Experimental and Theoretical Investigations on Active Earth Pressure Distributions Behind Rigid Retaining Walls with Narrow Backfill under a Translational Mode

The existing earth pressure theories, such as Rankine's theory and Coulomb's theory, adopt planar slip surfaces to establish force equilibrium equations. For retaining walls, especially for those with narrow backfill, the shape of slip surfaces may not be straight, and the earth pressure distribution behind the retaining wall may be nonlinear due to the influence of friction and soil arching effects. To investigate the shape of slip surfaces and the earth pressure distribution behind the retaining wall under a narrow backfill condition and a translational mode, six model tests with different boundary conditions were carried out using a self-developed experimental setup, in which an analogical soil was used as a backfill to stimulate the behavior of the soil. The model tests show that the shape of slip surfaces was highly dependent on the aspect ratio (i.e., the ratio of the backfill width to the fill height). When the aspect ratio was larger than one, the shape of slip surfaces tended to become arc-shaped. The aspect ratio of 1 was determined as the threshold value for the narrow backfill condition for the material investigated. An analytical model for the active pressure distribution under a narrow backfill condition and translational mode was proposed considering nonlinear slip surfaces and the soil arching effect. The accuracy of the proposed method was verified with the experimental data obtained in this study and those reported in the literature.