浮石検査に関する基礎研究

抄録

Generally, we detect or judge loose part. of rock by means of hearing the sound in the air originated by knocking the rock with hammer, but the results is not so reliable. The sound originated by knocking the rock with hammer would propagate in the air and rock.
This study is concentrated to clear the difference of these sounds according to the loose conditions of rock. There is little difference between the waveform of sound in the air originated by knocking the loose and crackless part of rock, but the waveform of sound in the rock has great difference according to the loose conditions of rock. Waveform of sound in the rock at the crackless part of rock is characterized by quickly weakening high frequency wave, i. e., 5, 000cps weakening its strength by 50% in 1/2, 000-1/3, 000sec. On the other hand, the sound in the rock at the loose part of rock contains the same high frequency wave as the case of the crackless part of rock in the very early part of the vibration wave, but it is followed by unique lower frequency wave, i. e., 10C-300cps decaying its strength rather slowly by 50% in 1/30-1/50sec.
In this regard, it can be said that the sound propagated in the rock is more dependable than that of in the air to make the practice of detecting loose part of rock more usefull.