露天矿山台阶爆破合理微差时间优选及应用

Optimal selection and application of reasonable millisecond delay time for bench blasting in open-pit mines

为了降低露天台阶爆破后的岩石块度,减少二次破碎成本,根据杨家岭矿山的实际地质情况建立有限元模型,研究了微差时间对岩石损伤程度的影响,分析了关键测点随延期时间变化的规律,最后开展现场试验并利用块度分析软件WipFrag4.0对爆后岩石进行块度分析。结果表明:随着微差时间的增加,岩石的损伤程度先增加后减小,在孔间、排间微差时间分别为40、70 ms时,岩石的损伤程度达到最大;通过在现场开展爆破试验发现,在孔间延期时间为35、40 ms,排间延期时间为65、70 ms时,块度主要集中在10 cm处,块度大于31.6 cm的占比分别为21.26%、23.19%,明显小于其他方案;分析后发现爆后块度分布规律与数值模拟得到的岩石损伤程度变化规律具有较好一致性,验证了数值模拟的准确性;通过数值模拟岩石损伤程度的量化与现场爆破试验相结合,为后续研究岩石损伤提供新思路。

In order to reduce the rock fragmentation after open-pit bench blasting and reduce the cost of secondary crushing,a finite element model is established according to the actual geological situation of Yangjialing Mine.The influence of millisecond delay time on the degree of rock damage is studied,and the variation laws of key measurement points with delay time are analyzed.Finally,on-site experiments are conducted and the fragmentation analysis software WipFrag4.0 is used to analyze the rock fragmentation after blasting.The results show that with the increase of the millisecond delay time,the damage degree of rocks first increases and then decreases.When the millisecond delay time between holes and rows is 40 ms and 70 ms,respectively,the damage degree of rock reaches the maximum.Through onsite blasting tests,it is found that when the delay time between holes are 35 ms,40 ms,and the delay time between rows are 65 ms,70 ms,the block size is mainly at 10 cm,and the proportion of blocks larger than 31.6 cm is 21.26%and 23.19%,respectively,which is significantly smaller than other schemes.After analysis,it is found that the distribution law of the block after blasting is in good agreement with the change law of the rock damage degree obtained from the numerical simulation,which verifies the accuracy of the numerical simulation.Through the combination of numerical simulation of rock damage degree with field blasting test,a new idea is provided for the follow-up study of rock damage.