scholarly journals Application of Electrical Resistivity Method in Site Characterization along Ado – Afao Road, Southwestern Nigeria

2018 ◽  
pp. 1-16
Author(s):  
S. O. Ilugbo ◽  
A. D. Adebiyi ◽  
S. O. Olaogun ◽  
T. Egunjobi
Keyword(s):  
Clay Content ◽  
Geophysical Investigation ◽  
Clayey Sand ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Resistivity Method ◽  
Sandy Clay ◽  
Geophysical Study ◽  
Weathered Layer ◽  
Subsurface Layers

A geophysical study was carried out at a proposed location for the construction of a structure along Ado-Afao road, Southwestern Nigeria. The aim of the study is to evaluate the electrical properties of the soil for Founding of Engineering structures. The geophysical investigation involved the Vertical Electrical Sounding (VES) technique using the Schlumberger configuration with a total of twenty-one (21) VES within the investigated area. The electrode separation varies from 1 to 100 m. The geoelectric sections identified three to five geoelectric/geologic subsurface layers along the traverses. The topsoil comprising of clay, clayey sand and sandy clay with the resistivity values range from 28 to 800 Ω-m with its thickness varying from 0.4 to 1.9 m. The second layer was found to be lateritic with resistivity ranging between 200 to 800 Ω-m and thickness ranges from 1 to 7.5 m while the weathered layer comprising of clay, clayey sand and sandy clay with resistivity varies from 30 to 220 Ω-m and its thickness varies from 1.2 to 54 m. The fractured basement with resistivity value of 763 Ωm and thickness value of 8m while the fresh basement has a resistivity value ranging from 365 to 2964 Ωm with depth to basement ranging from 8 to 58 m. The resistivity values of the topsoil are indicative of clay, sandy clay and clayey sand. This layer may not be of any special interest since topsoil is normally excavated. Hence, foundation of the proposed structures cannot be found on this layer. Based on the investigation, the subsurface of the study area can be generally classified as incompetent. There is a presence of lateral inhomogeneity of the subsurface layers and geologic features such as fractures and faults. The construction in the area should be founded on the lateritic layer or fresh basement layer coupled with pile foundation to ensure the stability of the building. The choice of foundation material, clay content and topography elevation should be put into consideration.

scholarly journals Geophysical and Geotechnical Studies of a Proposed Structure at Akure, Southwestern Nigeria

2018 ◽  
pp. 1-12
Author(s):  
Ilugbo Stephen Olubusola ◽  
Adebo A. Babatunde ◽  
Ajayi Oluwasayo Adegbola ◽  
Adewumi Olufemi Olaoluwa ◽  
Edunjobi Hazeez Owolabi
Keyword(s):  
Clay Content ◽  
Geotechnical Investigation ◽  
Cone Penetration ◽  
Geophysical Investigation ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Weathered Layer ◽  
Electrical Sounding ◽  
Geoelectric Resistivity ◽  
Geotechnical Studies

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.

scholarly journals Spatial Resistivity Mapping of Ureje Dam Floor, Southwestern Nigeria

2020 ◽  
Vol 66 (4) ◽  
pp. 245-255
Author(s):  
J.O. Fatoba ◽  
A.B. Eluwole ◽  
O.A. Sanuade ◽  
M.T. Aroyehun
Keyword(s):  
Storage Capacity ◽  
Geophysical Investigation ◽  
Southwestern Nigeria ◽  
Near Surface ◽  
Water Storage Capacity ◽  
Fractured Bedrock ◽  
Resistivity Method ◽  
Cumulative Response ◽  
Weathered Layer ◽  
Electrical Sounding

AbstractUreje Dam, Ado-Ekiti has witnessed drastic reduction in the water storage capacity of its reservoir. It became imperative to determine the possible cause(s) of the reduction in storage capacity. Geophysical investigation involving the vertical electrical sounding technique of the electrical resistivity method was conducted in the upstream part of the dam. Five lithologic units that include the mud/suspended materials, such as sandy clay, clay, weathered/fractured bedrock and fresh bedrock, were delineated. The respective resistivity and thickness range of the units are 2–19 ohm-m; 147–206 ohm-m, 2–38 ohm-m; 47–236 ohm-m and 455–1516 ohm-m and 0.4–1.9 m; 0.5–2.5 m; 1.0–12.2 m; 7.3–16.4 m and ∞. The thickness of suspended materials, resistivity/thickness of weathered layer and the presence of near-surface impervious layer were used as the main indices for the spatial demarcation of the dam axis in terms of vulnerability to loss of impounded water. Using the cumulative response of the indices, the study concluded that the eastern to southeastern parts of the dam axis showed the highest indications of vulnerability to loss of impounded water.

scholarly journals A Resistivity Survey of Phosphate Nodules in Oshoshun, Southwestern Nigeria

2018 ◽  
Vol 65 (2) ◽  
pp. 103-114 ◽  
Author(s):  
Oluseun Adetola Sanuade ◽  
Abayomi Adesola Olaojo ◽  
Adesoji Olumayowa Akanji ◽  
Michael Adeyinka Oladunjoye ◽  
Gabriel E. Omolaiye
Keyword(s):  
Electrical Resistivity ◽  
Apparent Resistivity ◽  
Inversion Algorithm ◽  
Clayey Sand ◽  
Southwestern Nigeria ◽  
Resistivity Data ◽  
Resistivity Method ◽  
Dahomey Basin ◽  
Geophysical Study ◽  
Electrical Resistivity Method

Abstract This geophysical study was carried out to determine the occurrence of phosphate nodules in the Oshoshun Formation of the Dahomey Basin, Southwestern Nigeria. The electrical resistivity method, comprising 1D vertical electrical sounding (VES; using Schlumberger array) and 2D geoelectrical imaging (using Wenner array), was used to determine the nature and depth of occurrence of the phosphate nodules. Six profile lines were established within the study area, and inverted sections were generated from the apparent resistivity data using DIPRO inversion algorithm. Five VES points were also acquired in the study area, and Win- Resist programme was used to process and interpret the field resistivity data. Four pits were dug along the profiles to verify the interpreted results. The results obtained by both techniques reveal similar geoelectric units: the top soil, clay, clayey sand and clay at different depths. These layers host pockets of phosphate nodules (78-≥651 Ωm) with varying thicknesses. The strong correlation between the lithology profiles obtained from the pits and the interpreted results of the inverted apparent resistivity sections demonstrates the efficacy of the electrical resistivity method in characterising phosphate occurrence within the formation.

scholarly journals Land satellite imagery and integrated geophysical investigations of highway pavement instability in southwestern Nigeria

2020 ◽  
Vol 46 (2) ◽  
pp. 135
Author(s):  
Omowumi Ademila ◽  
Abel Idowu Olayinka ◽  
Michael Adeyinka Oladunjoye
Keyword(s):  
High Resistivity ◽  
African Countries ◽  
Geophysical Investigation ◽  
Clayey Sand ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Near Surface ◽  
Subgrade Soils ◽  
Geophysical Investigations ◽  
Highway Pavement

The high global numbers of road accidents due to bad roads and the failure of other engineering structures have necessitated this study, particularly as road transport accounts for a higher percentage of cargo movement in African countries. The geophysical investigation was carried out on six failed and two stable sections along the Ibadan-Iwo-Osogbo highway to examine the geological factors responsible for highway failure in the area. A Landsat ETM+ (Enhanced Thematic Mapper Plus) imagery of the study area and its environs was acquired and processed for lineaments analyses. Magnetic, Very Low Frequency Electromagnetic (VLF-EM) and electrical resistivity methods involving Schlumberger Vertical Electrical Sounding (VES) and 2-D imaging using a dipole- dipole array were utilized. Lineaments were identified across failed localities. Lateral magnetic variations in the near-surface geological materials characterized the study area. The 2-D VLF-EM models generated showed conductive zones corresponding to fractured zones of conductive clay materials within the basement rocks. Subgrade soils below the highway pavement along the failed sections are typical of incompetent clayey and sandy clay/clayey sand formations with resistivity values between 20–475 Ω∙m. In comparison, the subgrade soil beneath the stable sections has moderate to high resistivity values of 196–616 Ω∙m. 2-D resistivity structures across the failed segments identified low resistivity water-absorbing clay and lithological contacts. Water absorbing, clay enriched subgrade soils and the identified near-surface linear conductive features are the major geologic factors, and poor drainage network resulted in the highway failure. Remote sensing and geophysical investigations of the geological sequence and structures underlying the highway should be carried out before construction to effectively complement the routine geotechnical studies to ensure the sustainability of road  nfrastructure.

scholarly journals Geoelectrical and geotechnical investigation of foundation failure in and around Oroke high school, Akungba- Akoko, southwestern Nigeria

2020 ◽  
Vol 8 (2) ◽  
pp. 237
Author(s):  
Odundun O.A ◽  
Fagorite V.I ◽  
Rogbitan E.O
Keyword(s):  
High School ◽  
Shear Zones ◽  
Structural Features ◽  
Building Structures ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Geoelectric Section ◽  
Effective Measure ◽  
Resistivity Method ◽  
Sandy Clay

Engineering structures are designed and constructed with an air of lifelong expectancy. Moreover, building foundation may experience failure due to presence of concealed geologic features such as cavity and shear zones which can lead to subsurface subsidence. Hence, it is imperative, prior to building construction, to investigate the physical properties of foundation soils and determine its suitability for design and construction of building structures. In the light of this, a geoelectric survey, involving three (3) electrical dipole - dipole array and geotechnical analysis methods were carried out around a distressed building at Oroke High School, opposite Adekunle Ajasin University, Akungba Akoko to establish the cause of failure for the structures foundation via delineating the subsurface structural features. The field electrical data were plotted on log –log graph sheets and the resulting curves were interpreted qualitatively by visual inspection, and quantitatively via partial curve matching and computer iteration techniques. For the geotechnical analysis, a total of twelve (12) soil samples were taken from different locations of about 30 meters intervals, at the depth of 1.5 meters. The pseudo – section and electrical sections indicate that the subsurface is heterogeneous in geological composition. The 2D dipole- dipole resistivity and pseudo – section delineated zones having resistivity values ranging from 200 to 700ohm meter, and those approaching infinity all within a depth of 0-5 m, the resistivity values of 27 to 139ohm meter suggest the presence of clay. The geoelectric section identified three subsurface geologic layers comprising clay /sandy, clay top soil / sub grade soil, clay / sandy clay and sand weathered layer and the basement (fresh) beneath the failed segment. Additionally, prominent fractures were discovered within some areas on the pseudo-sections. The results of the laboratory tests also included those of natural moisture content, specific gravity, grain size distribution curves, Atterberg limit, compaction test and California Bearing Ratio (CBR). In conclusion, electrical resistivity method was found to be an effective measure or tool in the site characterization. The soil/rock in these zones may require reinforcement in order to enhance its bearing capacity and increase the life span of the engineering foundation.  

scholarly journals Application of Electrical Resistivity Method to Site Characterisation for Construction Purposes at Institute of Agriculture Research and Training Moor Plantation Ibadan

2021 ◽  
Vol 1 (2) ◽  
pp. 49-62
Author(s):  
Babatunde A. Adebo ◽  
Oladipupo Emmanuel Makinde ◽  
Stephen Olubusola Ilugbo
Keyword(s):  
Electrical Resistivity ◽  
Clay Content ◽  
Site Investigation ◽  
Geophysical Investigation ◽  
Weak Zone ◽  
Southwestern Nigeria ◽  
Entire Study ◽  
Resistivity Method ◽  
Electrical Imaging ◽  
And Training

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.

scholarly journals Hydro-geologic, Corrosivity and Geotechnical Implications of Geoelectric Sounding Survey at FUTA Cooperative Housing Estate, Ilaramokin near Akure Southwestern Nigeria

2020 ◽  
pp. 40-50
Author(s):  
I. A. Adeyemo ◽  
V. O. Iwuala ◽  
T. S. Fadare ◽  
E. O. Otayemi
Keyword(s):  
Groundwater Potential ◽  
Housing Estate ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Low Resistivity ◽  
Cooperative Housing ◽  
Weathered Layer ◽  
Subsurface Layers ◽  
Electrical Sounding ◽  
Structural Failures

Aim: Groundwater potential evaluation, corrosivity and geotechnical competence investigations of the subsurface layers were carried at FUTA Cooperative Housing Estate, Ilaramokin near Akure Southwestern Nigeria in order to facilitate proper positioning of facilities within the estate. Methodology: A total of 14 vertical electrical sounding (VES) data was acquired across the estate using Schlumberger array. Results: The VES survey results delineated 3 - 5 geoelectric layers across the estate which corresponds to the topsoil, weathered layer, partially weathered basement, partially fractured basement and the presumed fresh bedrock. The groundwater potential map of the estate revealed that the groundwater potential is moderate (GWP of 0.5 - 0.75) to high (GWP of 0.75 - 1.0) in the western and southeastern parts of the estate. The depth slice corrosivity maps (1.0, 2.0 and 3.0 m) of the estate indicated that the corrosivity of the subsurface layers within the estate reduces with depth. The 0.5 m depth slice isoresistivity map of the estate indicates that the central and a segment of the southwestern parts of the estate are characterized with low resistivity (50 - 100 Ωm) indicating incompetence, while the estate flanks (west and east) are considered to be moderately competent (100 - 350 Ωm). Likewise, the 1.0 m depth slice isoresistivity map of the estate reveals that the central and western parts of the estate are characterized with low resistivity (50 - 100 Ωm) suggesting incompetent layer, while the northern, southern and eastern parts of the estate are moderately competent (100 - 350 Ωm). Conclusion: These results suggested that structural failures can be expected on any engineering structures sited at the central, northern, southern and eastern parts of the estate. Groundwater efforts should be concentrated at the western and southeastern parts of the estate.

scholarly journals Geophysical Investigation of Subsurface Water of Erunmu and its Environs, Southwestern Nigeria Using Electrical Resistivity Method

2015 ◽  
Vol 15 (5) ◽  
pp. 741-751 ◽  
Author(s):  
Lukuman Abudulawal ◽  
Sikiru A. Amidu ◽  
Kasim A. Apanpa ◽  
Olusola A. Adeagbo ◽  
Olukole A. Akinbiyi
Keyword(s):  
Electrical Resistivity ◽  
Subsurface Water ◽  
Geophysical Investigation ◽  
Southwestern Nigeria ◽  
Resistivity Method ◽  
Electrical Resistivity Method

scholarly journals Electrical Resistivity Tomography for Sustainable Groundwater Development in a Complex Geological Area

2019 ◽  
Vol 66 (2) ◽  
pp. 121-128
Author(s):  
Adedibu Sunny Akingboye ◽  
Isaac Babatunde Osazuwa ◽  
Muraina Zaid Mohammed
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Imaging System ◽  
Groundwater Development ◽  
Groundwater Storage ◽  
Southwestern Nigeria ◽  
Resistivity Tomography ◽  
Weathered Layer ◽  
Subsurface Layers ◽  
Sustainable Groundwater Development

AbstractElectrical resistivity tomography (ERT) was used for delineating significant subsurface hydrogeological features for sustainable groundwater development in Etioro-Akoko area, Southwestern Nigeria. This study was necessitated by challenges posed on groundwater supplies from wells and boreholes in Etioro-Akoko and the neighbouring fast growing towns and villages. Field data were acquired over the area with ABEM Lund Resistivity Imaging System and were subsequently processed and inverted through RES2DINVx64 software. Results showed four distinct subsurface layers: topsoil, weathered layer, fractured bedrock and fresh bedrock (basal unit). Localised bedrock depressions occasioned by fracturing and deep weathering of less stable bedrock minerals were delineated with resistivity and thickness values ranging from 50 to 650 Ωm and 12 to ---gt--- 25 m, respectively. The localised depressions mirrored uneven bedrock topography and served as the preferential groundwater storage and hydrogeological zones in the area. The two hydrogeological zones significant for groundwater development included overburden-dependent aquifers and fractured dependent bedrock aquifers. It was, therefore, concluded that groundwater storage potential was depended on hydrogeological zones particularly at major localised bedrock depressions where fractures and groundwater recharges/discharges were evident. Wells and boreholes were proposed at bedrock depressions with thickness value not less than 12 and ---gt--- 25 m, respectively, for enhanced groundwater sustainability and quality assurance in the area.

scholarly journals Integrated Geotechnical and Geophysical Investigation of a Proposed Construction Site at Mowe, Southwestern Nigeria

2018 ◽  
Vol 64 (3) ◽  
pp. 21-29
Author(s):  
Kayode F. Oyedele ◽  
Sunday Oladele ◽  
Adaobi C. Nduka
Keyword(s):  
Standard Penetration Test ◽  
Thin Layers ◽  
Electrode Spacing ◽  
Silty Clay ◽  
Geophysical Investigation ◽  
Clayey Sand ◽  
Deep Foundation ◽  
Southwestern Nigeria ◽  
Lateritic Clay ◽  
Wenner Array

Abstract The subsurface of a proposed site for building development in Mowe, Nigeria, using Standard Penetration Test (SPT), Cone Penetrometer Test (CPT) and Horizontal Electrical Profiling (HEP), was investigated with the aim of evaluating the suitability of the strata for foundation materials. Four SPT and CPT were conducted using 2.5 tonnes hammer. HEP utilizing Wenner array were performed with inter-electrode spacing of 10 – 60 m along four traverses coincident with each of the SPT and CPT. The HEP data were processed using DIPRO software and textural filtering of the resulting resistivity sections was implemented to enable delineation of hidden layers. Sandy lateritic clay, silty lateritic clay, clay, clayey sand and sand horizons were delineated. The SPT “N” value defined very soft to soft sandy lateritic (<4), stiff silty lateritic clay (7 – 12), very stiff silty clay (12 - 15), clayey sand (15-20) and sand (27 – 37). Sandy lateritic clay (5-40 kg/cm2) and silty lateritic clay (25 - 65 kg/cm2) were defined from the CPT response. Sandy lateritic clay (220-750 Ωm), clay (< 50 Ωm) and sand (415-5359 Ωm) were delineated from the resistivity sections with two thin layers of silty lateritic clay and clayey sand defined in the texturally filtered resistivity sections. Incompetent clayey materials that are unsuitable for the foundation of the proposed structure underlain the study area to a depth of about 18m. Deep foundation involving piling through the incompetent shallow layers to the competent sand at 20 m depth was recommended.

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