Table 2 PFC mesoscopic parameters of each rock layer.

From: Stress distribution characteristics of overburden strata during thick coal seam top coal caving

Name of the rock layer

Minimum particle size (m)

Parallel bonding modulus (GPa)

Parallel bonded stiffness ratio

Parallel bonding cohesion (MPa)

Parallel bonding tensile strength (MPa)

Friction factors

Porosity (%)

Gravel bearing coarse sandstone_1

0.420

25.96

1.77

21.67

26.00

0.5

0.2

Mudstone_1

0.300

6.99

1.37

10.21

12.25

0.5

0.2

Gravel bearing coarse sandstone_2

0.420

25.73

1.77

22.13

26.56

0.5

0.2

Coarse sandstone

0.450

34.08

1.91

24.18

29.02

0.5

0.2

Gravel bearing coarse sandstone_3

0.420

27.69

1.77

21.39

25.67

0.5

0.2

5_1 coal seam

0.250

5.52

1.96

17.26

20.71

0.5

0.2

Mudstone_2

0.300

6.92

1.37

9.41

11.29

0.5

0.2

5_1 coal seam

0.250

5.49

1.96

16.94

20.33

0.5

0.2

Silty mudstone

0.350

15.59

1.39

10.51

12.61

0.5

0.2

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