Use of acoustic emission to evaluate the micro-mechanical behavior of sands in single particle compression tests.

Particle breakage has been recognized as a crucial factor affecting the mechanical behavior of stressed granular assemblages. To understand such underlying micro-mechanical behavior, Acoustic Emission (AE) technique that is capable of continuously diagnosing the deterioration and failure process of stressed materials was employed into single particle compression tests on silica sands. Regardless of different particle sizes, the fracturing process could be highly featured by AE characteristics, in which AE hit rate and peak frequency characteristics were analyzed to evaluate the intensity and mode of micro-mechanical behaviors, respectively. "Early warning omens" regarding the impending failure of the stressed particle is revealed in terms of the initiation and rapid increase of high-frequency AE components, as well as the rapid increase of AE hit rate. The effect of "prehistory of failure" on the stressed particle is sensitively featured by the highly emitted AE events after the catastrophic failure. Furthermore, a frequency-based method is suggested to distinguish different modes of micro-mechanical behaviors associated with particle readjustment, asperity abrasion, and microcracking. Further employment of the present result is expected to continuously evaluate the intensity and mode of particle interactions in stressed granular assemblages.