SANISAND-H: A sand bounding surface model for high pressures

Abstract

This paper presents a new bounding surface constitutive model for sand, named SANISAND-H, capable of predicting the shear and volumetric behavior of the material under extra-high range of pressures, in addition to normal pressures. The model is an extension of the SANISAND08 model (Taiebat and Dafalias, 2008) with a closed cone-type yield surface that obeys rotational and isotropic hardening. The critical state line and the limiting isotropic compression curve of the SANISAND08 model are modified to accommodate a wide range of pressures. A new constitutive ingredient is the definition of a reference compression curve that serves as bounding surface for establishing the isotropic hardening rule of the yield surface. The kinematic hardening rule and stress-dilatancy relationship of the SANISAND08 model are significantly modified, to better capture the response of sands under high pressure. The value of the back stress ratio at the initiation of a new loading process is re-introduced, ensuring a smooth elastic-plastic transition necessary for accurate simulation of the response under loading reversals. The SANISAND-H model simulations are in very good agreement with test data for Toyoura and Cambria sands under various drained and undrained monotonic stress loading paths in a wide range of densities and pressures.