High strain rate compressive strength behavior of cemented paste backfill using split Hopkinson pressure bar

Abstract

The stability of cemented paste backfill (CPB) is threatened by dynamic disturbance, but the conventional low strain rate laboratory pressure test has difficulty achieving this research purpose. Therefore, a split Hopkinson pressure bar (SHPB) was utilized to investigate the high strain rate compressive behavior of CPB with dynamic loads of 0.4, 0.8, and 1.2 MPa. And the failure modes were determined by macro and micro analysis. CPB with different cement-to-tailings ratios, solid mass concentrations, and curing ages was prepared to conduct the SHPB test. The results showed that increasing the cement content, tailings content, and curing age can improve the dynamic compressive strength and elastic modulus. Under an impact load, a higher strain rate can lead to larger increasing times of the dynamic compressive strength when compared with static loading. And the dynamic compressive strength of CPB has an exponential correlation with the strain rate. The macroscopic failure modes indicated that CPB is more seriously damaged under dynamic loading. The local damage was enhanced, and fine cracks were formed in the interior of the CPB. This is because the CPB cannot dissipate the energy of the high strain rate stress wave in a short loading period.