软分层厚度对煤体爆破致裂效果的数值模拟

Numerical simulation of the effect of soft stratification thickness on blasting cracking of coal

根据煤体爆破致裂理论,结合工程实际,建立ANSYS/LS-DYNA有限元模型,研究了软分层厚度变化对含软分层煤体的致裂规律。结果表明:软分层改变了煤体内部裂纹扩展的方式和规律,导致上部硬煤层裂隙增多,下部硬煤层裂纹数量、扩展长度及分布集中度降低;软分层厚度变化只影响下部硬煤层的裂隙分布、裂隙集中度及裂隙贯通面积,对上部硬煤层几乎没有影响;拟合出了软分层厚度与峰值压力之间的关系曲线,结合致裂理论,可以估算出含软分层煤体致裂区域,为评估含软分层煤体致裂效果及有效治理瓦斯提供参考。

Based on the cracking theoretical of coal blasting and combined with the engineering practice,ANSYS/LS-DYNA finite element model is established.The influence of the change of the thickness of the soft stratification on the cracking of coal is mainly discussed.The results show that soft stratification changes the way and law of crack propagation in coal body,which leads to the increase of crack in upper hard coal seam and the decrease of crack number,expansion length and distribution concentration in lower hard coal seam.The variation of soft stratification thickness only affects the fracture distribution,fracture concentration and fracture connectivity area of hard coal seam,and has little effect on the upper hard coal body.The relation curve between the thickness of soft stratification and the peak pressure is fitted.Combined with the crack theory,the crack initiation region of stratification layer coal body can be estimated,providing a reference for evaluating the crack initiation effect of soft stratification coal body and effective gas control.