EFFECT OF EXPANSIVE SOIL ON STRESSES IN STRUCTURES

Abstract

Engineers are well aware of the severe distress, that lightly loaded structures can suffer when placed on a swelling soil subjected to • environmental changes. Changes in the environment result in changes in the soil-water phase , thereby producing volume changes in the soil. The main aim of this thesis is to investigate the effect of the .: type and rigidity qf structures on the behaviour of expansive soil -':beneath it. Footing heave and interfacial normal stresses generated due •to flow of water were investigated experimentally. An expansive sandy clay soil obtained from Golf area in Nasr City east of CAIRO were used in this investigation. The structural variables considered are: a) springs with different stiffnesses, b) fixed beams with different stiffnesses (inertias) and subjected to different imposed stresses, c) square footing subjected to different imposed pressures, d) plane frames with tie beam having different inertias and e) plane frame rested on sand cushion. The experimental results are shown as a relationship in the form of heave-time for footing. The soil water content profile at the end of each test are determined. A mathematical method is proposed to predict the heave for surface footing, fixed beam and frame based on expansive soil. A mathematical method is validated using the experimental results.