常规三轴压缩下花岗岩声发射特征及其主破裂前兆信息研究_纪洪广.pdf

34 4 Vol.34 No.4 2015 4 Chinese Journal of Rock Mechanics and Engineering April 2015 ( 100083) 12 (4050 150170 kHz )5 (25304050607090100 150160 kHz ) TU 45 A 2015 CHARACTERISTICS OF ACOUSTIC EMISSION AND ROCK FRACTURE PRECURSORS OF GRANITE UNDER CONVENTIONAL TRIAXIAL COMPRESSION JI HongguangLU Xiang (School of Civil and Environmental EngineeringUniversity of Science and Technology BeijingBeijing100083China) Abstract Laboratory experiments on the characteristics of acoustic emission(AE) in two frequency channels in the full failure process of granite specimens under different confining pressures were carried out. The mechanical properties and AE characteristics in low and high frequencies of granite were obtained. The relationships of AE ringing countsAE accumulative energystress with the time were analyzed. The distributions of peak frequencies of AE signals before the major fracturing of the granite were studied in detail. The basic characteristics of AE in the low and high frequencies are similar during the granite failurewhich matches well with the mechanical properties. The main difference between the basic characteristics of AE in the low and high frequency channels is the magnitude of the numerical values. In the aspect of spectrum signatures of AE the number of the concentrated ranges of peak frequency of AE was increased from 2(4050 and 150170 kHz) in the initial loading period to 5(25304050607090100 and 150160 kHz) in the period just before the major cracking of rock. Key words rock mechanics acoustic emission(AE) frequency cha