Impacts of Cyclic Loading and Unloading Rates on Acoustic Emission Evolution and Felicity Effect of Instable Rock Mass

Figure 7

Variation of the AE characteristics of red sandstone specimens (Ur = 0.5 kN/s; Lr = 0.5 kN/s∼4.0 kN/s). (a) Total AE rings versus loading rates; (b) total AE rings of each cycle versus loading stress levels; (c) total AE rings at the loading stage of each cycle versus loading stress levels; (d) total AE rings at the unloading stage of each cycle versus loading stress levels.

(a)

(b)

(c)

(d)