Characterization of acoustic emission parameters and identification of staged fracture propagation in solidified body-coal combination based on experimental and machine learning approaches
摘要
This study is aimed at exploring the instability failure mechanisms and precursory early-warning methods of the solidified body-coal (S-C) combination bearing structure. To achieve this aim, the dynamic response characteristics of multiple acoustic emission (AE) parameters from S-C combination specimens during loading were systematically analyzed through a combination of uniaxial compression experiments and AE monitoring. Furthermore, a crack propagation stage identification model was constructed based on machine learning. The following beneficial findings were yielded: The temporal evolution patterns of energy-frequency distribution indicators (Activity and b-value) and spectral characteristics (average frequency (AF) and risetime/amplitude (RA)), derived from AE time-frequency parameters, are highly correlated with the staged crack propagation behavior, and can be regarded as key precursors of instability in rock-coal combinations. Among the machine learning-based models constructed for identifying the staged fracture propagation states, light gradient boosting machine (LGB) performs the best overall, achieving a prediction accuracy of over 85% across all stages. Such a result verifies the strong characterization capability of fused AE parameter analysis for dynamic fracture evolution. The comprehensive early warning indicator CWI(t) was proposed, and its weight coefficients were optimized by SHapley Additive exPlanations (SHAP) interpretability analysis, which markedly enhances the systematicity and robustness of instability risk assessment. These findings provide both a theoretical foundation and a data-driven method for the stability monitoring and early warning of the S-C combination bearing structure in continuous driving and gangue backfilling systems.