| 摘要 |
PROBLEM TO BE SOLVED: To provide a survey method which allows for reliably understanding geological features of a tunnel face at a shield machine even at a depth below a groundwater table.SOLUTION: An elastic wave generated by an oscillator unit 9 propagates along a surface of a tunnel face 13 and reaches a receiver unit 11. The oscillator unit 9 and the receiver unit 11 are positioned to face a same direction. As such, the elastic wave propagating along the tunnel face 13 and received by the receiver unit 11 contains almost no P-wave component. On the other hand, S-wave (e.g. Sv-wave) component is efficiently received by the receiver unit 11 which is pressed against the tunnel face 13 in the same direction as the oscillator unit 9. In short, the receiver unit 11 is capable of efficiently receiving S-waves. Thus, the receiver unit 11 can receive the elastic wave generated by the oscillator unit 9 without being affected by groundwater. |
