UNDERGROUND DRILLING DEVICE AND METHOD

摘要

PROBLEM TO BE SOLVED: To provide an underground drilling device and method whereby an increased diameter part can be surely formed in an underground hole. SOLUTION: A cylinder 10 is attached to the shaft 2 of a screw shaft. To drill an underground hole, a claw 13 is kept inside a cylinder case 11. To form an increased diameter part in the underground hole, the pawl 13 is projected from the cylinder case 11 and the increased diameter part is formed by the pawl 13. The increased diameter part 21 can be surely formed by causing the pawl 13 to move in and out.