Guidelines for calibration and use of the severn-trent sand model in modeling cantilevered wall-supported excavations

The Severn-Trent sand model is an advanced elastoplastic constitutive model that accurately reproduces the nonlinear mechanical response of coarse-grained soils at small to relatively high strain levels under monotonic loading. The model, formulated within the framework of critical state soil mechanics, includes advanced plasticity modeling concepts such as kinematic hardening, multisurface plasticity, and bounding surface plasticity. This paper shows how the use of Severn-Trent can be extended in modeling cantilevered wall-supported excavations. Following a brief description of the approach taken to introduce the constitutive model into a finite-difference commercial code, guidelines for the model calibration are discussed. Accounting for the approximation, which affects the evaluations of some variables, several planestrain numerical analyses are performed. The parametric study aims to evaluate to what extent the response of a cantilevered retaining structure in a dry, normally consolidated Toyoura sand layer is influenced by these uncertainties. The results encourage the use of the Severn-Trent model in solving boundary value problems, such as excavations, particularly where accurate displacement field predictions are required.