Behind a retaining wall, the mean effective stress mainly decreases during an excavation phase following an unloading stress path. The volumetric strains generated by purely elastic soils are systematically dilative which induces aberrant ground uplifts. The introduction of plasticity along with a nonlinear elastic domain turns out to be essential for a realistic prediction of ground movements. In this paper, a numerical analysis is carried out using a finite element code considering an advanced soil constitutive model called Generalized Hardening Soil which has been recently developed. This model contains the exact same set of features as the Hardening Soil Small Strain model but with the possibility to activate each of its plastic and nonlinear elastic mechanisms independently. The role of these mechanisms are investigated to assess their impact on the shape and the amplitude of the ground movements. Numerical results demonstrated that plasticity triggers the main contractive volumetric strains leading to settlements. Nevertheless it cannot fully compensate the elastic uplifts due to unloading. The insertion of strain dependent stiffness is essential as well as the stress dependency. A back analysis of the historical excavation of the Taipei National Enterprise Center permitted to validate these findings.

Worldwide, an increasingly huge number of end-of-life tires (ELTs) are disposed of in landfills, illegally dumped, or otherwise unaccounted for, which causes significant environmental and socioeconomic issues. Finding sustainable engineering solutions to recycle and reuse ELTs, which transform them from unwanted waste into useful resources, has become a priority. In geotechnical engineering, researchers have performed laboratory and field tests to determine the mechanical properties of innovative geomaterials that consist of soil-rubber mixtures (SRMs) [i.e., gravel-rubber mixtures (GRMs)] that are obtained using recycled ELT-derived granulated rubber aggregates. Suitable engineering properties and low installation cost encourage the use of GRMs and SRMs in many applications, such as in free-draining energy-adsorption backfill material for retaining walls, underground layers for liquefaction mitigation and geotechnical seismic isolation systems for structures and infrastructures. However, due to the heterogeneity of SRMs, their ultimate adoption as geomaterials must be supported by constitutive relationships that can accurately describe their mechanical behavior 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), which is present in many finite-element (FE) codes, to model the behavior of GRMs in geotechnical engineering applications. An extensive finite-element method simulation of drained triaxial tests was performed.