Reduction of Earth Pressures on Rigid Retaining Walls with Narrow Backfill Width Using Compressible Geofoam Inclusions

Abstract

Installing geofoam inclusions between the rigid retaining wall and backfill can reduce the earth pressure against the retaining wall. However, there is currently a lack of research on the earth-pressure reduction effect of geofoam inclusions on rigid retaining walls with narrow backfill width. In this study, the compression from geofoam inclusions was equated to the displacement of the narrow backfill. An iterative method was introduced based on the displacement-dependent earth-pressure model. A calculation method was obtained to determine the earth pressure for rigid retaining walls with narrow backfill width using geofoam inclusions. Moreover, simplified formulae for at-rest, active, and passive earth-pressure coefficients of retaining walls with narrow backfill width were achieved based on the soil arching effect and horizontal differential element method. A series of laboratory model tests were performed to verify the calculated formulae, demonstrating a high level of formula accuracy. In addition, the parameter analysis results showed that the earth-pressure reduction effect of geofoam inclusions was directly proportional to the interface friction angle between the backfill and geofoam inclusions.