Influence of Pressure Relief Shelves on the Stability of Retaining Walls with Cohesive Backfill

Abstract

A retaining wall is a structure, designed and constructed to resist the lateral earth pressure of soil so that the soil on both sides of it can be retained at different levels, and the examples include gravity wall, piling wall, cantilever wall, and anchored wall, etc. Numerous researches have been conducted in this field to innovate methods and to improve the strength of retaining walls on economic grounds and several theories and hypothesis have been proposed in this respect so far such as counterfort wall, buttressed wall and providing key at the base of retaining wall, etc. One of the most effective but least studied methods is to construct pressure relief shelves monolithically with the wall and extend them within the backfill materials to increase its stability. The design of retaining walls including relief shelves is quite complex as it involves several parameters such as width, location, and thickness of shelves, etc. that need to be considered for its design. Secondly, all the literature on this type of wall is associated with non-cohesive backfill. Thus, this study elaborates the influence of pressure relief shelves on the stability of retaining walls, considering all important influential parameters of relief shelves, while cohesive soil is used as a backfill material. For the purpose a parametric study by finite element analysis of this type of wall using PLAXIS 2D is executed. The study allows a discussion on the effects of the width, location, and thickness of relief shelves on the resulting lateral earth thrust, shear stresses, wall top movement, base sliding and overturning bending moment along the wall. Reduction in active earth thrust up to 16.58 and 24.34 percent, top wall movement up to 114.98 and 85.14 percent, and base sliding up to 28.57 and 31.66 percent, etc. has been obtained due to the provision of single and two shelves, respectively, with certain size and location is shown; therefore, enhancing the stability of wall. However, for high retaining walls with cohesive soil behind them and have problems with stability, the study recommends to provide relief shelf at a certain location, along with some precautions to enhance the stability.