A Method for Determining Feasibility of Mining Residual Coal above Out-Fashioned Goaf under Variable Load: A Case Study

Table 2

Physical and mechanical parameters of lithology.

Lithology	Elasticity modulus, E (GPa)	Volume weight, ρ (kg·m^−3)	Cohesion, C (MPa)	Tensile strength, σt (MPa)	Friction angle, φ (◦)
No. 5 coal seam	5.1	14.00	3.0	1.2	30
Charcoal mudstone	10.3	24.83	5.5	4.1	32
Mudstone	12.4	23.69	3.5	3.5	35
Siltite	14.5	25.34	12.2	5.1	38
Charcoal mudstone	17.1	24.63	3.6	3.2	32
No. 8 coal seam	5.5	14.30	2.8	1.3	29