Accounting for cyclic and fabric effects in an enhanced hypoplastic model for sand
L. Mugele, Hans Henning Stutz, Zhongxuan Yang
Abstract
An enhanced hypoplastic constitutive model accounting for anisotropic fabric effects in modeling the mechanical behavior of granular materials subjected to monotonic and cyclic loading is presented. Based on von Wolffersdorff’s hypoplastic model (HP), the proposed formulation combines the recently published generalized intergranular strain (GIS) concept for the simulation of cyclic deformations and the anisotropic critical state theory (ACST) to account for the anisotropic fabric effects on the macroscopic stress–strain behavior. Using six state variables ( σ , e , h , Ω , F , H ), the proposed enhanced hypoplastic model called HP+GIS+ACST can effectively reproduce the soil behavior under both monotonic and cyclic loading. The HP+GIS+ACST solves the overshooting problem of the asymptotic state boundary surface (ASBS) and reproduces soil liquefaction effects due to cyclic loading in loose as well as in dense samples. The model’s performance is validated by simulating both monotonic and cyclic tests, with comparisons to experimental data from Karlsruhe fine sand (KFS) and Fraser River sand (FRS), as well as to two other hypoplastic models.