PURPOSE: To easily drill a large-sized shaft with an excavation service arm by drilling the shaft after having discharged water collected in a guide hole and discharging excavated earth and sand with a bucket without using water required in the prior art drilling method and simplify the structure of a drilling device.
CONSTITUTION: When a large-sized shaft 3 is to be drilled, a small sized-guide hole 4 is drilled at first. A pipe 5 is inserted into this guide hole 4. Then, the water in the pipe is drained. After the removal of water in the pipe 5, an earth and sand discharge bucket 6 is suspended in the pipe 5. The large-sized shaft 3 is drilled by rotating an excavation service arm 22. The excavated earth and sand is forced to drop into the bucket 6. The excavated earth and sand are discharged by pulling up the bucket 6.
TAKEDA KUNIO
TANAKA KIICHIROU
ASADA KENJI
SATO JOJI
HITACHI SHIPBUILDING ENG CO