Damage characteristics and damage constitutive modeling of cemented fill with blended fiber tailings based on energy...

To investigate the mechanical properties, energy damage evolution law, and crack evolution characteristics of doped basalt fiber (BF) and calcium carbonate whisker (CW) cemented sand filler (CPB), uniaxial compression experiments combined with microstructural characterization were conducted on the doped fiber cemented filler specimens to analyze their energy dissipation characteristics, and a segmental damage constitutive model was established based on the damage mechanics theory. The experimental results show that the appropriate amount of BF (the optimal dosage is 0.1%) and CW (the optimal dosage is 1%) can significantly improve the uniaxial compressive strength and ductility of the filling body. The two synergistic actions show a coupling enhancement effect so that the compressive strength of the filling body increased by 33.68%. The total strain energy, elastic strain energy, and dissipation energy of the mixed fiber cemented sand filling body before the peak stress showed different trends; at the same time, based on the damage theory to optimize the existing damage constitutive model of the applicable fiber filling body, the introduction of the damage correction factor α, the establishment of a segmented damage constitutive model considering the compaction stage and the influence of fibers, and found that the experimental curves and the theoretical curves match with the degree of agreement of more than 90%. Under uniaxial loading, the specimens of the filler not doped with BF usually showed brittle damage characteristics, and the main crack through the specimen appeared. However, after BF was doped, the damage mode changed to pure shear damage or mixed tensile-shear damage, with "Y" type cracks and multiple small microcracks, which indicated that BF could inhibit the crack extension, disperse the stress, and reduce the phenomenon of stress concentration, thus improving the ductility and safety of the filled body. In addition, Microanalysis showed that the synergistic enhancement of BF and CW improved the pore structure of the matrix, and the attachment of more hydration products on the surface of BF and CW promoted the fiber-matrix bonding, which effectively inhibited the emergence and expansion of internal cracks. This study provides valuable insights to improve the utilization of tailings and enhance the stability of mine fill bodies.