| 摘要 |
PURPOSE:To shorten a working time through reduction of an excavating load, by a method wherein small fins are attached to an outer periphery of a forward end part of a casing, and undercut chips are set to an attaching part of a bottom lid and a hook part thereof and in the rotation direction of the casing. CONSTITUTION:A forward end of a casing 1 is brought to a condition that is covered with a bottom lid 2, and a casing 1 is pressed into a ground while it is turning. The inside of the casing 1 is filled with sand through the opening at the upper end of the casing so pressed-in to form a sand pillar. Then, if the casing 1 is pulled off, the bottom lid 2 automatically opens through pressure, and only the sand pillar remains in the ground to form a sand pile. Small fins 5 are projectedly attached on the outer periphery of the forward end of the casing 1 and an attaching part 3 of the bottom lid 2 is attached, whereby the ground is easily excavated by the forward end through the rotation of the casing 1. |
