Abstract: The waveform of AE(acoustic emission)events during rock friction has been studied.112large AE events through AE transducers attached along the faults have been recorded by a multi-channel digital recording system.The Doppler effects are evident by the waveforms of large AE events. For example,the firsthalf cycle of acoustic wave at AE transducers 1～3 is longer and at AE transducers 4～6 shorter.So it is shown that the displacement propagates in direction from AE transducer 1 to AE trans-ducer 3 with a dimension of 5.1 cm.The first phase(fore-excitation wave),source spreadingphase and stopping phase can be easily distinguished from the waveform of AE events.The ve-locity of fore-excitation wave and stopping phase is the same as P-wave. According to the break-ing phase recorded in different channels the breaking velocity of AE source increases from 0km/sto 2.62 km/s.It shows that the large AE events have an accelerating breaking process.The waveform of different events in a sequence of AE events changes with time,In earlystage the amplitude of fore-excitation wave is smaller and the difference in arrival time betweenfore-excitation wave and stopping phase is larger,the stopping phase is ambiguous and the break-ing velocity of AE source is low(1.6 km/s).Then the amplitude of fore-excitation wave increas-es gradually,the difference in arrival time between fore-excitation wave and the stopping phasebecomes smaller and the stopping phase is obvious.At the same time,the breaking velocity of AEsource reaches about 2.62 km/s.After that the first wave is overlapped by a large special phasewith higher frequency.This shows that the displacement process along a single fault is a complexprocess.

Key words: Acoustic emission, Doppler measurement, Seismic phase, Rock frictional test

摘要： 在双剪摩擦滑动实验中可观测到声发射的多普勒效应。对于单个声发射事件,顺断裂扩展方向上的探头可记录到较短周期的初动波半周期,而在断裂扩展反方向上的探头记录则反之,在扩展过程中,声发射前续波由初始破裂引起的前激波、声源破裂扩展的扩展相和停止相组成,显示出声源破裂有一由静到动的加速过程。而在时间序列上,声发射事件存在着3个阶段:较强声发射事件发生初期,前激波时间超前较长,停止相不明显,声发射源的破裂速度较慢;第二阶段停止相突出,扩展速度加快,前激波到时超前量减小;最后,在原初始半周期处叠加了较大振幅的高频波。

关键词: 声发射, 多普勒测量, 震相, 岩石摩擦试验