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.

An experimental study on the spatial distribution of the focuses of acoustic emissions of Inada granite (coarse grained granodiorite) under triaxial compression is reported in this paper. It is pointed out that AE locations is fractal with a dimension of 2.2 in average,lower than the result of Oshima granite (fine grained granodiorite),which is 2.7,under similar deformation condition. For Inada granite a band-limited fractal had been observed. Fractal dimension changed around grain size of the rock (R_C=5mm) Fractal dimension D_s and D_l (below and above the grain size,respectively) had different developing tendency. D_s and D_l can be considered as indicators of the inhomogeneity of stress field in corresponding scale.