scholarly journals Investigating Road Pavement Failure in Oworonshoki, Kosofe Area of Lagos, Using Geophysical and Geotechnical Methods

2021 ◽  
pp. 56-67
Author(s):  
O. J. Airen ◽  
K. K. Oboshenure
Keyword(s):  
Cone Penetration ◽  
Clayey Sand ◽  
Near Surface ◽  
The Road ◽  
Cone Penetration Tests ◽  
Cone Penetration Testing ◽  
Road Pavement ◽  
Sandy Clay ◽  
Electrical Sounding ◽  
Lateral Extent

An assessment of the immediate causes of persistent road pavement failure in Oworonshoki, Koshofe area of Lagos, Nigeria using geophysical and geotechnical methods was carried out. Six traverses were occupied in the study area along the alignment of the road. Electrical Resistivity Imaging (ERI) data using the Wenner array were acquired along the six traverses. These were followed by six (6) Vertical Electrical Sounding (VES) data along the traverses. On traverse 1 are VES 1 and 2, on traverse 2 are VES 3 and 4, on traverse 3 are VES 5 and 6. One boring and three Cone Penetration Testing (CPT) were conducted along traverse 6 while the three CPTs were carried out on traverse 3, 4 and 5 respectively. The inverted 2D results reveal that resistivity values vary from 6.74 – 1333 Ωm in the study area. Four resistivity structures are delineated which are peat, clay/sandy clay, clayey sand and sand. The peat has resistivity values ranging from 6.74 – 17.7 Ωm, clay/sandy clay (20.9 – 86.9 Ωm), clayey sand (96.3 – 194 Ωm) and sand (245 – 1333 Ωm). The peat is laterally extensive and occurs from the surface to a depth of 25 m. The peat is underlain by the clay which is fairly extensive across the area of study with a thickness of 2.5 – 20 m in most location. The Cone Penetration Tests (CPT) reveal cone resistance values that progressively varies from 0 – 101 kg/m2 from the surface to a depth of 17 m, indicating dense earth materials at deeper depth while at near surface, they are incompetent soft clayey earth materials. The laterally extensive peat and clay units underlying the road pavement, extending up 30 m depth as revealed from the 2D ERI, the geoelectric investigation and the borehole are suspected to be responsible for the persistent settlement, rutting and pitting of the road pavement. The thickness of the peat/clay and the lateral extent may not be economically admissible for excavation during construction. Pile foundations to the dense gravely sand at 40 m depth along the stretch of the road is therefore recommended for stable road pavement.

Interpretation of cone penetration tests. Part II: Clay

1983 ◽  
Vol 20 (4) ◽  
pp. 734-745 ◽  
Author(s):  
P. K. Robertson ◽  
R. G. Campanella
Keyword(s):  
Shear Strength ◽  
Friction Angle ◽  
Companion Paper ◽  
Deformation Characteristics ◽  
Cone Penetration ◽  
Cone Penetration Tests ◽  
Cone Penetration Testing ◽  
Personal Experiences ◽  
Penetration Tests

This paper is the second of two parts and presents a summarized work guide for practicing engineers for interpretation of parameters for undrained conditions during the cone penetration test such as, undrained shear strength, overconsolidation ratio, and deformation characteristics of clay. The advantages, use, and interpretation of the piezometer cone are also discussed. Factors that influence the interpretations are discussed and guidelines provided. The companion paper, Part I: Sand, considers drained conditions during the test and summarizes interpretation of parameters such as relative density, friction angle, and deformation characteristics of sand. The authors' personal experiences and current recommendations are included. Keywords: static cone penetration testing, in-situ, interpretation, shear strength, modulus, stress history, pore pressures, permeability, consolidation.

scholarly journals The use of Geoeletric Methods for Post-foundation Assessments of Distressed Buildings in Ebute-meta, Mainland Local Government Area of Lagos State

2021 ◽  
pp. 104-119
Author(s):  
O. J. Airen
Keyword(s):  
Soft Clay ◽  
Maximum Depth ◽  
Silty Sand ◽  
Silty Clay ◽  
Clayey Sand ◽  
Near Surface ◽  
Cone Resistance ◽  
Sandy Clay ◽  
Geotechnical Investigations ◽  
Support Engineering

Geophysical and geotechnical investigations were combined to investigate the immediate causes of the distresses and foundation failures of buildings in Ebute-Meta area of Lagos, south-west Nigeria. Six (6) traverses were mapped in the study area across which six (6) 2D Wenner ERI, and fourteen (14) VES geophysical data were acquired. One (1) boring and five (5) CPT geotechnical data were also acquired. 2D ERI results reveal that resistivity values vary from 4.62 – 293 Ωm across the study area. Three resistivity structures were identified which denoted peat/clay, sandy clay, clayey sand and sand. The resistivity of the peat/clay varies from 4.62 – 27.9 Ωm with thickness varying from 12 - 25 m. The sandy clay varies in resistivity and thickness values from 26 – 86 Ωm and 8 – 29 m respectively. The clayey sand from 84.4 – 182 Ωm and 10 -15 m, and sand, having resistivity and thickness values of 293 Ωm and 3 – 5 m. The VES reveals similar results to the 2D ERI, delineating six geoelectric layers which are the topsoil, peat, clay, sandy clay, clayey sand and sand at maximum depth of 35.8 m. The borehole (BH) reveals a maximum boring depth of 45 m with eight zones comprising dark grey sandy clay, firm to stiff silty clay, soft, dark organic silty peaty clay, grey silty sand, dark grey silty sandy clay, dark grey organic peaty clay, grey silty sandy clay and medium dense to dense grey sand with occasional gravels. The CPT, which penetrated a maximum depth 15.8 m reveal that the cone resistance values vary progressively from 0 – 162 kg/cm2indicating very soft clay to soft clay near-surface and medium dense to dense geologic material at deeper depth. The peat/clay delineated by the 2D ERI and VES at 5 – 25 m depth with resistivity value varying from 4.62 -17 Ωm in the study area, and also revealed in the BH at 5.75 – 27.75 m depth as soft, dark organic silty peaty clay, having cone resistance values varying from 0 – 20 kg/cm2 is laterally extensive and incompetent to support engineering foundation.

Static Electric Cone Penetration Testing in Shallow Water

1986 ◽  
Vol 2 (1) ◽  
pp. 113-118
Author(s):  
C. H. Adam
Keyword(s):  
Water Depth ◽  
Cost Savings ◽  
Soil Conditions ◽  
Shallow Waters ◽  
Cone Penetration ◽  
Inland Waterways ◽  
Fine Grained ◽  
Cone Penetration Tests ◽  
Cone Penetration Testing ◽  
Recent Developments

AbstractThis paper describes the methods available to perform static electric cone penetration tests (CPT's) in shallow waters. It refers to both the coastal environment and inland waterways up to a water depth of around 25 to 30 m.Whilst the benefits of the speed of CPT's over water are reduced, compared with testing on land, the technique is still much quicker than conventional boring and sampling methods and offers significant cost savings. One of the other main advantages is the quality and accuracy of the information obtained particularly in submerged fine grained granular soils.There are a number of techniques which can be used to perform CPT's in shallow waters. These include detached CPT rigs mounted on small jack-up barges, fixed platforms and floating barges and seabed ballast block systems. The most suitable technique depends on a number of factors including water depth, site exposure, tidal conditions and seabed soil conditions.The cone design, testing methods and interpretation of CPT data are discussed briefly. Particular reference is made to recent developments in the use of the piezocone and other sensors.

Back analysis of the Nerlerk berm liquefaction slides

1985 ◽  
Vol 22 (4) ◽  
pp. 579-588 ◽  
Author(s):  
J. A. Sladen ◽  
R. D. D'Hollander ◽  
J. Krahn ◽  
D. E. Mitchell
Keyword(s):  
Back Analysis ◽  
Strength Loss ◽  
Hydrocarbon Exploration ◽  
Cone Penetration ◽  
Hydraulic Fill ◽  
Cone Penetration Tests ◽  
Cone Penetration Testing ◽  
Form Part ◽  
Slide Material ◽  
Penetration Tests

Five liquefaction slides occurred in 1983 during the construction of a hydraulically placed subsea sand berm designed to form part of a bottom-founded, offshore, hydrocarbon exploration platform at Nerlerk in the Canadian Beaufort Sea. These slides were triggered by simple static loading arising from the sand placement itself. Failures started at locally oversteepened side slopes and retrogressed to form bowl-shaped crests. The slide material came to rest beyond the berm at very flat slopes. Stability back analyses reveal that effective stress strength parameters consistent with limiting equilibrium are within the range of the collapse surface parameters determined from triaxial laboratory tests. This finding lends credibility to the collapse surface concepts introduced in another study. Back calculations show that the berm state prior to failure was much looser than the steady state, with the potential for a large strength loss. According to back calculations, the berm density was lower than that inferred from cone penetration tests. Key words: liquefaction, sand, hydraulic fill, slope stability, cone penetration testing.

Guidance on Pressuremeter, Flat Dilatometer and Cone Penetration Testing

1986 ◽  
Vol 2 (1) ◽  
pp. 223-233 ◽  
Author(s):  
P. S. Finn ◽  
R. M. Nisbet ◽  
P. G. Hawkins
Keyword(s):  
Cone Penetrometer ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Cone Penetration Tests ◽  
Cone Penetration Testing ◽  
The United Kingdom ◽  
Different Types ◽  
Cone Penetrometer Testing ◽  
Penetration Tests

AbstractBS 5930 provides little guidance on the specification, practice and interpretation of pressuremeter, flat dilatometer and cone penetration tests. This paper describes certain key elements in the successful use of such tests which are frequently overlooked in practice. The different types of pressuremeter available in the United Kingdom are reviewed and the importance of care in the installation of pressuremeters of all types is highlighted. The principles of operation of the flat dilatometer are presented and comments made on the interpretation and application of results. Cone penetrometer testing and the types of equipment available are also discussed. The necessity for frequent and thorough calibration of all testing devices is emphasised and requirements for data presentation and reporting of these in situ tests are indicated.

scholarly journals Integrated Analysis of Geophysical Data for Road Networks Sub Base Lithology Integrity Assessment Case Study in Crystalline Basement Complex, Southwestern Nigeria

2020 ◽  
pp. 15-28
Author(s):  
I. A. Adeyemo ◽  
A. A. Akinlalu ◽  
K. A. Mogaji ◽  
O. O. Odumosu
Keyword(s):  
Vertical Electrical Sounding ◽  
Magnetic Data ◽  
Integrated Analysis ◽  
Magnetic Survey ◽  
Fracture Zones ◽  
Near Surface ◽  
Fractured Bedrock ◽  
Integrity Assessment ◽  
The Road ◽  
Electrical Sounding

Magnetics and Electrical resistivity methods were used in the evaluation of the subsurface integrity of a 2500 m segment of Ipinsa road off the Ilesha-Akure expressway adjacent to the Federal University of Technology, Akure, Ondo State, Nigeria in order to provide guidelines for the authority whenever the road is to be constructed. The road was investigated using geophysical prospecting methods involving Magnetics profiling and Vertical Electrical Sounding (VES) technique. The magnetic data were analysed first by taking care of diurnal variation and the results were presented as relative magnetic. The VES results were presented as geoelectric sections. The results from the two methods were stacked for easy correlation. The results from the Magnetics method study shows the presence of near-surface linear geologic structures and of varying length, depth, and altitude at different distances (350, 550, 650, 840, 870, 900, 1080 and 1160 m) and depths (5, 12, 13, 15, 15.5, 16, 17 and 19 m) respectively, which suggest the probable fracture zones that are inimical to the foundation of the road subgrade. The vertical electrical sounding survey were conducted at points of anomaly and non-anomalous zones based on the magnetic survey results. This is done to further delineate the fracture zones and correlate the results to get enough information of the subsurface. The corresponding geoelectric results delineated weathered/fractured bedrock with resistivity range of 222 - 412 Ωm at distances 650, 800 - 900 and 1080 - 1160 m along Traverses A and B. Likewise at distances 1380 - 1600 m, 2040 m, 2240 m, 2260 m and 2540 m along traverses’ C and D. The integrity assessment of the Ipinsa road network sub base lithology was successfully assessed using the geophysical modeled results and possible fractured bedrock and saturated/clayey sub soil material zones that are inimical to road stability were delineated. The research findings are valuable for precise decision in road infrastructural design.

scholarly journals 2-D Electrical Resistivity Imaging Survey for Lithological Assessment at Igwete Primary School, Amai, South-South Nigeria

2021 ◽  
Vol 25 (5) ◽  
pp. 823-827
Author(s):  
V.C. Enebeli ◽  
C.N. Okorafor ◽  
R.E. Kolagbodi
Keyword(s):  
Electrical Resistivity ◽  
Primary School ◽  
Electrode Array ◽  
Lateral Position ◽  
Electrical Resistivity Imaging ◽  
Clayey Sand ◽  
Near Surface ◽  
Resistivity Imaging ◽  
Lateral Extent ◽  
2D Resistivity

Electrical Resistivity Imaging (ERI) is a useful near-surface imaging technique, which mainly include data acquisition, numerical modelling and tomographic inversion. Within the study area, only one – dimensional (1-D) Electrical Resistivity survey has been carried out for Geophysical investigations. Therefore, 2-D ERI survey was carried out at the Igwete Primary School, Amai to provide electrical picture of the subsurface from which discrete bodies and lithology are better revealed vertically and in lateral extent. The 2-D ERT survey data were acquired using the Petrozenith Earth Resistivity meter while employing the Wenner electrode array. The 2-D apparent resistivity data were inverted to obtain true resistivities of the subsurface using res2dinv software running on personal computer. The subsurface resistivity models were displayed as pseudo sections and inverted resistivity section in the form of colour shaded contour maps. The inverse resistivity model images indicate that at a lateral extent in the range (15.00-21.00) m and (33.00-39.00) m, anomalies suspected to be gravel mixed with sand is in place with resistivities of about (254.00-948.00) Ωm. From the geologic section we can infer that a geological formation is observed at a lateral position of (27.00-32.00) m of resistivity in the range (90.00-93.00) Ωm. This structure is inferred to be a clay pocket. The sandy nature of the formation requires that underground water development be sought for at (9.00-15.00) m over a depth (2.30-8.00) m in the sandy environment. Results of 2D resistivity imaging has helped to delineate the lithology which comprise mainly of; sand, sandy clay, clayey sand depositional environment. The resistivity of these lithology falls in the range (90.00-93.00) Ωm with depth to formation of about (2.30-6.00) m.

scholarly journals Engineering Geophysical Investigation of Road Failure in a Basement Complex Terrain, Southwestern Nigeria

2021 ◽  
pp. 40-51
Author(s):  
Ismaila Abiodun Akinlabi ◽  
Christianah Oluwakemi Adegboyega
Keyword(s):  
California Bearing Ratio ◽  
Electrode Spacing ◽  
Dry Density ◽  
High Plasticity ◽  
Southwestern Nigeria ◽  
The Road ◽  
Road Pavement ◽  
Sandy Clay ◽  
2D Resistivity ◽  
Poor Drainage

Geoelectrical and geotechnical investigations were conducted to determine factors responsible for pavement failure in some segments of Adebayo Alao-Akala road in Ibadan, southwestern Nigeria. The geoelectrical investigation employed Schlumberger vertical electrical sounding conducted at fifteen stations occupied along two failed segments and one stable segment of the road, using station spacing of 25 m and maximum electrode spread of 100 m. 2D electrical resistivity survey was also conducted using the dipole-dipole electrode array with electrode spacing, a, of 1 m and expansion factor, n varied from 1 to 5 m. The VES data were interpreted quantitatively by partial curve matching and computer iteration technique and geoelectric sections were generated while 2D resistivity structures of the subsurface were produced from the inverted 2D resistivity data. The geotechnical investigation involved Grain size distribution, Atterberg limits, Compaction and California Bearing Ratio tests conducted on subsoils collected beneath the segment. The failed segments are underlain by low-resistivity clayey subgrade of resistivity mostly less than 100Ωm while the stable segment overlies sandy clay/clayey sand mixture of relatively higher resistivity, ranging from 200Ωm to 530Ωm. The subsoils of the failed segments comprise high-plasticity sandy clay and sandy gravelly clay while those of the stable segment are medium plasticity sandy clayey gravel. The values of maximum dry density are 1.46 Mg/m3-1.73 Mg/m3, 1.71 Mg/m3-1.86 Mg/m3 and 1.75 Mg/m3-1.82 Mg/m3 respectively, with corresponding optimum moisture content of 7%-8%, 11%-20% and 10%-17% and California bearing ratio under soaked condition for 48 hours of 7%-8%, 17%-20% and 11%-17% respectively. The failure of the road pavement is attributable to the clayey nature of the subgrade, and poor drainage. The stable segment is underlain by excellent-to-good subgrade materials. Ingress of surface water into the clayey subgrade occasioned by poor drainage of run-off resulted in deformation of the road pavement in response to vehicular load.

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