岩爆的超声波监测及预测预报方法试验研究

针对岩爆监测研究的不足,开展了完整硬岩岩爆单轴压缩试验及全过程超声波监测,分析了完整硬岩岩爆破坏特征及超声波前兆规律,探讨了完整硬岩岩爆的预测预报。结果表明:对于完整硬岩岩爆,当加载载荷达到其峰值强度便产生噼啪声响,随之发生爆裂,通过分析碎片,发现试样靠近外部区域劈裂现象明显,越靠近试样内部其破裂面的粉化程度越严重,剪切现象越明显,是源于内部被约束程度的增加导致的强烈摩擦作用和高耗能的结果;通过对完整硬岩岩爆全过程超声波监测,发现波速由平稳不变发展到波动状态、首波波幅由微小的起伏波动发展到较大的起伏波动、衰减系数从增加转为下降均可作为岩爆发生的前兆;首波波幅由总体上减小转为明显增加也可作为岩爆发生的前兆,首波波幅由一直减小发展到微小起伏波动可作为岩爆发生的前兆;硬岩超声波频谱图可反映硬岩试样在载荷作用下其内部由变形发展到产生损伤再到破裂随即岩爆的过程。

Experimental research on ultrasonic monitoring and forecast methods of rockburst

With the paucity of research on rockburst monitoring,the uniaxial compression test of the rockburst of complete hard rock was carried out with whole-course ultrasonic monitoring. On this ba-sis,failure characteristics and ultrasonic precursor law of rockburst was analyzed and the forecast of rockburst was discussed. The results have shown that the crackling sound produces when the load reaches its peak intensity and then rockburst of complete hard rock occurs. The analysis of sample de-bris helps find evident splitting phenomenon in the outer region and more serious powder degree of fracture surface and shear phenomenon close to the interior of the specimen, which was the consequence of the strong friction and high energy consumption caused by the increase of internal constraint degree. According to the whole-course ultrasonic monitoring of the rockburst of the complete hard rock, wave velocity develops from stability to fluctuations with the first wave amplitude fluctuating from slightly to violently and the attenuation coefficient from increasing to declining, which can be used as the precur-sor of rockburst; the first wave amplitude changing from the overall decreasing to significantly increase-ing or from continuous decreasing to small fluctuations can also be used as the precursor of rockburst;besides, the process of hard rock specimens rockburst from deformation to damage and fracture and fi-nally burst under load can be reflected by hard rock ultrasonic spectrum.