Table 1 Physical-mechanical parameters of the rock layer at the top and bottom plates of the 1315 working face in zhaozhuang 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

/(°)

mudstone

4

7.4

4.9

0.8

4.3

29

fine-sandstone

6.5

11.3

5.7

1.5

6.8

33

sandy mudstone

6.8

9.5

8.5

1.9

7.9

30

fine-sandstone

1.9

12.5

6.3

1.6

6.6

33

sandy mudstone

2.2

9.3

8.7

2.5

8.1

31

black sandy mudstone

11

10.1

6.5

1.6

6.3

28

black mudstone

1.5

7.6

4.9

0.8

4.5

28

no. 3 coal seam

5

6.2

3.7

0.6

2.7

27

black mudstone

2.8

7.1

5.3

0.7

4.0

29

sandy mudstone

4

9.2

6.1

1.1

7.2

30

fine-sandstone

2.1

12.5

6.0

1.6

6.9

32

sandy mudstone

3.4

9.3

8.2

2.6

8.3

31

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