Numerical Modeling of Roadway Embankment Construction Over Existing Sewers

Abstract

Abstract This article presents a case study of the influence of a roadway embankment on existing sewers with a diameter or width in the range of 3.3 to 4.3 m using numerical modeling. The proposed embankment would be constructed directly above the existing sewers, which would induce an additional load on the sewers. Traditional analysis methods cannot account for the soil–structure interaction and the benefit of the lateral supporting characteristics of the soils. In order to evaluate the loading of the proposed embankment on the existing sewers, a soil–structure interaction analysis using a two-dimensional finite element analysis was performed for various loading cases. The sensitivity of soil parameters was also studied in the analysis. From the analysis, the loads on the sewers, including axial force, bending moment and shear force, were obtained, and then the structural capacity of the existing sewers was checked. Lightweight sand fill or expanded polystyrene (EPS) geofoam was considered to reduce the additional vertical and horizontal loads on the sewers. The EPS geofoam or a structural protection system consisting of a concrete slab supported by concrete piles was proposed to eliminate any incremental vertical and horizontal loads on the sewers. Findings from the analysis concluded that the lightweight sand fill was the most economical material for reducing the additional loads on the sewers, EPS geofoam was the most suitable material to eliminate incremental loading on the sewers for a lower embankment, and the structural protection system was necessary to eliminate the incremental loads on the sewers for a higher embankment.