A New Method for Controlling Rockbursts in the Mining Roadway of Ultrathick Coal Seams Based on the Dual Pressure Relief Method

Table 1

Mechanical parameters of the model strata.

Lithology	Density (kg/m^3)	Tensile strength (MPa)	Friction angle (°)	Cohesion (MPa)	Bulk modulus (GPa)	Shear modulus (GPa)
Tuff	2240	2.38	36	2.7	2.76	1.3
Coarse sandstone	2560	1.50	34	5.0	4.2	2.9
Siltstone	2702	1.31	38	2.5	2.8	1.2
Fine stone	2873	1.29	24	3.2	2.1	1.35
Coal	1346	1.48	39	2.8	2.8	3.6
Carbonaceous mudstone	2891	1.15	29	1.3	2.17	1.0
Tuffaceous siltstone	2360	1.33	38	2.06	10.6	8.03
Conglomerate	2580	1.2	27	2.3	3.3	2.5