Evolution of acoustic emission and failure precursor characteristics of Malan loess under uniaxial compression

Li Yanrong; Wang Zhibin; Sun Xiaohui; He Shengdi; Zhao Jianbo

doi:10.16186/j.cnki.1673-9787.2024010067

Abstract：Objectives This study aims to identify effective precursor signals during the deformation and fail-ure process of Malan loess under uniaxial compression.Methods Uniaxial compression tests were conducted on Malan loess specimens.Stress-strain data and acoustic emission(AE)signals were collected throughout the deformation and failure process.The evolution of AE characteristics under compressive loading was ana-lyzed.Results Distinct AE signals were observed during the failure process of dry Malan loess,with AE ringing counts corresponding well to different deformation stages.As moisture content increased,the regu-larity of AE signals gradually weakened.Under dry conditions,AE ringing counts increased sharply near peak strength,with peaks occurring immediately prior to specimen failure.This indicates that AE anoma-lies precede axial strain and can serve as early warning indicators for loess failure.The distribution of AE RA(rise time/amplitude)and AF(average frequency)values reflected crack propagation modes,with shear failure being the dominant mechanism.Before reaching peak strength,both AE fractal dimension and b-value dropped significantly;high-frequency components disappeared,while low-frequency and high-energy signals increased and shifted markedly toward lower frequency bands.These observations reflect an evolution from small-scale microcracking to large-scale macro-fracture during the compression failure pro-cess of Malan loess.Conclusions Key precursor indicators for failure in Malan loess include:a peak in AE ringing counts,a sudden drop in fractal dimension and b-value,and a spectral shift characterized by the disappearance of high-frequency and emergence of low-frequency AE signals.These features can be used for early detection and prediction of failure in loess under compression.