Damage constitutive model for cemented paste backfill after mixing waste rock

The usage of cemented paste backfill (CPB) in the underground by mining industry is becoming increasingly. In this study, three kinds of CPB with waste rock content of 15%, 20% and 25% respectively were tested, and their stress-strain curves were obtained. According to the damage mechanism of CPB during the uniaxial compressive failure process, this paper further established the damage constitutive model of backfill subjected to uniaxial compressive stress based on the equivalent strain hypothesis theory. According to the measured full stress-strain curve of backfill, the damage evolution equation of backfill was formulated and the damage constitutive relation was analyzed. The results of damage analysis showed that the backfill with different waste rock ratio had different damage characters. And their damage constitutive equations investigated with damage mechanics whose calculating coincide with experiment results well were proposed.