Monitoring the failure process of cemented paste backfill at different curing times by using a digital image correlation technique

Understanding the mechanical properties and failure process of cemented paste backfill (CPB) is fundamental for the backfill design in underground mining. In this research, physical and mechanical tests were conducted on CPB having different hardening times. The volumetric water content (VWC) was used to reflect the CPB hard -ening process because it is a confirmed controlling variable that strongly correlated with the peak strength, brittleness index and maximum strain at fracture initiation. Moreover, the deformation behavior, fracture development and failure pattern of CPB having different curing times were observed by using a digital image correlation (DIC) technique. The experimental results suggest that the fracture development can be divided into four stages, the gestation, initiation, propagation and coalescence of fractures. The failure pattern changed from shear to tensile-shear composite and finally to tensile failure as the water content decreased. The results contribute to better understanding the time-dependent mechanical behavior of CPB after it is back-filled into underground stopes.

Automated summary

This study investigated the mechanical properties and failure process of cemented paste backfill (CPB) with different hardening times. The experimental results showed that the hardening process of CPB is closely related to peak strength, brittleness index, and maximum strain. Furthermore, the fracture development of CPB can be divided into four stages, and the failure pattern changes as the water content decreases.