Numerical Analysis of Stress Fields and Crack Growths in the Floor Strata of Coal Seam for Longwall Mining

Table 1

The roof and floor strata of the extracted coal seam in No. 2710 working face.

Strata	Thickness(m)	Elastic modulus (GPa)	Poisson’s ratio
Sandstone	14	25	0.28
Extracted coal seam	1.5	4	0.33
Sandstone	17	25	0.28
Limestone	5	40	0.28
Shale	4.2	15	0.29
Coal seam	1.8	4	0.33
Shale	20	20	0.30
Ordovician Limestone	Larger than 650	45	0.30