| 摘要 |
<p>PURPOSE: To directly measure the amount of soil covering a casing buried in the bottom of the sea by mounting a parametric sound source and an echo sounder receiver on an underwater navigation boat, and moving the boat underwater with specified height kept from the bottom of the sea. CONSTITUTION: An underwater navigation boat 1 has a parametric sound source and an echo sounder receiver 2 mounted on board. The sound source transmits a sound having a secondary frequency between 10kHz and 30kH toward the sea bottom 4, and the echo sounder receiver 2 receives reflected sound pressure along a direction from the sea bottom 4. Then, the boat 1, while being moved along the sea bottom 4 with several meters of height maintained therefrom, is made to probe an area within a plane vertical to the travel direction thereof, and a reflected sound pressure change is measured with the receiver 2. As a result, a cable 5 buried in the sea bottom 4 can be probed with underground transmissibility (approximately 5m underground), a distance resolution of approximately 10cm and a spatial resolution of approximately 10cm, regarding the soft nature of the soil. Also, a stratum near the sea bottom 4 can be accurately probed.</p> |
