The Research of the Influence on Stress below the Roadway Floor of the Coal Seam Becoming Thin

Table 1

Properties of the coal and rock.

	Density kg/m^3	Bulk modulus (Pa)	Poisson’s coefficient	Cohesion (Pa)	Friction angle (°)
Coal	1400	29	0.26	2.56	30
Rock	2500	3E10	0.3	47	40