Geosynthetic-reinforced and pile-supported embankments

Abstract

Piled foundations are commonly employed to reduce settlements of artificial earth embankments on soft soil strata and geosynthetic reinforcements are installed at the embankment base to increase pile spacing and reduce construction costs. Despite the well-documented effectiveness of this technique, the mechanical processes, developing during the construction in the different elements constituting the ‘geo-structure’, are not fully understood and the design approaches are based on very simplified assumptions. They disregard the deformability of the various elements constituting the system and cannot be employed to estimate settlements. With the aim of introducing a displacement-based design approach to optimise the use of reinforcements and piles, in this article, the mechanical response of the system during the embankment construction is studied by means of large displacement non-linear finite difference numerical analyses, in which the geosynthetic reinforcement is modelled as an elastic membrane. The arching effect developing within the embankment body is described and the evolution of the process zone, where shear strains localise, is discussed. The global system response is described in terms of (i) average, (ii) differential settlements at the top of the embankment and (iii) maximum tensile force within the geosynthetic reinforcement.