Effects of constant acidity on the early mechanical and acoustic emission characteristics of cemented tailings backfill

Acid mine water significantly impacts the stability of backfill. Backfill samples were placed in acidic solutions with constant pH values of 2, 3, 4, 5 and 6 to simulate the mine water environment for maintenance, and a distilled water solution pH=7 without dilute sulfuric acid was used as the control. Combined with the uniaxial compression and sound emission tests, the cemented tailings backfill samples of different ages under constant acid curing were tested. A damage constitutive model for the cemented tailings backfill was established based on Lemaitre’s strain equivalence principle. The results showed that the strong acid curing environment degraded the internal structure of the backfill, leading to a reduction in compressive performance. In curing solutions with pH 2, 3 and 4, the compressive strength of the cemented backfill decayed in the last 12 days of curing period. The lower the pH, the greater the density of the acoustic emission signal during the growth stage. The peak value of acoustic emission ringing count rate in the active period was positively correlated with pH, and the peak value of ringing count rate did not necessarily coincide with the peak stress point. Comparison of experimental data with theoretical values from the constitutive model verified the model’s reliability.