NUMERICAL ANALYSIS OF ISOLATED FOOTING RESTING ON REPLACEMENT LAYER OVERLYING EXPANSIVE SOIL

This paper examines the effectiveness of using replacement soil layers, such as sandy soils with different densities values, in mitigating heave and settlement in foundations constructed on expansive clay soils. Expansive soils are prone to substantial volumetric changes due to moisture fluctuations, often compromising structural stability. The study uses a 3D finite element model (PLAXIS 3D) to simulate the behavior of isolated footings resting on various replacement layers stiffness overlying Regina clay, a highly expansive soil. Parametric analyses were conducted to evaluate the impact of replacement layer thickness and stiffness (Young’s modulus) on soil heave and settlement under different applied pressures and volumetric strains. The results demonstrate that increasing both the thickness and stiffness of the replacement layer significantly reduces heave and settlement, particularly under higher applied pressures and swelling potentials. Stiffer replacement materials consistently outperformed less stiff alternatives, minimizing both heave and post-heave settlement. The numerical outcomes were validated against established analytical and numerical models, demonstrating excellent agreement and confirming the model’s reliability. The findings highlight the importance of selecting appropriate replacement materials and layer thicknesses to enhance foundation performance on expansive soils. For severe swelling conditions, supplementary mitigation measures may be necessary. The study provides practical insights for geotechnical engineers in designing foundations on problematic soils, emphasizing the role of replacement layer properties in controlling soil expansion and improving structural stability.