Research on Formation Mechanism and Evolution Pattern of Bed Separation Zone during Repeated Mining in Multiple Coal Seams

Table 3

Physical and mechanical parameters of joints between rock blocks.

No.	Lithology	Normal stiffness (GPa)	Tangential stiffness (GPa)	(MPa)	(°)	Tensile strength (MPa)
6	Medium sandstone	15.25	5.32	10.63	24.00	1.00
5	Fine sandstone	18.45	6.18	12.55	28.00	1.65
4	Siltstone	12.09	4.30	9.11	35.00	1.40
3	Sandy mudstone	7.42	3.24	6.83	25.00	0
2	Mudstone	5.05	2.16	4.98	20.00	0
1	Limestone	6.53	2.21	3.63	30.00	0