| 1 |
Author(s):
Charles Kennedy, Mohammed Ganiyu Oluwaseun.
Page No : 1-25
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Probabilistic and Deterministic Assessment of Seismic Soil Liquefaction Potential in The Niger Delta Region of Nigeria Using Standard Penetration Test-Based
Abstract
This study aimed to evaluate the liquefaction potential of soils in Nembe Town, Bayelsa State located in the Niger Delta region of Nigeria through probabilistic and deterministic analyses using Standard Penetration Test (SPT) data. The objectives were to characterize the subsurface stratigraphy and soil properties through field and laboratory investigations, develop predictive models for soil parameters using a regional database, and apply simplified procedures to assess liquefaction risk. Ten borehole locations were selected across the town where SPT, undisturbed and disturbed sampling was conducted to a depth of 30m. Index tests classified the soils and determined density, plasticity and composition trends with depth. Shear wave velocity measurements aided subsurface profiling. Empirical predictive models through regression correlated key properties with stress factors demonstrating accuracy in characterizing limited site data. Simplified procedures using corrected SPT-N values classified the upper 30m as NEHRP Site Class D and evaluated the factor of safety against liquefaction. The extensive investigation program provided a robust framework for deterministic and probabilistic seismic hazard assessments through subsurface profiling and model validation. Results reliably characterized the deposit stratigraphy, compositions and properties to evaluate liquefaction potential in the Niger Delta region.
| 2 |
Author(s):
Mohammed Ganiyu Oluwaseun1, Charles Kennedy.
Page No : 26-42
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Comparative Evaluation of Stabilized Soil Properties Incorporating Bagasse Ash with Cement Vs Lime on Determination of Best Additive Combinations
Abstract
This study investigated the use of bagasse ash from Custus arabicus L. as a pozzolanic admixture for stabilizing expansive black cotton soil alongside cement and lime. Samples of the problem soil were collected and treated with varying proportions (2.5-10% by dry weight) of bagasse ash in combination with a constant 8% content of cement or lime. The engineering properties of the treated composites such as maximum dry density, optimum moisture content, consistency limits, California bearing ratio and unconfined compressive strength were evaluated based on standard procedures. The results showed that both the cement-bagasse ash and lime-bagasse ash composites were effective in modifying the expansive behavior and improving the strength of the black cotton soil. Key indicators like liquid limit, plastic limit and plasticity index decreased with rising bagasse ash content, indicating a reduction in soil shrink-swell potential. Meanwhile, properties enhancing load-bearing capacity such as maximum dry density, optimum moisture content, CBR and UCS values increased upon treatment. Among the mixtures, soil stabilized with 8% cement and 7.5% bagasse ash composite exhibited the optimal performance. Compared to untreated soil, maximum improvements of 66.4% and 102.6% were recorded in the CBR and UCS values respectively for the optimal cement-bagasse ash blend. Overall, both lime and cement-based composites incorporating bagasse ash from Custus arabicus L. showed potential for modifying expansive subgrades and increasing their structural capacity. The study established the viability of utilizing agro-industrial waste alongside conventional stabilizers for ground improvement works.
| 3 |
Author(s):
Mohammed Ganiyu Oluwaseun, Charles Kennedy.
Page No : 43-56
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Modelling of Cyclic Shear Modulus and Factor of Safety in Clay Soil
Abstract
The liquefaction potential of Niger Delta soil was studied through formulated models based on cyclic shear modulus and factor of safety (FS). Data from the experiment were fitted into models to predict the cyclic shear modulus and Factor of Safety. The test analysis shows effective prediction of cyclic shear modulus for a given number of cycles (1–40) and cyclic shear strain (0.01–5 %). Comparison of results shows no significant differences between the measured and predicted cyclic shear modulus, especially from 0.1% shear strain and above. Similarly, the values of factor of safety predicted by the model were very close to those obtained from the experiment; the predicted FS obtained at depths close to 30 m across the sites were slightly greater than 1.0, as against the observed results. Despite this slight variation, the FS model still shows a high degree of prediction. Therefore, the formulated models can be utilised in the study of liquefaction potential, especially in the Niger Delta region.
| 4 |
Author(s):
Charles Kennedy, Ikebude Chiedozie Francis , Barango Daye Owuna.
Page No : 57-75
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Spatial Trends and Distribution Patterns of Toxic Heavy Metal Contamination in an Urbanized Watershed
Abstract
Rapid urban growth in developing nations exacerbates pressures on water resources through increased pollution loading if management practices cannot adapt efficiently. This study evaluated industrial effluent impacts on river systems in Nigeria contaminated by discharge from beverage, oil and biscuit manufacturing plants. Physicochemical parameters and heavy metal concentrations were monitored at sites upstream and downstream from waste outfalls during wet and dry seasons. Results demonstrated exceedances of national water quality standards for indicators of organic pollution like biochemical oxygen demand and chemical oxygen demand. Notably, highly toxic heavy metals exceeded World Health Organization limits by over 100 times, posing serious public health concerns through various exposure pathways. Seasonal variations reflected changes in pollution inputs. Spatial trends showed metal levels decreasing with distance, though remaining well above safe levels 100m downstream. A predictive transport model was formulated based on field measurements incorporated into the advection-dispersion equation. Key coefficients for the dispersion rate and velocity/dispersion ratio were quantified, allowing simulation of concentration changes under differing scenarios. Model predictions closely aligned with observed metal distribution patterns. Findings highlight the need for upgraded wastewater treatment and emissions controls to mitigate pollution over-burdening natural assimilative capacity. Continuous monitoring programs should track remediation effectiveness. This study provides insights to help authorities balance rapid industrialization, environmental protection and sustainable development goals through evidence-based regulatory strategies ensuring public health.
| 5 |
Author(s):
Charles Kennedy, Barango Daye Owuna, Ikebude Chiedozie Francis.
Page No : 76-97
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Physicochemical and Heavy Metal Analysis of Industrial Pollution Model Calibration and Validation Using Field Measurements
Abstract
This study assessed industrial pollution impacts on rivers near Port Harcourt, Nigeria using physicochemical analysis, heavy metal data, and contaminant transport modeling. Key findings show the rivers are severely degraded with extreme levels of heavy metals, low dissolved oxygen, high conductivity, nutrients, and fecal bacteria exceeding water quality guidelines. Uncontrolled effluent discharges from industries are primarily responsible. A first-order advection-diffusion model reliably predicted the rapid initial dilution and slower downstream attenuation of metals like magnesium and cadmium. The model was successfully calibrated and validated using field measurements to determine key transport parameters including dispersion coefficients. The severe contamination indicates current effluent treatment and regulations are inadequate and require urgent strengthening to control sources, expand monitoring, remediate contamination, restore habitats, and protect ecosystem and public health. Sustained engagement of government, industry, communities and researchers is essential to devise integrated solutions that improve water quality. The modeling provides quantitative guidance on pollution impacts and mitigation needs. Further work should refine predictions, establish ecological thresholds, and validate model results with biomonitoring to support evidence-based, adaptive management.
