Table 2 Physical-mechanical parameters of the rock layer of the top and bottom plates of the 23,107 working face in the xiegou coal mine.

From: Predictive model for the instability of flexible formwork concrete wall in secondary mining of non-pillar coal mining

Stratum lithologic

Thickness of stratum /m

Bulk modulus /GPa

Shear modulus /GPa

Tensile strength /MPa

Cohesive force /MPa

Angle of internal friction

/(°)

coarse sandstone

14

8.8

5.9

1.2

3.1

31

fine-sandstone

6

6.6

5.9

0.7

2.4

30

mudstone

10

10

5.7

0.9

2.6

27

sandy mudstone

22

16.9

8.5

1

2.5

27

silty sandstone

4

7.9

6.3

2.4

1.1

30

middle-fine sandstone

8

4.4

8.7

1,4

1

23

fine-sandstone

2

10.1

6.5

2.8

7.2

22

sandy mudstone

4

6.7

4.9

1

2.4

30

no. 13 coal seam

5

3.7

3.7

0.7

2

29

mudstone

7

4.4

5.3

0.9

1.2

28

sandy mudstone

4

6.7

6.1

1

2.4

30

limestone

3

8.5

6

2

4.2

26

fine sandstone

16

9.8

8.2

2.3

3.6

35

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