| 摘要 |
<p>PURPOSE:To accurately detect the position of an embedded joint on the basis of the intensity change of a large magnetic field equal to or more than a set value by measuring the intensity change of a magnetic field in the longitudinal direction of an embedded metal pipe by the detector from the ground. CONSTITUTION:An AC power supply 10 is connected to an electrode rod 8 and earthed to generate a magnetic field from an embedded metal pipe 1 and a detector 2 is moved in the longitudinal direction of the embedded metal pipe 1 on the ground and the intensity change of the magnetic field is quantitatively measured in the longitudinal direction of the embedded metal pipe 1 by the detector 2. Then, it is judged that the joint of the embedded metal pipe 1 is present at a place where the intensity of the magnetic field in the longitudinal direction of the embedded metal pipe 1 is a set value or more on the basis of the measured result of the intensity density of the magnetic field and a measuring position. By this constitution, the position of the embedded joint is accurately detected and the digging-out of the embedded joint can be executed inexpensively and rapidly.</p> |
