HS-small constitutive model for innovative geomaterials: effectiveness and limits

Worldwide, an increasingly huge number of End-of-Life Tires (ELT) is disposed of in landfills, illegally dumped, or otherwise unaccounted for, causing significant environmental and socio-economic issues. Finding sustainable engineering solutions to recycle and reuse ELT, transform-ing them from unwanted waste to useful resource, has become a priority. In geotechnical engineer-ing, researchers have performed laboratory and field tests to determine the mechanical properties of innovative geomaterials consisting of soil-rubber mixtures (i.e., gravel-rubber mixtures, GRMs, and sand-rubber mixtures, SRMs) obtained by using recycled ELT-derived granulated rubber ag-gregates. Suitable engineering properties and low installation cost encourage the use of GRMs and SRMs in many applications, such as free-draining energy-adsorption backfill material for retain-ing walls, underground layers for liquefaction mitigation and geotechnical seismic-isolation sys-tems for structures and infrastructures. However, due to the heterogeneity of soil-rubber mixtures, their ultimate adoption as geomaterials must be supported by constitutive relationships capable of accurately describing their mechanical behaviour under typical field loading conditions. The aim of the paper is to evaluate the effectiveness and limits of the Hardening Soil model with Small-Strain Stiffness (HS-small) – that is present in many finite element codes – to model the behav-iour of GRMs in geotechnical engineering applications. An extensive FEM simulation of drained triaxial tests was performed.