Transition of earth pressure on rigid retaining walls subjected to surcharge loading

Abstract

Retaining walls are an integral part of various infrastructural projects and are used to support deep excavations, or steep embankments, and deep basements. The earth pressure on these walls plays a crucial role in deciding the cross-sectional dimensions of the wall. An attempt was made in this research study to examine the variation of both the magnitude and distribution of earth pressure at-rest, and with reference to various possible wall movements, necessary to mobilize the active and passive earth pressures on the wall. Experimental studies were carried out on small-scale retaining walls supporting a cohesionless backfill material, and subjected to surcharge loading. Wall movement was modeled in the laboratory by allowing the wall to rotate about its base to simulate the case of rigid cantilever retaining walls. It was found that under surcharge loading, the earth pressure on the wall was gradually decreased as the wall moved away from the backfill but increased as the wall moved towards the backfill. It was also observed that the earth pressure due to surcharge load was greater near the top of the wall and decreased nonlinearly with depth down the wall. The lowest earth pressure occurred at the bottom of the wall, in contrast to the usual assumption that the earth pressure due to surcharge loading is uniform throughout the retaining wall. Finally, it was demonstrated that the distance between the surcharge load and the edge of the wall had a significant effect on the measured earth pressure values.