Research on the damage characteristics of macro and microscopic scales of a loaded coal under uniaxial compression
The macro damage and failure characteristics of coal are fundamentally determined by the mechanical behavior of its micro components and defect structures.This study analyzes these characteris-tics through uniaxial compression experiments and PFC numerical calculations.Based on the Weibull probability distribution function,a macro-micro damage constitutive equation for coal is established.The research findings indicate that the uniaxial compression process of loaded coal can be divided into three phases:initiation,propagation,and evolution of microfracture structural units,characterized by acciden-tal AE signals,development,and peak stages.During the yield stage,the acceleration of the internal damage rate in loaded coal leads to an increase in AE cumulative event variance and autocorrelation coef-ficient,enabling prediction of the future damage process during loading.The research findings also dem-onstrate that the application of external loads leads to continuous expansion and evolution of internal mi-cro-crack structural units,exhibiting clear macroscopic damage and failure characteristics.Additionally,the preparatory,initiation,development,and cessation stages of damage and failure in the loaded coal mass are proposed by drawing an analogy to the process of coal and gas outbursts.
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