Active earth pressure coefficients based on a 3D rotational mechanism

Abstract The research on active earth pressure has historically been conducted either based on two-dimensional (2D) conditions or focused on vertical walls and horizontal backfills. An analytical method is developed in this work to calculate the coefficients of three-dimensional (3D) active earth pressure in the typical case of an inclined wall and a sloping backfill within the framework of the kinematic approach of limit analysis. A 3D horn-like mechanism is postulated first. On the basis of this mechanism, the active earth pressure coefficients due to soil weight and surcharge loading are calculated from the principle of energy-work balance. The proposed approach is validated by comparing with previous studies under 2D and 3D conditions. Two sets of charts are presented for a sensitivity analysis. The results of this work show that including the 3D effect can yield more economical results. The 3D effect is obvious when the width-to-height ratio of the retaining wall is small and becomes less obvious as the ratio increases. After the ratio reaches a sufficiently high value, the 3D effect is negligible and the evaluation of active earth pressure can be regarded as a 2D problem.