Study on energy dissipation and acoustic emission characteristics of fiber tailings cemented backfill with different ash-sand ratios

Abstract

In this paper, acoustic emission (AE) monitoring technique was used to study the mechanical lifting mechanism of polyacrylonitrile (PAN) fibers on the CPB material under uniaxial compression and the specific energy characteristics and AE response characteristics and damage precursors during the damage of fiber tailings cemented backfill specimens with different ash-sand ratios. In this experiment, cemented paste backfill (CPB) and polyacrylonitrile fiber tailings cemented backfill (P-FTCB) specimens with 68% concentration and 1:6, 1:8, 1:10 and 1:12 ash-sand ratios were fabricated using PAN fibers. The study shows that the fracture arresting effect and bridging effect of PAN fibers inhibited the expansion of fracture development inside the CPB, thus enhancing the compressive strength and post-peak damage toughness of the CPB, while the fracture arresting effect and bridging effect of fibers depended on the fiber pull-out process, and the fiber pull-out process is divided into three stages: micro-slip stage, slip stage and detachment stage; the higher the ratio of ash-sand in P-FTCB specimens, the stronger the cementing force, the higher the energy required for material destruction, the greater the elastic strain energy that can be stored, and the greater the energy dissipated per unit volume; CPB specimens without fiber incorporation show a decreasing trend in AE parameters before damage; while P-FTCB specimens show a surge in AE parameters after the specimens reached their stress peaks under the effect of fiber fracture arrest; in addition, there is a significant relationship between the ratio of ash-sand of the filling material and its AE parameters: the AE energy parameters of CPB specimens and P-FTCB specimens increas as the ratio of ash-sand decreased. The results of the study can provide a reference basis for the use of P-FTCB materials in mines, and provide theoretical support for promoting the recycling of mine solid waste.