Study on the Permeability Change Characteristic of Gas-Bearing Coal under Cyclic Loading and Unloading Path

Table 5

Permeability change rate and permeability damage rate.

Tension	Loading and unloading path	(%)	(%)	(%)
Axial force	Load and unload 1	36.65	21.8	21.8
	Load and unload 2	26.92	12.82	31.83
	Load and unload 3	20.59	8.82	37.84
Confining force	Load and unload 1	58.33	27.08	27.08
	Load and unload 2	54.29	25.71	45.83
	Load and unload 3	51.92	23.08	58.34

is accumulated coal sample permeability damage rate, %.