Engineering Geology – Journal of Engineering Geology and Environmental Research (JEGER)

Author: Fidelis A. Abija Abstract The coastal zone is a dynamic environment under hydrodynamic forcings and adverse consequences of geohazards with potential for disasters. In this this studies, ASTER DEMs and LandSat 4,5 imageries have been analyzed in ArcGIS to determine the amount and rates of coastal subsidence, shoreline movements and coastal erosion and supplemented with secondary tide and wave data to model wave conditions in the face of climate change. Results indicates that the average ground subsidence was -2.6m at a rate of – 0.144m/yr. on the Bayelsa coast and -3.75m at a rate of -0.208m/yr on the Rivers coast. The rate of coastal erosion along the Akwa Ibom, Rivers and Bayelsa States in the Niger Delta coastline depicts a linear erosion of -13,054m, -17,519m and -81,532m in Akwa Ibom, Rivers andBayelsa respectively with erosion rates of -5.5m/yr along Akwa Ibom, -7.2m/yr along Rivers and -11.1m/yr along the Bayelsa coastline. The net shoreline retreat equivalent of incidental erosion was -8,590m along the Akwa coastline, – 9,240m along Rivers coastline and -70,383m along the Bayelsa coastline. Modeled hydrodynamics parameters predicted waves with mean wavelength of 178.95m, wave celerity of 13.01m/sec, group wave celerity of 11.27m/sec with maximum horizontal velocity of 0.4m/sec exerting an energy flux of 15, 902.00w/m. In considerations the stack realities of climate change, vulnerability assessment, integrated coastal zone management and climate change adaptation strategies for coastal protection are recommended.

Engineering Geology, Hydrogeology

Groundwater Contamination due to the Activities of Auto – Mechanics in Lagos Metropolis, South-western Nigeria

Engineering Geology, Hydrogeology / webmanager

Authors: Umbugadu, A.A. and Akinwumi, T.V. Abstract The release of wastes generated from the activities at automobile workshops leads to heavy metals contamination of groundwater which can be harmful to human health. The study is aimed at investigating the physicochemical andheavy metal contamination of groundwater from three automobile workshops at Super, Jankara and Kola areas located at Alimosho, Ifako – Ijaye and Agege Local Government areas of Lagos State. Fifteen (15) samples were collected from residential houses near the automobile workshops, at 5m – 75m depth and taken to Federal Institute of Industrial Research (FIIRO) laboratory at Oshodi, Lagos. Electrical conductivity (EC), pH, temperature and total dissolved solids (TDS) were measured onsite using a 107 model pH meter. The samples were analysed for lead, magnesium, manganese, cadmium, arsenic, chromium and mercury using Atomic Absorption Spectroscopy; Perkin Elmer model Analyst 3000.The TDS value of all the samples in this research ranged from 0.017 mg/l – 0.097mg/l which is within the W.H.O. standards of 500mg/l. The pH value of all the analysed groundwater samples ranged from 4.4 – 7. This implied that groundwater in the study area are slightly acidic to neutral. The groundwater samples from JW03 are below the acceptable pH limit of W.H.O while the groundwater from the remaining 14 sampling points have pH values less than 6.5, hence, they are slightly acidic. Only two sampling points in Jankara; JW06 and JW07, falls within the W.H.O acceptable limit while the remaining samples have values lower than 6.5. The electricalconductivity in the water analysed ranged from 0.72 μS/cm – 194 μS/cm. The electrical conductivity value of all the water samples analysed are below the W.H.O standard of 1000μS/cm. This result reflects a low input of solute in the groundwater. The temperature values of the groundwater samples of the three areas of the research ranged from 26.8 ºC – 37.8ºC with a median value of 30.2ºC. The values exceeded that of W.H.O limit of 25ºC. The concentration of heavy metal in groundwater of the three mechanic workshops are in this trend; Pb>Mn>Cd>Cr. Arsenic was not detected in all the groundwater samples from the three mechanic workshops. The metal Pb have a range of 0.382 mg/l – 1.895mg/l and an average of 1.070mg/l, Mn ranged from 0.067 mg/l – 2.0933mg/l with an average of 0.7468mg/l, Cd ranged from 0.146 mg/l – 0.5937mg/l with an average of 0.36mg/l while Cr ranged from 0.036 mg/l -0.098mg/l with an average of 0.060mg/l.

Engineering Geology

Exploring Subsoil Geotechnical Properties for Foundation Design of a Proposed Modern Market in Port Harcourt, Rivers State, Southern Nigeria

Engineering Geology / webmanager

Authors: Morrison, T. and Esonanjor, E.E. Abstract A geotechnical soil investigation was performed to determine the subsoil conditions at the proposed site to provide parameters for the design of foundation for a proposed modern market in Port Harcourt. Both field study and laboratory analysis of samples were done. Field works included five (5) number boreholes drilled to 20.3m by the use of Shell and Auger manually operated rig, six (6) number 10Tm CPT tests conducted to refused depth ranging from 12.00 to 21.00m and SPT-N values determinations. Disturbed and undisturbed soil samples were collected foranalysis. The disturbed samples were analyzed according to BS standard for index properties such as grain size analysis, Atterberg limits, moisture content, and bulk density, while relatively undisturbed samples were analyzed for strength properties and parameters. From the results, the subsoil in the area consists of a thick layer of lateritic clayey/sandy clay with a plasticity index of 40%, coefficient of volume compressibility (mv) 0.278m2/KN and cohesion 40KN/m2 at the top followed by a larger of 9.75m thick medium dense five to coarse sand with frictional angle 28 to 3500. Safe bearing capacities were computed for pad footings and raft foundation in the range of 122 to 173kPa and 122 to 151kPa respectively at various foundation width and LB rations. Groundwater was encountered between 5.64m and 6.10m below ground level.

Engineering Geology

Uncertainties in Subsurface Characterisation For Building Construction: Case Studies of Two Site Investigations in Lagos Metropolis

Engineering Geology / webmanager

Authors: Olagunju, K.T., Olobaniyi, S.B., Oyedele, K.F. and Adefuwa, A. Abstract Geotechnical frameworks and calculations rely on adequate characterisation of the subsurface soil units. Boring tests and their distribution provide, not only geotechnical parameters but also to reveal geotechnical units and lateral extent, which are particularly important for safe and cost-effective foundation design. This study presents two cases of geotechnical site investigation involving boring tests in two areas of Lagos metropolises that raised concerns about uncertainties in subsurface characterisation caused by the inadequacy of field techniques employed. This study revealed the limitation of geotechnical designs at A and B, largely due to the uncertainty of subsurface characterisation induced by inadequate quality and quantities of field tests. Using data from geotechnical boring(percussion drilling) and resistivity survey (2D tomography and VES), the occurrence of unusual ironstone was established between 9 to 15m depth at Site A, which prevented further drilling with a percussion rig. However, this ironstone occurrence is non-lateral as the resistivity obtained in 2D profiles ranges from 15 Ωm – 74 Ωm from the surface to 35 m, suggestive of Clay and Sand. Thereby complicating geotechnical design. Notably, one boring is grossly inadequate for characterising the complexity of the geology at Site A. Similarly, a forensic investigation atSite B indicates the inadequacy of one boring test since the correlation of results from three new borings revealed a complex geology which was missed using only one. Installed piles on this site were mostly seated on Organic Clay between 15 and 30m depth. Evidence presented in these case studies underscores the importance of comprehensive subsurface characterisation to enhance design decisions for geotechnical recommendations.

Engineering Geology

3D Engineering Geological Models of subsurface soil profiles using Artificial Intelligence (AI) in parts of Port Harcourt Metropolis, Rivers State, Nigeria

Engineering Geology / webmanager

Authors: Hector, D.D., Udom, G.J., Giadom, F.D. and Tse, A.C. Abstract The integration of artificial intelligence (AI) techniques with Geoscientific data has revolutionized the creation of 3D Engineering Geological Models for subsurface soil profiles. ChatGPT-4 is a large multimodal model AI tool, it accepts both text and image inputs, that allows its users to specify the type of language task, by combining natural language understanding with visual information GPT-4 generates accurate and nuanced 3D models, aiding in proper foundation design, groundwater flow modeling, and environmental management. Its reliability, creativity and abilityto handle complex design makes it a valuable tool for geotechnical applications. In this paper, ChatGPT-4 was used to create 3D Engineering Geological Models of subsurface soil profiles in parts of Port Harcourt Metropolis. Data, including coordinates and static water levels from five geotechnical boreholes drilled to depth of 30 meters were used as input parameters. The elevation of the area ranged from 10 m to 7 m above sea level. The soil profile consists of 3 meters thick medium grained sand succeeded by 10 meters thick clay of low plasticity which in turn, is underlain by 17 meters of thick poorly graded sand (SP). A 3D soil profile of the study area was created showing the elevations, topography and weak stratigraphic layers. This model enables engineers and researchers to optimize infrastructuraldesign, reduce costs and mitigate risk.

Engineering Geology, Environmental

Analysis of Soil and Environmental Conditions for Resilient Pavements in the Niger Delta

Engineering Geology, Environmental / webmanager

Authors: Abam, T.K.S., Giadom, F.D. and Abija, F.A. Abstract The short service life of pavements in the Niger Delta has resulted in high recurrent maintenance cost of roads. Pavement failures have been attributed to widespread weak, expansive clays and silty soils, which lead to high water table issues and poor drainage without an understanding of the mechanisms involved and an appreciation of theadequacy of the codes used in their design. This paper explores the concepts of pavement design, assessing the necessity and functions of individual layers as well as the geological materials they are made of. The paper then identifies the weaknesses in the pavement design culture practiced in Nigeria to include poorly prepared subgrades, use of unsuitable aggregates, insensitivity to the environmental conditions among others. It further investigates the relationship between the distribution of axial load and the thicknesses of pavement layers to identify vulnerabilities particularly in the Niger Delta that can promote pavement failure. It examines the influence of moisture on the attainment of adequate compaction as well as on the resilience of pavements. The paper argues that the extensive weak subgrades and rapid variability of superficial geology such as exist in the Niger Delta demands a review of the national design code to accommodate the peculiarities of the region. To ensure resilient pavements, understandingsoil and environmental conditions is paramount. This involves integrating soil-structure interaction principles, ground improvement and stabilization techniques, as well as risk assessment methodologies to enhance structural integrity and sustainability of pavements.

Engineering Geology

Potential of Mid-Infrared Spectroscopy as ComplementaryTechnique for Assessment of Soil Engineering Properties

Engineering Geology / webmanager

Authors: Fakeye, A.M., Ige, O.O. and Oluwafemi, O. Abstract Mid-infrared (MIR) spectroscopy has emerged as a rapid and cost effective complementary to conventional laboratory methods utilized for assessing soil properties. The study intends to evaluate the potential of MIR spectroscopy for non-destructive estimation of some engineering soil properties along Ilorin – Kabba expressway. Fifty georeferenced soil samples from different Basement Complex rock of Southwestern Nigeria were subjected to Fourier-Transform-Infrared-Spectrometric (FTIR) analysis within the spectral region ranging from 4000 – 400 cm-1 of electromagnetic radiation. Four preprocessed filtering methods such as moving average, normalization, multiplicative scatter correction, Savitzky-Golay (SG) first derivative algorithm were applied in the pre-treatment of spectral information. Partial Least Squares Regression (PLSR) was employed to develop calibration models for soil properties, with model performance assessed using the coefficient of determination (R2), root mean square error (RMSE) and ratio of performance to deviation (RPD). The results showed that MIR spectroscopy effectivelyestimated the properties including sand and clay content, liquid limit, plasticity index, optimum moisture content, maximum dry density, and soaked California Bearing Ratio, achieving an average R2 of 0.6, RMSE of 1.32, and RPD of 2.1. This study demonstrates the capability of MIR spectroscopy as a rapid and efficient tool for simultaneous estimation of multiple soil properties relevant for engineering purposes. Further research is recommended using diverse non-parametric data mining techniques to enhance soil predictive accuracy.

Engineering Geology, Environmental

Experimental Study of Use of Waste Glass for SustainableStabilization of Highway Foundation Soils

Engineering Geology, Environmental / webmanager

Authors: Owoyemi, O.O., Ejikunle, O.B. and Afolagboye, L.O. Abstract Recycling waste glass for subgrade soil improvement not only contributes to the development of sustainable and resilient highways but also mitigates the environmental impact of the vast quantities of glass generated daily. This study examines the potential of using waste glass to enhance the geotechnical properties of soil intended for highway subgrade applications. Soil sample was obtained from a borrow pit in Oyun, Southwestern Nigeria, where lateritic soils are quarried for construction purposes. The mineralogical and geochemical properties of the natural soil were analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF). Pulverized waste glass underwent grain size distribution analysis, and the soil samples were mixed with waste glass in proportions of 0.5%, 1%, 1.5%, and 2% by weight. The impact of waste glass powder addition on Atterberg limits, linear shrinkage, compaction parameters, swell potential, and both soaked and unsoaked California Bearing Ratio (CBR) was investigated. The aging effect on the CBR of the stabilized samples was assessed by repeating the soaked CBR tests after 7, 14, and 21 days. Results indicated that the liquid limit, plastic limit, plasticity index, linear shrinkage, swell potential, and of the stabilized soils decreased with increasing glass content. Conversely, the maximum dry density and both soaked and unsoakedCBR values increased, while the optimum moisture content decreased with higher glass content. The stabilized soils maintained their strength even after 21 days of soaking. Waste glass, even at a 0.5% inclusion by weight, acts as an effective cementing agent, improving soil properties for highway foundations.