Stress-strain behavior of railway embankments stabilized with grouted micropiles

Excessive ballasted track deformations may occur during the railway operations due to poor load bearing capacity of the embankment (placed soil or natural ground) or the manifest accumulation of subsidence caused by the soil consolidation and the passage of trains. The principles of pressure grouting (or jet-grouting) technologies, used to create reinforcement elements for the rail trackbed stabilization, are presented, with reference to the specific construction condition on an existing and in-service railway track. A single-track railway, including the superstructure and substructure components, was modeled using the finite element method (FEM). Some soil stabilization options, based on the installation of grouted micropiles according to different layout configurations, were considered. The results of the numerical analyses, in the form of stress and strain behavior of the whole track structure, demonstrated that the use of jet-grouted micropiles is a rational and less expensive option, which can be installed on or close to the track, having positive effects on limiting the vertical deformations of the embankment without affecting the expected distribution of stress states in the embankment middle.