Creep properties and resistivity-ultrasonic-AE responses of cemented gangue backfill column under high-stress area

Abstract To investigate the creep and instability properties of a cemented gangue backfill column under a high-stress area, the uniaxial compression creep tests were conducted by single-step and multi-step loading of prismatic samples made of cemented gangue backfill material (CGBM) under the high stress-strength ratio. The creep damage was monitored using an electrical resistivity device, ultrasonic testing device, and acoustic emission (AE) instrument. The results showed that the CGBM sample has a creep hardening property. The creep failure strength (CFS) is slightly larger than the uniaxial compressive strength (UCS), ranging in ratio from 108.9% to 116.5%. The instantaneous strain, creep strain, and creep rate increase with increasing stress-strength ratio in the single-step loading creep tests. The instantaneous strain and creep strain decrease first and then increase during the multi-step loading creep process. The axial creep strain of the CGBM column can be expressed by the viscoelastic-plastic creep model. Creep instability is caused by the accumulation of strain energy under multi-step loading and the continuous lateral expansion at the unconstrained middle position during the creep process. The creep stability of a CGBM column in a high-stress area can be monitored based on the variation of electrical resistivity, ultrasonic pulse velocity (UPV), and AE signals.