Numerical Modelling of Lateral Deformation of the Cantilever Retaining Wall in Expansive Clays

Abstract

Retaining walls are relatively rigid walls used for supporting the soil mass laterally. The soil properties of the retained material exert lateral pressure on the wall. Thus, the important consideration in the design of retaining wall is to counter the lateral pressure generated by the backfill. The present study focuses on theoretical study on the retaining wall parameters such as the heel width, stem height, inclined backfill, with cohesive and expansive soil backfill. The lateral earth pressure is evaluated in each of these cases using the Rankine’s lateral earth pressure theory. The numerical modelling of the cantilever retaining wall in cohesive backfill (expansive in nature) is carried out using the finite element software (PLAXIS 2D). Two soil models, Mohr–Coulomb model and the Hardening Soil model, are used for modelling the backfill. The expansive nature of the backfill is incorporated in terms of the positive volumetric strain of the backfill. To cater to the large lateral pressure induced by the expansive backfill, geofoam layer is introduced in between the backfill layer and the retaining wall and modelled using Mohr–Coulomb model. A comparative evaluation is made for the behaviour of the retaining wall in terms of the lateral deformation. The expansive soil with 12% volumetric strain caused nearly 900 mm lateral deformation, compared to 600 mm on inclusion of the 2 m thick geofoam layers. The hardening soil model used for modelling of the expansive soil depicts an reduction in deformation compared to the elasto-plastic, Mohr–Coulomb model.