Constitutive Model for Brittle Granular Materials Considering Competition between Breakage and Dilation

Abstract

A constitutive model is presented for brittle granular materials based on a recent reformulation of the breakage mechanics theory. The primary objective of the study is to capture peak strength with subsequent strain softening in dilatant specimens under shearing and the simultaneous evolution of breakage and dilation. The predictive performance of the model is assessed relative to two experimental datasets from the literature. The influence of the model parameters on the overall material response is described through a detailed calibration procedure based on a benchmark experimental dataset. Comparison of the results of drained triaxial compression experiments on two sands with the predictions of the model indicates that the enriched model can successfully capture the evolution of stress-strain behavior at different confinement levels. The predicted response of dilatant specimens exhibits stress- and density-dependent peak strength and strain softening toward the critical state, which is in agreement with experimental evidence. The simulations of Kurnell sand can reproduce the transition of the volumetric strain from −0.05 to 0.14 as the confining pressure increases from 760 to 7,800 kPa. The predicted breakage of specimens subjected to different confining pressures is slightly higher than experimental measurements, whereas they exhibit similar trends. The proposed framework is capable of qualitatively reproducing many aspects of the experimentally observed stress-dilatancy-breakage relationship in brittle granular materials.