LAUSR

Remote sensing, geotechnical studies and geophysical data have been applied to determine the causes of the continuous pavement failure of the Minna – Suleja highway in a part of North-Central Nigeria. In this study, remotely sensed data in the form of Landsat 8 OLI and SRTM DEM were processed to extract structural lineaments and drainage pattern of the area. Geotechnical evaluation of soil samples such as grain size analyses, Compaction Test, Atterberg Limits and California Bearing Ratio (CBR) determination were also conducted. Geophysical data acquired were in the form of lateral resistivity profiling data at 500 m intervals and twenty-one Vertical Electrical Sounding (VES) spread across the selected sections of the road. Lineament analysis revealed predominant NNE-SSW trending structures. A notable percentage of the Lineaments trend NW- SE. Both sets of lineaments constitute a conjugate fracture system. CBR values in both portions range from 5 – 15% in soaked condition and unsoaked condition at OMC. Plasticity index range from 14 – 30 and 19 – 45 in both portions. Quantitative interpretation of the VES results established the presence of mostly three geologic layers which are: Clayey top soil, sand/lateritic sand and weathered basement. Resistivity values range from 20 Ωm to 300 Ωm for the top soil layer. The depths of this layer were generally less than 3 m. Preponderance of intersections of lineaments along failed portions account for near surface fractures, making these zones weak. This can be linked to low resistivity of the near surface materials and shallowness of the water bearing zones especially on the failed portions on which the road pavement foundation was laid. A distinction could not be made on the results of the geotechnical properties in both the failed and stable portions of the road. Hence, failure factors are not linked to the geotechnical properties of the soils.