Analysis on Evolution Law of Small Structure Stress Arch and Composite Bearing Arch in Island Gob-Side Entry Driving

Table 2

Physical and mechanical parameters of rock.

Lithology	Density	Bulk modulus (GPa)	Shear modulus (GPa)	Tensile strength (MPa)	Cohesion (MPa)	Friction angle (°)
Mudstone	2382	5.93	4.74	2.74	3.52	28
Sand mudstone	2447	6.68	5.27	3.58	3.2	27
Mudstone	2382	5.93	4.74	2.74	3.52	28
Coal line	1421	3.8	1.63	0.6	1.9	27
Sand mudstone	2312	5.3	4	2.4	2.8	25
Fine sandstone	2335	4.15	3.2	1.5	3.6	34
Sand mudstone	2270	4.76	3.85	1.35	2.5	21
6-coal	1390	4.33	1.77	0.8	1.8	25
Siltstone	2210	6.1	4.79	2.68	3.25	28
Coal line	1265	4.6	3.54	1.13	2.1	26
Siltstone	2286	6.38	5.6	3.26	4.5	31
M-granted sandstone	2080	5.4	4.1	1.89	4.7	35
Sand mudstone	2312	5.3	4	2.4	2.8	25