Nonlinear stress growth and failure characteristics of gangue-cemented backfill

Abstract

The stability of a filling body is the main control index of the filling effect, which is significantly affected by the strength and damage characteristics, and its stress increases nonlinearly with damage evolution. In this study, the uniaxial compression test and digital image correlation (DIC) method were used to investigate the stress and damage characteristics of a gangue-cemented backfill, and the stress–strain characteristics and crack propagation laws of the backfill under different curing ages were analyzed. A modified damage model of the gangue-cemented backfill based on the Weibull distribution characteristics of the microelement damage of the backfill and pore closure characteristics in the compression stage was constructed. Through numerical simulations, the nonlinear growth characteristics of stress in the specimen were revealed from the perspective of energy dissipation. The results showed that the nonlinear increase in stress originated mainly from pore closure and crack extension. The crack propagation in the backfill was divided into intermediate crack budding and symmetric crack propagation at the corners. The key signs of the peak stress and fracture of the specimen are the connection of the surface cracks and fracture surfaces on both sides. The proposed modified damage model was proven to be in relatively close agreement with the experimental results. The stress growth in the backfill exhibited a nonlinear-linear-nonlinear growth pattern before the peak stress. This study provides a theoretical basis for studying the strength characteristics and damage evolution of backfill, which is important for optimizing the material proportions and analyzing the stability of the quarry and other aspects.