Concrete spillway-earthfill interface for large dams: A parametric study on soil-structure interaction.

Abstract

Ever since earth dams have been constructed, engineers are faced with the problems of interfaces within or adjacent to the impervious core material. The design approach to these interfaces are based on engineering judgement and empirical procedures of which their implementation is largely left to the discretion of the site engineers. Although the design of such interfaces is important to the safety of the dam, very little is reported on this subject in the technical literature. A parametric study was conducted to determine the influence of wall inclination, wall roughness, foundation compressibility and various backfill materials on the stresses and deformations developed in the region of the soil-structure interface. Using a non-linear finite element program (SSTIPN), the results show that the normal stress distribution, although approximating at-rest conditions, has larger magnitudes than anticipated in the lower region of the wall if a compressible foundation is present. The large settlements observed in the soil mass due to the compressible foundation, combined with a rough interface at the spillway/earthfill junction, may cause large deformations problems. Based on these findings and the behaviour of the interface when varying the parameters being studied, a recommendation for the selection of the materials is presented.