Study on the Instability Mechanism and Control Measures of a Roadway in a Mine with Retained Coal Pillars and Close Coal Seams

Table 1

Physical parameters of the rock strata.

Rock types	Thickness (m)	Density (kg/m^3)	Bulk modulus (GPa)	Shear modulus (GPa)	Cohesion (MPa)	Friction (°)	Tensile modulus (MPa)
Siltstone	9.0	2460	10.82	8.20	2.75	35.0	1.8
Sandy mudstone	1.0	2400	10.26	5.50	1.16	35.0	2.1
#17 coal seam	4.0	1380	1.78	0.83	0.80	27.0	0.4
Fine sandstone	4.0	2600	14.26	11.50	2.66	38.0	3.5
Interlayered sandstone and mudstone	4.0	2530	13.14	10.23	2.60	34.0	2.0
#181 coal seam	2.6	1380	1.78	0.83	0.80	27.0	0.4
Argillaceous fine sandstone	5.0	2460	11.62	8.73	2.60	34.0	3.2
Mudstone	3.0	2483	6.08	3.47	1.23	30.0	0.7
#18 coal seam	2.1	1380	1.78	0.83	0.80	27.0	0.4
Mudstone	1.0	2483	6.08	3.47	1.23	30.0	0.7
Siltstone	5.0	2460	10.82	8.20	2.75	35.0	1.8
Mudstone	13.0	2483	6.08	3.47	1.23	30.0	0.7