Distribution and Variation of Earth Pressure Applied on Submerged Toe-Retaining Walls in Rockfill Dam Engineering

Abstract

A high concrete gravity retaining wall is usually built at the toe of concrete face rockfill dams to accommodate the toe plinth, to avoid adverse natural conditions or excessive excavation. However, earth pressure on the back of the wall is generally neglected due to lack of information on the distribution and evolution of earth pressure during dam construction and reservoir impounding. In this study, two historic cases are reviewed, and a series of plane strain finite element method simulations are performed with an elastoplastic constitutive model for the retained rockfill. The distribution and variation of the normal and shear stresses along the wall–rockfill interface during construction and impounding are studied, and the influence of the interface friction angle is investigated. The evolution of the total normal and shear forces, as well as their application positions, are also analyzed based on the obtained numerical results. Simplifying the dam above the top of the wall as an evenly distributed surface pressure, an empirical formula is proposed to enable evaluation of earth pressure at rest for design purposes. The involved earth pressure coefficient, equivalent dam height, and correcting factor are suggested based on the numerical results. Earth pressures under empty and full reservoir conditions, as well as some favorable design features, are also suggested.