Dynamic damage and energy dissipation of fiber-reinforced cemented tailings backfill under confinement

In this paper, the mechanical damage characteristics and energy dissipation patterns of fibre-reinforced cemented tailings backfill (FRCTB) under different strain rates are investigated based on the Hopkinson pressure bar apparatus equipped with confining pressure facilities, and this investigation is conducted by combining the theories of box fractal dimension and energy dissipation. The findings reveal notable observations: under lower confining pressures, the strain rate strengthening effect exhibits pronounced influences on both failure patterns and energy dissipation. However, as the confining pressure escalates, the strengthening effect gradually diminishes. The dissipation energy density displays an increasing trend with the rise in confining pressure, while the energy dissipation rate exhibits a quadratic decline as the strain rate increases. The stress-strain curves of FRCTB, under both unconfined and confined conditions, can be subdivided into four and five distinct segments, respectively. Under the lower confining pressure conditions, the fractal dimension exhibits linear growth with the increasing dissipation energy. As the confining pressure increases, this trend gradually transforms into a cubic function. Remarkably, a strong resemblance emerges between the fractal dimension, energy dissipation rate, strain rate, and confining pressure, reflecting the intricate interplay among these crucial mechanical parameters.