An efficient three-dimensional soil–structure interaction model for analysis of earth retaining structures

Using the integrated form of Mindlin's equations that relate the stress and displacement field anywhere within a three-dimensional space in an isotropic and elastic soil medium, a boundary-element-based numerical model is presented for analyzing soil–structure interaction problems involving excavations around embedded structures. The solution procedure involves combining the stiffness matrix of the wall and soil system and computing the displacements from a knowledge of the stress changes due to excavation. An interative approach is adopted to apply the correcting forces at locations that reach active or passive states, thus resulting in correct displacements for plastic conditions that cannot be accounted for by the Mindlin's elastic solutions. The model is shown to provide matching results against a finite-element model under plane-strain conditions. Application of the proposed model within the context of a practical project has demonstrated its role both as a predictive tool and as a theoretical model for performing sensitivity analysis and establishing practical guidelines to control magnitude and mode of wall deflections, which are important design considerations in excavations close to movement-sensitive structures. Key words : numerical modelling, elasticity, three-dimensional effects, soil–structure interaction, retaining wall, excavation.