Prestressed reinforced soil for infrastructure projects - a microscopic research

In this paper, investigations on prestressed geogrids installed to reinforce embankments for motorand railways are presented. A microscopic three dimensional (3D) model using the Discrete Element Method (DEM) is constituted to evaluate displacements and contact forces between discrete gravelly particles in a prestressed reinforced soil element. The granular soil particles and the discrete geogrid reinforcement were numerically modeled by “Computer Aided Design” (CAD). The load transfer mechanism between the soil particles and the geogrid reinforcement was evaluated. Arching effects occurred randomly between the granular soil particles and the discrete longitudinal and transverse members of the geogrid. These arching effects lead to local force concentrations between the generated particles and to high tensile forces in the numerically bonded geogrid. In addition, three soil geogrid interaction effects were determined. In the case of discrete clumps entering the gaps of the discrete geogrid, the longitudinal and transverse members of the reinforcement were expanded. This effect had already been classified as static or dynamic interlocking effect in literature. While loading the reinforced soil element, grains also entered between the single strings of the longitudinal and transverse members of the woven geogrid reinforcement. This effect was newly defined as single string interaction effect. In longitudinal but also in transverse direction the geogrid aligned to the surrounding granular particles. This newly defined alignment effect led to a permanent contact between geogrid and soil particles and thereby resulted in a permanent interfriction effect. The provided numerical model gave a realistic and detailed insight in the fundamental load transfer and soil geogrid interaction behavior in case of utilizing the concept of prestressed reinforced soil for innovative infrastructure projects.