Study on Rib Sloughage Prevention Based on Geological Structure Exploration and Deep Borehole Grouting in Front Abutment Zones

Table 2

Coal parameters.

Coal parameter	Volume modulus (GPa)	Shear modulus (GPa)	Internal friction angle (°)	Cohesion	Body force
Scheme 1	6.9	0.2	12	5.3	1400
Scheme 2	7.9	1.2	15	7.3	1400
Scheme 3	8.9	2.2	18	8.3	1400
Scheme 4	9.9	3.2	21	9.3	1400
Scheme 5	The coal parameters are the same as those used in Scheme 1; the direct roof rock parameters are increased by 50% to compare to Scheme 1