Abstract: The geological conditions of the east boundary of the stope of Shuichang Iron Mine is complex,the joint sand fissures are well developed,the pre—spliting blasting quality of the boundary is influenced.Through investigation and analysis of the influence factors of drilling quality and blasting design,the improvement measures are proposed.The blasting quality can be improved by increasing the hole diameter of pre—spliting blasting appropriately,controlling the overdepth of the main horizontal buffer hole reasonably,sub—level drainage pre—spliting blasting,retaining 1~2 empty holes at each end of the pre—spliting blasting area without blasting,cleaning slag blasting and increasing the amount of pre—spliting blasting charge appropriately and reducing the charge of buffer blasting.The results show that half porosity of pre—spliting blasting of L8 drilling machine with 150 mm diameter can be improved to more than 70%,the maximum value is 85％,compared with F9 drilling machine,the hole depth qualified rate,angle qualified rate and half hole rate of the areas with complex geological condition of L8 drilling machine is improved by 10%,7% and 20% respectively,the average half porosity is 65％,the whole blasting quality is improved effectively,the mining cost is reduced significantly,the above study experience can provide some reference for the similar mines.

Key words: Complex geological condition, Pre—spliting blasting, Technical measures