| 摘要 |
An air-pressure impact type drilling method and an apparatus for the same in which a piston of an air hammer drill is moved up and down by pressure air to produce impact energy and the impact energy of the piston is used to give impact vibrations repetitively to a drill bit. In the air-pressure impact type drilling method and the apparatus for the same, the air hammer drill is operated by the pressure air to be supplied from the ground, the air that has already been used for operation of the air hammer drill is exhausted onto the ground through an air exhaust pipe provided in a drilling pipe and communicating with an air exhaust passage formed in the air hammer drill, and substances cut out by the air hammer drill together with muddy water within the trench are discharged by means of a reverse circulation system while drilling on through the earth. As a result of this, even if the water head pressure acts on the tip end of the drill bit, the pressure of the air for operation of the piston will not be affected by such water head pressure and thus the drilling performance of the air hammer drill will not be ill affected even under the muddy water. |
