Effect of a shear key on the behaviour and stability of cantilever type retaining walls

Retaining walls are categorized into several types, out of which cantilever retaining walls are the commonly used retaining wall type. Shear keys are the structures incorporated in the cantilever retaining walls to increase their resistance to sliding. The current study investigates the optimal location and depth of the shear key. A theoretical approach based on limit equilibrium and numerical modelling were adopted in the analysis. Limit equilibrium analysis was carried out using the Excel spreadsheet application. The values of Factor of Safety against sliding and overturning, varying with the shear key’s depth and location, are presented as graphical representations. Finite Element Analysis was carried out using PLAXIS 2D software to analyze the variation of the overall stability with the increasing depth of the shear key. The limit equilibrium analysis observed that utilizing a shear key enhances the stability of the retaining wall against sliding. It was also found that the increase in the depth of the shear key reduces the stability of the retaining wall against overturning, and the optimum location of the shear key is at the heel of the wall base. Results from the Finite Element Analysis showed that the retaining wall’s overall stability increases with the increase in the depth of the shear key.