Table 1 Physical and mechanical parameters of coal and rock mass.

From: Mechanism and application of competitive fracture propagation in layered group fracturing of massive thick overburden strata

Lithology

ρ/kg m−3

σc/MPa

E/GPa

μ

θ/°

C/MPa

σt/MPa

Medium sandstone

2586

43.46

3.73

0.25

24

1.9

3.6

Sandy mudstone

2198

5.80

1.48

0.22

43

2.6

2.3

Coarse sandstone

2625

45.21

4.52

0.26

21

1.7

4.6

Siltstone

2510

31.93

3.41

0.29

29

2.1

3.1

Coal

1437

5.00

0.52

0.27

35

1.3

1.7

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