Effect of curing pressure on the stability of bottom cemented paste backfill under different types of barricade

In this paper, a multi-physical field coupling curing experimental instrument was developed to study the effect of curing pressure on the stability of bottom cemented paste backfill (CPB) under two different barricades. The effect mechanism was analyzed by using 5TE, MPS-6 sensor, scanning electron microscope (SEM), and binary processing of SEM images. And then, the strength prediction model of CPB under different curing conditions was established. The findings show that the strength of CPB increases with curing pressure regardless of permeable or impermeable barricade, and the relationship between CPB strength and curing pressure conforms to the law of linear function, and the change law of strength grow rate can also be expressed by a linear function. The curing pressure will accelerate the hydration reaction rate and compress the internal pores of the CPB, making the structure of the CPB more denser, thus promoting the formation of strength. It is worth noting that after the curing pressure was increased to 600 kPa, the strength growth rate of CPB slowed down in the later period, and obvious cracks appeared in the bottom CPB during sampling. The results will be helpful to better consider setting different types of barricade at different stope heights