact of a sledge hammer on a flat plate served as the source of generating seismic waves.
The “SERCOM1” software was employed in the interpretation of the field result for the forward and reversed shooting respectively. From which the subsurface reveals two layers of velocities, which are 980ms-1 and 1283ms-1 for the forward shooting, 851ms-1 and 1276ms-1 for the reversed shooting respectively. The investigation also shows that at twenty three metres (23 m) from the surface of the forward shooting, clay deposit could be discovered. And even at thirteen metres (13 m) from the surface of the reversed shooting clay deposit could also be encountered. The form of road failure identified in this study is due to subsidence associated with clayey material and the delineated clayey water absorbing sections which are major geologic factors responsible for road failure in the area.