Development of Modified Grouting Material and Its Application in Roadway Repair Engineering

Table 8

Mechanical parameters of contact surface.

Rock stratum	Normal stiffness (GPa)	Tangential stiffness (GPa)	Internal friction angle (°)	Cohesion (MPa)	Tensile strength (MPa)
Overlying strata	4.90	0.45	30	0.27	0.11
Main roof	3.20	0.26	24	0.16	0.08
Immediate roof	2.92	0.18	19	0.11	0.05
9# coal seam	1.11	0.10	16	0.06	0.03
Immediate floor	2.82	0.16	18	0.12	0.06
Main floor	3.31	0.24	23	0.15	0.09
Underlying strata	4.86	0.46	32	0.26	0.12