Effect of Mining Thickness on Overburden Movement and Underground Pressure Characteristics for Extrathick Coal Seam by Sublevel Caving with High Bottom Cutting Height

Table 3

Factor of stress concentration and the distance between peak stress and coal wall in different mining thicknesses.

Distance from coal seam roof (m)	9 m		15 m		25 m
	Factor (k)	Distance (m)	Factor (k)	Distance (m)	Factor (k)	Distance (m)
0	2.26	24	2.14	26	1.99	29
10	2.39	22	2.71	24	2.59	27
25	2.46	21	3.15	23	2.96	25
40	2.53	18	3.42	20	3.17	23
80	1.68	12	3.55	18	3.28	21
150	1.34	4	2.13	13	3.35	19
250			1.15	4	2.26	14