Investigation of the Optimal Layout of the Roadway in Closely Spaced Ultra-Thick Coal Seams Mining with Remaining Coal Pillars

Table 1

Physicomechanical parameters of the coal rock block.

Coal rock seam	Density (kg·m^−3)	Young’s modulus (GPa)	Poisson’s ratio	Cohesion (MPa)	Internal friction angle (°)	Tensile strength (MPa)
Sandy mudstone	2420	25.01	0.25	2.60	55.26	6.32
Siltstone	2738	39.23	0.15	3.27	61.42	8.65
Clastic rock	2147	26.07	0.23	2.55	52.45	7.41
Silty sand, sandy mudstone	2180	27.42	0.20	2.95	55.45	68.3
2 coal	1290	14.43	0.40	1.20	37.18	2.15
Aged mudstone	2287	17.97	0.24	2.55	42.45	4.06
3–5 coal	1310	15.32	0.37	1.20	39.37	2.80
Sandy mudstone	2120	24.28	0.21	2.41	40.26	6.29
High water content filling material	1310	10.41	0.31	0.884	30.5	1.05