| 摘要 |
PURPOSE:To measure the length of a steel pipe pile by a system wherein a steel pipe for measurement fitted with an exciting coil and a detecting coil is joined to the upper end of a steel pipe pile buried in the ground and an output of the detecting coil is measured. CONSTITUTION:A sine wave having a frequency of about 10kHz oscillated by an oscillator circuit 1 is amplified by an amplifier 2 and applied to an exciting coil 3 wound on the uppermost part of a steel pipe 8 for measurement, so as to generate an induction field in a steel pipe 8 and a steel pipe pile 7 buried in the ground. An output of a detecting coil 4 wound about 1 meter below the coil 3 is applied to a detecting circuit 6 through a filter circuit 5 which allows only an oscillated frequency component to pass through. The steel pipe 8 has a diameter equal to that of the steel pipe pile 7, and a belt 9 made of steel is wound round on the joint thereof to enhance a magnetic coupling property. The amplified output of the circuit 1 applied to the coil 3 generates the induction field in the steel pipe 8 and the steel pipe pile 7 and around them, and by measuring the strength of the field passing through the steel pipe by means of the coil 4, the length of the steel pipe pile 7 buried in the ground can be determined.
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