Acoustic emission (AE) source location for multi-layer media has urgent application requirement in micro fracture location of the triaxial rock test. However, the existing AE source location algorithms always fail to get accurate results. That is because there are multi-layer medium between AE sources and AE sensors in triaxial rock test. The acoustic paths from AE sources to AE sensors will change at the interface of the two media according to the Snell's law. To solve this problem, an AE source location method considering refraction between interfaces of multi-layer media was proposed. A two-layer linear media was established to simulate the specimen and the pressure head of the true compression test. And a two-layer curved media model was established to simulate the specimen and the oil chamber of the conventional triaxial rock test machine. The path equations for the source coordinates and corresponding refractive point coordinates are established firstly. Then a series of equations of time difference of arrival will be obtained. After that, the error matrix of the calculated and measured time difference of arrival is established. Finally, the coordinates of AE source can be obtained when the error is trend to be zero. In addition, the traditional method was used to comparing with the new method. The results show that the new method can obtain accurate positioning coordinates and the algorithm is stable.


Accurate AE source location is significant for the study of crack propagation in rock mechanics [1–2]. In 1968, Scholz first discovers that the crack expansion of rock under pressure was accompanied by the occurrence of AE [3]. With the improvement of acoustic emission acquisition system software and hardware, a substantial effort has been devoted to the study of acoustic emission source location in rock mechanics [4–6]. But it's found that the AE source location method used in triaxial compression method cannot get accurate results.

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