Time-dependent behavior and creep-damage model of basalt-fiber-reinforced high-water material under uniaxial compression

High-water material (HWM) is extensively employed as a backfill material in mining engineering. With increasing mining depths, the time-dependent deformation and creep failure of HWM backfill bodies become more significant under high-stress conditions. To investigate the influence of basalt fiber (BF) on the time-dependent mechanical properties of HWM, this study prepared BF-reinforced HWM specimens and performed a series of uniaxial compressive tests and multi-stage loading creep tests. The results indicate that stress levels are crucial in influencing the time-dependent deformation behavior, while BF volume fractions predominantly affect the long-term strength (LTS) and creep failure time. To accurately characterize the time-dependent behavior of BF-reinforced HWM, a nonlinear creep-damage model was developed. The creep model integrates a Hooke body, Kelvin body, and novel viscoplastic damage component using the combination element method. The parameters of the creep model for each fiber volume fraction were determined through nonlinear fitting, and the fitting curves demonstrated excellent consistency with the experimental data. Furthermore, the finite difference form of the creep model was derived, and a corresponding computer application was implemented on the FLAC3D platform. Numerical simulations of HWM specimens with different BF volume fractions were performed, and the results showed strong agreement with laboratory observations, validating the accuracy and reliability of the creep model.