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.

scholarly journals Geoelectrical Investigation of Subsurface Structures for Mapping Groundwater Potential of Joseph Ayo Babalola University Campus Environment, Ikeji Arakeji, Osun State, Southwestern Nigeria

2019 ◽  
pp. 1-12
Author(s):  
O. E. Odeyemi ◽  
O. M. Odeyemi ◽  
S. A. Owolabi ◽  
E. A. Mamukuyomi ◽  
R. A. Salako
Keyword(s):  
Electrode Array ◽  
Groundwater Potential ◽  
Vertical Electrical Sounding ◽  
Electrode Spacing ◽  
Clayey Sand ◽  
Southwestern Nigeria ◽  
Current Electrode ◽  
Campus Environment ◽  
Lateritic Clay ◽  
Electrical Sounding

Owing to fast increase in number of staff and students of Joseph Ayo Babalola University, Ikeji Arakeji, Southwestern Nigeria, it is therefore very important to carry out this research in order to recommend the actual locations where boreholes can be sunk for good potential yields of groundwater when the time comes. The aim of this research is to carry out vertical electrical sounding geophysical survey at study area with a view to determining good aquifers that are good for the accumulation of groundwater. The study area is located between latitude 0820225 m to 0820345 m (UTM) Northings and longitude 717320 m to 717450 m (UTM) Eastings. Schlumberger electrode array was employed for the study using Ohmega Resistivity meter for the data acquisition. The geoelectric survey of the study area comprised of twelve vertical electrical soundings, with maximum current electrode spacing (AB) of 100 m. The modeled curves are mainly KH-type. The geoelectric sections generated from the sounding curves revealed 4 major layers earth models. The topsoil is made up of clay, clayey sand/lateritic sand with resistivity and thicknesses varying from 54.7 – 210.1ohm-m and 0.2 –0.8m respectively. The second layer is the lateritic clay with resistivities and thicknesses varying from 334 – 963ohm-m and 1.5 – 10.8m respectively. The third layer constitutes the clay / sandy fractured quartzite and it serves as the aquifer unit. The resistivity values lie between 71.7 and 498 ohm-m while the thicknesses vary from 2.1 – 76.3 m. The fourth layer is the fractured/presumably fresh basement bedrock with the resistivity varying from 1879 – 13991.8 ohm-m. Areas characterized with fractured basement of low resistivity with appreciable thickness are therefore recommended for the siting of boreholes. It is concluded that the vertical electrical sounding points of the study area are good aquifers for groundwater accumulation.

scholarly journals GEOPHYSICAL INVESTIGATION OF GROUNDWATER POTENTIAL OF A SITE IN OBALE AREA OF AKURE, NIGERIA.

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Eebo Festus Olusola ◽  
Yusuf Gbenga Ayodele
Keyword(s):  
Soil Layer ◽  
Groundwater Potential ◽  
Clay Layer ◽  
Geophysical Investigation ◽  
Southwestern Nigeria ◽  
Geoelectric Section ◽  
Lateritic Clay ◽  
Top Soil ◽  
Geoelectric Layer ◽  
A Site

Electrical Resistivity method using Vertical Electrical Soundings (VES) were carried out at a site in Aba-Oyo area FUTA Southgate area, Akure, Nigeria, with the aim to access groundwater potential of the site. The study area is underlain by crystalline rocks of the Precambrian basement complex of the Southwestern Nigeria. Twelve (12) VES were carried out using Schlumberger electrode array configuration with AB/2from 1 to 65m. The VES data generated were processed and interpreted using partial curve matching method and computer iteration techniques. The interpreted data revealed three to four geoelectric sections with varied thicknesses and resistivity. The top soil layer ranges from 44 to 181?m, lateritic clay layer ranges from 20 to 174?m, the weathered horizon resistivity ranges from 20.0 to 424.0?m while the competent rock/fresh rock has resistivity values greater than 424.0.3?m. The top soil layer resistivity and thickness ranges from 44 to 181?m and 0.4 to 2m, the lateritic clay layer resistivity and thickness range from 20 to 174?m and 1.7 to 6.0m respectively, the weathered horizon resistivity ranges from 20.0 to 424.0?m and 1.4 to 7.4m respectively while the competent rock has resistivity values greater than 424.0?m and ?m respectively. The third geoelectric layer constitutes the aquiferous zone in the 4-layer geoelectric section while the second geoelectric layer is the aquiferous zone in all the 3- layer geoelectric sections. VES station 2, 7, 9 stations shows good groundwater potential as revealed by the thick overburden and weathered layer with low resistivity values. VES stations 1, 4, 5, 6, 8, 10 and 12 shows moderate groundwater potentials while VES stations 3 and 11 are non-aquifereous in nature.

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 Assessment of Hydrogeological Potential and Aquifer Protective Capacity of Odeda, Southwestern Nigeria

2020 ◽  
Vol 66 (3) ◽  
pp. 199-209
Author(s):  
J.O. Aina ◽  
O.O. Adeleke ◽  
V. Makinde ◽  
H.A. Egunjobi ◽  
P.E. Biere
Keyword(s):  
Groundwater Resources ◽  
Electrode Array ◽  
Electrode Spacing ◽  
Protective Capacity ◽  
Clayey Sand ◽  
Southwestern Nigeria ◽  
Current Electrode ◽  
Ogun State ◽  
Weathered Layer ◽  
Longitudinal Unit Conductance

AbstractHydrogeological assessment of groundwater resources was carried out with a view to evaluate the potential of the aquifers to provide portable water supply and access the distribution of electrical parameters of hydrogeologic units in some areas in Odeda, Ogun State, Nigeria. A geophysical survey using vertical electrical sounding (VES) with the Schlumberger electrode array, with half-current electrode spacing (AB/2) varying from 1 to 132 m was carried out at 30 different stations in the study area. The VES data were interpreted qualitatively and quantitatively. Three-to-five sub-surface layers consisting of topsoil, weathered layer consisting of clay, sandy clay, clayey sand and sand layers, and fractured/fresh basement were delineated. Layer resistivities and thicknesses obtained on the curves within the study area showed one main aquifer type, which is the fractured basement. The longitudinal unit conductance (ranging from 0.049720 to 1.4520000 mhos) of the study area aided the protective capacity to be rated into good, moderate and weak. About 33% of the study area falls within the weak protective capacity, 57% falls within the moderate protective capacity and 10% falls within the good protective capacity.

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 INVESTIGATION OF GROUNDWATER POLLUTION RESULTING FROM LEACHATE FLOW AT IKOTO AND ORU DUMPSITES IN OGUN STATE OF NIGERIA

2020 ◽  
Vol 6 ◽  
pp. 1
Author(s):  
Adetoro Temitope Talabi ◽  
Taiwo Olakunle Roy-Layinde ◽  
Rasaki Kola Odunaike ◽  
Hamid Titilope Oladunjoye ◽  
Aina Opeyemi Adebanjo
Keyword(s):  
Groundwater Pollution ◽  
Health Hazard ◽  
Subsurface Layer ◽  
Groundwater Table ◽  
Electrode Spacing ◽  
Geophysical Investigation ◽  
The Road ◽  
Ogun State ◽  
Electrical Resistivity Survey ◽  
Electrical Sounding

An electrical resistivity survey was carried out to detect the level of groundwater pollution on Oru and Ikoto dumpsites respectively as it was observed that the dumpsites were sited ignoring the environmental and health hazard. The survey was conducted using ABEM model terrameter with schlumberger array for 1-D vertical electrical sounding (VES) of electrode spacing ranging from 0.25m to 4m. Four VES was conducted on each dumpsite with length between 1m to 120m. The data obtained from the field were interpreted using WINRESIST from which the curve types of each study area were identified. On Oru dumpsite, measurement of VES1 was taken on the dumpsite, VES2 was taken 20m away from the dumpsite, VES3 and VES4 were taken across the road serving as control. Here, there is indication of leachate pollution in VES1 (layer 2) and VES2 (layer 3) while VES3 and VES4 are leachate free, but this leachate present in VES1 and VES2 cannot penetrate into the groundwater table because of the stratigraphy of the area.  At Ikoto dumpsite, measurement of VES4 was taken on the dumpsite, VES1 and VES2 were taken 30m away from the dumpsite on both sides, and while VES3 was taken across the Lagos/Ibadan expressway, serving as control. There is indication of leachate pollution in VES4 (layer2) while in VES1, VES2 and VES3 there is no presence of leachate flow. The leachate present in VES4 can infiltrate into the groundwater table through the highly porous and permeable material in the subsurface layer of the location.

FIELD MEASUREMENT OF THE ELECTROSEISMIC RESPONSE

Geophysics ◽  
1975 ◽  
Vol 40 (2) ◽  
pp. 233-245 ◽  
Author(s):  
Leland Timothy Long ◽  
Wayne K. Rivers
Keyword(s):  
Coastal Plain ◽  
Layered Medium ◽  
Sedimentary Rocks ◽  
Taylor Series Expansion ◽  
Seismic Source ◽  
Body Waves ◽  
Seismic Excitation ◽  
Electrode Spacing ◽  
Rayleigh Surface Waves ◽  
Wenner Array

The electroseismic response is a change in apparent resistivity induced by seismic excitation. It can be measured under field conditions with a conventional Wenner array and an explosive seismic source. In coastal plain sedimentary rocks near Gordon, Georgia, a Wenner array with 9-m electrode spacing measured a change in voltage of 100 to 300 μv per mm/sec of 15 hz vertical particle velocity at the surface. The response correlates best with the Rayleigh surface waves and compressional body waves. By assuming a layered medium which is excited uniformly by a seismic disturbance, we can use a Taylor series expansion of the voltage expression for a Wenner array in terms of layer resistivities to obtain estimates of the perturbations of the resistivities in the layers.

Use of geophysical methods for soil profile evaluation

2011 ◽  
Vol 48 (9) ◽  
pp. 1364-1377 ◽  
Author(s):  
Paul Groves ◽  
Giovanni Cascante ◽  
Dave Dundas ◽  
P.K. Chatterji
Keyword(s):  
Seismic Refraction ◽  
Geophysical Methods ◽  
Electrode Spacing ◽  
Geophysical Investigation ◽  
Multiple Channel ◽  
Site Investigations ◽  
Successful Approach ◽  
Channel Analysis ◽  
Environmentally Sensitive ◽  
Soil Units

A geophysical investigation was performed to evaluate the effectiveness of three geophysical methods (electrical resistivity imaging (ERI), seismic refraction (SR), and multiple-channel analysis of surface waves (MASW)) for geotechnical site characterization in swamps and environmentally sensitive wetland areas. The geophysical test results were verified against the results from borehole and cone penetrometer test logs. The ERI results were best for determining the depth to the glacial till. However, the resolution of the ERI survey was not sufficient to accurately predict the upper lithologies. The electrode spacing (4 m) was instead selected to reliably predict the depth to the till, which in this case varied between 4.6 and 10.7 m. The SR results overestimated the depth to the till because of the presence of a stiffness reversal. The MASW results predicted the depth to the refusal till layer less accurately than the ERI method. However, this method was able to detect the three distinct layers above the till, even though the layer thicknesses were consistently underestimated. The complementary use of geophysical techniques was a successful approach in determining the main soil units and the depth to the competent layer (till) at the site. These methods can be used as a basis for further development to optimize a procedure to reduce the number of boreholes required for conventional site investigations in areas that are environmentally sensitive or where access is restricted.

Exploration for Marble Deposit in Parts of Okpella, South-Southern Nigeria

2019 ◽  
pp. 1-7
Author(s):  
K. O. Ozegin
Keyword(s):  
Electrical Resistivity ◽  
Electrode Spacing ◽  
Clayey Sand ◽  
Current Electrode ◽  
Electrical Resistivity Survey ◽  
Resistivity Method ◽  
Resistivity Survey ◽  
Surface Measurements ◽  
Electrical Sounding ◽  
Electrical Resistivity Method

The ultimate aim of the electrical resistivity survey is to determine the resistivity distribution with depth on the basis of surface measurements of the apparent resistivity and to interpret it in terms of geology. Marble deposit was investigated with the application of electrical resistivity method using Vertical Electrical Sounding (VES) technique with the aim of characterising this deposit in parts of Okpella. Six (6) VES were acquired using the Schlumberger array for data acquisition with current electrode spacing varying from 1.0 to 150.0 m. The VES data obtained were interpreted using ipi2win Software. The results showed three layers indicating subsurface geologic sequence probed 26.4 m and beyond with clay/clayey sand (23.3 – 219.1 Ωm), sand (423 - 2040 Ωm) and marble (12661 - 404498 Ωm). The occurrence of marble deposit was revealed at VES points at 1, 2 and 5 in the studied area.  This study concluded that the study area had occurrence of the marble deposits, which would be of economic importance, if exploited.

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