| 摘要 |
<p>PURPOSE:To inspect a tunnel structure widely in a nondestructive manner by providing a sweep oscillation circuit for supply to a transmission antenna and an arithmetic means of determining the presence or absence of reflection in respect to a prescribed frequency and a delay time thereof. CONSTITUTION:When the canopy of a tunnel is inspected, a truck 20 is put in the tunnel and a transmission antenna 10 is fixed in a state of being directed to the canopy. With the truck 20 moved along the tunnel, an oscillation frequency of a sweep oscillation circuit 22 is swept and a radar wave is applied to the canopy from the transmission antenna 10. The wave applied to the canopy is reflected by a cavity, underground water or others and a reception antenna 12 receives a direct reflected wave therefrom or a primary reflected wave. The wave received by the reception antennas 12 and 14 is amplified and impressed on arithmetic processing circuits 34 and 36. In the case of observing the whole roughly, an output of the arithmetic processing circuit 36 is subtracted from an output of the arithmetic processing circuit 34 to remove the effect of multiple reflection, and the result is impressed on a video monitor device 40.</p> |
