Behavior of Rigid Retaining Walls with Relief Shelves: An Analytical Approach

Out of numerous available methods to reduce the lateral earth pressure on the retaining structures, a retaining wall with relief shelves, though known for more than a few decades, is one of the least practiced approaches to minimize the earth pressure on a wall due to the complex behavior of such walls as well as the lack of design recommendations or the codal provisions. Moreover, the previous studies were silent on explaining the mechanics behind the working of these walls. This study focuses on static force analysis of a wall with multiple relief shelves retaining a dry cohesionless backfill using principles of mechanics and theory of bending to develop a novel closed-form solution to handle the discontinuity at the joint of the relief shelf and wall stem for the evaluation of the distribution of shear force, bending moment, and deflection of the wall at any wall section and furnish design recommendations on the optimum width of the relief shelves. The outcomes of the present work establish the fact that the relief shelves reduce shear force, bending moment, and deflection of the wall and increase the overall stability of the structure. Furthermore, it is concluded that the bending moment at any section of the wall with relief shelves is governed by the position as well as the width of the relief shelves, though, the shear force depends only on the positioning of the relief shelves along the height of the wall. A comparison of the structural design of the walls demonstrated that the use of relief shelves to walls substantially reduces the volume of excavation, concrete, and reinforcing steel compared to the wall having no relief shelf.