Study on the Ground Movement in an Open-Pit Mine in the Case of Combined Surface and Underground Mining

Table 2

Mechanical properties for different lithologies.

Lithology	Compression strength (MPa)	Internal friction angle (°)	Cohesion (MPa)	Unit weight (kg·m^−3)	Elastic modulus (MPa)	Poisson’s ratio
Artificial fill	1.8	16	0.112	1650	12	0.45
Loose soil	1.8	18	0.125	1960	15	0.42
Weathered sandstone	56.3	38	2.5	2300	2000	0.36
Sandstone	95.1	39	3	2380	4200	0.33
Clay	58.1	40	0.5	2355	2015	0.23
No. 4 coal seam	40.7	36	1.62	1440	1000	0.38
Sandy mudstone	63.8	39	0.5	2360	2050	0.24
Fine sandstone	99.4	40	3.1	2380	4300	0.33
Siltstone	107.4	38	5	2600	4800	0.32
Malmstone	54.4	38	0.4	2350	2000	0.25
No. 9 coal seam	38.4	39	1.62	1330	1200	0.36
Mudstone	54.5	38	0.4	2300	2000	0.25
No. 11 coal seam	36.6	36	1.62	1400	1300	0.35
Medium-fine sandstone	99.8	40	3.1	2390	4300	0.33