Table 1 Numerical Calculation Parameters.

From: Study of the mechanism of enhanced gas extraction by pressure relief and permeability enhancement in protective mining in a coal seam group

Lithology

Modulus of elasticity/GPa

Tensile strength/MPa

Cohesion/ MPa

Friction angle/°

Poisson’s ratio

Fine-grained sandstone

10

5

4

25

0.3

Mudstone

6

3

2

24

0.25

Fine sandstone

10

5

4

25

0.3

Sandy mudstone

6

3

2

24

0.25

Siltstone

10

5

4

25

0.3

Coal seam

1

1

1

22

0.23

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