| 摘要 |
PROBLEM TO BE SOLVED: To enable a Q-value to be easily measured in-situ by utilizing a vertical array seismograph buried underground and using a frequency-variable vibrator type vibration source installed on the ground surface. SOLUTION: A plurality of vibration receivers 10 are buried underground at different depths respectively as a vertical array seismograph, while a frequency-variable vibrator type vibration source 12 is installed on the ground. Vibrations are generated at different oscillation frequencies of 10 Hz to 50 Hz by the vibration source and received by the vibration receivers. Then, each of vibration reception waveforms is recorded at time intervals of 4 ms or less; the recorded waveform record is Fourier-transformed to obtain an amplitude spectrum; an amplitude spectrum ratio between arbitrary two vibration receivers is calculated; and an attenuation coefficient is obtained by dividing the natural logarithm of the amplitude spectrum by the distance between the vibration receivers. Thus, a Q-value of the ground between the two vibration receivers is calculated from the attenuation coefficient and an elastic wave velocity. COPYRIGHT: (C)2012,JPO&INPIT |
