Table 2 Physical and mechanical parameters of different strength floors.

From: Safety evaluation method of bottom coal thickness in thick coal seam roadway

Floor strength

Bulk modulus/GPa

Shear modulus/GPa

Cohesion force/MPa

Friction angle/°

Tension strength/MPa

σRC < σMC

2.41

1.52

1.29

25

1.36

σRC = σMC

2.56

1.72

1.55

26

1.58

σRC > σMC

2.74

1.87

1.70

28

1.87

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