Earth Pressures Under Rotational Movement Mode for Red Soil Backfill Partially Replaced with Building Derived Materials

Abstract

The variation of earth pressures plays a crucial role in the construction of retaining walls. The present study proposes a sustainable and eco-friendly usage of building derived materials (BDM) mixed with red soil as a backfill for these retaining walls. An attempt is made to examine the variation of magnitude of at-rest earth pressure, with reference to various possible wall movements, necessary to mobilize passive earth pressures on the wall. Small-scale laboratory model tests are conducted on a cantilever rigid retaining wall with different red soil–BDM blends as backfill. The BDM content is varied from 0 to 30% by weight of red soil. The retaining wall is rotated about its base with the help of a hydraulic jack. The earth pressures are measured with earth pressure cells fixed at different heights of the wall. The width of the backfill is varied at 0.35L, 0.5L, and 0.65L to assess its effect on the variation of earth pressures, L being the base length of the retaining wall. The experimental results indicate that the earth pressures are not increased significantly by the inclusion of BDM to red soil, which suggests that BDM can be used as an effective lightweight backfill. The optimum pressure is obtained on mixing 20% BDM with red soil. It is observed that since the wall is made to rotate about its base, the earth pressure is greater near the top of the wall and decreased nonlinearly with depth, in contrast to classical earth pressure theories. The results of the tests also demonstrate that the failure surfaces are limited by the width of the backfill.