岩爆机理声发射试验研究

STUDY ON MECHANISM OF ROCK BURST BY ACOUSITC EMISSION TESTING

采用单向和三向应力状态下的岩石声发射测试技术,对不同岩性岩石的岩爆机理进行了系统地试验研究。研究表明,强度不同、结构差异、不同岩性的岩石,其在单向和三向应力状态下的声发射特性明显不同,而同种岩性岩石在单轴压缩和围压条件下的声发射特性则极为相似,其声发射特征应力值之间也存在一定的规律性关系,对于强度高的岩石和强度低的岩石这一规律都存在,由此总结出不同岩性岩石在不同应力状态下的岩爆发生特征。试验研究表明,采用岩石声发射测试技术追踪岩爆的产生和发展过程,是进行岩爆机理研究的一种科学、有效的方法。

A detailed experimental research on the mechanism of rock burst of rock with varied properties was conducted by testing technique of acoustic emission （AE） under uniaxial and triaxial stress conditions. The results of research indicate that the characteristics of acoustic emission of rock with different properties, structures, and strengths are obviously different under uniaxial conditions from those under triaxial stress conditions. But those of rocks with same property are very similar, and a regular relation is found between the special stress values of acoustic emission under two types of stress conditions in the rocks with high and lower strengthes. According to the research results, several types of rock burst is generalized, i.e., very strong, strong, middle, weak or so, and so on. First, for some types of rocks with high strength and many tiny cracks just like granite, many centralized AE signals with high frequeny can be got from the compressive test, so the rock burst intensity level of this kind of rock can be classified as middle one. Second, for the rock with high strength and some tiny cracks just like porphyrite, AE signals can only be achieved on the high stress level from the compressison test, so the rock burst intensity level of this kind of rocks can be classified as strong one. Third, for the compact basalt with high strength and few tiny cracks, and the kinds of other rock with the similar structure and mineral, AE signals usually can be found when compression the stress is over 90% of the uniaxial compressive strength of rock; the rock burst intensity level of this kink of rock can be classified as very strong one. Fourth, for the most sedimentary rock with many cracks and pores and middle strength, just like sand rock and conglomerate, the character of AE is that the initial signals usually can be got under the lower compressive stress level; and the frequeny is too lower. So the rock burst intensity level of this kink of rock can be classified as weak or so. From the above-mentioned, another conclusion can be got that testing technique of rock acoustic emission is a scientific and effective method to track the developing procedure of rock burst and to research the mechanicsm of rock burst.