Model of Overlying Strata Structure in Large Mining Height Excavating Condition and Calculation of Support Working Resistance

Table 2

Physical and mechanical parameters of coal strata with large mining height.

Serial number	Lithological characteristics	Paved thickness of the model (cm)	Compressive strength (kPa)	No. of mixture	Sublayer
14	Medium gritstone	4.8	392	455	3
13	Gritstone	6.8	383	455	4
12	Fine sandstone	14.2	450	337	4
11	Coal	1.5	167	764
10	Sandy shale	6.5	208	546	3
9	Coal	1.2	167	764
8	Sandy shale	6.5	208	546	3
7	Fine sandstone	2.0	358	455
6	Sandy shale	3.8	208	546	2
5	Medium sandstone	11.5	392	455	3
4	Gritstone	11.2	358	455	3
3	Fine sandstone	2.9	450	337
2	Sandy shale	1.1	217	546
1	Coal	7.1	167	764

Note. The meaning of No. of mixture: the first digit represents the ratio of sand to cement, and the second and third digits represent the ratio of calcium carbonate to gypsum in the cement. For example, No. 455 of mixture in the table indicates that the sand-to-rubber ratio is 4 : 1, and the calcium carbonate:gypsum in a cement is 5 : 5.