Propulsion direction method of detection null of propulsion machine for jacking method

摘要

PURPOSE:To detect the propulsion direction of a propulsion machine through the measurement at one place. CONSTITUTION:When the propulsion direction of a propulsion machine 2 is detected, a receiving coil 9 on the ground is turned around the vertical axis in the state where a coil shaft is set horizontal, and the intensity distribution of the magnetic field 8 supplied from a transmission coil 7 which is received by the receiving coil 9 is measured. The direction of the coil shaft of the receiving coil 9 in the case where the received magnetic field becomes max. and the direction vertical to the coil shaft of the receiving coil in the case where the received magnetic field becomes min. are the propulsion directions of the propulsion machine 2 respectively.