Investigation of static mechanical characteristics and numerical simulation of fractal gangue cemented backfill materials

Abstract

This study investigated the static mechanical responses of gangue cemented backfill materials (GCBM) with aggregate particle size distribution (APSD) satisfied fractal grading theory. The recycling of gangue in GCBM alleviates gangue accumulation pollution and improves mining production efficiency. Macroscopically, uniaxial compression experiments regarding various loading strain rates (ε̇) on gangue cemented backfill specimens (GCBS) were conducted. Acoustic emission monitoring and digital image correlation technique were employed to reveal crack activities and strain field evolution in real time. Microscopically, scanning electron microscopy and numerical specimens considering APSD were utilized to analyze the microstructure and damage process. The deterioration mechanisms and quantified number of cracks were explored at the micro level. The conclusions are as follows: (1) The axial stress (σ) of GCBM increased with fractal dimension (D) of APSD and ε̇. For the same σ, cumulative AE counts decreased with increasing ε̇ and D. (2) The main failure mode of the GCBS under static loading was tensile failure, exhibiting tensile cracks initiating at the bonding–aggregate interface. (3) The increase in the proportion of fine aggregate contributed to the optimization of the microstructures of the GCBS (4) An increased proportion of fine aggregate in the GCBS improved the synergistic load-bearing capacity between the cementing and aggregate mediums, leading to an enhancement in the σ.