Acoustic emission and crack evolution characteristics of cemented tailings backfill under different loading rates

YIN Shenghua; ZHOU Yun; YANG Xiaobing; CHEN Wei; CHEN Junwei

doi:10.12438/cst.2025-0299

Abstract：To investigate the dynamic regulation mechanism of loading rate on crack evolution in cemented tailings backfill(CTB),uniaxi-al compression tests with acoustic emission(AE)monitoring were conducted at loading rates v of 0.002,0.004,0.008,and 0.010 mm/s.By analyzing the time-varying characteristics of AE parameters,including ring count,average frequency AF,rise time-amplitude ratio RA,and r-value(RA/AF),and applying unsupervised clustering to RA-AF datasets using Gaussian Mixture Model(GMM)combined with a moving average filter,crack types and their evolution patterns were identified.The results indicate that:①Near peak stress,AE ring counts of CTB exhibit interval oscillations.With increasing loading rate,the fluctuation amplitude of ring counts during elastic and plastic yield stages decreases.②As the loading rate increases from 0.002 to 0.010 mm/s,the concentrated range of AF distribution exhibited a progressive compression from 0-150 kHz to 0-100 kHz,while the RA distribution range expanded from 0-5 ms/V to 0-10 ms/V,with high-RA signals concentrated in the narrow band of AF<80 kHz.③The increase in loading rate significantly affects the post-peak failure mode:the proportion of shear cracks rises sharply from 19.11%(v=0.002 mm/s)to 64.23%(0.010 mm/s),indicating a shift in fail-ure mechanism from tensile-dominated to tensile-shear composite failure.④Based on stress stages,GMM clustering divides crack evolu-tion into four phases:tensile crack dominance(0-20%σf),tensile-shear crack transition(20%σf-80%σf),rapid shear crack growth(80%σf-100%σf),and tensile-shear co-dominance(post-peak failure).Among them,the rapid increase in shear cracks at 80%-100%of peak stress is identified as a precursor to localized instability.This study provides theoretical support for stability analysis and failure pre-diction of CTB.