| 摘要 |
PURPOSE:To easily detect an underground buried material by measuring impedance between a boring rod and the conductive buried material at the time underground drilling such as ground boring or the like. CONSTITUTION:A terminal T1 of a bridge circuit 1 is connected to the drill rod 2 of a boring machine by means of a wiring 3, and the other terminal T2 is connected to a conductive material 4 such as a gas pipe, a water feed pipe or the like buried underground by means of a wiring 5. The wiring 5 connected to the above described terminal T2 is fitted to a part of the buried material exposed on the ground or a connectable part within a manhole. The variation in the impedance when the drill 6 of the rod 2 approaches the buried material 4 is detected by the bridge circuit 1, and an alarm signal or a signal for controlling the boring machine is transmitted. By these procedures, the existance or non-existence of the buried material 4 can be detected prior to the contact of the tip of the drill 6 with the buried material 4. |
