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

Table 2

Basic parameters and Proximate analysis.

Coal seam							TRD	ARD
N-2	1.62	9.07	6.29	0.65	92.52	3.03	1.59	1.56

Note: is the moisture content on air-dry (ad) basis, %; is the ash content on air-dry (ad) basis, %; is the volatile matter content on dry-ash-free (daf) basis, %; is the total sulfur on dry basis, %. is the carbon content on dry-ash-free (daf) basis, %; and is the vitrinite group maximum reflectance. TRD is the true relative density, g/cm³; ARD is the apparent relative density, g/cm³.