We conducted many uniaxial compression tests on the rock salt before the cyclic loading test, and obtained an average compres- sion strength of 47 MPa. Based on the average compression strength, a cyclic loading test under different upper stresses was conducted under a lower stress of 9.4 MPa, which is 20% of the average compression strength. The upper stresses were 95%, 90%,
85%, and 80% of the compression strength. We also performed cyclic loading tests under different lower stresses with an upper stress of 90% of the compression strength and lower stresses of
20%, 30%, 40%, and 50% of the compression strength.