Unified model of critical state line for rockfill material with and without considering particle breakage

摘要

The critical state line (CSL) is important for characterizing soils' properties. However, particle breakage is inevitable for granular soils such as rockfill. Therefore, the impact of particle breakage on CSL has always been one of the main focuses. Unfortunately, it has not yet been adequately resolved how particle breakage influences CSL quantitatively. Large-scale drained triaxial shearing tests of rockfill materials under various initial gradations, initial void ratios and confining pressure have been conducted in this paper. It shows that particle breakage could result in decrements in both of the stress ratio and void ratio at the critical state. The equation for a critical state line with none breakage (NBCSL) was theoretically derived and demonstrated. The intercept and gradient of CSL and NBCSL are inextricably related because of particle breakage, which has been quantified as follows: the intercept of CSL is identical to NBCSL's, and the gradient of CSL is a breakage-related constant plus that of NBCSL. In other words, the CSL and NBCSL of rockfill materials has actually been described by a unified equation. Based on this, the translation and rotation of CSL induced by changing gradation and void ratio can be explained from the essence of particle breakage.

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