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

Table 5

Evolution laws of the mechanical properties under different loading rates and initial peak stresses.

		Continuity of the loading curve in the plastic stage and previous cycle	Concave tendency of the curve before the plastic stage	Initial tangent modulus of each cycle	εmax	σr	σc	Remark
As the loading rate increases	IA	Worse	More obvious	Smaller	Larger	Lower	Lower	Earlier large perturbation formation
	RIA	Better	More obvious	Smaller	Larger	Lower	Higher
	DIA	Worse	Less obvious	Larger	Smaller	Higher	Lower
As the initial peak stress σ0 increases	IA	Better	Less obvious	Larger	Smaller	Higher	Higher	Earlier decrease of load curve tangent modulus; Less strain between adjacent cycles
	RIA	Better	More obvious	Smaller	Smaller	Higher	Higher
	DIA	Better	Less obvious	Larger	Smaller	Higher	Higher