Exploration and Practice of Pressure Relief by Slotting Coal Seams with a Diamond Wire Saw

Table 2

Rock mechanics properties.

Type	H		E	μ	c	t	φ
Fine sandstone	4	2560	8.83	0.27	5.8	3.5	38
Mudstone	4	2150	5.51	0.31	3.5	2.8	30
Coal	2	1400	3.28	0.26	1.8	0.8	24
Mudstone	4	2150	5.51	0.31	3.5	2.8	30
Fine sandstone	4	2560	8.83	0.27	5.8	3.5	38

H = thickness, m;  = unit weight, kgm⁻³; E = Young’s modulus, GPa; μ = Poisson’s ratio; c = cohesive forces, MPa; t = tensile strength, MPa; φ = angle of internal friction, °.