Abstract
In the study of the acoustic emission (AE) characteristics of rock samples or coal samples under triaxial compression conditions, most scholars carry out relevant experiments by placing the AE detector on the outer wall of the triaxial chamber of the rock mechanics test system. Owing to the continuous obstruction of AE signals by hydraulic oil in the triaxial chamber and the frequent interference of external noises, the final experimental data cannot objectively and truly reflect the essential characteristics of AE of rock or coal under triaxial compression conditions. It is difficult to scientifically guide and accurately predict precursory information of rock’s or coal’s rupture and instability. Based on this, a series of improvements and optimizations were made to the original triaxial compression AE test method, which is based on the modification of the communication interface of the rock mechanics test system, a test head which can put the AE detector into the triaxial chamber and withstands high confining pressure, in order to obtain the true, comprehensive, and reliable AE signals. It is of considerable significance to the scientific determination of the precursory characteristics of rock’s or coal’s rupture and instability.
Highlights
Down-pressing head a ecting the accuracy of test results
At the same time, when the detector was placed at the outer wall of the triaxial chamber, the electromagnetic noise received by the detector was relatively large, and the received acoustic emission (AE) signals were relatively low. erefore, it was di cult to obtain the comprehensive and reliable AE detection signals
Developing a triaxial AE test head capable of sealing the AE detector, placing the AE detector inside the triaxial chamber and enabling the AE detector to work normally under high con ning pressure is of considerable signi cance to ensure the authenticity and reliability of the AE signals during triaxial compression AE test
Summary
A ecting the accuracy of test results. the compressed wave (P-wave) could be normally spread in the liquid such as hydraulic oil, the AE energy greatly attenuated due to the increase of the transmission distance and the re ection of the triaxial chamber cylinder. Developing a triaxial AE test head capable of sealing the AE detector, placing the AE detector inside the triaxial chamber and enabling the AE detector to work normally under high con ning pressure is of considerable signi cance to ensure the authenticity and reliability of the AE signals during triaxial compression AE test. 2. Test System Overview e rock’s or coal’s triaxial compression AE test in this study was carried out on MTS815.02 electrohydraulic servo rock test system independently developed by MTS company of America and AE21C acoustic emission tester developed and manufactured by Shenyang Computer Technology Research and Design Institute. In dealing with conventional AE parameters, high-speed data acquisition card is equipped to record the AE waveform of 1∼2 channel, and spectrum analysis and wavelet analysis can be carried out. e AE21C acoustic
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