Research on Failure Mechanism and Strengthening of Broken Roadway Affected by Upper Coal Pillar

Table 1

Mechanical parameters of coal and rock mass.

Rock stratum	Density (g/cm^3)	Bulk modulus (GPa)	Shear modulus (GPa)	Cohesion (MPa)	Internal friction angle (°)	Thickness (m)
Silt	2.65	9.1	7.8	7.2	34	3.5
Fine sand	2.7	13.3	10	10.2	37	4.5
Medium sand	2.34	12.3	9.1	5.2	37	11
#15 coal seam	1.3	5	2.08	1.68	28	3
Silt	2.65	9.1	7.8	7.2	34	2
Fine sand	2.7	13.3	10	10.2	37	2
Sandy mudstone	2.63	12.5	10	10	35	1.5
Medium sand	2.34	12.3	9.1	5.2	37	2.5
Coarse sand	3.05	9.9	10.6	10.8	34	10
Silt	2.65	9.1	7.8	7.2	34	2
Mudstone	2.24	3.2	6.69	8.1	36	1
#16 coal seam	1.3	5	2.08	1.68	28	5
Fine sand	2.7	13.3	10	10.2	37	8
Silt	2.65	9.1	7.8	7.2	34	9