为研究毫秒延时间隔对岩石破碎的影响,利用有限元软件ANSYS/LS-DYNA对露天矿山台阶爆破进行数值模拟研究。微差时间过小,无法形成有效自由面,微小裂纹提前产生导致爆生气体逸出,不利于岩石破碎;微差时间过大,相当于单炮孔起爆,不能够形成叠加的应力场,影响岩石破碎效果。当微差时间为20ms时,所选介质单元应力达到最大,有利于岩石破碎,能够改变爆破效果。现场进行台阶深孔微差爆破试验,使用WipFrag图像分析软件分析评价爆破效果。统计结果表明,爆区岩石尺寸小于下料口筛网尺寸的岩石占整个爆区的93.24%;爆区块度均匀度系数离散性很小,证明岩石破碎块度均匀、整体爆破效果较好。

In order to study the influence of millisecond delay time interval on rock fragmentation, the finite element software ANSYS/ LS-DYNA is used to carry out numerical simulation of bench blasting in open-pit mine. If the millisecond delay time is too small to form an effective free surface, the early generation of micro - cracks leads to the escape of explosive gas, which is not conducive to rock fragmentation. If the millisecond delay time is too large, it is equivalent to a single borehole initiation, which cannot form a superimposed stress field and affect the rock crushing effect. When the millisecond delay time is 20 ms, the stress of the selected medium unit reaches the maximum, which is beneficial to rock breaking and can change the blasting effect. The bench deep-hole millisecond blasting test is carried out on site, and the blasting effect is analyzed and evaluated by WipFrag image analysis software. The statistical results show that the rock size of the blasting area is smaller than the size of the screen mesh, accounting for 93. 24% of the whole blasting area. In addition, the dispersion of uniformity coefficient of blasting block is very small, which proves that the rock fragmentation is uniform and the overall blasting effect is ideal.