The creep behavior and damage evolution evaluated by acoustic emission of thermally-cycled argillaceous siltstone at selected temperatures

In order to study the effect of high-temperature and water-cooling on the argillaceous siltstone creep mechanical behavior, the samples were treated at 200 °C, 600 °C, and 1000 °C respectively, and then cooled with water. Then, the uniaxial compression creep mechanics test was carried out, and the acoustic emission (AE) characteristics were monitored in the entire creep process in synchronization. The results show that: (1) With the increase in temperature, the creep failure strength of argillaceous siltstone decreases, and its macroscopic failure mode transition from shear failure mode to split failure mode. (2) High temperature inhibits both the instantaneous strain and the creep strain and steady creep rate are significantly reduced after high-temperature treatment. (3) The creep curves were fitted and identified by the L-M optimization algorithm under different high-temperature and water-cooling conditions. The Burgers creep model can better describe the argillaceous siltstone creep characteristics. Elastic coefficients \(E_{1}\), and \(E_{2}\), and viscosity coefficients \(\eta _{1}\), and \(\eta _{2}\) decreased after high-temperature and water-cooling treatment. The viscosity is enhanced, and the damage-hardening characteristics are obvious. (4) The AE ringing count rate decreases at the initial loading moment and the steady creep stage after high-temperature treatment. The evolution trend of the AE event ringing count rate at the steady creep stage is consistent with that of the creep rate.