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Description
While critical state soil mechanics (CSSM) and advanced constitutive models, such as NorSand, have been widely applied to natural soils and tailings, their extension to coarser grained materials such as rockfill and mine waste rock has not been comprehensively evaluated. This limitation is important for the analysis and design of large geotechnical structures, where design decisions are often informed by a limited number of large‑scale laboratory tests and assumptions regarding material state dependent behaviour.
This paper presents a comparative study of NorSand constitutive model calibrations based on 30 large-scale triaxial test results performed on four types of coarse granular materials, including rockfill, mine waste rock, and blast debris. These materials were sourced from multiple geographically and geologically distinct sites across US and Canada, and were tested using a large-scale triaxial apparatus with specimen diameter of approximately 300 mm.
All materials exhibited well-defined critical state lines (CSLs) in e–log p′ space, with slopes and intercepts that were parallel or near-parallel across the material types. The critical state friction angles (φ′cs) fell within a narrow range of 38° to 42°. The derived NorSand plastic hardening parameters (Ho, Hψ) and dilation parameters (N, χtc) were found to be of similar magnitude, indicating comparable post-peak softening and dilative tendencies.
These findings may support the broader applicability of critical state soil mechanics (CSSM) to coarse granular materials and reinforce the utility of the NorSand model in capturing the state dependent behaviour of rockfill and waste rock. The observed parameter consistency provides a compelling basis for developing generalized NorSand parameter sets for preliminary design and numerical modelling of large-scale geotechnical structures such as tailings dams, waste dumps, and embankments.