| 摘要 |
<p>PURPOSE:To extend the detection limit distance and facilitate construction by fitting a required number of detecting sensors each constituted of a resonance circuit or a hole element around a spacer side, and allowing them to freely scan via the rotary spacer. CONSTITUTION:Detecting sensors 15a-15l are fitted to angular faces of a 12-side angular face-shaped spacer 14 screwed 13 to the tip section of an underground excavating machine to form a detecting sensor assembly beta', and it is horizontally stored with its front face directed to the tip. The sensors 15a-15l are LCR resonance circuits having the same resonance frequency as the output frequency of a ground transmission AC power source. When an AC current is fed from the ground transmission AC power source to electrodes buried near the excavation start point and the completion point, if a metal buried object having very small inherent electrical resistivity as compared with the electrical resistivity of the ground exists, the current flows in the metal buried object, and the alternating magnetic field is generated around it. When the magnetic lines of force of the alternating magnetic field are extracted by the LCR resonance circuits of the sensors 15a-15l by resonance, the existence of the metal buried object can be detected.</p> |
