DOI: 10.11799/ce202511019
Experimental study on the response of catastrophic mechanical properties of large-size coal under different confining pressures
MA Ji
LIU Dongsheng
REN Jianju
ZHANG Wenlong
KOU Honggang
Abstract：Studying the response mechanism of mechanical characteristics during catastrophic failure of coal is crucial for maintaining mining stability.Using large-size coal specimens as the research subject,conventional triaxial compression tests were conducted to monitor the mechanical behavior of coal under different confining pressures.The conditions and laws of the coal's sub-instability stage were identified,and the failure mechanism of coal under triaxial compression was revealed.The results indicate that the thresholds of the five stages in the complete stress-strain curve increase with rising confining pressure,with peak strain showing a high correlation with confining pressure.The power-law equation provides a good fit for the axial strain rate during the accelerating phase of coal catastrophe.The sub-instability stage only appears when the test environment closely approximates the actual underground conditions of coal.The quasi-static and quasi-dynamic phases account for approximately 37.5%and 62.5%of the total sub-instability time,respectively,with more intense evolution of stress and radial strain occurring during the quasi-dynamic phase.Residual strength is more sensitive than peak strength,and the strength attenuation coefficient gradually decreases as confining pressure increases.Coal failure is predominantly shear-based,accompanied by tensile failure,with varying crack widths at different locations.
Keywords：rock mechanicscomplete stress-strain curvesub-instabilitycatastrophic precursorsmechanical characteristics
Publication Date：2025-11-20
Online Publishing Date：2026-01-15(First online date of this platform, not the publication date of the document)
Pages：8( 150-157 )