Study on Failure Mechanism and Control Technology of Roadway Surrounding Rock under Complex Occurrence Coal Seam

Table 2

Numerical calculation parameters.

Surrounding rock type	Bulk modulus/MPa	Shear modulus/MPa	Rock mass density/	Internal friction angle/(°)	Cohesive force/MPa
Medium-grained sandstone	2100	1.32	2750	32	3.50
Siltstone	3200	2.70	2650	30	2.30
Coal	270	0.16	2235	22	0.75
Sandy mudstone	900	0.01	2600	25	2.95