Theory and application of an efficient computer program for analysis of flexible earth-retaining structures

Abstract

A computer program is described for analysing the behaviour of flexible retaining walls. This program is efficient, versatile and easy to use and is considered to provide a powerful tool for completing design of earth-retaining structures. A novel method is adopted for forming the soil stiffness and earth pressure limits that differs significantly from the traditional subgrade reaction approach. Three stiffness matrices are used in the analysis. One matrix represents the wall in bending while the other two represents the soil on each side of the wall. Each soil stiffness matrix is assembled using pre-calculated flexibility matrices obtained from finite element computations for elastic soil blocks. 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 iterative 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 elastic soil blocks. The model is shown to provide matching results against a finite-element model under plane strain conditions and depict the response of a wall rotated about its base in a laboratory model test. 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.