Table 1 Macroscopic and microscopic physical and mechanical properties of strata.

From: Fracture propagation and water seepage behavior in overburden strata at Tunbao coal mine

Stratum

Lithology

Poisson’s ratio

Elastic modulus

Tensile strength /MPa

cohesion /MPa

Angle of internal friction /(°)

J15

Mudstone

0.15

7.2

1.36

6.32

39.4

J14

Fine-grained sandstone

0.21

24.8

3.06

5.77

38.8

J13

Gritstone

0.18

15.4

2.58

4.35

35.3

J12

Gritstone

0.18

15.4

2.58

4.35

35.3

J11

Siltstone

0.23

18.2

4.66

11.05

36.0

J10

Siltstone

0.23

18.2

4.66

11.05

36.0

J9

Coal

0.27

6.9

1.33

2.42

42.6

J8

Siltstone

0.23

18.2

4.66

11.05

36.0

J7

Coal

0.27

6.9

1.33

2.42

42.6

J6

Siltstone

0.23

18.2

4.66

11.05

36.0

J5

Coa

0.27

6.9

1.33

2.42

42.6

J4

Siltstone

0.23

18.2

4.66

11.05

36.0

J3

Coal

0.27

6.9

1.33

2.42

42.6

J2

Siltstone

0.23

18.2

4.66

11.05

36.0

J1

Medium-grained sandstone

0.18

15.4

2.58

4.35

35.3

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