DEVELOPMENT OF LONG-TERM ROCK MONITORING SYSTEM AND ITS APPLICATION TEST

开发岩石长期监测系统及其应用试验是本课题研究的目的。岩石监测采用的方法是探测微尺度裂缝周围发射的声发射信号，利用声发射信号预测岩体的大尺度失稳。首先，我们制作了几个包含运算放大器和高通滤波器的声发射传感器；它们被设计安装在岩体的钻孔中，它们的性能也在实验室进行了测试。通过对三种岩石进行单轴压缩和拉伸，诱发微观裂缝，验证我们的手工声发射传感器能否探测到任何声发射信号，并识别出任何声发射波形和谱的特征。结果发现，有两种类型的声发射信号。其中一个的主要频率在100千赫左右，另一个的低频成分在50千赫左右。然而，我们没有发现声发射特征与破坏模式/岩石类型之间的明显相关性。通过对同类岩石的拉伸试验，发现声发射信号的一个显著特征是高频分量叠加在低频分量上。然而，不可能确定这些信号是否在扩展测试中是固有的。此外，还在实验室进行了源定位试验，以检验监测系统在现场的适用性。最后，在神冈矿业冶炼株式会社的土千博拉矿进行了声发射传播速度和衰减常数的现场测量。位于岐阜县。获得了成功的现场测量结果，验证了所研制的声发射监测系统的可靠性；然而，不幸的是，在现场检查中没有发现自然诱发的声发射。我们希望本文的研究能为岩石长期监测的进一步研究和发展做出贡献。

Development of a long-term rock monitoring system and its application test is the purpose of the present research project. The employed method for rock monitoring is to detect AE signals emitted around micro-scaled fracturing, which can be used to predict a large-scaled instability inrock mass.First, we have made a couple of AE sensors incorporating operational amplifiers and highpass filters ; they were designed to be installed in drilled holes in rock mass and their performances were also examined in the laboratory.Three kinds of rocks were uniaxially compressed and elongated to induce microscopic fractures in order to check whether our handmade AE sensors can detect any AE signals and identify any characteristics of AE wavetrains and spectra. It was found, there were two types of AE signals. One of them has a predominant frequency around 100 kHz and the other one has low frequency components around 50 kHz. We could not find clear correlation between AE characteristics and failure modes/rock types, however. From the tensile experiments on same kinds of rocks, one of distinctive features of AE signals is found to be high frequency components superimposed on low frequency ones. However, it was impossible to identify whether these signals are inherent in extension tests. Moreover, source location tests were also conducted in the laboratory to examine the applicability of the monitoring system in in-situ.Finally, we have had in-situ measurements of propagation velocity of AE and attenuation constant in the Tochibora Mine of Kamioka Mining & Smelting Co.Ltd., in Gifu prefecture. Wecould obtain successful results about field measurements and confirm the reliability of the developed AE monitoring systems ; however, it was unfortunate that none of naturally induced AE were picked-up during the site examination. We hope that the present research may contribute to further investigation and development of long-term rock monitoring.