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Site characterization of Ayetoro Housing Scheme, Oyo, Nigeria

Adagunodo, T. A. and Sunmonu, L. A. and Oladejo, Olagoke Peter and Hammed, O.S. and Oyeyemi , Kehinde D. and Kayode, O.T (2018) Site characterization of Ayetoro Housing Scheme, Oyo, Nigeria. In: 2nd International Conference on Science and Sustainable Development.

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Detail knowledge about the subsurface properties and its engineering implications is crucial in pre-foundational studies. Geophysical investigation has been found relevant in probing the subsurface for the purpose of deducing its characteristics before any engineering construction activities would commence because of its non-invasiveness. The deduced soil characteristics are used as preliminary information to determine the suitability of the site under investigation. When the results from such study are properly utilized, it prevents prospective structural failure and loss of valuable asset. Ground magnetic technique and Vertical Electrical Sounding (VES) was used to characterize the subsurface layers of Ayetoro Housing Scheme, Ojongbodu, Oyo West Local Government Area, with a view to determining the competency of the subsurface and hydrogeological prospect of the study area. A total of six traverses were established in the E-W direction and N-S direction in order to map the magnetic signatures in the study area. Thirty VES stations were occupied across the study area using the Schlumberger electrode array configuration with current electrode spacing varying from 130 to 200 m. The data acquired was interpreted qualitatively and quantitatively. The magnetic highs and lows were observed in all traverses. The magnetic highs represent regions of magnetic minerals such as metamorphic or igneous rocks while magnetic lows represent regions with linear geologic features. Power spectrum and analytical signal filtering techniques were used for the ground magnetic interpretation. Depth to magnetic sources from power spectrum analysis (local field) ranged from 5 to 62 m. However, depth to magnetic sources from analytical signal varied from 20 to 160 m with an average variation from 38.3 to 77.6 m. The western part, some part of the northwestern zone, base of the northeastern zone and some part (probably base) of the southern region of the study area were interpreted as regions of magnetic highs while others belong to average and low magnetic distribution. Twelve of the thirty modeled curves were H-type, eight were QH-type, three were HA-type, one was Q-type, two were A-type, two were HK-type and two were KH-type. The overburden thickness ranges from 1.8 m to 44.8 m, the geoelectrical sections obtained from the Sounding curves showed both 3- layer and 4-layer earth model. Nine of the VES stations show fresh bedrock while the remaining twenty one showed fractured basement. The models showed that the subsurface layers categorized into topsoil, weathered/clay layer, and fractured/fresh basement. It was concluded that the subsurface is incompetent for high-rise buildings since the lithology of the area showed that clayey zones, thick overburden and fractured bedrocks constitute two-third of the study area. However, groundwater exploration (hand dug wells and boreholes) for domestic uses would not be problematic in the study area.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Site characterization, Structural failure, Competent zone, Incompetent zone, Basement complex.
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Divisions: Faculty of Engineering, Science and Mathematics > School of Physics
Depositing User: Mrs Hannah Akinwumi
Date Deposited: 31 Jul 2018 15:35
Last Modified: 31 Jul 2018 15:35

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