Research and Application of Open-Off Cut Roof Cutting Pressure Releasing Technology

Table 1

Physical and mechanical parameters of each rock layer.

Lithology	Density/kN/m^3	Tensile strength/MPa	Internal friction angle/°	Cohesion/MPa	Bulk modulus/GPa	Shear modulus/GPa
Medium sandstone	25	8.4	33	2.6	11.49	7.26
Mudstone	23	3.2	28	0.2	0.20	0.15
Coal	13	3.3	29	0.2	0.35	0.18
Siltstone	23	4.3	32	0.8	2.11	1.86
Fine sandstone	24	7.3	32	1.0	3.81	3.05