Investigation into Mechanism of Floor Dynamic Rupture by Evolution Characteristics of Stress and Mine Tremors: A Case Study in Guojiahe Coal Mine, China

Table 3

The parameters of joints.

Lithology	Normal stiffness/GPa	Shear stiffness/GPa	Friction angle/°	Cohesion/MPa	Tension/MPa
Fine sandstone	7500	3100	26	15.8	6.4
Siltstone	5200	2100	25	10.3	5.6
Mudstone	3300	1400	20	8.2	3.2
3^# coal	2000	800	18	3.0	1.1
Mudstone	3300	1400	20	8.2	3.2
Siltstone	5200	2100	25	10.3	5.6
Fine sandstone	7500	3100	26	15.8	6.4