Acoustic Emission and Force Drop in Grain Crushing of Carbonate Sands

The crushing behavior of carbonate sand, due to its porous and fragile structure, exerts a significant influence on the construction of coastal engineering. The collapse of porous material usually produces elastic wave dissipation and force drop in stress-strain curves. To study the acoustic and mechanical characteristics of carbonate sand crushing, both force and acoustic emission (AE) signals were measured as a function of run time in single-particle uniaxial compression tests. Rapid large force drops corresponding to avalanches led to obvious AE signals. The AE signal analysis of carbonate sand was consistent with avalanche statistic laws, e.g., the Gutenberg–Richter law of energies, the double power law distributions of waiting time, the statistics of aftershocks, and Båth's law. The force drop data also exhibited good power law behavior. Moreover, the Weibull distribution of the peak stress and accumulated energy up to the peak state were established. Although carbonate sand had two failure modes in the experiments, these modes had the same statistical properties in terms of both mechanics and AE.