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Abstract Foundations constructed on swelling clays are subjected to vertical and lateral pressures which act on them and results in uplifting forces pushing them upwards. These pressures are generated due to the increase of the clay volume as it absorbs water. The main aim of this thesis is to investigate the behaviour of experimental models of square and rectangular footings with different dimensions resting on expansive soil under constant stress condition. Expansive soil was collected from El-Kattamia. Geotechnical properties of this soil were determined. Effect of initial soil density on swelling characteristics, using Oedometer and Geonor apparatus, was studied. Two groups of tests have been performed under two different values of stresses to examine their behaviour during unsaturated upward water flow for a period of up to 4 months for each test. The extensive data obtained from each model confirmed the applicability of fitting heave-time curves using the nonlinear hyperbolic function. Treatment of expansive soils with sand as a cushion beneath footings is one among the methods suggested for tackling problems associated with swelling clays. Therefore, the behaviour of the experimental models, used in this thesis, as well as the underlying expansive soil is also examined in a third group of model tests. |