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

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.

2021 ◽  
Vol 5 (2) ◽  
pp. 635-639
Author(s):  
Y. S. Onifade ◽  
V. B. Olaseni ◽  
I. G. Baoku ◽  
C. Eravwodoke

Geophysical investigation using the 2D Electrical Resistivity Tomography (ERT) was carried out to assess the subsurface of Ugoneki and its environs in order to investigate for minerals. A total of six (6) traverses, 200 m long each, three (3) transverse lines were in the North-South direction and the other three (3) traverses in the West-East direction using the Wenner electrode configuration. 2D Wenner resistivity data were acquired along each traverse. The data were inverted to reveal a spatially continuous resistivity distribution in 2D within the study area. The 2D results reveal a depth of 39.6 m across each traverse. Resistivity values vary from 87.1 – 3423 Ωm in the entire study area. From the standard resistivity table, the following solid and non-metallic type of minerals can be delineated in the study area which is representative of sandy clay, lateritic clay sand, sandstone and limestone with resistivity values that range from 87.1 – 89.9 Ωm, 1201 – 1462 Ωm, 2069 – 3423 Ωm, and 2069 – 3423 Ωm respectively. The implication of this research is to know the type and the particular location where these non-metallic solid minerals are located in the subsurface for future exploration. The results of resistivity values are compared with those in the literature and are found to be in good agreement. In order to quantify these minerals, it is also recommended to use higher dimension (3D) of resistivity method (ERT) in the study area.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Olaseeni Olayiwola ◽  
Fagbemigun Tokunbo ◽  
Ojo Bosede ◽  
Amosun Joel ◽  
Oyebamiji Ajibola

Abstract An appraisal of the groundwater vulnerability to contamination risk at Adebayo in Ado-Ekiti, Southwestern Nigeria, was carried out using the electrical resistivity method of geophysical prospecting. Two traverses of length 100 m each were established for both vertical electrical sounding (VES) and dipole-dipole. Six (6) Vertical Electrical Sounding (VES) and 2-D dipole-dipole profiling techniques of the electrical resistivity method were adopted for the geophysical investigation. The results show variations in resistivity values, depicting four to five geologic layers: the topsoil, laterite, weathered layer, fractured, and the fresh basement. It was observed from the correlation of the geoelectric section and 2-D resistivity image along traverse 1 (TR1) that the groundwater in the study area flows towards the southwestern part, and the fractured basement serves as a migration pathway to the diesel oil in the same direction as groundwater flow. The fractured basement (Well 2) with no lateritic cover has higher resistivity values compare to the fracture zone that was found directly under the mast which was overlain by the laterite. Comparing the resistivity values of Well 1 and 2, Well 2 that was drilled into the fractured basement has more traces of the contaminant than Well 1.


Author(s):  
S. O. Ilugbo ◽  
A. D. Adebiyi ◽  
S. O. Olaogun ◽  
T. Egunjobi

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.


Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 234
Author(s):  
Marián Homolák ◽  
Erika Gömöryová ◽  
Viliam Pichler

This study investigates how certain forest soil properties influence the propensity of beech forests to windthrow disturbances. The field measurements of soil electrical resistivity were carried out in an old-growth natural beech forest where the soil has developed from Cainozoic sedimentary rock with mudstone–claystone stratigraphy. In 2014, the forest was hit by a severe windstorm, and dispersed windthrow occurred at certain plots. Apparent electrical resistivity measurements were performed to investigate whether some soil properties could influence the forest trees’ predisposition to windthrow. The increases in the clay content and soil bulk density below 30 cm were associated with weathered claystone and mudstone, which created a physiological barrier for deeper root penetration. The result of the χ 2 test suggested that the windthrown spots were not distributed evenly over the entire study area. They were mainly concentrated over approximately 50% of the area, and their positions coincided with low resistivity values, indicating low soil skeleton content, high clay content and soil moisture. Therefore, electrical resistivity tomography could be considered a useful predictive tool for reducing the risk of natural disturbances by preventive forest management.


Author(s):  
Ilugbo Stephen Olubusola ◽  
Adebo A. Babatunde ◽  
Ajayi Oluwasayo Adegbola ◽  
Adewumi Olufemi Olaoluwa ◽  
Edunjobi Hazeez Owolabi

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.


Author(s):  
Bawallah Musa Adesola ◽  
Ilugbo Stephen Olubusola ◽  
Aigbedion Isaac ◽  
Aina Adebayo O. ◽  
Oyedele Akindele Akintunde

In this present study area, most building failures often start with minor/major cracks which widen over time, and it is often followed by post construction remedial measures which fail after sometime, thereby leading to total collapse and sinking of such buildings. The research was carried out in order to be able to unravel the causes of major cracks along the side of a major class room block at Ikekogbe, UBE Primary School, Ekpoma, Edo State, Nigeria in less than five (5) years after it was constructed. The cracks were visible both at the front and at the back of the building along the same axis and almost at this same distance as it was at the front of the building. The investigation involved Electrical Resistivity method using three techniques; Vertical Electrical Sounding (VES), 2-D Electrical Resistivity Tomography (ERT) and Horizontal Profiling (HP). The traverses were established along E-W directions and Eight (8) VES were carried out using Schlumberger array with current electrode spacing varying from 1 to 40 m, with 2-D ERT using Dipole-Dipole electrode array with inter-station separation of 5 m and an expansion factor that varied from 1 to 5 and HP using Wenner array with an electrode spacing of 5 m interval. The VES interpretation results were used to determine the second order parameters for modeling of subsurface integrity/competence. The 2 D imaging (Dipole-Dipole) gave information on the subsurface characteristic and the Wenner profile was characterised by low resistivity at the region of 30 to 45 m considered as the weak zone. Correlating the results with subsurface integrity model along traverses one and three, there was a high degree of correlation as this region coincides with the very low/low integrity/competence with the foundation of the classroom overlying this layers. The research revealed that the problem of structural failures/crack noticed along the building walls and axis was not as a result of human problem alone but mainly the existence of very low/low integrity/competence layers which contributed greatly to the cracks observed on the classroom block. These results reveal that the three Electrical resistivity techniques used for this study are complimentary to each other.


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