| 摘要 |
<p>PURPOSE:To accurately and easily made a survey by sending a P wave, an S wave, and a Rayleigh wave into the ground from oscillators for the P wave, S wave, and Rayleigh wave which are provided on the front surface plate of a shield main body. CONSTITUTION:The vibration generator (oscillator) 5 which generates the Rayleigh wave B (surface wave) is provided nearby the center of the surface plate 2a of a cutter head 2 and at least two hydrophones 6 which detect the underground transmitted wave of the Rayleigh wave generated by the vibration generator are provided nearby the vibration generator 5 at a specific mutual distance. The Rayleigh wave which is sent into the ground from the vibration generator 5 reaches the closer hydrophone 6 first and then the farther hydrophone 6B. For the purpose, the Rayleigh wave detection time difference between the hydrophones 6A and 6B is measured to calculate the Rayleigh wave speed, and consequently the soil structure, obstacle, cavity, etc., of the front ground are investigated.</p> |
