| 摘要 |
PROBLEM TO BE SOLVED: To reliably and easily inspect the back face of a lining. SOLUTION: The value of the transfer function which is the ratio of the first physical quantity to the second physical quantity to be received by a first geophone 6 and a second geophone 7 is calculated by using the first geophone 6 to be joined with the surface side of a lining layer 2 which is a surface side layer of a laminar structure, the second geophone 7 joined with its surface side, and an exciter 5 to give the vibration of low frequency less easily influenced by the physical properties of the lining layer 2 to the lining layer 2. The first physical quantity and the second physical quantity are expressed in terms of the function of the low frequency ω, and in particular, the phase velocity CR is obtained, and a flaw in a back face layer can be clearly detected from the comparison with the reference value. |
