| 摘要 |
The present invention relates to a drilling method of a reverse circulation drilling machine and, more specifically, to the drilling method of the reverse circulation drilling machine capable of drilling a deep portion by preventing a pressure decrease. The drilling method of the reverse circulation drilling machine according to one aspect of the present invention performs a first drilling step which drills at a predetermined depth with a drill bit fixed to one end portion of a chamber type drill rod pipe to be detached after assembling drill rod pipes of a large diameter in a row between the chamber type drill rod pipe on which a power swivel and an air chamber are formed. Thereafter, the drill rod pipes of a large diameter are separated after drilling at a predetermined depth, and the drill bit is lifted. Drill rod pipes of a small diameter are assembled in a row between the chamber type drill rod pipe and the drill bit after separating the drill bit from the chamber type drill rod pipe. After assembling the drill rod pipes of a small diameter, a second drilling step which drills deeper than the predetermined depth with the drill bit by assembling the drill rod pipes of a large diameter in a row between the power swivel and the chamber type drill rod pipe is performed. According to the present invention, the drilling method of the reverse circulation drilling machine is provided to drill bedrock at a deep depth by utilizing the drill rod pipes of a small diameter at pressure identical to pressure actuated on the drill rod pipes of a large diameter without increasing pressure as the drill rod pipes of a large diameter are utilized for drilling at a predetermined depth, and the drill rod pipes of a small diameter are utilized for drilling a depth deeper than the predetermined depth. |
