Fig. 11

The acoustic emission (AE) energy was computed as a function of displacement for four distinct levels of normal stress, specifically: (a) CG1-4, (b) CG3-8, (c) CG3-12, and(d)CG1-16.

The acoustic emission (AE) energy was computed as a function of displacement for four distinct levels of normal stress, specifically: (a) CG1-4, (b) CG3-8, (c) CG3-12, and(d)CG1-16.