我矿经过二十五年连续开采，在穿爆过程中，由于种种原因使整个采场不同程度地出现采场底板抬高，最高部位达3m左右。而且在爆破过程中经常产生根底，其主要原因是底板抬高后穿孔深度不够。每年用于二层台根底的穿孔费用这12万元之多。为减少不必要的二次消耗，我们给后孔钻增 After mine continuously mining for twenty-five years, in the process of wearing blasting, due to various reasons, the stope raises the stope to varying degrees in the entire stope and the highest part reaches about 3m. But also in the blasting process often produce the bottom, the main reason is that after the floor raised the depth of perforation is not enough. Each year for the second floor of the perforation costs 120,000 yuan as much. To reduce unnecessary secondary consumption, we drill to the rear hole