Influence of Filling Fissure Structure on Coal Rock Strength and Failure Characteristics
Filling fissure structures are commonly occured in coal rock of mines.To study the influence of filling fissure structures on the coal rock strength and failure behaviors,numerical models with different filling fissure widths are established based on the discrete element method.The characteristics of coal rock sample strength,AE count,failure behaviors and others under different filling fissure widths are analyzed.The results show that the crack initiation stress and peak strength of coal rock samples with filling fissures decrease with the increase of filling fissure width,while the peak strain and elastic modulus show a negative correlation trend.The evolution process of acoustic emission in coal rock samples can be divided into a calm period,a steady increasing period,and a peak period,with the occurrence period decreasing with the increase of filling fissure width.Coal rock samples with filling fissures generally initiate cracks at the location of filling fissure particles,and the crack initiation positions are mostly located at the contact position between coal rock particles and filling fissure particles,under low stress levels,it only develops inside the filling fissures with relatively weak attribute.When the width of the filling fissures is relatively small,the crack group inside the fissures cannot connect with the end crack group.When the width of the filling fissures is relatively large,the development degree of the crack group is significantly improved,which affects the final failure mode of the samples.
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