Modelling the failure of a cantilever sheet pile wall

Abstract

Cantilever sheet pile walls are routinely used to retain medium heights of earth in geotechnical practice. Earth pressures developed on either side of the sheet pile wall ensure its moment and force equilibrium. One of the mechanisms governing the failure of cantilever sheet pile wall can be described as structural failure of the sheet pile elements because of high stresses and/or loss of serviceability due to large deformation. This mechanism is particularly important with the advent of plastic bending in Eurocode 3 Part 5. Centrifuge tests were carried out on model cantilever sheet pile walls supporting granular fill by subjecting to varied g-levels (in steps of 5 g from 10 g onwards) up to a maximum set target g-level of 75 g or to excessive deformation of wall, whichever occurred first. The bending moment distribution, deflections of the sheet pile wall and the settlement of the backfill were monitored during the centrifuge test. The same problem was analyzed using the finite element method and closed-form solutions using Coulombs earth pressure theory. It was shown that the finite element analysis was able to capture the formation of the plastic hinge observed in the sheet pile walls during the centrifuge model tests. Location of the maximum bending moment obtained both from finite element analyses and closed-form solutions was found to be in agreement with the physically observed centrifuge model test results. This gives confidence in the numerical analyses of sheet pile walls where plastic bending is allowed in the design provided the deformations remain within the Serviceability Limit State.