Analysis and Monitoring Technology of Upper Seam Mining in Multiunderlayer Goaf

Table 2

Parameters of coal and rock used in the calculation.

Rock	Density (kg/m^3)	Tensile strength (MPa)	Elastic modulus (MPa)	Poisson’s ratio	Cohesion (MPa)	Internal friction angle (°)
Siltstone	2.600	1.10	15.125	0.26	1.30	34
Coal	1.323	0.28	2.173	0.28	0.28	32
Medium sand	2.502	0.66	35.696	0.20	0.66	33
Mudstone	2.668	0.36	11.399	0.25	0.83	31