Experimental study on the macro-micro failure mechanism of inclined layer-cutting coal-rock composite structure under different cyclic stresses
PENG Rui
SHEN Chunyang
LIU Jiang
YANG Xuehong
ZHENG Di
Abstract：With the increasing intensity of deep coal resource extraction,the stability of interbedded roadways has become a critical concern.This study focuses on coal-rock composite structures with varying dip angles(0°,10°,15°)from the Xiaoyun Coal Mine in Shandong Province.Two cyclic loading-unloading paths—constant lower bound(Path I)and variable lower bound(Path Ⅱ)—were designed to simulate static and dy-namic stress conditions,respectively.Mechanical behaviors,acoustic emission(AE)signals,energy dissipation,and microstructural damage evolution were systematically investigated using AE monitoring and scanning electron microscopy(SEM).The key findings are as follows.The cyclic stress paths significantly affect mechanical prop-erties.Cyclic loading paths exert a pronounced influence on mechanical properties.Path Ⅱ induces enhanced compaction effects through dynamic stress perturbations,resulting in significantly higher peak stress and strain compared to Path I.Mechanical degradation correlates with dip angle.The peak strength of 0° specimens ex-ceeds that of 15°specimens by 58.8％,accompanied by a marked reduction in hysteresis loop area,indicating di-minished energy dissipation efficiency and heightened brittle fracture.AE characteristics exhibit dip angle de-pendency.The peak AE ringing counts for 0°specimens are approximately 50％higher than those of 15°speci-mens,with AE events concentrated along coal-rock interfaces for low-angle specimens,while localized failure dominates at higher angles.Microscopic analysis reveals reduced ductile dimples and increased brittle fractures with higher dip angles.The fractal dimension under Path I(2.31)is 8.9％,which is higher than thar under Path Ⅱ).It reflects more intricate crack networks under constant lower bound conditions.This research eluci-dates the synergistic effects of dip angle and cyclic stress paths on failure mechanisms,which will provide theo-retical insights for stability assessment and dynamic hazard mitigation in deep interbedded roadways.
Keywords：cross-layer roadwaycyclic loading-unloadingacoustic emissionscanning electron microscopyfractal dimension
Publication Date：2025-06-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 1-11 )