| 摘要 |
PURPOSE:To make it possible to accurately determine the position of an embedded pipe, by moving a sensor along the ground surface in the manner to make the same to be spaced apart from said groudn surface. CONSTITUTION:Soil is put in a box 6 having a width of about 80cm and a depth of about 90cm so as to reach a depth of about 50cm and, for example, an iron pipe 7 having an outer diameter of 2cm and a length of 90cm is embedded at a position of a depth of about 20cm and an iron pipe 8 having the same dimension is placed on the surface of soil at a position of about 90cm in a horizontal distance from said pipe 7 to be used as an electrode and the output voltage of a transmitter 3 is amplified by an amplifier 9 to be added to both iron pipes 7, 8. A magnetic sensor 10 is connected to an oscilloscope 12 through a filter 11 for removing a noise signal, and the sensor 10 and the amplifier 9 together detect a magnetic field 5 due to the current 4 in an X- direction. When transmission frequency is set to 1kHz and the distance between the sensor 10 and the ground surface is to about 5cm while the sensor 10 is moved to the X-direction and th distance between the sensor 10 and the iron pipe 8 is changed, the voltage shown by the scope 12 shows a constant vale of about 0.2V on the iron pipes 8, 7 and, when the sensor 10 is shifted to the outside of each iron pipe, said voltage is abruptly reduced. Therefore, the position of the embedded iron pipe 7 can be determined. |
