| 摘要 |
PURPOSE:To increase the degree of accuracy of measurement by using transmitting coils provided to a segment to generate a magnetic field and a receiving sensor suspended to a measuring hole bored in the direction of the segment to detect the slippage. CONSTITUTION:Grid-transmitting coils 4 are provided to the peripheral surface of the upper part of a segment 2 lining the internal wall of a tunnel, and a receiving sensor 6 is suspended to a measuring hole 10 bored in the direction of the segment 2 perpendicularly from the ground. After that, an AC power supply 5 is applied to the transmitting coils 4 to generate the magnetic field, it is received by the receiving coil 6, when there is slippage in the center 01 of the sensor 6 against the center 0 of the coil 4, the slippage delta is calculated from the difference of the value of induced electromotive force generated in receiving coils 6a and 6b in accordance with the slippage delta, and a position of a shield excavator 1 antecedent to the segment 2 is detected from the slippage delta. According to the constitution, high degree of accuracy of position detection can be made. |
