Instability Mode and Control Technology of Surrounding Rock in Composite Roof Coal Roadway under Multiple Dynamic Pressure Disturbances

Table 1

Rock stratum distribution and mechanical parameters.

Lithology	Thickness (m)	Density (kg·m^-3)	Bulk modulus (GPa)	Shear modulus (GPa)	Internal friction angle (°)	Tensile strength (MPa)	Cohesion (MPa)
Siltstone	17.4	2600	9.4	3.4	36	5.78	1.7
Sandy mudstone	10.0	2300	6.0	2.2	32	2.36	1.2
Fine sandstone	4.0	2600	9.4	3.4	36	5.78	1.7
Coal line	0.7	1600	0.2	0.5	32	0.3	0.2
Sandy mudstone	3.0	2300	6.0	2.2	32	2.36	1.2
Carbonaceous mudstone	0.7	1700	0.2	0.5	32	0.3	0.2
2# coal	3.8	1300	2.0	1.2	30	1.08	0.8
Siltstone	5.4	2600	9.4	3.4	36	5.78	1.7
Sandy mudstone	21.0	2300	6.0	2.2	32	2.36	1.2