Damage and Failure Evolution Mechanism for Coal Pillar Dams Affected by Water Immersion in Underground Reservoirs

Table 3

Physical and mechanical properties of coal and rock.

Lithology	Thickness (m)	Volumetric weight (kN·m^−3)	Elastic modulus (GPa)	Compressive strength (MPa)	Poisson ratio
Aeolian sand	10	15.8	—	—	—
Medium-grain sandstone	11	23.9	33	45.3	0.25
Sandy mudstone	49	22.4	23	22.8	0.28
Siltstone	33	23.5	35	40.6	0.25
1^−2 coal	6	14.8	15	6.6	0.35
Medium-grain sandstone	11	23.9	33	45.3	0.25
Siltstone	30	23.5	35	40.6	0.25
Sandy mudstone	6	22.4	23	22.8	0.28
2^−2 coal	7	15.1	14	6.6	0.22
Mudstone	2	22.3	20	20.7	0.3
Clay rock	5	20.4	35	19.6	0.28
Fine sandstone	15	23.4	13	6.6	0.22