Mechanical Characteristics and Mesostructural Damage of Saturated Limestone under Different Load and Unload Paths

Table 4

Loading and unloading scheme.

Rate and initial peak stress control	Loading and unloading methods
	IA cycling	RIA cycling	DIA cycling
= 0.15 mm/min, σ0 = 2.5 MPa	(1)	(6)	(11)
= 0.2 mm/min, σ0 = 2.5 MPa	(2)	(7)	(12)
= 0.3 mm/min, σ0 = 2.5 MPa	(3)	(8)	(13)
= 0.2 mm/min, σ0 = 7.5 MPa	(4)	(9)	(14)
= 0.2 mm/min, σ0 = 12.5 MPa	(5)	(10)	(15)