Effect of prefabricated flaw angle on the mechanical properties and failure characteristics of stratified cemented tailings backfill

Abstract

The process of exposing stratified cemented tailings backfill (SCTB) underground is prone to damage due to blasting disturbances. To investigate the effect of flaws on the mechanical properties and failure characteristics of exposed SCTB, prefabricated flaws were used to simulate blasting damage. In this study, a uniaxial compression test, based on the digital image correlation (DIC) method, was used to investigate the mechanical characteristics of SCTB under different flaw dip angles. Additionally, the Particle Flow Code program was used to analyze the propagation of secondary cracks. The results show that: (1) With an increase in the flaw angle, the uniaxial compressive strength (UCS) of SCTB samples exhibit an initial decrease followed by an increase, and the elastic modulus of SCTB samples exhibit an increase. (2) When the flaw angle is between 0° and 45°, wing cracks and resistance tensile cracks mainly develop at the end of the flaw. For flaw angles between 60° and 75°, coplanar secondary cracks form at the end of the flaw and penetrate the stratified surface. (3) There are three main forms of crack propagation at the stratified surface: cracks passing through the stratified surface without deflecting, cracks deflecting at the stratified surface, and cracks that do not penetrate the stratified surface. (4) When cracks pass through the stratified surface without deflecting, the X-direction stress on both sides of the stratified surface changes synergistically, resulting in a large stress value. When the crack propagation direction deflects at the stratified surface, the X-direction stress differs on both sides, with smaller stress observed on the side away from the flaw. The larger the deflection angle of the crack propagation, the smaller the X-direction stress on the side away from the flaw. These results provide a basis for the stability evaluation and strength design of SCTB with flaws.