Experimental study on bearing failure bedding effect of coal seam boreholes in true triaxial environment
In order to explore the influence of bedding on the dynamic failure characteristics of coal seam boreholes in true triaxial environment,the single-sided visual true triaxial test instrument of coal and rock mass was used to carry out the bore-hole bearing failure test of bedding coal seam,and the research was carried out combined with the digital image correlation and acoustic emission analysis method.The results show that the failure of sample can be divided into three stages.In stage Ⅰ,the shear strain is concentrated at the edge of analysis region,the hole wall fracture is accompanied by coal particle ejec-tion,and the cumulative number of acoustic emission events and energy activity are low;In stage Ⅱ,the shear strain field around the borehole is in the shape of butterfly,the coal fragments on both sides of borehole wall are ejected,and the coal blocks peel off,presenting V-shaped failure,and the cumulative number of acoustic emission events and energy activity are high;In stage Ⅲ,the shear strain is concentrated at the bedding of sample,and the macroscopic shear cracks appear,which presents the characteristics of arch distribution,and the cumulative number of acoustic emission events and energy activity are strong.The research results are of reference significance for the study of borehole pressure relief mechanism.
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