| 摘要 |
PURPOSE:To make it possible to apply an underground drilling machine to the boring of a tunnel including curved portions by providing plural magnetism generating elements inside the underground drilling machine and detecting magnetism generated by the element by magnetism detecting elements provided in a truck on the ground. CONSTITUTION:Magnetism generating elements 1, 1 are supplied with signals from a signal supply device 19 through a cable for transmitting signal 18. On the other hand, magnetism detecting elements 7-1-7-8 are independently connected to a receiver 21 through signal cables 20 respectively, and the strength of a signal of each element is compared by a signal comparator 22. A measuring truck 8 is moved in the direction of a magnetism detecting element of which reception level is highest. By repeating these steps, it is possible to determine that the horizontal position of the magnetism generating element 1 (or 1'), in other words the horizontal position of the underground drilling machine 6, is directly below a point where the strength of received signal of all the magnetism detecting elements 7-1-7-8 becomes equal. |
