岩石构造对声发射统计特征的影响

EFFECT OF ROCK STRUCTURE ON STATISTIC CHARACTERISTICS OF ACOUSTIC EMISSION

利用一套最新型的全波形、宽动态声发射观测系统,对两种不同构造的花岗岩在三轴压缩变形实验中的声发射活动进行了对比研究。二者在声发射空间分布,声发射与体积扩容的对应关系,声发射频谱特征及频度能级统计参数等方面均有明显差异。这表明,岩石构造对声发射的基本统计特征有显著的控制作用。其原因在于岩石构造的差异造成变形方式和变形过程的不同。

A comparative study on acoustic emission during deformation of two kinds of granites with different structures under triaxial compression is performed by using a new acoustic emission recording system with fullwaveform record and broaddynamic range. One is Inada aplitegranite of homogeneous structure from Japan and the other is Mayet granite with cemented natural joints from France. For the former granite, acoustic emission events are dispersed randomly and there is no clearly clustering along the major fracture. For the latter granite, acoustic emission events are mainly concentrated nearby the joint. Acoustic emission events occur synchronously with the volumetric dilatation in the former one but far earlier than the volumetric dilatation in the latter one. The two kinds of granite are also clearly different in the frequency spectrum of acoustic emission. The former has narrower frequency band and more highfrequency component, while the latter has wider frequency band and generally lower frequency spectrum. In frequencyenergy relation, the number of acoustic emission events in the former shows a welllinear progressive relation from highenergy level to lowenergy level and it shows an apparent intermittent or nonlinear variation in the middlehigh energy interval, with higher proportion of large events. It indicates that the rock structure has an apparent controlling role in the basic statistic characteristics of acoustic emission events. The cause for the phenomena may be that the different rock structures result in different deformation modes and processes.