DETECTION METHOD AND DEVICE OF EMBEDDED MATERIAL

摘要

PROBLEM TO BE SOLVED: To adjust the lowering pressure of a rotary shaft in order to detect an embedded material without damage thereof when detecting it by the vibration of the cutter edge of a drilling machine. SOLUTION: This detection device of an embedded material is provided with an excavating blade at the front end of the rotary shaft 4 and a cylindrical easing whose lower end peripheral part is shaped to have a corrugated form, below the excavating blade. Vibration resulting from the corrugated form, generated when the lower end peripheral part of the cylindrical casing contacts an embedded material is detected to judge it. A damper 16 against the lowering pressure is provided between the rotary shaft 4 and a boom 3 rotatably supporting the rotary shaft 4. The lowering pressure of the boom 3 is absorbed by the damper 16 and at least the lowering pressure of the rotary shaft 4 can be controlled to make it lower than the breakdown strength of the embedded pipe in the ground, when an abrupt lowering pressure acts on the boom.