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| Experimental study of characteristics of irreversibility and fracture precursors of acoustic emission in rock under different confining pressures |
| ZENG Peng1，JI Hongguang1，SUN Lihui1，2，ZHANG Zijian3，GAO Yu1，JIANG Hua1，LI Chengjiang4 |
(1. School of Civil and Environmental Engineering，University of Science and Technology Beijing，Beijing 100083，China；
2. College of Resources，Hebei University of Engineering，Handan，Hebei 056038，China；3. Engineering Construction Company，Qingdao Metro Group Co.，Ltd.，Qingdao，Shandong 266000，China；4. Central Research Institute of
Building and Construction Co.，Ltd.，MCC Group，Beijing 100088，China) |
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Abstract Laboratory experiments on the characteristics of acoustic emission(AE) in high and low frequency channels of granite specimens under different confining pressures of cyclic loading and unloading were carried out. The relationships of the time with stress and AE cumulative counts were analyzed. On the basis，the characteristics of AE irreversibility in rock were studied. Then inverse fast Fourier transform(IFFT) was used to denoise the AE signals at Kaiser points and the characteristics of spectrums of denoised signals were analyzed with fast Fourier transform(FFT). The characteristics before the major fracturing in rock were studied. The basic characteristics of AE counts，the Kaiser effect(KE) and the felicity effect(FE) are similar in two frequency channels. The main difference between the characteristics of cumulated AE counts in two frequency channels is the quantity. The dominant frequencies at Kaiser points mainly distribute in the range of 46.39–70.80 and 151.37–166.99 kHz. With the increasing of axial stress level，the dominant frequencies at Kaiser points shift from the lower frequencies to the higher ones in the low frequency channel and shift from the higher frequencies to lower ones in the high frequency channel before the major fracturing in rock. The upper limit of KE of the granite is about 65% of the ultimate compressive strength. The results of the dominant frequencies at Kaiser points provide evidence for the damage and failure of rock.
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陈宇龙，魏作安，张千贵. 等幅循环加载与分级循环加载下砂岩声发射Felicity效应试验研究[J]. 煤炭学报，2012，37(2)：226-230. (CHEN Yulong，WEI Zuoan，ZHANG Qiangui. Experimental study on felicity effect of acoustic emission in rock under cyclic loading and tiered cyclic loading[J]. Journal of China Coal Society，2012，37(2)：226-230.(in Chinese))
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李庶林，唐海燕. 不同加载条件下岩石材料破裂过程的声发射特性研究[J]. 岩土工程学报，2010，32(1)：147-152.(LI Shulin，TANG Haiyan. Acoustic emission characteristics in failure process of rock under different uniaxial compressive loads[J]. Chinese Journal of Geotechnical Engineering，2010，32(1)：147-152.(in Chinese))
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2016, Vol. 35 
