期刊名称：Journal of Emerging Trends in Economics and Management Sciences
电子版ISSN：2141-7024
出版年度：2018
卷号：9
期号：1
页码：20-26
出版社：Scholarlink Resource Centre
摘要：A highway foundation study from geophysical tools involving the Very Low Electromagnetic (VLF-EM) and electrical resistivity surveys was undertaken along Ikare – Owo Highway at site located in the central part of Akungba – Akoko town, southwestern Nigeria. The aim of the study was to evaluate the geological influence of the failed and stable segments of the highway pavement. Seventy stations were occupied on the VLF-EM profile. A dipole-dipole resistivity profiling and six Schlumberger vertical electrical sounding datasets were also collected along the highway shoulder. ABEM SAS 1000 resistivity meter and ABEM WADI VLF-EM Unit were used for the data collections. The resistivity data were quantitatively interpreted and refined by a computer iteration technique involving the RESIST and Dippro TM software programmes while the KHFILT software was used for the VLF-EM datasets. Results showed three geoelectric/geologic sequences which included the sandy clay/clayey sand topsoil with resistivity values ranging between 66 and 178 ohm-m and thickness values of 0.5 and 3.6 m; the clayey weathered layer with resistivity values between 18 and 81 ohm-m and thickness values 2.2 and 15.3 m and partially weathered/fractured/fresh basement with resistivity values ranging between 461and 2594 ohm-m. The geoelectric section reflected the near/shallow uneven basement topography beneath the segments. The area beneath the stable segment was underlain by sandy materials characterized by relatively high topsoil resistivity (>170 ohm-m) and thickness values (>3.5 m), while the distressed/failed segments are characterized by a thin topsoil cover (< 2.5 m) and very low resistivity values (<100 ohm-m) typical of clayey materials. It may, therefore, be concluded that the causes of the total failures of the highway pavement beneath the site investigated were geologically controlled to include near surface local geological features such as lithological contact, basement depressions/relief structures, subsidence/differential settlements occasioned by the clayey weathering products/clay-filled buried river channel with tendency for a good soak and swelling potential of the highway pavement materials.
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