等体积空孔直眼掏槽槽腔形成过程及其分析

Formation Process and Analysis of Cavity by Burn Cut with Equal Volume Empty Hole

在巷道掘进爆破中,空孔能够引起掏槽眼周围应力集中,为槽腔的形成提供自由面。根据空孔效应理论推导出装药孔与空孔之间的距离公式,采用LS-DYNA有限元软件建立数值模型,分析不同直径下的直眼掏槽槽腔的形成过程及有效应力传播规律。模拟得出空孔具有应力波导向作用、产生反向拉伸应力波和应力集中现象,且随着空孔直径的增大作用效果更加明显;四空孔直眼掏槽相比于八空孔直眼掏槽爆破作用形成的裂纹扩展更加丰富,四空孔直眼掏槽空孔直径为八空孔直眼掏槽空孔直径的1.42倍,最大有效应力峰值增长1.2倍。

In tunneling blasting,an empty hole can cause stress concentration around the cutting holes,providing free surface for the formation of the cavity.According to the theory of empty hole effect,the formula of the distance between the charge hole and the empty hole was deduced.The numerical model was established by the finite element software LS-DYNA to analyze the formation process and effective stress propagation law of burn cut blasting cavity under different diameters.The simulation results show that the empty hole presents a guiding effect for stress wave,producing the reverse tensile stress wave and stress concentration,and the effect becomes more obvious with the increase of the empty hole diameter.Compared with the eight-hole burn cut,the four-hole burn cut exhibits more abundant crack propagation.The diameter of the four-hole burn cut blasting is 1.42 times that of the eight-hole burn cut blasting,and the maximum effective peak stress is increased by 1.2 times.