Geo-Electrical Subsurface Survey for Foundation Purposes: A Case Study of Federal University Wukari, Taraba State, Northeast Nigeria
[1]
Ayuni Ngo Kilian, Department of Pure and Applied Physics, Federal University Wukari, Wukari, Nigeria.
[2]
Ayoola Waliu Fagbenro, Department of Pure and Applied Physics, Federal University Wukari, Wukari, Nigeria.
[3]
Agyo Awudu Angyu, Department of Pure and Applied Physics, Federal University Wukari, Wukari, Nigeria.
Subsurface investigation and characterization prior to every construction have become an essential component to ensure safety of human lives and properties. Incessant building collapse and foundation failures in Nigeria have continued unabated in recent years, causing loss of lives and properties. The necessity for site characterization for construction purposes has therefore become vital so as to prevent loss of valuable lives and properties that always accompany such failure. The purpose of this study is to carry out Geo-electrical subsurface characterization for foundation purposes. The method employed in this study is the Vertical Electrical Sounding (VES) technique using the Schlumberger configuration. Ten (10) vertical electrical sounding points were conducted. The data obtained were interpreted by computer iteration process and results indicate a three (3) to four (4) layered lithology with the exception of VES 9 which has only two (2) layers. Different zones were delineated with respect to their resistivity values. The investigation revealed the first and second layers to be the most competent for founding small to medium engineering structures due to the presence of high resistive lithological units in both layers. The first layer which is top lateritic soil has a resistivity value ranging between 136-42,738 ohm-meters. The second layer has an average resistivity of 371.335 ohm-meters with thickness that varies from 1.309 meter to 22.440 meters. The average resistivity value of the second layer has been asymmetrically skewed by the extremely low resistivity of VES 3 (32.117 ohm-meters) and VES 9 (23.370 ohm-meters): indicating that the second layers of the aforementioned VES points are unsuitable for founding civil engineering structures. The lateritic materials in layer one indicate high load bearing capacity suitable for shallow foundation. The estimated best depth for foundation in the study area is 1-2 meters. The aforementioned depth range is recommended because it does not exceed the high resistive layers (layers 1 and 2) which possess a combined average depth of 8.41 meters.
Characterization, Engineering Structures, Foundation, Geo-Electric Section, Schlumberger Array Vertical Electrical Sounding
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