Analytical Analysis and Field Observation of Break Line in the Main Roof over the Goaf Edge of Longwall Coal Mines

Table 1

Generalised stratigraphy and key geotechnical parameters.

Stratum number	Geological legend	Rock type	Rock thickness (m)			Density (kg/m^3)	Young’s modulus (GPa)	Poisson’s ratio	UCS (MPa)	Cohesion (MPa)	Friction angle (°)
			Maximum	Minimum	Average
1		Fine sandstone	4.9	6.22	5.6	2700	27.73	0.22	165.3	11.6	41.64
2		Mudstone	1.49	2.12	1.8	2140	6.85	0.24	44.6	2.6	32
3		Fine sandstone	0.2	1.52	0.9	2700	27.73	0.22	165.3	11.6	41.64
4		Mudstone	0.9	1.58	1.3	2140	6.85	0.24	44.6	2.6	32
5		Medium sandstone	1.89	2.56	2.3	2675	28.14	0.21	146.2	10.9	47.64
6		Gritstone	1.4	2.2	1.7	2730	32.66	0.24	162.4	12.4	48.23
7		Coal seam	0.9	1.2	1.0	1412	2.06	0.36	13.89	2.3	44.34
8		Mudstone	2.1	3.2	2.3	2140	6.85	0.24	44.6	2.6	32
9		Siltstone	8.9	12.6	9.2	2680	30.73	0.22	142.3	9.4	39.42
10		Sandy mudstone	1.66	2.3	2.0	2659	11.58	0.27	63.28	8.9	47.39
11		Coal seam #2	5.96	6.6	6.2	1412	2.06	0.36	13.89	2.3	44.34
12		Mudstone	1.4	1.8	1.6	2140	6.85	0.24	44.6	2.6	32
13		Siltstone	5.9	7.7	6.8	2680	30.73	0.22	142.3	9.4	39.42