Experimental Study on the Effect of Brittleness on the Dynamic Mechanical Behaviors of the Coal Measures Sandstone

Table 1

Several methods for calculating rock brittleness.

Methods	Equation	Remarks	Reference
Mineral composition		is the fraction of brittle/ductile mineral; Qtz, Cl, Cb, and Toc are the quartz, clay carbonates, and total organic carbon, respectively	[14]
			[11]
Strain		e, , and r are the total elastic strain, failure strain, and residual strain, respectively	[22]
			[23]
Stress		and r are the peak stress and residual stress	[24]
			[25]
Rock strength		denotes uniaxial compressive strength; t is the tensile strength	[26]
			[22]
Energy balance		is the total elastic energy; is the plastic energy; is the rupture energy; is the postpeak addition energy; and is the consumed elastic energy	[27]
			[5]