Finite element analysis of a cantilever retaining wall : deflection and lateral earth pressure

Abstract

In the design of a cantilever retaining wall, magnitude and distribution of earth pressures are often determined using classical earth pressure theories. This is under the assumption that sufficient deformations will occur to allow for full development of active earth pressure behind the wall and partial mobilisation of passive pressures in front of the wall. However, during serviceability state, actual lateral pressures might not reach its limiting values, thus making determination of lateral pressures difficult. Simulating backfilling as close as possible using staged construction, lateral pressures acting on both sides of the cantilever gravity wall is analysed with a numerical model constructed using PLAXIS. Mohr-Coulomb model is chosen as the soil’s material model after generation of considerably reasonable predictions of wall displacements during validation of the material model. With a wall designed for stability in accordance to EC7 standards, results of parametric studies revealed that for walls with a shorter heel, surcharge, weaker friction along the wall base, varied stiffness of the foundation soil, lateral pressures on the active side agrees well with the Log-Spiral theory for the top two-thirds of the wall stem. For a wall with partial roughness, predicted lateral pressures abide to the values proposed by Coulomb for top one-third of wall stem. From the global factor of safety generated using phi-c reduction, passive pressures were able to provide considerable amount of stabilization to the overall wall system.