Constant shear drained behaviour of tailings predicted by hypoplasticity

The constant shear drained (CSD) stress path mimics a loading that can occur in slopes due to a rise in the phreatic surface. This stress path has been reported in the literature as the primary cause for triggering static liquefaction of loose materials used to build water dams and tailings storage facilities. This study evaluates how sand and clay hypoplasticity reproduce the behaviour of two tailings materials when subjected to a CSD stress path under plane-strain conditions. Experiments show that clays, even when initially only normally to slightly overconsolidated, tend to reach stress ratios above the critical value during CSD loading, whereas loose sands and sandy silts fail at stress ratios below the critical stress ratio. These contrasting trends serve as a benchmark for the hypoplastic models. Our simulations reproduce the observed differences between sand and clay and are interpreted within the framework of critical-state soil mechanics. The models further capture the main experimental trends in stress–strain behaviour, volumetric response, stress paths, and principal stress rotation, as well as the consolidation phase preceding CSD loading. Overall, the results support the applicability of the hypoplastic models for analysing CSD loading scenarios relevant to tailings dam stability.