| 摘要 |
PURPOSE:To enable an elastic wave survey on a soft ground by finding the S-wave speed of an elastic wave which is propagated in the ground from the difference in wave front arrival time between two vibration receivers. CONSTITUTION:A clockwise and an anticlockwise shock are applied alternately to the ground through a gear-shaped ring 8 to generate two S waves which are inverted in waveform in the ground. The two elastic waves which are inverted in waveform are detected by the receivers 4 and 5 to confirm that the waves are S waves and also finds the elastic wave speed in the ground from the wave front arrival time difference between the receivers 4 and 5 and the distance between both the receivers 4 and 5. At this time, the measurement signals of the receivers 4 and 5 are contrasted with each other to remove a noise transmitted through a casing pipe 1, etc. While the casing pipe 1 is inserted into the ground, the S-wave speed is found in the depth direction to find the S-wave speed distribution of respective beds in the ground in detail. |
