Table 1 Cyclic loading and unloading test scheme.

From: Research on stress release and pressure relief mechanism of underlying coal and rock under protective layer mining

No.

Displacement control/mm/min

Stress control /MPa

Number of cycles

Uniaxial compressive strength/MPa

The peak axial strain

1

0.3

0

0

15.78

−3291

2

0.3

4

1

15.47

−3788

3

0.3

8

1

14.92

−4267

4

0.3

10

1

14.01

−5259

  1. Note: The unloading stress in mechanical tests is all 0.1 MPa.
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