Influence of water saturation on the strength characteristics and deformation behavior of hardened cement paste backfill

Abstract

In this study, a uniaxial compression experimental was conducted to examine the mechanical properties of hardened cemented paste backfill (CPB) with different water saturations (0.18%, 4.98%, 9.30%, 21.6%, 32.8%, and 100%). The experimental results demonstrated that water saturation loosened the overall structure of the CPB, which led to the deterioration of its mechanical properties. As the water saturation increased, the uniaxial compressive strength (UCS), residual strength, strength difference, deformation modulus, secant modulus, E50 (the secant modulus at 50% of the UCS), peak strain, and elastic strain decreased, while the plastic strain ratio increased. The UCS, E50, and peak strain demonstrated exponential function relationships with the water saturation. After the peak point, when the water saturation was less than 20%, the strength of the CPB decreased rapidly, and when the water saturation was greater than 30%, the strength decreased slowly. Lastly, the plastic strain, the strain at 50% of the UCS, and the strain at the maximum secant modulus conformed to the normal distribution, and the water saturation had a minimal impact on these three strains. The fractal dimension, D, of the cracks in the CPB increased exponentially with increasing water saturation and demonstrated a negative linear correlation with the UCS.

Mechanical properties and mesoscopic analysis of rockbackfill-rock composite sample under dynamic loading

“…For the influence of the interaction between the CPB and the host rock, many researchers have also carried out relevant studies through physical tests and numerical simulations (Tan et al 2020). In most cases, the statics behaviour of CPB and host rock was studied with sublevel open stoping as the research background (Ping et al 2019;Wang & Fu 2021;Wu et al 2013). Ercikdi et al (2009) argue that the dynamic matching design strength of the CPB and host rock must meet the self-stability requirements of CPB and the three-way stress strength criterion under multi-factor conditions.…”