Energy conservation validates deformation mechanisms around model cantilever wall excavations in sand

Abstract

Based on soil movement measurements in two centrifuge models simulating cantilever wall excavation in dense and loose sand respectively, simplified deformation mechanisms are proposed on both sides of the wall. Negative dilation angles are used in the mechanism to model sand volume change at a moderate strain level corresponding with the typical serviceability limit of facilities on the retained ground within the zone of influence of the wall. An energy calculation is then performed for each of the two centrifuge tests to check the internal consistency of the inferred deformation mechanisms, and the adequacy of the stress–strain model used for the sand. It is found that energy balances within an error of 7% in both tests. The major energy flow happens on the active side of the wall, where the potential energy loss is roughly equal to the work done due to sand shear and contraction. The energy stored in wall bending and the energy lost due to boundary friction are small in comparison. The validated model of the settlement and shearing of the retained ground is then used to illustrate how to assess the degree of building damage in relation to angular distortion and tensile strain in the retained ground supporting its shallow foundations.