Volume 1 Issue 1 (2025): In Progress

This study investigates the influence of used motor oil contamination on the geotechnical behavior of soils collected from motor-mechanic workshop areas along Kohat Road and Barra Road in Peshawar, Pakistan. Soil samples were obtained from the ground surface and from a depth of 1 m to assess site-specific and depth-dependent variations in soil behavior. Laboratory tests were conducted to evaluate particle-size distribution, Atterberg limits, moisture-related behavior, unconfined compressive strength, and direct shear strength in comparison with uncontaminated control soils. The results show that oil contamination altered the consistency characteristics of the tested soils, with noticeable changes in liquid limit, plastic limit, plasticity index, and flow behavior. These variations indicate that the influence of contamination depends on soil composition, sampling depth, and local site conditions. The mechanical test results further reveal that oil contamination reduced compressive strength and shear resistance, mainly due to the coating and lubricating effect of oil on soil particles, which weakens interparticle bonding, reduces cohesion, and disturbs the soil structure. The reduction in strength was more evident in some surface samples, although the magnitude of degradation varied between the two sites. Overall, the study demonstrates that used motor-oil contamination can significantly affect the engineering performance of soils and should be carefully considered in geotechnical investigation, foundation design, and construction planning in contaminated urban workshop areas.

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Water infiltration and recharge cause stresses, deformations, and displacements in the soil, which can lead to landslides, subsidence, erosion, etc. The objective was to propose a solution for the internal energy equation, (water flow in the soil mass) based on modern mechanics and underground hydraulics. From continuum mechanics, the internal energy equation was analyzed: i) the distribution of water flow at the surface as a source; ii) the expansion of water flow within the soil mass in cylindrical coordinates; iii) the distribution at the upper boundary, and the transient conduction of internal radial flow. Analogous near-surface and internal conduction were proposed as a load source. Stresses, deformations, displacements, and potentials were reviewed using modern mechanics, and the superposition principle was applied. The formulation was applied to a case study. It was found that Cartesian equations best represent the external surface flow of water (runoff), while cylindrical and radial equations best fit the internal flow in the soil (conduction-distribution). The proposed solution is in terms of the supplied load (precipitation). At different soil moisture contents—dry, saturated, and supersaturated—dynamic processes generate different energy rates. Externally, in supersaturated soils, the energy is purely hydraulic and is a parallel mobilization force on the surface (runoff or flooding). This solution could be applied to other multidisciplinary problems in mechanics, geomechanics, and hydrogeology, given the rigor of mathematical formulations that have described problems independently.

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