充填裂隙结构对煤岩强度及破坏特征的影响

Influence of Filling Fissure Structure on Coal Rock Strength and Failure Characteristics

矿井煤岩中常赋存充填裂隙结构,为研究充填裂隙结构对煤岩强度和破坏行为的影响,基于离散元方法建立不同充填裂隙宽度的数值模型,分析了不同充填裂隙宽度下煤岩试样强度、AE计数和破坏行为等特征。结果表明:含充填裂隙煤岩试样起裂应力和峰值强度均随充填裂隙宽度增加而降低,峰值应变和弹性模量表现为负相关趋势;煤岩试样声发射演化过程可划分为平静期、平稳递增期和峰值期,出现时期随充填裂隙宽度的增加而减小;含充填裂隙煤岩试样一般由充填裂隙颗粒处起裂,且起裂位置大多位于煤岩颗粒和充填裂隙颗粒间的接触位置,在低应力水平下仅在属性较弱的充填裂隙内部发育;充填裂隙宽度较小时,裂隙内裂纹群不能与端部裂纹群贯通,充填裂隙宽度较大时,裂纹群发育程度显著提高,并影响试样最终破坏模式。

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.