Geo-Electrical Subsurface Survey for Foundation Purposes: A Case Study of Federal University Wukari, Taraba State, Northeast 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
A. S. Ogungbe, A. R. Balogun, A. A. Umar, and O. A. Adejo (2017): Site Characterisation using Electrical Resistivity Methods: A case study of the Nursery/Primary School, Ojo, Southwest Nigeria. Journal of Scientific Research and Reports 13 (1) pp 1-16.
Adegbola R. B., Oseni S. O., Sovi S. T., Oyedele K. F. and Adeoti L. (2010): Subsurface Characterization and its Environmental Implications using the Electrical Resistivity Survey: Case with LASU Foundation Programme Campus Badagry, Lagos State, Nigeria. Nature and Science, Vol. 8 (8).
Adepelumi, A. A. and Olorunfemi, M. O. (2000). Engineering geological and geophysical investigation of reclaimed Lekki Peninsula, Lagos, Southwest Nigeria. Bulletin of Engineering Geology and Environment, Vol. 58; Page125.
Akintorinwa O. J. (2017): Application of Engineering Geophysics in Site Investigation: A case study of Ondo State University of Science and Technology, Okitipupa, Southwest Nigeria. Federal University of Technology, Akure Center for Research and Development (CEDRAD).
Akintorinwa O. J. and Adesoji J. I. (2009). Application of geophysical and geotechnical investigations in engineering site evaluation. International Journal of Physical Sciences, Vol. 4 (8), Page 443.
Aroyehun M. Tope and Akintorinwa O. James (2018): Application of Geophysics in Post Foundation Study: A case study of the Faculty of Social Science Building, Phase I, Federal University, Oye-Ekiti, Southwest Nigeria. OMICS International.
G. M. Olayanju, K. A. Mogaji, H. S. Lim and T. S. Ojo (2017): Foundation Integrity Assessment Using intergrated Geophysical and Geotechnical Techniques: A case study of Crystalline Basement Complex, Southwest Nigeria. Journal of Geophysics and Engineering.
El-Nafaty J. M. (2015). Geology and Petrography of the Rocks around Gulani Area, Northeastern Nigeria. Journal of Geology and Mining Research, 7 (5), Page 42.
Ogungbe A. S., Olowofela J. A., Da-Silva O. J., Alabi A. A. and Onori E. O. (2010). Subsurface Characterization using Electrical Resistivity (Dipole-Dipole) method at Lagos State University (LASU) Foundation School, Badagry. Pelagria Research Library: Advances in Applied Science Research, 1 (1), Page 174.
Ogungbemi, O. S. and Ademilua, O. L. (2013). Integrated Geophysical Studies for Post- Foundational Investigation in Part of Afe Babalola University, Ado Ekiti, Nigeria. Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS), 4 (4), Page 654.
Oladele S., Oyedele K. F. and Dinyo M. O. (2015). Pre-Construction Geo-electrical and Geotechnical Assessment of an Engineering Site at Alapere/Agboyi, Lagos, Nigeria. Ife Journal of Science, 17 (3), Page 543.
Omowumi F. P. (2014). Application of Electrical Resistivity in Buildings Foundation Investigation in Ibese Southwestern Nigeria. Asia Pacific Journal of Energy and Environment, 1 (2), Page 95.
Onyedim G. C., Alagoa K. D., Adedokun I. O., Aderogba A. A. and Ovuru C. (2009). Mapping High-Angle Basement Faults in the Middle Benue Trough, Nigeria from Gravity Inversion Surface. Earth Science Resources Journal, 13 (2); Pp. 141-142.
Oyedele, K. F. and Ekpoette, K. U. (2011). Resistivity attributes of foundation beds in a sedimentary terrain: Implications on geo-engineering soil conditions. American Journal of Scientific and Industrial Research, 2 (5), Page 734.
Popoola O. I. and Okhaifo B. O. (2012). Evaluation of Highway Failure of a portion of Ibadan Iwo Road, South Western Nigeria, Using Very Low Frequency Electromagnetic and Resistivity Methods. Electronic Journal of Geotechnical Engineering, Vol. 17, Page 2541.