【摘要】 运用扫描电镜观测了冲击倾向煤破坏断口的微观形貌,分析了煤体受载破坏断面的裂纹、孔隙等缺陷特征及裂纹扩展特征,探讨了煤样破坏裂纹扩展途径及其微观断裂机理.结果表明,冲击倾向煤内部含有大量的孔隙裂隙,在其受载破坏过程中,这些孔隙裂隙均充当了Griffith缺陷,促使大量新裂纹生成和煤样发生破坏.煤样中大量的尖锐孔隙及张性裂隙的微观断面特征表现出冲击倾向煤的脆性特征.由于煤的非均质性及煤样内部应力分布的非均衡性,其裂纹扩展也是不均匀、间歇式的,且裂纹的扩展路线也是曲折的,扩展过程中往往产生分岔、拐折等现象.孔隙、裂纹在应力作用下分岔、扩展、汇合贯通是导致煤体宏观断裂的直接原因.更多还原

【Abstract】 Based on observation results of the micro-topography of impact trend coal fracture surface with SEM method,the characteristics of defect such as pores,cracks and crack propagation in fracture surface of coal samples were analyzed,and the crack growth route and micro-fracture mechanisms of the hard brittle coal were studied.The results show that there are plenty of pores and cracks in impact trend coal,and they act as Griffith defects in the fracture process of coal that advancing the growth of new cracks and fracture of coal samples.The microscopic characteristics of fracture section of plenty of acute pores and tensile cracks indicate the brittle characteristics of impact trend coal.The crack growth in coal is heterogeneous and intermittent for the heterogeneity and non-proportionality of coal structure,and the crack propagation path is flexuose with bifurcation and inflection.The direct reason of the macroscopic fracture of coal is the bifurcation,expand,confluence and connection of the cracks or pores under load.更多还原