Study on characteristic stress and energy damage evolution mechanism of cemented tailings backfill under uniaxial compression

摘要

This study attempted to explore, at curing age, the characteristics stress and energy evolution of the cemented tailings backfill (CTB) under uniaxial compression. Based on the energy consumption theory, the energy parameters at the characteristic stress varing with the curing age was analyzed. Furthermore, the evolution law of energy distribution and the energy damage mechanism of the CTB were revealed, and the failure criterion of the CTB was established based on the elastic energy consumption ratio. The results showed that the characteristic stress of the CTB follow an exponential function increasing law with the increase of curing age and the characteristic stress of the CTB with larger cement-to-tailings (c/t) ratio increases more rapidly when the curing age is 3d similar to 14d. The total energy, elastic strain energy and consumption energy at the peak stress point of the CTB all follow the exponential function increasing law with the increase of curing age, and the increase of cement-totailings (c/t) ratio and curing age can significantly improve the energy storage limit of the CTB. The deformation and failure of the CTB mainly go through five stages: initial crack compaction stage, linear elastic deformation stage, steady development stage of microcrack, accelerated crack expansion stage and post-peak failure stage. According to the damage value D of the CTB and the growth law of dissipated energy, elastic strain energy and axial strain, the loading damage of cemented CTB can be divided as follow: initial damage stage, damage stationary stage, damage stable stage, damage rapid stage and damage failure stage. The slow growth and abrupt change of the elastic energy consumption ratio K in the post-peak stage can be used as the criterion for strength instability of the CTB.