Mechanical properties and acoustic emission response of cemented tailings backfill under variable angle shear

Abstract

To investigate the mechanical properties and acoustic emission (AE) response of cemented tailings backfill (CTB) under the action of compression–shear, 30°, 45°, and 60° variable angle shear tests (VAST) were conducted. Based on the stress–strain law and AE parameter characteristics, the rupture law of the CTB with different shear angles was analyzed. The evolution of the fractal dimension (FD) and b-value and the relationship between them were investigated. The results indicate the following: (1) With increasing shear angle, the peak stress and normal stress show a decreasing trend, the plastic yield stage shortens or disappears, and damage evolution is accelerated; with a shear angle greater than 45°, the specimen deformation and damage mode change. (2) The AE ringing counts and energy evolution at 30° and 45°, and the ringing count evolution at 60° show an inverted U-shaped distribution; the energy evolution at 60° shows a stepped distribution. As the shear angle increases, the active and decline periods move rearward, and the proportion of ringing count and AE events before peak stress decreases. (3) With increasing shear angle, the crack evolution mode of the specimen changes from intermittent local failure repeatedly to progressive expansion. The fracture evolution is a dimensionality reduction and an orderly process; before failure, crack development is a process from disorder to order, producing a state in which large-scale crack propagation stabilizes and small-scale cracks expand. The conclusion provides a basis for analyzing the rupture evolution of CTB under different compression–shear angles and provides a reference for the stability analysis of CTB backfilled goaf.