| 摘要 |
<p>PURPOSE:To obtain an usableness even of a boring hole with no water in the hole by an obtainableness of a large vibratory force even by the use of a small boring bore. CONSTITUTION:An elastic material 14 and a plate material 16 are laminated with alternations by ten to several tens of them, a rubber tube 24 is mounted so as to encircle the laminated body 18 and a water filling means into the rubber tube is connected. And a heavy bob 22 is forced to fall from an upper side of the laminated body. For example, at an under side of a cylindrical casing 10 the laminated body is arranged, in the casing a piston material 20 is arranged, and at an upper side of it the heavy bob is arranged. As an elastic material, a wave shaped metal washer or a ring made of rubber and the like is used. In the casing, a heavy bob lifting and holding or releasing mechanism is mounted. A spontaneously falling type may be used, however, a forced fall type wherein a spring mechanism is included is preferable. By an impulsive force caused by a fall of the heavy bob the elastic material is deformed, water in the hole between the plate materials is extruded outward, and an elastic wave is generated on a hole wall 28.</p> |
