This research was carried out within Institute of Agriculture Research and Training Moor Plantation Ibadan, Southwestern Nigeria, with the aim to ascertain suitability of the proposed site for ...building construction and usage. The geophysical investigation involved three electrical resistivity techniques; Vertical Electrical Sounding (VES) using the Schlumberger configuration, 2D ERT and 2-D electrical imaging using Dipole-dipole electrode configuration. Two traverses were established E–W direction cutting across geologic strike with a distance of 80 m and of varying inter-traverse spacing. Eight (8) VES stations were occupied covering the entire study area for layer stratification and geoelectric parameters. The results were qualitatively and quantitatively interpreted and are presented as sounding curves and geoelectric sections. The 2-D imaging gave information on the subsurface characteristic in the area with generally low apparent resistivity indicating low competence material. The results obtained from the VES delineate three geoelectric units which comprise of the topsoil, weathered layer and fresh basement. The results from the VES were used to determine the second order parameters. The entire results correlate well with one another showing that all the techniques used were complemented. This study has further justified the need for geophysical site investigation as pre-condition before any construction to avoid problems of differential settlement. In determining of foundation material, topography elevation, clay content and the depth of weak zones should be put into consideration, since the depth of the weak zone is appreciably high.
A geophysical investigation for buried human remains after 8 years of burial involving the use of Electrical Resistivity Tomography (ERT) was carried out at Owo, Ondo State, Southwestern Nigeria. ...This study was aimed at identifying the burial location of a corpse buried in a coffin about 8 years ago for exhumation and reburial in another location consequent upon litigations and controversies surrounding the land of the burial. The results obtained were used to generate 2D model and different resistivity maps which were able to identify suspected zone. Excavation of the suspected zone was carried out for the exhumed and relocation of the buried human remains. Electrical Resistivity has therefore been found useful in search for detecting human remains buried in a coffin with the key indicator being lower electrical resistivity relative to the surrounding area.
Geophysical investigations were carried out around the ministry of Justice building, Ekiti State Secretariat, Ado-Ekiti, with the aim of investigating the possible cause(s) of failures from the ...foundation of the building in the government Secretariat. The Electromagnetic and Electrical Resistivity methods were used for the investigation. The Electrical Resistivity method involves Vertical Electrical Sounding (VES) and 2D Electrical Resistivity Tomography using Schlumberger and dipole-dipole configuration. Three (3) VES points were conducted along the traverse within the investigated area with half current electrode separation (AB/2) varying from 2 m to a maximum of 65 m. The electromagnetic measurements were taken at distance separation of 10 m along the traverse line in the SE-NW direction. The VES curve types obtained in the area are H and HKH. Four geoelectric layers were delineated within the investigated area which includes the topsoil, lateritic clay, clay, and partly weathered basement which is a quartzite rock with resistivity values ranging from 47-280 ohm-m, 383-435 ohm-m, 47-78 ohm-m, and 239-4999 ohm-m and the thickness ranges from 1-1.6 m, 2.8-4.2 m, and 9.1-27.9 m respectively. The dipole-dipole results also delineate four geologic formations that revealed the differential settlement within the clayey zone of the building foundations. The electromagnetic method also delineated seven subsurface geologic formations which revealed that most of the materials characterizing the subsurface are of clayey composition. The integration of the results showed that the possible cause(s) of failures in part of the building is due to the presence of clayey formations and geologic fractures within the foundation of the studied area.
This research evaluates the significance of geotechnical and Electrical Resistivity methods in studying structural integrity as fundamental factors that may account for failure in a typical ...sedimentary environment of Ukpenu Primary School, Ekpoma, Edo State, Nigeria. Two methods were used in this study such as the Electrical Resistivity approach involving the use of Lateral Horizontal Profiling (LHP), 2D Electrical Resistivity Tomography (ERT), and Vertical Electrical Sounding (VES) techniques. While geotechnical method involved the collection of soil samples from the study locations for the characterization of the soil properties that are very vital to foundation studies. Nine VES were carried out using Schlumberger array with current electrode spacing varying from 1 to 40 m, with 2-D ERT using Dipole-Dipole electrode array with inter-station separation of 5 m and an expansion factor varied from 1 to 5 while LHP involve Wenner array with an electrode spacing of 5 m interval and was used to determine the vulnerability factors for the building sustainability. The VES interpretation results were used to determine the second-order parameters for the determination of vulnerability. The results obtained from the two methods review that both are very fundamental to foundation dynamics. However, electrical attributes were found to give better information in terms of depth, lateral extent, layer stratification, and nature of materials which make it an indispensable tool over geotechnical attributes whose depth of investigation is up to a maximum of 5 m which poses great limitation in the evaluation of structural integrity, against stress, and strain occasion by geodynamic activities that often result into fracture, crack, highly weathered formation that usually goes beyond the shallow depth of investigation. Therefore, it can be stated that resistivity attributes account for 90% of the major contributing factors that affect foundation vulnerability.
This study has evaluated the post-construction subsoil integrity of a distressed building in Ado-Ekiti, Southwestern Nigeria, to decipher the in-situ lithology and structural disposition. Four ...traverses of 100 m length were established in approximately E-W direction with an inter-station spacing of 10 m. Two Geophysical methods were deployed including the ground magnetic method using Proton Precession Magnetometer and Electrical Resistivity method utilizing 2D Electrical Imaging and Vertical Electrical Sounding (VES) techniques. Twelve (20) VES station points were acquired within the investigated area using Schlumberger configuration which gave relevant information on layer stratification and geoelectric parameters. The obtained results from the VES showed four geo-electric layers comprises topsoil, clayey layer, weathered layer, fractured bedrock, and fresh basement. Low apparent resistivity was delineated from the 2D imaging exhibiting unfit materials at distance between 50 to 75 m and 80 to 100m. The magnetic results showed a series of bedrock ridges and depressions. The integration of results revealed that the majority of the study areas are unsuitable except for central parts which indicate appreciable competence and stability.
A statistic is found useful in many applications of science where data and analysis are used for illustration and description for better understanding and justification of the data sets. Therefore in ...an attempt to achieve a better understanding and illustration of the dynamics of foundation integrity and vulnerability of failure, which often remain a major challenge to mankind, especially in Nigeria where foundation failures remain a major concern to both the Government and citizen. In this present study, a statistical approach was carried out on the Geophysical parameters in Issele-Mkitim area, South South Nigeria, to evaluate the dynamic factors that affect foundation integrity and vulnerability of subsurface lithologies. Very Low Frequency Electromagnetic (VLF-EM), Magnetic, and Electrical Resistivity Methods were used in this study. The Electrical Resistivity Method involved Lateral Horizontal Profiling (LRP) utilizing Wenner configuration. The three (3) methods correlated in terms of statistical prediction and understanding of the geologic dynamics natured associated with foundation failure and integrity. It was deduced that profiles one to six has high tendency of weak geological material which can easily lead to subsidence if any engineering construction is erected on it. However, proper consideration must be put in place to avoid future differential settlements. All the methods give useful information about the dynamics of the geological trends from the preliminary data analysis and interpretations, and a better understanding of the geodynamics nature of the soil as well as the region of a weak and competent zone in terms of engineering constructions.
This research work asses the problems of building foundation within Sagari Estate, Akure, Southwestern Nigeria, using remotely sensed data and geophysical methods. The slope, lineament, hill, and ...contour map were generated using terrain analysis in ArcGIS 10.5 environment. Electrical Resistivity (ER) and Very Low Frequency (EM-VLF) Electromagnetic methods were used in this study. The ER method involves the use of Vertical Electrical Sounding (VES) with Schlumberger configuration. The initial geoelectric parameters obtained from the fifty three (53) VES station points interpretation (layer resistivities and thicknesses) were used to generate geoelectric maps. The variation of strata and physical strength information within the investigated area were determined from the integrated results of the three methods. Results revealed that substantial portion of the areas studied is relatively unsuitable for high rise civil engineering foundations. However, it was showed that the northern and southern parts of the investigated area were more suitable for foundations. The dominant presence of lineaments, steep slopes , fractures, streams, and thick clayey topsoil as well as weathered layers within the western, eastern, and the central portions reveals susceptibility to subsidence if adequate structural supports mitigate the effect of the persistent foundation failure are not provided.
A geoelectric investigation of groundwater prospect at Omitogun Estate, along Benin/Ilesha express way Akure, within the basement complex of southwestern Nigeria was carried out with a view to ...providing information on the geoelectric characteristic of the subsurface sequence, bedrock topography, subsurface structural features and their hydrogeologic significance, in order to identify aquifer units and determine possible areas for groundwater potential zones. The study involved the use of Schlumberger vertical electrical sounding data at thirty (30) stations. The vertical electrical sounding data presented as field curves were interpreted quantitatively by partial curve matching method and computer iteration technique. Fracture resistivity map, aquifer resistivity map, aquifer thickness map and overburden thickness map were generated from the results. Groundwater potential map was also generated from the integration of these maps using multi-criteria decision analysis (MCDA). The study area has been classified into low, medium, high groundwater potential zones and the results from well data across the entire study area were used to validate the accuracy of the groundwater potential map. From the results obtained, it could be concluded that the study area is generalized to be of low groundwater potential.
Geophysical and geotechnical studies were carried out at a proposed location for the construction of a multi-storey structure in Akure, Southwestern, Nigeria. The aim was to ascertain the suitability ...of this location for both Founding and Engineering structures. The geophysical investigation involved the Vertical Electrical Sounding (VES) technique using the Schlumberger configuration, Dipole-Dipole Horizontal Profiling and a geotechnical investigation. A total of twenty-one (21) VES and five (5) Cone Penetration Test (CPT) locations were occupied within the study site. Dipole-Dipole Horizontal Profiling was occupied along traverses 1 and 2 within the investigated area. The electrode separation varies from 1 to 75 m. The investigation delineated three major layers which are topsoil, which is excavated before any foundation is laid. The second layer delineated was lateritic and the last was weathered layer. From the result obtained, depth to lateritic layer ranges from 1.1 to 9.0 m while resistivity defining the lateritic layer ranges from 150 Ωm to 792 Ωm. Some of the sounding curves generated over the VES stations and Dipole-Dipole Horizontal Profiling fairly correlated with those of the CPT profile. The high cone penetration resistance recorded at CPT point 4 and 5 is manifested as high geoelectric resistivity values recorded at VES 13. This shows that the soil has fairly low clay content. It also seen from the study that the geophysical studies has a greater depth penetration, and it also provide better layer characterization compared to geotechnical studies. The choice of foundation material, clay content and topography elevation should be taken into cognizance, since the load bearing capacity of the lateritic layer was appreciably high.
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