Table 2 Material ratios for the physical similarity model.

From: Overburden structure fracture evolution and ground pressure behavior under oblique residual coal pillars in thick seam mining

Rock layers

Ratio

Materials required for each slice (kg·cm− 1)

Sand

Plaster

Calcium carbonate powder

Fly ash

Mudstone, conglomerate

80:3:7

8.53

0.32

0.75

—

Sandy mudstone

80:3:7

8.53

0.32

0.75

—

Conglomerate

80:3:7

8.53

0.32

0.75

—

Silty mudstone

40:2:3

8.53

0.43

0.64

—

Mudstone

45:1:4

8.64

0.19

0.77

—

Fine sandstone

70:3:7

8.40

0.36

0.84

—

Argillaceous siltstone

40:2:3

8.53

0.43

0.64

—

Silty mudstone

40:2:3

8.53

0.43

0.64

—

Argillaceous siltstone

40:2:3

8.53

0.43

0.64

—

Medium-grained sandstone

45:1:4

8.64

0.19

0.77

—

3# coal seam

21:1:2:21

2.69

0.13

0.26

2.69

Fine sandstone

70:3:7

8.40

0.36

0.84

—

Mudstone

45:1:4

8.64

0.19

0.77

—

Coarse sandstone

40:1:4

8.53

0.21

0.85

—

Fine sandstone

70:3:7

8.40

0.36

0.84

—

Silty mudstone

40:2:3

8.53

0.43

0.64

—

Fine sandstone

70:3:7

8.40

0.36

0.84

—

Siltstone

40:2:3

8.53

0.43

0.64

—

Silty mudstone

40:2:3

8.53

0.43

0.64

—

5# coal seam

21:1:2:21

2.69

0.13

0.26

2.69

Coarse sandstone

35:2:3

8.40

0.48

0.72

—

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