Study on the Mine Pressure Law and the Pressure Frame Mechanism of an Overlying Goaf in a Shallow Coal Seam

Table 1

Mechanical parameters of the coal and rock strata considered in the numerical model.

Lithology	Thickness (m)	Density (kg/m^3)	Elastic modulus (MPa)	Poisson’s ratio	Cohesion (MPa)	Tensile strength (MPa)	Internal friction angle (°)
Carbonaceous mudstone	5.0	2482	7700	0.21	5.60	5.60	39.3
22 coal seam	1.7	1290	2080	0.22	1.08	1.08	28.2
Sandy mudstone	1.2	2482	7700	0.21	5.60	5.60	39.3
Medium-grained sandstone	10.0	2430	1400	0.24	9.26	9.26	24.7
Fine-grained sandstone	1.9	2360	1410	0.36	4.93	4.93	33.6
Siltstone	3.0	2494	1570	0.19	8.08	8.08	31.8
Sandy mudstone	1.6	2482	7700	0.21	5.60	5.60	39.3
22 upper coal	1.5	1290	2080	0.22	1.08	1.08	28.2
Medium-grained sandstone	10.0	2430	14000	0.24	6.00	6.00	24.7
Load layer	5.0	2482	7700	0.21	5.60	5.60	39.3