Authors : Michael Ilesanmi Oladapo , Martins Olusola Olorunfemi and John Sunday Ojo
Abstract: Causes of failures on three roadways located in the Precambrian Crystalline Basement Complex area of Southwestern Nigeria have been investigated in this study. The electrical resistivity method involving dipole-dipole and Wenner Vertical Electrical Sounding (VES) techniques were utilized. The failed segments of the roadways are characterized by relatively low resistivity (mostly < 200 -m) with the stable zones typically resistive (>> 400 -m). Forms of road failures identified from the study are failures arising from differential settlement on road cut sections that intercept clayey saprolite with high moisture content as observed on Igbaraoke-Igbaraodo roadway; failures precipitated by differential settlements associated with significantly thick, low resistivity clay topsoil as observed on Itaogbolu portion of the Akure-Ado Ekiti roadway and failures initiated and sustained by geological features such as lithological contacts/faults, inclined interfaces between basement rocks and or collapse subsurface strata (e.g., cavity or sinkhole structure) as observed on study segment of Igbaraodo-Ikere Ekiti roadway. Pre-construction geophysical studies of roadways could effectively compliment routine geotechnical studies.
Michael Ilesanmi Oladapo , Martins Olusola Olorunfemi and John Sunday Ojo , 2008. Geophysical Investigation of Road Failures in the Basement Complex Areas of Southwestern Nigeria. Research Journal of Applied Sciences, 3: 103-112.