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Geotechnical structures often have position-dependent soil strength parameters as a consequence of stress history, deposition process, mineralogical composition, and weathering effect. However, most available theoretical models for estimating active earth pressures focus only on homogeneous cases. By a point by point technique, this work develops a friction-angle-dependent discretized failure mechanism to evaluate the active earth pressure on backfills in the framework of the limit-equilibrium slice method. The generated failure mechanism is composed of a series of horizontal elements. Compared with previous theoretical models, the benefits of the proposed method are twofold: (1) the friction-angle-dependent failure mechanism agrees well with the actual failure surface for heterogeneous backfills; (2) not only the multilayer frictional backfill but also the backfill with a position-dependent friction angle can be accounted for. The total active earth pressure coefficient, the earth pressure distributions, and the failure mechanisms are obtained, all showing excellent agreement with the available experimental data and the existing analytical solutions. For practical use, applications to backfills with a weathered zone and spatially variable frictional angles are then conducted. Finally, the proposed model is degraded into a two-layer case in which the active earth pressure coefficients under various mechanical and geometrical parameters are tabulated. [ABSTRACT FROM AUTHOR]

The existing analytical models for predicting earth pressures based on the kinematical approach of limit analysis are limited to soil masses with homogeneous internal frictional angles. To overcome this drawback, this work proposes a discretised failure mechanism to calculate the location of earth forces and evaluate the active and passive earth pressures against inclined retaining walls with horizontal backfills for the first time. Comparisons with other existing analytical solutions, numerical simulations and experimental tests are made to verify the proposed method for the cases of single-layer and multi-layer backfills. Practical design tables are presented for a two-layer case. Application of the proposed model to three-layer backfills with a middle weak layer is presented. The influence of the position of the weak layer on the critical earth pressures and failure mechanisms is discussed. [ABSTRACT FROM AUTHOR]