| 摘要 |
PROBLEM TO BE SOLVED: To enable the detection of the state of failure, etc., in a water-shielding sheet with ease. SOLUTION: In a detecting device of the state of a water-shielding sheet 1, a large number of ultrasonic generators 2 and ultrasonic receivers 3 are installed in the periphery of the water shielding sheet 1, and ultrasonic waves are transmitted all over the water-shielding sheet 1 by the ultrasonic generators 2. Ultrasonic waves propagated through the water-shielding sheet 1 are received by the ultrasonic receivers 3 located point-symmetrically. Received signals are analyzed to detect the state of the water-shielding sheet 1. |
