The document summarizes the results of a geophysical investigation using vertical electrical soundings around Makiyaye village in Nigeria. 18 vertical electrical soundings were conducted and analyzed. The subsurface was found to consist of 4 main layers - a topsoil layer, a weathered basement layer, a partly weathered/fractured basement layer, and a fresh basement layer. Resistivity values and thicknesses of the layers varied across the study area. The geoelectric sections revealed dips and a synclinal structure in the subsurface. Based on the investigation, the subsurface material up to 20m depth was found to be competent for construction, while low resistivity zones indicated high clay content and saturation, requiring consideration in engineering
Evaluation of sub-soil geo-electric properties in a proposed power sub-statio...IJERA Editor
Electrical resistivity survey was carried out in a site proposed for the construction and installation of a Power sub-station. The project will involve subsurface installation of cables and other objects that easily conduct electricity. Extant laws including EIA also require knowledge of subsurface distribution of resistivity in construction projects that would involve burial of steel pipes and cables. The imperative of this is emphasized by the location of the project in an area of shallow groundwater conditions. Field resistivity measurements were undertaken using ABEM Terrameter SAS 1000, adopting Schlumberger configuration in vertical electric sounding at 12 locations within the study site. The results were used to generate geo-electric log models. Three geo-electric profile models (pseudo- profiles) were also taken NE-SW of the site. Interpretation of the models shows that the area is characterized by two geo-electric layers to the depth of 30m. The upper layer of lower resistivity occurs to a depth of 2-3m. This layer consists of lateritic to silty sands. The lower layer has a resistivity of between 900 - >2000 Ωm and represents fine to coarse sands and gravels. On the Soil Electrical Resistivity Classification (BS 1377), the subsoil falls within non-corrosive class. Objects installed in the soil are not likely to suffer corrosion soon. Similarly, subsurface electrical installations will pose minimal hazards and would require basic precautions to avoid electrical accidents.
Integrated Geophysical and Geotechnical Evaluation of Foundation Failure in P...inventionjournals
Geophysical and geotechnical methods have been integrated with the aim of assessing characteristics of sub-surface layers to identify why structures in some parts of Ikere-Ekiti Southwestern Nigeria are failing or sinking as a result of foundation failure. Eight (8) vertical electrical sounding (VES) were carried out using resistivity meter and six (6) pits were dug to a depth of 1.2m. Six disturbed soil samples were collected from the six dug pits for the study. These samples were subjected to geotechnical tests in the laboratory, which include moisture content, shear test, Atterberg limit and grain size analysis. The acquired VES data were processed and interpreted using partial curve matching technique. The results of the all the mall the eight VES produced H curves. This curve type manifested three layers which are composed of sandy-clay, clayeysand/weathered basement and weathered basement/rock head. The depth o rockhead ranges from 12.1 to 43.2m. VES stations four and five have deeper depth to rock head (i.e. 21.3 to 43.2m) while other locations have lesser depth to rockhead (i.e.1 12.1m to 17.5m). The second layer has the lowest resistivity values meaning that it is somewhat conductive owing to clayey sand deposition and weathered area. Geotechnical test shows that the soils in the study area generally has high moisture content, low plasticity, and from grain size distribution, high concentrations of silt and clay. From the result, it is established that the layer in which the foundations are built upon are rated as poor to fairly competent. This might be as a result of poor drainage system characterised the study area which brought about the local deposition of the supposed subsoil. Therefore, high moisture content made the subsoil to lose its competency thereby causing the structures in the study area to subside
This study was carried out to determine the subsurface lithology and possible depths for structural foundations in Ignatius Ajuru University of Education, Port Harcourt in southern Nigeria using electrical resistivity techniques of VES and borehole logging. Model ABEM SAS 300B Terrameter aided by SAS 200 log meter were used for the data collection while version IPWIN2 software was used for the processing of the VES data. Six profiles of different locations, using maximum current electrode spread of 200 m and maximum potential electrode spread of 30 m, were used to obtain resistivity range of 1.2 to 4335 Ωm for three to four geoelectric sections covering depth interval of 19.8 m in the area. The borehole data covered a depth range of 0 to 20 m. The results show lithostratigraphy sequence of silty sands, laterite, grain and coarse sands with resistivity values of 721 to 4000 Ωm. These soils can support structures with foundations as close as 0.5 m to 3 m or more below the earth surface because laterite and sandy soils have the ability of a firm grasp of structural foundations as they do not retain moisture that will cause foundational deformation and shifting that may eventually lead to collapse of the structures.
Geo Environmental Investigation of Abuad Dumpsite, Southwestern NigeriaIJERA Editor
Geoenvironmental study of ABUAD female dumpsite was conducted to investigate the suitability of its location
and potential impact on groundwater in the environment. Profiling and Vertical electrical sounding methods
were employed using Dipole - Dipole and Schlumberger configuration respectively. Five points were sounded
and one profile was occupied. Three heterogeneous subsurface lithologic units were established namely; lateritic
topsoil, clayey-sand, and, fresh basement. The curve types are simple H and HA. The topsoil and clayey-sand
materials are characterized with relatively low resistivity values while the fresh basement materials are
characterized with high resistivity values. The average resistivity and thickness values for the topsoil are
280.0Ωm and.2.3m respectively. Clayey-sand was encountered in all the locations with average resistivity and
thickness values of 32.0Ωm and 7.3m respectively. Basement is relatively shallow in the study area, it was
encountered in all the locations with an average resistivity and depth values to the top of basement of 674Ωm,
and 9.6m respectively. Overburden materials are relatively thin within the area with an average resistivity and
thickness values of 156Ωm, and 9.6m respectively. The overburden materials constituting the aquiferous units
within the study area are porous, vulnerable, and good paths for leachate migration. The relatively low
resistivity values within the clayey-sand layers (14 - 61Ωm) are suggestive of leachate intrusion, while relatively
high resistivity values of the impervious basement are due to their crystalline nature. The proximity of the
dumpsite to both the cafeteria and residential halls is a cause for concern.
Evaluation of sub-soil geo-electric properties in a proposed power sub-statio...IJERA Editor
Electrical resistivity survey was carried out in a site proposed for the construction and installation of a Power sub-station. The project will involve subsurface installation of cables and other objects that easily conduct electricity. Extant laws including EIA also require knowledge of subsurface distribution of resistivity in construction projects that would involve burial of steel pipes and cables. The imperative of this is emphasized by the location of the project in an area of shallow groundwater conditions. Field resistivity measurements were undertaken using ABEM Terrameter SAS 1000, adopting Schlumberger configuration in vertical electric sounding at 12 locations within the study site. The results were used to generate geo-electric log models. Three geo-electric profile models (pseudo- profiles) were also taken NE-SW of the site. Interpretation of the models shows that the area is characterized by two geo-electric layers to the depth of 30m. The upper layer of lower resistivity occurs to a depth of 2-3m. This layer consists of lateritic to silty sands. The lower layer has a resistivity of between 900 - >2000 Ωm and represents fine to coarse sands and gravels. On the Soil Electrical Resistivity Classification (BS 1377), the subsoil falls within non-corrosive class. Objects installed in the soil are not likely to suffer corrosion soon. Similarly, subsurface electrical installations will pose minimal hazards and would require basic precautions to avoid electrical accidents.
Integrated Geophysical and Geotechnical Evaluation of Foundation Failure in P...inventionjournals
Geophysical and geotechnical methods have been integrated with the aim of assessing characteristics of sub-surface layers to identify why structures in some parts of Ikere-Ekiti Southwestern Nigeria are failing or sinking as a result of foundation failure. Eight (8) vertical electrical sounding (VES) were carried out using resistivity meter and six (6) pits were dug to a depth of 1.2m. Six disturbed soil samples were collected from the six dug pits for the study. These samples were subjected to geotechnical tests in the laboratory, which include moisture content, shear test, Atterberg limit and grain size analysis. The acquired VES data were processed and interpreted using partial curve matching technique. The results of the all the mall the eight VES produced H curves. This curve type manifested three layers which are composed of sandy-clay, clayeysand/weathered basement and weathered basement/rock head. The depth o rockhead ranges from 12.1 to 43.2m. VES stations four and five have deeper depth to rock head (i.e. 21.3 to 43.2m) while other locations have lesser depth to rockhead (i.e.1 12.1m to 17.5m). The second layer has the lowest resistivity values meaning that it is somewhat conductive owing to clayey sand deposition and weathered area. Geotechnical test shows that the soils in the study area generally has high moisture content, low plasticity, and from grain size distribution, high concentrations of silt and clay. From the result, it is established that the layer in which the foundations are built upon are rated as poor to fairly competent. This might be as a result of poor drainage system characterised the study area which brought about the local deposition of the supposed subsoil. Therefore, high moisture content made the subsoil to lose its competency thereby causing the structures in the study area to subside
This study was carried out to determine the subsurface lithology and possible depths for structural foundations in Ignatius Ajuru University of Education, Port Harcourt in southern Nigeria using electrical resistivity techniques of VES and borehole logging. Model ABEM SAS 300B Terrameter aided by SAS 200 log meter were used for the data collection while version IPWIN2 software was used for the processing of the VES data. Six profiles of different locations, using maximum current electrode spread of 200 m and maximum potential electrode spread of 30 m, were used to obtain resistivity range of 1.2 to 4335 Ωm for three to four geoelectric sections covering depth interval of 19.8 m in the area. The borehole data covered a depth range of 0 to 20 m. The results show lithostratigraphy sequence of silty sands, laterite, grain and coarse sands with resistivity values of 721 to 4000 Ωm. These soils can support structures with foundations as close as 0.5 m to 3 m or more below the earth surface because laterite and sandy soils have the ability of a firm grasp of structural foundations as they do not retain moisture that will cause foundational deformation and shifting that may eventually lead to collapse of the structures.
Geo Environmental Investigation of Abuad Dumpsite, Southwestern NigeriaIJERA Editor
Geoenvironmental study of ABUAD female dumpsite was conducted to investigate the suitability of its location
and potential impact on groundwater in the environment. Profiling and Vertical electrical sounding methods
were employed using Dipole - Dipole and Schlumberger configuration respectively. Five points were sounded
and one profile was occupied. Three heterogeneous subsurface lithologic units were established namely; lateritic
topsoil, clayey-sand, and, fresh basement. The curve types are simple H and HA. The topsoil and clayey-sand
materials are characterized with relatively low resistivity values while the fresh basement materials are
characterized with high resistivity values. The average resistivity and thickness values for the topsoil are
280.0Ωm and.2.3m respectively. Clayey-sand was encountered in all the locations with average resistivity and
thickness values of 32.0Ωm and 7.3m respectively. Basement is relatively shallow in the study area, it was
encountered in all the locations with an average resistivity and depth values to the top of basement of 674Ωm,
and 9.6m respectively. Overburden materials are relatively thin within the area with an average resistivity and
thickness values of 156Ωm, and 9.6m respectively. The overburden materials constituting the aquiferous units
within the study area are porous, vulnerable, and good paths for leachate migration. The relatively low
resistivity values within the clayey-sand layers (14 - 61Ωm) are suggestive of leachate intrusion, while relatively
high resistivity values of the impervious basement are due to their crystalline nature. The proximity of the
dumpsite to both the cafeteria and residential halls is a cause for concern.
Subsurface 2D Image Analyses of the Uyangha Basement Area, South-Eastern NigeriaIOSR Journals
Geo-electric soundings were made in Stella Maris Secondary School, in Uyangha, Nigeria to image
the subsurface and obtain thicknesses and resistivities of different layers. A quantitative interpretation of the
data obtained clearly reveals the presence of four (4) geo-electric sections which are interpreted to be dry
laterite, moist laterite, weathered basement, and saturated basement. The depth probed is about 100m. The
saturated basement is the aquifer unit. Depth to aquifer unit in the area is at about 65m to 80m.The thickness of
the aquifer unit ranges from 20m to 35m. For ground water exploitation, boreholes in the area should therefore
be drilled to the depth of 91m, for reasonable groundwater yield. The lateritic layer makes the study area
suitable for building construction in the area.
Application of Electrical Resistivity Tomography for Soil Competence Study in...IIJSRJournal
This study was carried out to determine soil competence around University of Benin Teaching Hospital and its environs using electrical resistivity tomography method. The Wenner Schlumberger Array Profiling method was used to give information of the subsurface resistivity. The result of the study showed that in ERT 1, highly competent soil were observed with resistivity values between 725Ωm and greater than 6546Ωm, which means that the area is underlain by clay sand at the top and sand/laterite/bedrock at the bottom. ERT 2 is characterized by highly competent soils with high resistivity values between 899Ωm to greater than 7851 Ωm, which indicates that the soil is underlain by sand/laterite/bedrocks. Furthermore, ERT 3 is group as highly competent soils, with resistivity values between762Ωm and greater than 6980 Ωm; this shows that the profile 3 is underlain by sand/laterite/bed rock. The study shows that though most part of the area contains soils that are competent, because of the presence of clay which on most occasion in the Niger Delta are expandable, detailed Geophysical and Civil engineering studies should be carried out before the erection of high rising engineering structures such as network masts, buildings and water tanks within the study area.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Seismic Refraction Survey for Groundwater Potentials of Northern Paiko Area. ...iosrjce
This paper titled Seismic Refraction Survey for Groundwater Potentials of Southern Paiko Area.
Niger State, Nigeria, employs the service of seismic refraction survey method. A twelve-channel seistronix was
used for the data collection. The profiles were marked at 100 m intervals, while the profiles lines traversed
1000 m (1km). A Total of 44 spreads were shot. Data were collected, Time – distance (T-S) graphs were plotted
using matrix laboratory software, velocities of the underlying layers obtained and depths to the refractor layer
computed and geologic cross sections were obtained. The results obtained gave an overview of the lateral
variation in the lithological changes of the subsurface earth materials in the surveyed area. The basement
surface varied in depth, from 10.16 m to a maximum of 14.80 m. weathered layer velocities ranging from 809
m/s to 3612 m/s and consolidated layer velocities varying between 2858 m/s to 9696 m/s. Four shot points were
delineated as aquifer potentials of the area having depth to refractor varying between 13.70 m and 14.80 m with
overburden velocities ranging from 1940 m/s to 3462 m/s. The rock materials identified in the surveyed area are
chiefly sand, saturated clay, gravel, gneiss, igneous rock and granite.
Combined Geophysical And Geotechnical Techniques For Assessment Of Foundation...IRJESJOURNAL
Abstract: This study was carried out to assess the subsurface conditions around the school of technology complex in Lagos State Polytechnic, Ikorodu, using integrated geophysical and geotechnical techniques. The site lies within the Sedimentary terrain of southwestern Nigeria. Allied Ohmega Resistivity meter was used for data collection of 1-D and 2-D resistivitymeasurement while WinResist software and Dipro software were used for the processing respectively.The results of the vertical electrical sounding indicate that the depth to basement values ranges between 27.6 and 39.5m. The 2D resistivitysurvey has provided valuable information on the lateral and vertical variation of the layer competent for erecting foundation of engineering structures. The CPT probed an average depth of 4.8m and has identified material of very high shear strength associated with dense sand materials. The correlation of the three techniques used revealed similar soil layering consisting of topsoilsandy clay, coarse sand and sand.A mechanically stable coarse sand material was discovered as weathered layer which indicates high load bearing capacity suitable for foundation in the area and can support massive structures.
Geo-electric Investigation of the Cause of Structural Failure Indices on a Se...iosrjce
Electrical resistivity imaging has been employed to investigate the causes of structural failure related
cracks on a set of administrative buildings in southwestern Nigeria. The goals were to determine the
distribution of subsurface geologic lithologies beneath the set of buildings and therefrom infer the relative
strengths of such lithologies. Data were collected along four geo-electric traverses using the ABEM1000
Terrameter unit. The dipole-dipole array was utilized with an electrode separation of 5 m. Observed field data
were processed and inverted using a 2.5D finite-element modeling inversion algorithm. Results indicate that the
northeastern half of the site is underlain by unweathered basement rocks overlain by thin (generally < 4 m) soil
cover, while the southwestern region is dominated at depths beyond 4 m by low-resistivity water-saturated clays
and some weathering tills. The clays apparently receive abundant supply of water from a seasonal stream
channel adjacent to the westerly administrative blocks. The block presenting with the most damage has been
built out over the edge of the shallow basement rocks onto these less competent water-saturated clays in the
southeastern region resulting in cantilever-style differential settling. A second damaged block is situated
entirely on low resistivity water-saturated clays. Differential settling on this block is likely related to the
difference in thicknesses of the clays between sites of the north and south facing walls of the structure. Beneath
the northern wall, the clays are thinner and could be expected to compress less than at the southern wall.
Though uncalibrated to core or log data, the results allowed a first insight into possible causes of structural
failure on the buildings and it is hoped that palliative measures will benefit from these results.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Geotechnical Investigation for Design and Construction of Civil Infrastructur...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Twelve vertical electrical soundings, VES, were carried out in parts of Abua in northwestern part of Rivers State in the sedimentary basin of the Niger delta of Nigeria, to determine the overburden layering and infer the aquifer depth/thickness and probable safe structural foundation depths in the region. The Schlumberger array method was employed using an ABEM 300B Terrameter and maximum current electrode spread of 400 m. The computed apparent resistivity field log values were plotted against the current electrode spreads and interpreted with IPWIN 2 and Sulphure 8 software to obtain the overburden thickness/depth, resistivity and the isopach map and then infer the subsoil layering thickness including potential aquifer zones within the depths of investigation in the area. The curve types revealed that three and four geoelectric sections were penetrated by the survey array with overburden thickness ranging from 4.2 m in Elok community to 91.7 m in Ilghom community. Potential aquifers with variable thickness from 5 to 60 m at depths of from 4.5 m and below the earth surface were identified. The subsurface soils types can support structural foundations from depths of 1.0 m and below the earth surface based on the type of building/engineering structures.
Evaluation of Heterogeneous Aquifers in Crystalline Rocks from Resistivity So...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Mer än 90 % av verksamheterna i Davidshallsområdet i Malmö, är privatägda. Inga större butiks- och restaurangkedjor finns vid torget. Alla är helt unika och tillhandahåller oftast varor handplockade för kunderna. Detta åskådliggörs med fotoutställningen ”Vi är Davidshallare” och lanseringen av områdets logotyp under Höstfesten 24/9.
Subsurface 2D Image Analyses of the Uyangha Basement Area, South-Eastern NigeriaIOSR Journals
Geo-electric soundings were made in Stella Maris Secondary School, in Uyangha, Nigeria to image
the subsurface and obtain thicknesses and resistivities of different layers. A quantitative interpretation of the
data obtained clearly reveals the presence of four (4) geo-electric sections which are interpreted to be dry
laterite, moist laterite, weathered basement, and saturated basement. The depth probed is about 100m. The
saturated basement is the aquifer unit. Depth to aquifer unit in the area is at about 65m to 80m.The thickness of
the aquifer unit ranges from 20m to 35m. For ground water exploitation, boreholes in the area should therefore
be drilled to the depth of 91m, for reasonable groundwater yield. The lateritic layer makes the study area
suitable for building construction in the area.
Application of Electrical Resistivity Tomography for Soil Competence Study in...IIJSRJournal
This study was carried out to determine soil competence around University of Benin Teaching Hospital and its environs using electrical resistivity tomography method. The Wenner Schlumberger Array Profiling method was used to give information of the subsurface resistivity. The result of the study showed that in ERT 1, highly competent soil were observed with resistivity values between 725Ωm and greater than 6546Ωm, which means that the area is underlain by clay sand at the top and sand/laterite/bedrock at the bottom. ERT 2 is characterized by highly competent soils with high resistivity values between 899Ωm to greater than 7851 Ωm, which indicates that the soil is underlain by sand/laterite/bedrocks. Furthermore, ERT 3 is group as highly competent soils, with resistivity values between762Ωm and greater than 6980 Ωm; this shows that the profile 3 is underlain by sand/laterite/bed rock. The study shows that though most part of the area contains soils that are competent, because of the presence of clay which on most occasion in the Niger Delta are expandable, detailed Geophysical and Civil engineering studies should be carried out before the erection of high rising engineering structures such as network masts, buildings and water tanks within the study area.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Seismic Refraction Survey for Groundwater Potentials of Northern Paiko Area. ...iosrjce
This paper titled Seismic Refraction Survey for Groundwater Potentials of Southern Paiko Area.
Niger State, Nigeria, employs the service of seismic refraction survey method. A twelve-channel seistronix was
used for the data collection. The profiles were marked at 100 m intervals, while the profiles lines traversed
1000 m (1km). A Total of 44 spreads were shot. Data were collected, Time – distance (T-S) graphs were plotted
using matrix laboratory software, velocities of the underlying layers obtained and depths to the refractor layer
computed and geologic cross sections were obtained. The results obtained gave an overview of the lateral
variation in the lithological changes of the subsurface earth materials in the surveyed area. The basement
surface varied in depth, from 10.16 m to a maximum of 14.80 m. weathered layer velocities ranging from 809
m/s to 3612 m/s and consolidated layer velocities varying between 2858 m/s to 9696 m/s. Four shot points were
delineated as aquifer potentials of the area having depth to refractor varying between 13.70 m and 14.80 m with
overburden velocities ranging from 1940 m/s to 3462 m/s. The rock materials identified in the surveyed area are
chiefly sand, saturated clay, gravel, gneiss, igneous rock and granite.
Combined Geophysical And Geotechnical Techniques For Assessment Of Foundation...IRJESJOURNAL
Abstract: This study was carried out to assess the subsurface conditions around the school of technology complex in Lagos State Polytechnic, Ikorodu, using integrated geophysical and geotechnical techniques. The site lies within the Sedimentary terrain of southwestern Nigeria. Allied Ohmega Resistivity meter was used for data collection of 1-D and 2-D resistivitymeasurement while WinResist software and Dipro software were used for the processing respectively.The results of the vertical electrical sounding indicate that the depth to basement values ranges between 27.6 and 39.5m. The 2D resistivitysurvey has provided valuable information on the lateral and vertical variation of the layer competent for erecting foundation of engineering structures. The CPT probed an average depth of 4.8m and has identified material of very high shear strength associated with dense sand materials. The correlation of the three techniques used revealed similar soil layering consisting of topsoilsandy clay, coarse sand and sand.A mechanically stable coarse sand material was discovered as weathered layer which indicates high load bearing capacity suitable for foundation in the area and can support massive structures.
Geo-electric Investigation of the Cause of Structural Failure Indices on a Se...iosrjce
Electrical resistivity imaging has been employed to investigate the causes of structural failure related
cracks on a set of administrative buildings in southwestern Nigeria. The goals were to determine the
distribution of subsurface geologic lithologies beneath the set of buildings and therefrom infer the relative
strengths of such lithologies. Data were collected along four geo-electric traverses using the ABEM1000
Terrameter unit. The dipole-dipole array was utilized with an electrode separation of 5 m. Observed field data
were processed and inverted using a 2.5D finite-element modeling inversion algorithm. Results indicate that the
northeastern half of the site is underlain by unweathered basement rocks overlain by thin (generally < 4 m) soil
cover, while the southwestern region is dominated at depths beyond 4 m by low-resistivity water-saturated clays
and some weathering tills. The clays apparently receive abundant supply of water from a seasonal stream
channel adjacent to the westerly administrative blocks. The block presenting with the most damage has been
built out over the edge of the shallow basement rocks onto these less competent water-saturated clays in the
southeastern region resulting in cantilever-style differential settling. A second damaged block is situated
entirely on low resistivity water-saturated clays. Differential settling on this block is likely related to the
difference in thicknesses of the clays between sites of the north and south facing walls of the structure. Beneath
the northern wall, the clays are thinner and could be expected to compress less than at the southern wall.
Though uncalibrated to core or log data, the results allowed a first insight into possible causes of structural
failure on the buildings and it is hoped that palliative measures will benefit from these results.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Geotechnical Investigation for Design and Construction of Civil Infrastructur...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Twelve vertical electrical soundings, VES, were carried out in parts of Abua in northwestern part of Rivers State in the sedimentary basin of the Niger delta of Nigeria, to determine the overburden layering and infer the aquifer depth/thickness and probable safe structural foundation depths in the region. The Schlumberger array method was employed using an ABEM 300B Terrameter and maximum current electrode spread of 400 m. The computed apparent resistivity field log values were plotted against the current electrode spreads and interpreted with IPWIN 2 and Sulphure 8 software to obtain the overburden thickness/depth, resistivity and the isopach map and then infer the subsoil layering thickness including potential aquifer zones within the depths of investigation in the area. The curve types revealed that three and four geoelectric sections were penetrated by the survey array with overburden thickness ranging from 4.2 m in Elok community to 91.7 m in Ilghom community. Potential aquifers with variable thickness from 5 to 60 m at depths of from 4.5 m and below the earth surface were identified. The subsurface soils types can support structural foundations from depths of 1.0 m and below the earth surface based on the type of building/engineering structures.
Evaluation of Heterogeneous Aquifers in Crystalline Rocks from Resistivity So...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Mer än 90 % av verksamheterna i Davidshallsområdet i Malmö, är privatägda. Inga större butiks- och restaurangkedjor finns vid torget. Alla är helt unika och tillhandahåller oftast varor handplockade för kunderna. Detta åskådliggörs med fotoutställningen ”Vi är Davidshallare” och lanseringen av områdets logotyp under Höstfesten 24/9.
Surge de la necesidad de las pequeñas y medianas empresas asociadas a AJE, que demandan desde hace un tiempo asesoramiento experto en temas de innovación empresarial, abarcando diferentes ámbitos de la empresa, con el fin de mejorar su competitividad y ampliar su mercado actual mediante la internacionalización de su oferta de productos y servicios.
Se pretende potenciar el crecimiento y desarrollo de las pymes participantes mediante la elaboración de un Plan Director de Innovación e Internacionalización que incremente su capacidad tecnológica y de atractivo en el mercado nacional e internacional, que mediante un ejercicio de reflexión estratégica, incorpore la gestión de la innovación en la planificación empresarial.
La innovación es aplicable a cualquier sector, industria, comercio, turismo, servicios…
Las sinergias se pueden establecer en cualquier sector y mercado, sea emergente, maduro, tradicional, tecnológico…
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Determination of Thickness of Overburden in Basement Area Using Schlumberger ...iosrjce
The overburden thickness of Abuja (Lat. 70
12´N – 9
0 30´ N and Long. 50
24´E- 7
0
19´E)
has been estimated. The geophysical method used was the electrical resistivity and the electrodes
array was Schlumberger type. The equipment utilized were four electrodes, hammer, four reels of
wires, crocodile clips, measuring tape, global positioning systems(GPS) and a terrameter. The survey
was carried out in two locations and the average resistivity values of the first four geoelectrical layers
were from the surface, 590 Ωm, 1800 Ωm, 1900 Ωm and 760 Ωm. These layers were interpreted as
probably top soil, laterite, weathered basement rock and fairly weathered basement rock. The
average thickness of the overburden was found to be 5.43m
Electrical Resistivity Survey Forground Water At Eye Zheba Village, Off Bida ...iosrjce
The paper titled “Electrical Resistivity survey for ground water” at EL-HALAL Farms, covered an
area of about 10km2
, located at Eye Zheba village along Minna-Bida Road, located on latitude 60
.001
and 6
0
7
1
West and longitude 90
3
1
and 9.101 North. As a result of water problem in Bida and its environs, the people living
in this environment suffered a lot due to lack of portable drinking water and water for domestic use. A
Geophysical survey carried out, employed the schlumberger Array method in which current were sent beneath
the earth surfaces, this was done at various points and the data collected. The area revealed three lithological
formations in some places while in some place five. With the lowest resistivty found to be 6.85 Ωm and the
highest resistivity was 12,774.46 Ωm. The lithotogical formation includes the sandstones, clayey sandstones,
sandy clay and ferruginised sandstone. Since this is a sedimentary area drilling is expected to be deep down to a
depth of about 70-75m
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
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Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Resistivity Imaging of Shallow Sediments within University of Maiduguri Campu...iosrjce
Electrical resistivity imaging within University of Maiduguri campus shows varying resistivity values
and thicknesses for shallow sediments from one profile line to another. Sequence stratigraphy of the sediments
indicates they were deposited at different times and varying conditions. Structure of the medium of deposition
conditioned the lithological structures of the sediments. Basin or bowl-shapes of some resistivity structures are
characteristics of some gravelly and clayey sediments. In most cases where such structures are encountered,
gravels seem to host sands; while clays are located at the central parts. This situation may suggest that the
sediments were deposited at the same time, where heavier ones settled to the bottom of the stratigraphy.
Sometimes clayey sediments host sandy sediments; a situation that may be associated with different times of
deposition. Some sediments were laid horizontally, some inclined and others nosed into overlying ones.
Majority of the resistivity images indicate clayey sediments occupying the basal resistivity units. Lower
resistivity values associated with some clayey sediment suggest high degree of saturation. The water might have
been derived through infiltration of the overlying porous sediments. The clays may be followed upwardly by
sands, while gravels sometimes form the capping sediments. Few resistivity profiles host the three sediments at
the bottom of the resistivity structures. Stratigraphic thicknesses for the sediments vary both laterally and
vertically. These are associated with the structure of the medium and prevailing conditions at the time of
deposition
1-D Electrical Resistivity Survey For Groundwater In Ketu-Adie Owe, Ogun Stat...iosrjce
This research involved the use of 1-D electrical resistivity survey method for groundwater
investigation in Ketu-Adie Owe, Ogun State. Seven (7) vertical electrical resistivity soundings (VES) using
Schlumberger array were carried out at different locations. The Schlumberger resistivity soundings were
executed with half-spacing in the range of 1.00 – 100.00 metres. The curve types are AAK, AAK, KHAK, AKQ,
KQH, AK. The study shows that viable aquifer is within 17.30 – 52.90 metres square.
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Lithological Investigation at Tombia and Opolo Using Vertical Electrical Soun...IJLT EMAS
Vertical electrical soundings (VES) was carried out in Opolo and Tombia all in Yenagoa local government area, Bayelsa state, Nigeria to understand the resistivity distribution of its subsurface which serves as a tool in investigating subsurface lithology. All VES sounding were stacked together to generate 1D pseudo tomogram and was subsequently interpreted. The interpreted VES curve results shows that Opolo consists of three layers within the depth of investigation. Sandy clay with mixture of silt make up the first layer (Top layer) with resistance value ranging from 24-63Ωm. The second layer is made up of thick clay with very low resistivity values ranging from 3-19Ωm. The third layer is sandyclay with its resistance value ranging from 26-727Ωm.Tombia also reveals that the area is in three layers within the depth of investigation. Sandy clay with a mixture of fine sand made up the first layer (Top soil) with its resistance values ranging from 40-1194Ωm. The second layer is made up of fine sand with resistivity value ranging from 475-5285Ωm. The third layer is made up of sandy clay/sand with its resistance value ranging from 24-28943Ωm.The results of the 1D pseudo tomogram also reveals that Tombia and Opolo consists of three layers within the depth of investigation and pseudo tomograms serves as a basis tool for interpreting lithology and identifying lithological boundaries for the subsurface
Determination of Thickness of Aquifer with Vertical Electrical Sounding iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Subsurface Determination Of Cavities In Limestone Rock Area By Geoelectric Me...IJERA Editor
Two Dimensional of geoelectric method can be used to find out the conductive formation in the earth surface. The purpose of this research is to give the description about the geological subsurface formation, that the high resistivity value is indicate the potential area of cave and void in the limestone rocks. The dipole dipolegeoelectric method is used in this research with the path of lines is 250 m with 10 m electrode spacing. The total lines is 7 and the azimuth is from east to west. Resistivity method is started with inject the electrical current into the earth by current electrode, then potential difference will arise and measured by potential electrode. Variation value of resistance for each layer rock can calculated by divided potential defference with current value. The existence of the cavity is known by the resistivity value is more than 2500 ohm-m, while the cracks have a resistivity of 1500 to 2500 ohm-m.
Geophysical Investigation of Groundwater Potential in Ahmadu Bello University...
Gh2511431153
1. Fadele, Jatau, Patrick / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
Geophysical Engineering Investigation Around Makiyaye Village,
Shika Area Within The Basement Complex Of North-Western
Nigeria.
FADELE S.I, JATAU B.S AND PATRICK N.O
Nasarawa State University, Keffi, Nigeria
Abstract
Geophysical investigation for engineering studies as septic tanks and sewage channels are planned
was carried out around Makiyaye village which for the area under study.
falls within the Basement Complex of North-
Western Nigeria. The study is aimed at (Key words: VES, Top soil, Weathered Basement,
evaluating the competence of the near surface Partly weathered or Fractured Basement, Fresh
formation as foundation materials, and to Basement)
unravel the subsurface profile which in turn
determines if there would be any subsurface I. Introduction
lithological variation(s) that might lead to The failure statistic of structures such as
structural failure at the site and evaluating the buildings, tarred roads and bridges throughout the
groundwater potential of the site and nation is increasing geometrically. Most of these
determining the level of safety of the failures were caused by swelling clays (Blyth and
hydrogeologic system. Vertical Electrical Freitas, 1988). In recent times, the collapse of civil
Sounding (VES) using Schlumberger array was engineering structures has been on the increase for
carried out at eighteen (18) VES stations. ABEM reasons associated with subsurface geological
terrameter (SAS 300) was used for the data sequence (Omoyoloye et al., 2008). The need for
acquisition. The field data obtained have been subsurface geophysical investigation has therefore
analysed using computer software (IPI2win) become very imperative so as to prevent loss of
which gives an automatic interpretation of the valuable properties and lives that always accompany
apparent resistivity. The geoelectric section such a failure. Foundation evaluation of a new site is
revealed three to four lithologic units defined by necessary so as to provide subsurface and aerial
the topsoil, which comprises clayey-sandy and information that normally assist civil engineers,
sandy lateritic hard pan; the weathered builders and town planners in the design and siting
basement; partly weathered/fractured basement of foundations of civil engineering structures
and the fresh basement. The resistivity values (Omoyoloye, et al., 2008). Geophysical methods
range from 28 - 354Ωm in the topsoil, 70 - such as the Electrical Resistivity (ER), Seismic
356Ωm in the weathered basement, 245 - 694Ωm refraction, Electromagnetic (EM), Magnetic and
in the fractured basement and 1114 - 3699Ωm in Ground Penetrating Radar (GPR) are used singly or
the fresh basement . Layer thicknesses vary from in combinations for engineering site investigations.
0.38 – 2.64m in the topsoil, 0.7 – 37.36m in the The applications of such geophysical investigation
weathered layer, 5.86 – 34.2m in the fractured are used for the determination of depth to bedrock,
basement. Depth from the surface to structural mapping and evaluation of subsoil
bedrock/fresh basement generally varied competence (Burland, J.B and Burbidge, M.C
between 2.64 and 44.11m. Based on the resistivity 1981). The engineering geophysical investigation
values, it is concluded that the subsurface was carried out around Makiyaye village, Zaria,
material up to the depth greater than 20m is Kaduna State, North-Western Nigeria, aimed at
competent and has high load-bearing capacity. determining the depth to the competent stratum in
However, resistivity values less than 100Ωm at the subsurface, delineation of areas that are prone to
depths of 10 - 15m indicate high porosity, high subsidence or some form of instability, evaluating
clayey sand content and high degree of saturation the groundwater potential of the site and
which are indications of soil conditions requiring determining the level of safety of the hydrogeologic
serious consideration in the design of massive system in the study area.
engineering structures. The hydrogeologic system
at the site is vulnerable to contamination. Hence, II. Location and Topography of the
the result reasonably provide a basis for which
Study area
groundwater potential zones are appraised for
The study area lies between Latitudes 110
safety in case potential sources of groundwater
10’ 09”N - 110 11’00’’N and Longitudes 70
contamination sites such
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(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
35’50”E - 70 38’ 40” E. The site is situated along northwest trend. They have a pronounced effect on
the Sokoto road, North West of Zaria (Fig. 1). The the drainage pattern of the state.
topography is that of high plain (flat terrain) of
Hausa land. The site is located within the tropical IV. Methodology
climatic belt with Sudan Savannah vegetation. The Vertical Electrical Soundings (VES) using
environment is Savannah type with distinct wet and Schlumberger array were carried out at eighteen
dry season. The rainfall regime is simple but with (18) stations. A regular direction of N-S azimuth
slight variation which consists of wet season lasting was maintained in the orientation of the profiles.
from May to September and characterized by heavy Overburden in the basement area is not as thick as to
down pour at the start and end of the rainy season. warrant large current electrode spacing for deeper
The annual rainfall varies between 800 mm to 1090 penetration (Oseji, et al., 2005; Okolie, et al., 2005),
mm while the mean annual temperature ranges therefore the largest Current electrode spacing AB
between 240C to 310C reaching a maximum of about used was 200m, that is, 1/2AB=100m. The
360C around April (Hore,1970; Goh Cheng Leong principal instrument used for this survey is the
and Adeleke, 1978). ABEM (Signal Averaging System, (SAS 300)
Terrameter. The resistance readings at every VES
III. Geology of Study Area point were automatically displayed on the digital
The study area is laid on undifferentiated readout screen and then written down on paper.
basement. Though there were no rock out-crops
within the site, observation however revealed that V. Results and Discussion
the weathered bedrock in some existing hand-dug The geometric factor, K, was first
wells within the site and environs indicates the calculated for all the electrode spacings using the
occurrence of granitic rocks within the site which formula; K= π (L2/2b – b/2), for Schlumberger array
are porphiritic in texture. The study area falls within with MN=2b and 1/2AB=L. The values obtained,
the Metasediments of the Basement Complex were then multiplied with the resistance values to
(McCurry, 1970). The Basement Complex in obtain the apparent resistivity, ρa, values. Then the
Kaduna state was affected by an Orogeny, which apparent resistivity, ρa, values were plotted against
predated the emplacement of the Older Granite. the electrode spacings (1/2AB) on a log-log scale to
During this event, deformation of the basement obtain the VES sounding curves using an
produced north-south trending basins of appropriate computer software IPI2win in the
Metasediment in the form of Synclinoria. Tertiary present study. Some sounding
earth movements tilted the Metasediments to north
and warped the basement along the axis of the uplift
pass through the present Kaduna state having
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3. Fadele, Jatau, Patrick / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
Study Area
Figure 1: Location Map Showing the Study Area (From Northern Nigerian Survey Map)
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(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
curves and their models are shown in Fig 2. structural features have some geological, physical
Similarly, geoelectric sections are shown in Figs. 3 and near-surface engineering significance.
and 4.Three resistivity sounding curve types were
obtained from the studied area and these are the H Profile A-A’
(ρ1>ρ2<ρ3), A (ρ1< ρ2<ρ3) and KH (ρ1>ρ2< ρ3>ρ4) Profile A-A’ geoelectric section suggests
type curves. The results of the interpreted VES that the site is characterized by lateritic hard pan at
curves are shown in Table 1 and 2. The modeling different consolidation levels within shallow
of the VES measurements carried out at eighteen depths, while gneiss and granites mainly,
(18) stations has been used to derive the geoelectric characterize the basements. The fresh basements
sections for the various profiles (Figs. 4 and 5). have synclinal structure which cut across the
These have revealed that there are mostly four and profile (fig. 4). The weathered/fractured basements
three geologic layers beneath each VES station. have sharp dipping layers along VES 5, 6, 7 and 8.
The geologic sequence beneath the study area is The probable feature that may cause building
composed of top soil, weathered basement, partly failure could be geologic feature like dipping
weathered/fractured basement, and fresh basement. bedrock or synclinal structure. This is because
The topsoil is composed of clayey-sandy and while overburden materials fill the synclinal
sandy-lateritic hard crust with resistivity values structure, their columns undergo ground movement
ranging from 28Ωm to 354Ωm and thickness by subsidence and thereby could amount to uneven
varying from 0.38m to 2.64m, thinnest at VES 12 settlement at the foundation depths of buildings. In
and thickest at VES 6, 11 and 14. It is however, other words, uneven stress distribution may occur
observed from the geoelectric sections that VES 2, at the foundation depths of subsurface, that is one
3, 4, 9, 10, 11, 12, 13, 14 and 15 are characterized side of building structure may have a stronger
with low resistivity values varying between 26Ωm support than the other adjacent of it. Another
to 53Ωm suggesting the clayey nature of the topsoil factor that could contribute to structural defect of
in these areas and possibly high moisture content. building is the seasonal variation in the saturation
The second layer is the weathered basement with of clay which causes ground movement and is
resistivity values varying from 70Ωm to 356Ωm caused by clay swells and shrinkages which are
and thickness ranges between 0.7m to 37.36m, occasioned by alternate wet and dry seasons. The
thinnest at VES 1and thickest at VES 6. The third area is characterized by clay soils with lateritic
layer is the partly weathered and fractured patches at shallow depths with their thickness
basement with resistivity and thickness values ranging between 1.37m and 2.64m, which are
varying between 245Ωm to 694Ωm and 5.86m to considerably thin and are resting on the shallow
34.2m respectively. The layer is extensive and weathered/fractured basement.
thickest at VES 18 and thinnest at VES 16. The
fourth layer is presumably fresh basement whose
resistivity values vary from 1114Ωm to 3699Ωm
with an infinite depth. Though the thickness of the
bedrock is assumed to be infinite, the depth from
the earth’s surface to the bedrock surface varies
between 2.64m to 44.11m. Quite a few of the
profiles dipping and a negligible number of them
show synclinal and fractured structure. These
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5. Fadele, Jatau, Patrick / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
Table 1: The results of the interpreted VEScurves
VES Thickness (m) Layer resistivity Remarks Curve types Numb of layers
Stations (Ωm)
1.23 152 TP
1 0.70 113 WB KH 4
9.69 426 PWB
- 1329 FB
2.29 45 TP
2 12.2 171 WB A 3
- 1765 FB
3 1.71 48 TP 3
11.2 298 WB A
- 1198 FB
1.13 48 TP
4 5.96 326 WB KH 4
11.6 433 PWB
- 2112 FB
1.23 196 TB
5 0.78 152 WB KH 4
10.2 245 PWB
- 1960 FB
2.64 256 TP
6 37.36 114 WB H 3
- 1450 FB
1.87 249 TP
7 12.1 169 WB H 3
- 1365 FB
1.37 154 TP
8 2.14 199 WB KH 4
15.2 565 PWB
- 1289 FB
2.09 53 TP
9 7.82 70 WB KH 4
34.2 450 PWB
- 1114 FB
1.13 26 TP
10 2.33 316 WB A 3
- 1251 FB
2.64 28 TB
11 8.84 162 WB A 3
- 1410 FB
0.38 27 TP
12 5.10 162 WB A 3
- 3600 FB
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(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
Table 2: The results of the interpreted VES curves
VES Thickness (m) Layer resistivity Remarks Curve types Numb of layers
Stations (Ωm)
Apparent resistivity (Ωm)
Where,
N is the number of layers,
ρ is the apperent resistivity,
h is the thickness and
d is the depth to interface of
each layer.
Electrode spacing (m)
(a) TYPE KH CURVE
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7. Fadele, Jatau, Patrick / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
Apparent resistivity (Ωm)
Where,
N is the number of layers,
ρ is the apperent resistivity,
h is the thickness and
d is the depth to interface of
each layer.
Electrode spacing (m)
(b) TYPE A CURVE
Apparent resistivity (Ωm)
Where,
N is the layer number,
ρ is the apperent resistivity
in ohm-metre,
h is the layer thickness and
d is the depth to interface of
each layer
Electrode spacing (m)
(c) TYPE A CURVE
Figure 2: Typical curve types and models obtained from the study area.
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8. Fadele, Jatau, Patrick / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
VES 1 VES 2 VES 3 VES 4 VES 5 VES 6 VES 7 VES 8 VES 9
A
1A
52𝜴𝒎
2A 3A
𝟒𝟖𝜴𝒎
4A
𝟒𝟖𝜴𝒎
5A
𝟏𝟗𝟔𝜴𝒎
6A
𝟐𝟓𝟕𝜴𝒎
7A
𝟐𝟒𝟗𝜴𝒎
8A
𝟏𝟓𝟒𝜴𝒎
9A
𝟓𝟎𝜴𝒎
A’
𝟒𝟓𝜴𝒎
113 𝜴𝒎
𝟏𝟓𝟐𝜴𝒎
𝟏𝟗𝟗𝜴𝒎
𝟐𝟎𝜴𝒎
326𝛺𝑚
𝟏𝟕𝟏𝜴𝒎 𝟐𝟗𝟖𝜴𝒎
10 426 𝜴𝒎 𝟏𝟔𝟗𝜴𝒎
𝟐𝟒𝟓𝜴𝒎 𝟏𝟏𝟒𝜴𝒎
𝟏𝟓𝟐𝜴𝒎
𝟒𝟑𝟑𝜴𝒎
𝟏𝟓𝟑𝜴𝒎
𝟐𝟔𝟒𝟑 𝜴𝒎
𝟏𝟑𝟎𝟗 𝜴𝒎
DEPTH (m)
20 𝟏𝟏𝟔𝟓 𝜴𝒎
𝟏𝟗𝟔𝟎 𝜴𝒎
𝟏𝟑𝟎𝟗𝜴𝒎
𝟐𝟏𝟏𝟐 𝜴𝒎 𝟏𝟐𝟖𝟗𝜴𝒎
30
𝟏𝟏𝟒𝟒𝜴𝒎
40
𝟏𝟒𝟏𝟎 𝜴𝒎
Clay/clayey sandy (Top soil) Lateritic hard pan (Top soil)
Weathered layer Partly weathered/fractured layer
Fresh basement
Figure 3: Geoelectric section along profiles A-Ai
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Vol. 2, Issue 5, September- October 2012, pp.1143-1153
VES 10 VES 11 VES 12 VES 13 VES 14 VES 15 VES 16 VES 17 VES 18
1D 3D 4D 5D 6D 7D 8D 9D B’
B 26 𝜴𝒎 28 𝜴𝒎
30 𝜴𝒎 254 𝜴𝒎
281 𝜴𝒎 256 𝜴𝒎
28 𝜴𝒎 30 𝜴𝒎
316 𝜴𝒎 347 𝜴𝒎 358 𝜴𝒎
356 𝜴𝒎
261 𝜴𝒎
162 𝜴𝒎 199 𝜴𝒎
519 𝜴𝒎
694 𝜴𝒎
302 𝜴𝒎 3699 𝜴𝒎 2593 𝜴𝒎
3307 𝜴𝒎
1270 𝜴𝒎
2935 𝜴𝒎
10
1519 𝜴𝒎 658 𝜴𝒎
1410 𝜴𝒎
DEPTH (m)
20
30
1614 𝜴𝒎
40 Clay/clayey sandy (Top soil) Lateritic hard pan (Top soil)
3511 𝜴𝒎
Weathered layer Partly weathered/fractured layer
Fresh basement
Figure 4: Geoelectric section along profiles B-Bi
Profile B-B’ Competence Evaluation
The geoelectric section revealed clayey There are no indications of any major
sandy topsoil having some lateritic hard crust linear structure such as fracture or faults that could
patches (fig. 5). The synclinal structure at VES aid building subsidence. The geologic sequence
point 11 is not well pronounced and may not pose beneath the area is composed of thin layer of
any serious danger to building foundation. topsoil, thick weathered layer, partly
However, there is a deep weathering beneath VES weathered/fractured basement and fresh bedrock.
point 17 and 18. The presence of laterite beneath The topsoil constitutes the layer within which small
the clayey topsoil which hardly extends beyond civil engineering structures can be constructed.
2.64m reduces the danger posed by clay formation From the table of resistivity values (Table 1), the
to large buildings. This area forms a good site for topsoil is composed of sandy clay, clayey sand and
the erection of high-rise civil engineering patches of lateritic hard pans. Engineering
structures. competence of the subsurface can be qualitatively
evaluated from the layer resistivity. The higher the
layer resistivity value, the higher the competence of
a layer; hence from the point of view of the
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(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
resistivity value therefore, laterite is the most areas and possibly high moisture content. The
competent of the delineated topsoil, followed by second layer is the weathered basement with
clayey sand and sandy clay being the least resistivity values varying from 70Ωm to 356Ωm
competent. Based on the resistivity values, depths and thickness ranges between 0.7m to 37.36m,
of about 10 - 15m can support small to medium thinnest at VES 1 and thickest at VES 6. The third
size structures while depth in excess of 25m can layer is the partly weathered and fractured
support massive civil engineering structures in the basement with resistivity and thickness values
study area. varying between 245Ωm to 694Ωm and 5.86m to
34.2m respectively. The layer is extensive and
Groundwater Potential thickest at VES 18 and thinnest at VES 16. The
Even though experience has shown that fourth layer is presumably fresh basement whose
there is no direct relationship between groundwater resistivity values vary from 1114Ωm to 3699Ωm
yield and borehole depth in a basement complex with an infinite depth. Though the thickness of the
environment, studies (Bala and Ike, 2001; Omosuyi bedrock is assumed to be infinite, the depth from
et al., 2008; Ariyo and Osinawo, 2007) revealed the earth’s surface to the bedrock surface varies
that areas with thick overburden cover in such between 2.64m to 44.11m. A-curve type which
basement complex terrain has high potential for shows a continuous and uniform increase in
groundwater. According to Ariyo and Oguntade resistivity predominates. This curve typifies an area
(2009), in a basement complex terrain, areas with showing characteristics of high load-bearing
overburden thickness of 15m and above are good strength. This is followed by HK-curve showing
for groundwater development. The highest that some areas have overburden saturation which
groundwater yield is often obtained from a recharges the main aquifer units. The rest of the
weathered/fractured aquifer, or simply a subsurface curves are minority in number with H-type curve
sequence that has a combination of a significantly which has a minimum resistivity intermediate layer
thick and sandy weathered layer and fractured underlain and overlain by more resistant materials
aquifer. Where the bedrock is not fractured, a reminiscent of areas promising for groundwater
borehole can be located at a point having a development. Based on the resistivity values of the
relatively high layer resistivity greater than 150Ωm different geoelectric layers, the various geologic
but less than 600Ωm (Olorunfemi, 2009). From the units up to depth of 25m are competent and can
foregoing two parameters – overburden thickness support massive civil engineering structures. The
and resistivity values, VES 2, 3, 4, 5, 6, 8, 9, 17 presence of laterite beneath the clayey topsoil
and 18 can be considered to be productive zones which hardly extends beyond 2.64m reduces the
for groundwater development in the study area. danger posed by clay formation to large buildings.
Since the area is generally shallow to the water Other probable causes of foundation defects are the
aquifer and groundwater in this area is vulnerable growth of tree roots, organic deposits, sink holes,
to pollution, the depth of sewage system should be cavities or ground surface saturation due to
<10m to the weathered basement (aquiferrous seepages and this should be taken care of during
zone) in order to avoid groundwater contamination. building project implementation to ensure that
It is suggested that potential sources of buildings erected at the site stands the test of time.
contamination site like sewage channels should be In a basement complex terrain, areas with
sited far away from viable aquifer units to ensure overburden thickness of 15m and above are good
safety consumption of groundwater within the area. for groundwater development. The highest
groundwater yield is often obtained from a
VI. Conclusion weathered/fractured aquifer, or simply a subsurface
The VES results revealed heterogeneous sequence that has a combination of a significantly
nature of the subsurface geological sequence. thick and sandy weathered layer and fractured
Though the geoelectric section showed complexity aquifer. Where the bedrock is not fractured, a
in the Subsurface lithology, there is however, no borehole can be located at a point having a
indication of any major fracture or fault that could relatively high layer resistivity greater than 150Ωm
aid subsidence. The geologic sequence beneath the but less than 600Ωm (Olorunfemi, 2009). From the
study area is composed of topsoil, weathered layer, foregoing two parameters – overburden thickness
partly weathered/fractured basement, and fresh and resistivity values, VES 2, 3, 4, 5, 6, 8, 9, 17
basement. The topsoil is composed of clayey-sandy and 18 can be considered to be productive zones
and sandy-lateritic hard crust with resistivity values for groundwater development in the study area. To
ranging from 26Ωm to 391Ωm and thickness ensure safety appraisal of groundwater
varying from 0.38m to 2.64m, however, observed consumption in the area, potential sources of
from the geoelectric sections that VES 2, 3, 4, 10, contamination site should be sited far away from
11, 12, 13, 14 and 15 are characterized with low viable aquifer units to ensure safety consumption of
resistivity values varying between 26Ωm to 53Ωm groundwater within the study area.
suggesting the clayey nature of the topsoil in these
1152 | P a g e
11. Fadele, Jatau, Patrick / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1143-1153
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