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The 60 double drill bit is installed at the lowest end of the drill pipe. The top of the drill bit is inlaid with alloy to facilitate the drilling of the drill pipe. Two nozzles are installed on both sides of the cylinder of the drill bit. The diameter of the nozzles is between 1.6~3.0mm. Annular gas nozzles are installed around the nozzles to ensure the coaxial injection of slurry and gas. After some soft geological structures are emptied to the bottom, it is not necessary to replace the drill bit, and the rotary jet can be slowly lifted to improve the work efficiency.