2D ELECTRICAL RESISTIVITY IMAGING INVESTIGATION ON CAUSES OF ROAD FAILURE ALONG KUTIGI STREET, MINNA, NORTH CENTRAL, NIGERIA

Abstract

Background: Road failure is most common in developing countries and this has led to the loss of billions of dollars over decades due to either poorly constructed road and under maintained roads. The consequent daily loss of human life and economically significant properties, should make road failure an alarming issue to the Nigerian Government. A proper geophysical investigation must be conducted on the road to examine the subsurface soil characteristics Objectives: Consequently, this study investigate the causes of road failure along Kutigi Street to determine the geo-electric properties of the subsurface of the study area. Methods: The technique employed for this study was 2D Electrical Resistivity Wenner Array Method. Two profiles covering a distance of 300 meters each were established parallel to the road pavement along the stable and unstable sections of the road. Data were collected along the two profile using ABEM Terra meter SAS 4000. The observed field data were processed and inverted using 2-D modelling inversion algorithm (RES2DINV Software). Results: The results reveals the presence of low resistivity values at several portion of both profile A and Profile B. Resistivity values ranging from 9.25 Ωm – 115.30 Ωm to a depth of 11.25 m from the topsoil was observed along profile A and resistivity values ranging from 5.20 Ωm – 25.6 Ωm to a depth of 11.25 m from the topsoil was observed along profile B. Conclusions: The low resistivity values observed in both profiles comprises of expansive clay and sandy clay materials which has the tendency of absorbing water. These makes them swell and eventually collapse under imposed wheel load stress which leads to failure. Regions of the road with sandy and clayey materials should be excavated from the subsurface to a depth of 4 m – 6 m from the topsoil of the road and replaced with competent fill materials.