The sublevel open stoping with delayed filling mining method has the advantages of large production capacity，high efficiency and low cost，and it is widely used in underground metal mines.However，at the same time，this method has a large amount of blasting charge and poor flexibility in application of the method，which puts forward higher requirements for blasting control.In particular，the cutoff slot blasting to provide the initial free surface and the blasting compensation space for the mining blasting is more important for the successful application of this method.When this type of mining method is used for cutoff slot blasting，it is easily confinement by surrounding rock，which can easily lead to over blasting and under blasting of cutoff slot，or even failure of cutoff slot blasting.The traditional long hole VCR method for cutoff slot blasting is limited by the blasting free surface，and the blasting effect is difficult to guarantee.In view of this problem，this paper taked Xincheng gold mine as the engineering background，analyzed the existing problems of traditional long hole VCR method for cutoff slot blasting，and proposed a new method for large-diameter long hole cutoff slot blasting method without cutting wells.Based on Livingston’s blasting filler theory，combined with the current production experience，the blast hole diameter，hole arrangement parameters，explosive unit consumption，primary blasting height，charge and packing parameters for large-diameter deep hole cutoff slot blasting were calculated.The traditional vertical deep hole retreat blasting method and the“Pin”-shaped retreat blasting method were compared and analyzed. The results show that when the “Pin”-shaped retreat blasting method is adopted，not only the free space in the lower part of the stope is used，but also the advanced free surface and compensation space created in the center due to the “Pin”-shaped layout，which can significantly improve the effect of deep hole blasting without cutoff well.At the same time，in order to improve the blasting effect of the central cut blasting hole，four blasting space compensation blasting holes are set between the blasting holes.Based on the above analysis results，a field industrial test was carried out in the -380 m sublevel of Xincheng gold mine.The blasting height is 3~6 m，the blast hole diameter is 100 mm，the row spacing and hole spacing of the blasting holes are 1.5 m respectively，the distance between the blasting side holes and the blasting boundary is 0.5 m，and the distance of space compensation hole and the blasting hole is 1.0 m，and the thickness of the blasting top is 6.75~12.75 m in the large-diameter deep hole cutoff slot blasting of Xincheng gold mine.The field industrial test results show that the designed caving amount of cutting slot is 4 105 t，the actual ore caving amount is 4 300 t，and the unit explosive consumption is 0.85 kg/t.The shape and size of the open stoping after blasting meet the blasting design requirements.

http://www.goldsci.ac.cn/article/2022/1005-2518/1005-2518-2022-30-4-585.shtml