岩盤内部の音速度の測定と音速度変化に関する基礎的実験
音波による坑内構造周辺の岩石力学的研究 (第2報)
1971 年 87 巻 994 号 p. 7-10
詳細
1971 年 87 巻 994 号 p. 7-10
A sound velocity measurement was successfully carried out on the mine pillar of the Kawayama mine by using the sonic system reported in the 1st report.
report. Besides the field measurement, laboratory tests were performed for gathering informations of the effect of cracks or pressures to the sound propagation velocity in rocks. In the tests, several rock blocks, about 25×20×20 cm in size, were prepared and sound velocities were measured in the perpendicular direction to the applied vertical pressure.
Considerable velocity decreases were observed on the sandstone and taff. Slightly decreasing velocity change was found on the Kawayama phyllite just before its failure. On the Ashio liparite, however, no velocity change was observed up to the failure. Finally, based on the both measurements, a discussion on seismic field study for the state of stresses or cracks of rock around mining openings was done.
