Mechanical Damage Test and Model Study of Layered Composite Rock Based on Acoustic Emission and DIC Characteristics

Table 5

The feature comparison between different damage models.

Different types of damage models	Damage evolution equation	Feature analysis
Damage model defined based on the micro-defect area [32]		The physical meaning is clear and the form is simple, but the micro-defects are difficult to measure in the test
Damage model defined based on elastic modulus [35]		The macroscopic elastic modulus is easy to measure and widely used in practice
Damage model defined based on ultrasonic velocity [36]		Operability is strong, due to rock heterogeneity resulting in low accuracy
Damage model defined based on energy change [37]		It is difficult to measure the energy dissipation directly, but the damage variable can be calculated accurately
Damage model defined based on strain [35]		Damage evolves as a function of strain, which can be extended from one dimension to three dimensions
Damage model defined based on DIC and AE		High calculation accuracy and complementary effects, the two can be compared and verified, and the damage can be described accurately