Speakers
Description
Conventional triaxial devices typically operate below approximately 1-2 MPa, a stress range in which coarse granular materials exhibit predominantly friction-controlled behavior. Within this domain, differences in gradation, density state, and structure often produce limited separation in shear envelopes, encouraging the use of smooth empirical extrapolations.
Large rockfill and waste dumps operate at substantially higher stress levels, where particle breakage, densification, and contact-network restructuring influence load transfer. Large-scale triaxial datasets extending into the multi-megapascal range demonstrate systematic divergence from low-stress trends. Shear-envelope curvature increases, peak strain evolves, volumetric response shifts toward contraction, and available breakage indicators intensify with stress level.
This work evaluates the mechanical implications of extending low-stress envelopes into higher stress domains. Analysis of compiled large-scale datasets shows that curvature parameter m and associated response metrics are stress-range dependent rather than constant material properties. The apparent continuity suggested by low-stress testing conceals a transition in governing mechanisms.
The results indicate that stress range, not specimen size alone, controls the observable mechanical regime. Large-scale testing is required to access the stress domains governing large rockfill and waste dumps. A stress-regime interpretation framework is proposed to replace routine extrapolation practices in coarse granular systems.