scholarly journals Geophysical and Geotechnical Site Characterization at Lagos Central Area of Lagos State, Nigeria

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Rafiu Adegbola ◽  
Kayode Oyedele ◽  
Elizabeth Abidoye
Keyword(s):  
Central Area ◽  
Maximum Load ◽  
Shallow Foundation ◽  
Silty Sand ◽  
Cone Penetration ◽  
Engineering Structures ◽  
Shallow Subsurface ◽  
Subsurface Geology ◽  
Electrical Sounding ◽  
A Site

Introduction: Geophysical characterization refers to the collection of information associated with subsurface features. Geotechnical involves engineering structural performance studies which are used to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused by subsurface conditions. Aim: The study was aimed at characterizing the subsurface formations for the purpose of determining its capacity to withstand engineering structures. Materials and Methods: Geophysical techniques involving eight (8) vertical electrical sounding (VES) and Wenner array were carried out with two (2) traverses. Geotechnical investigation involving cone penetration test (CPT) was also carried out. Results: The results obtained were presented as 1D resistivity profiles and Pseudo-sections of 2-D. Three (3) geo-electric layers were delineated within the study area and these comprise of topsoil, peat or clay and silty sand. The CPT results were used in the calculation of bearing capacity using Bustamante and Gianeselli equation for pile foundations and Meyehorf equation to determine the maximum load the materials can withstand respectively. Conclusion: The shallow subsurface geology was adjudged to be mechanically unstable with low penetration resistance values up to the depth of 11m. The methods conformed and confirmed that shallow foundation was considered unsuitable for the intended engineering structure. Keywords: Meyehorf, Bustamante and Gianeselli, Subsurface, Geology, Unstable, Foundation.

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

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

Geophysical and geotechnical studies were carried out at a proposed location for the construction of a multi-storey structure in Akure, Southwestern, Nigeria. The aim was to ascertain the suitability of this location for both Founding and Engineering structures. The geophysical investigation involved the Vertical Electrical Sounding (VES) technique using the Schlumberger configuration, Dipole-Dipole Horizontal Profiling and a geotechnical investigation. A total of twenty-one (21) VES and five (5) Cone Penetration Test (CPT) locations were occupied within the study site. Dipole-Dipole Horizontal Profiling was occupied along traverses 1 and 2 within the investigated area. The electrode separation varies from 1 to 75 m. The investigation delineated three major layers which are topsoil, which is excavated before any foundation is laid. The second layer delineated was lateritic and the last was weathered layer. From the result obtained, depth to lateritic layer ranges from 1.1 to 9.0 m while resistivity defining the lateritic layer ranges from 150 Ωm to 792 Ωm. Some of the sounding curves generated over the VES stations and Dipole-Dipole Horizontal Profiling fairly correlated with those of the CPT profile. The high cone penetration resistance recorded at CPT point 4 and 5 is manifested as high geoelectric resistivity values recorded at VES 13. This shows that the soil has fairly low clay content. It also seen from the study that the geophysical studies has a greater depth penetration, and it also provide better layer characterization compared to geotechnical studies. The choice of foundation material, clay content and topography elevation should be taken into cognizance, since the load bearing capacity of the lateritic layer was appreciably high.

scholarly journals Application of Vertical Electrical Sounding for Study the Proposed dam site at Wadi Ma’doo, Shabwah Governorate, Yemen

2020 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Two Dimensions ◽  
Shallow Foundation ◽  
Vertical Electrical Sounding ◽  
Electrode Spacing ◽  
Geophysical Investigation ◽  
Engineering Structures ◽  
Geoelectric Section ◽  
True Resistivity ◽  
Dam Site ◽  
Electrical Sounding

Application of geophysical investigation has been carried out using Vertical Electrical Sounding (VES) at the proposed site in wadi Ma’doo, Shabwah Governorate, Yemen to determine the geophysical parameters that can be used to evaluate the subsurface geological layering characteristics of the selection proposed site for dam construction. The Schlumberger array was used for the data acquisition. One-dimensional numerical inversion of individual DC resistivity was used to enhance the processing of the results for better achievement of the aim of the study. Model obtained from the 2D inversion of each VES were used for construction of geoelectric section which exhibit the main geoelectric characteristics of the geological units present in the site. The interpretation of the field data was carried out using the IP12WIN software, which converts the apparent resistivity as a function of electrode spacing to the true resistivity as a function of depth in two dimensions. The interpretation results showed that the geoelectric section consists of three layers namely: boulders and gravels, sandy to pebbly and hard limestone. The layer resistivities and thicknesses range from 18.17 to 746.20 Ω.m/0.20 to 1.084 m, 53 to 60 Ω.m/ 0.20 to 3.059 m and 455 to 1890 Ω.m, respectively. The investigation revealed that the limestone rocks is suitable for shallow foundation for proposed dam engineering structures.

Application of Electrical Resistivity in Buildings Foundation Investigation in Ibese Southwestern Nigeria

2014 ◽  
Vol 1 (2) ◽  
pp. 91-102
Author(s):  
Falae Philips Omowumi
Keyword(s):  
Shallow Foundation ◽  
Geophysical Investigation ◽  
Engineering Structures ◽  
Building Site ◽  
Southwestern Nigeria ◽  
2D Inversion ◽  
One Dimensional ◽  
Southwest Nigeria ◽  
Electrical Sounding ◽  
Geological Units

Application of geophysical investigation has been carried out using Vertical Electrical Sounding (VES) at the proposed building site in Ibese Southwest Nigeria to determine the geophysical parameters that can be used to evaluate the structural competence of the subsurface geological characteristics of the site for construction purposes and building development. The Schlumberger configuration was used for the data acquisition. One-dimensional numerical inversion of individual DC resistivity was used to enhance the processing of the results for better achievement of the aim of the study. Models obtained from the 2D inversion of each VES were used for construction of geo-electric sections which exhibit the main geo-electric characteristics of the geological units present in the area. The interpretation results showed that the geo-electric sections consist of three-four layers namely: topsoil, pebble clay, limestone and sand/limestone. The layer resistivities and thicknesses range from 11 - 404 Ohm-m/0.4 - 1.5 m, 2-210 Ohm-m/ 0.8 - 9.2m and 33 - 160Ohm-m respectively. The investigation revealed that the sand/limestone litho unit is to be the most competent for shallow foundation for small to medium engineering structures.  

scholarly journals Engineering Site Investigation and Shallow Foundation Design in Ore Area of Ondo State, Nigeria

2020 ◽  
Vol 67 (1) ◽  
pp. 21-33
Author(s):  
O. Falowo Olumuyiwa
Keyword(s):  
Bearing Capacity ◽  
Soil Analysis ◽  
Site Investigation ◽  
Shallow Foundation ◽  
Cone Penetration ◽  
Foundation Design ◽  
Overburden Thickness ◽  
Allowable Bearing Capacity ◽  
Weathered Layer ◽  
Electrical Sounding

AbstractThe study integrates geophysical and geotechnical methods for subsoil evaluation and shallow foundation design. The study involved six vertical electrical sounding and geotechnical investigation involving cone penetration test and laboratory soil analysis. Three major geologic units were delineated; the topsoil, weathered layer and partly weathered/fractured/fresh bedrock. The overburden thickness is in between 15.2–32.9 m. Based on resistivity (16–890 ohm-m) and thickness (12.7–32 m) the weathered layer is competent to distribute structural load to underlying soil/rock. The groundwater level varies from 4.5 to 12.3 m. Therefore an average allowable bearing capacity of 200 kPa is recommended and would be appropriate for design of shallow foundation in the area, at a depth not less than 1.0 m with an expected settlement ranging from 9.03–48.20 mm. The ultimate bearing and allowable bearing capacity for depth levels of 1–3 m vary from 1403–2666 kPa and 468–889 kPa for strip footing while square footing varies in between 1956–3489 kPa and 652–1163 kPa respectively.

Geotechnical Investigation, Field Load Test and Analysis of Full-Scale Bored Pile

2015 ◽  
Vol 813-814 ◽  
pp. 1126-1130
Author(s):  
G. Kesavan ◽  
S.S. Chandrasekaran
Keyword(s):  
Tamil Nadu ◽  
Ground Level ◽  
Maximum Load ◽  
Field Investigation ◽  
Complex Problem ◽  
Load Test ◽  
Bored Pile ◽  
Economical Design ◽  
Pile Load Test ◽  
A Site

The maximum load carrying capacity of bored piles is a complex problem because it is a function of a number of factors, these factors include methods of soil exploration, ground water condition, types of grading of concrete, quantity and quality of concrete. The knowledge of Geotechnical test is important for the most economical design of the piles. This paper describes some important aspects of field investigation, design and construction of in-situ bored pile foundation, field pile load test of experience gained from the construction of the pile at a site in Aathoor in Tamil Nadu, India. The site was fully sandy soil from existing ground level. The design of bored pile under axial compression was done using Empirical formula, pile load test and by using PLAXIS 2D software. Results were compared with vertical load and settlement in this site.

scholarly journals Evaluation of Salt-water Intrusion in the Coastal Area of Igbokoda, Southwestern Nigeria

2018 ◽  
Vol 6 (01) ◽  
Author(s):  
Talabi A. O ◽  
Ajayi C. A ◽  
Afolagboye L. O ◽  
Oyedele A. A ◽  
Ojo O. F ◽  
...  
Keyword(s):  
Coastal Area ◽  
Salt Water ◽  
Silty Sand ◽  
High Resistivity ◽  
Salt Water Intrusion ◽  
Southwestern Nigeria ◽  
Major Threat ◽  
Sandy Clay ◽  
The World ◽  
Electrical Sounding

Saltwater intrusion into the coastal aquifer has long been recognized as a major threat to groundwater quality around the world. Groundwater evaluation of salt water intrusions in Igbokoda coastal area, southwestern Nigeria was carried out employing combined Horizontal Profiling and Vertical electrical sounding. Two traverses each with two sounding points were occupied. The result from the survey revealed 4 to 5 major layers comprising the unconsolidated silty sand and sandy clay (overburden), clayey zone, consolidated sand zone, partly intruded salt water intruded sandy clay zone and salt water intruded clay zone. The curves were the complex types KQH, KHA, QH and HKH curves. The overburden has resistivity that ranged from 253 to 1316.7Ω-m, thickness that ranged from 0.2 m to 7m. The clayey zone had resistivity of 846.0 Ω-m and thickness of 4m. The consolidated sand zone had resistivity that ranged from 2848.7 to 2865.7Ω-m and thickness that ranged between 4 and 21m. The partly intruded salt water zone is characterized by resistivity that varies between 18.4Ω-m and 93.0Ω-m and thickness of about 7-25m. The salt water intruded zone is characterized by resistivity that ranges between 4.1Ω-m and 9.7Ω-m and thickness of 4-48m. The partly-salt water intruded zones and salt water intruded zone were characterized with low resistivity while the high resistivity zones of consolidated sand layer constitute fresh water bearing zone that could serve as boreholes in the study area.

A supply-base (c. AD 43–52)

2021 ◽  
pp. 63-71
Author(s):  
Dominic Perring
Keyword(s):  
Central Area ◽  
The North ◽  
North Bank ◽  
Permanent Settlement ◽  
A Site

The archaeology of the first permanent settlement of London is described. New roads were laid out c. AD 48 leading to a site that may have served as a supply-base on the north bank of the Thames. This was set out following a grid-plan around a central area where the forum was later established. Various features illustrate the importance of the managed traffic of military supplies. The topographic, ritual, and political importance of the Thames crossing at London Bridge is stressed, and the evidence of foundation burials and deposits associated with the early layout of the settlement summarized.

Seismic cone penetration test for evaluating liquefaction potential under cyclic loading

1992 ◽  
Vol 29 (4) ◽  
pp. 686-695 ◽  
Author(s):  
P. K. Robertson ◽  
D. J. Woeller ◽  
W. D. L. Finn
Keyword(s):  
Cyclic Loading ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Penetration Resistance ◽  
Penetration Test ◽  
Cone Penetration ◽  
Liquefaction Potential ◽  
A Site ◽  
Seismic Cone Penetration Test

Impressive progress has been made in the last 25 years in recognizing liquefaction hazards, understanding liquefaction phenomena, and analyzing and evaluating the potential for liquefaction at a site. Recent findings related to the application of the seismic cone penetration test (SCPT) for the evaluation of liquefaction potential under cyclic loading are presented and discussed. The SCPT provides independent measurements of penetration resistance, pore pressures, and shear-wave velocity in a fast, continuous, and economic manner. The current methods available for evaluating liquefaction using penetration resistance are presented and discussed. Recent developments in the application of shear-wave velocity to evaluate liquefaction potential are discussed, and a new method based on normalized shear-wave velocity is proposed. Limited case-history data are used to evaluate and support the proposed correlation. A worked example is presented to illustrate the potential usefulness of the SCPT for evaluating liquefaction potential at a site. Key words : liquefaction, in situ tests, seismic.

The behavior of a compressible silty fine sand

1999 ◽  
Vol 36 (1) ◽  
pp. 88-101 ◽  
Author(s):  
An-Bin Huang ◽  
Huai-Houh Hsu ◽  
Jia-Wei Chang
Keyword(s):  
Quartz Sand ◽  
Experimental Studies ◽  
Fine Sand ◽  
Silty Sand ◽  
Small Range ◽  
Cone Penetration ◽  
Fines Content ◽  
Cone Penetration Tests ◽  
Extensive Field ◽  
Tip Resistance

Publications associated with sands are often limited to clean (i.e., little fines content), uniform, uncemented silica or quartz sand. On the other hand, the importance of mineral content, particle shapes, as well as gradation to the behavior of sand has long been recognized. Although systematic studies of sands other than clean quartz sand have been limited, there is increasing attention being paid to sands with an appreciable fines content. Because of a major construction project, extensive field and laboratory experiments were performed on a silty fine sand from Mai-Liao, which is located on the central west coast of Taiwan. Results show that Mai-Liao Sand (MLS), a silty sand, can be significantly more compressible than clean quartz sand under static load. The particles of MLS have moderate strength, and significant crushing can be induced by triaxial shearing. As a result, MLS has low dilatancy and a relatively small range of peak friction angles. Cone penetration tests in MLS were conducted in a calibration chamber. Analyses of the data indicate that interpreting cone tip resistance in MLS using methods developed based on clean quartz sand without considering the differences of compressibility can be unrealistic. This paper documents results of the experimental studies on MLS.Key words: silty fine sand, strength, dilatancy, compressibility, crushing, in situ test.

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