Fractal Characteristics of Coal and Sandstone Failure under Different Unloading Confining Pressure Tests

Table 9

Fractal dimension of fragmentation under different unloading rates.

Unloading rate (MPa/s)	Coal		Sandstone
	k	D	k	D
0.02	0.5174	2.4826	0.584	2.416
0.05	0.6172	2.3828	0.646	2.354
0.08	0.6495	2.3505	0.6803	2.3197
0.11	0.6724	2.3276	0.7152	2.2848
0.14	0.7216	2.2784	0.769	2.231