GEOPHYSICAL INVESTIGATION OF PAVEMENT FAILURE ALONG JONATHAN BY-PASS - AKANSOKO AND ATIMBO - PARLIAMENTARY ROADS IN CALABAR METROPOLIS CROSS RIVER STATE, NIGERIA
This study examined pavement failure in some roads in Calabar Metropolis using electrical resistivity tomography method. Seven (7) measurements were taken at the natural soil opposite the failed and stable segments of the road with the aid of Wenner electrode configuration at spacing of 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 and 35.0m with spread length of 105m. The findings of this study revealed that along Jonathan by- pass – Lafarge – Akansoko road, low resistivity values were 8.0Ωm – 73.0Ωm at Akansoko a stable segment; 6.0Ωm - 17.0Ωm at Ukwua Itiat and 30.0Ωm - 94.0Ωm at Idundu market a failed segment. Along Atimbo - Jonathan – Parliamentary road, moderate/high electrical resistivity values in the range 331.0 Ωm – 1018.0 Ωm across the profile was obtained at Federal Government Girls’ College by airport a control segment; 26.0 Ωm – 68.0 Ωm at opposite rice seedling site a failed segment and 49.0 Ωm – 74.0 Ωm at Message point Assembly Church. These results showed that the remote cause of road failure in the area is clay/shale/weathered geologic materials with low resistivity values. It was recommended that detailed geophysical investigation should always be conducted on any proposed site for road construction and/or rehabilitation before embarking on the project.