Figure 6

RA-AF signal distribution and damage morphology. (1) Compaction stage (2) Elasticity stage (3) Fissure stable extension stage (4) Fissure unstable extension stage.

RA-AF signal distribution and damage morphology. (1) Compaction stage (2) Elasticity stage (3) Fissure stable extension stage (4) Fissure unstable extension stage.