Acoustic Emission monitoring of crushing of an 1 analogue granular material 2 3

35 36 A two-dimensional analogue material formed of rod cylinders of chalk is tested under one37 dimensional oedometric loading conditions. Passive non-destructive Acoustic Emission (AE) 38 monitoring technique is used to document the occurrence of crushing of individual particles. 39 While the AE activity is recorded by a sensor placed on the sample boundaries, the AE signals 40 are also corroborated with the observations based on video records of the exposed face of the 41 2D sample, as well as vertical loading and displacement measurements of the global sample. In 42 the process, one-dimensional tests on individual cylindrical rods were also conducted and their 43 AE crushing signatures compared with the AE data recorded at the 2D sample scale. While AE 44 signal features can capture the particle crushing in the 2D granular systems, their occurrence 45 shows high complexities driven by internal crushing particle mechanisms and geometrical 46 position of particles with respect to the AE monitoring device. The frequency content of AE 47 signals shows some evidence of the existence of an AE signature for a typical particle crushing 48 mechanism, which may be a consequence of the dynamic properties of the whole system. 49 50 51 52 53