An Improved Wave Velocity Model for Acoustic Emission Source Localization in Heterogeneous Rock Materials with Unknown Inclusions

The accuracy of locating acoustic emission (AE) source location is closely related to the reasonability of the adopted wave velocity model. However, it is literally hard to obtain an accurate wave velocity model for a heterogeneous rock material due to its inner invisible inclusions and local defects, making the AE source localization very challenging. To obtain a more appropriate wave velocity model for the heterogeneous rock material having unknown inclusions, in this study the projective reconstruction method (PRM) was utilized to determine the wave velocity model. Because the PRM is irrelevant to the continuous assumption, the proposed wave velocity model can well reflect the discontinuous characteristics of the real wave velocity field in rock materials. Then, the proposed wave velocity model was incorporated into an arrival time-based governing equation to locate the AE source. To demonstrate the effectiveness of the proposed method in improving the AE source location accuracy and monitoring the rock failure process, lead-break tests and three-point bending tests were conducted on the composite rock and rock-like specimens, respectively. Results show that the improved wave velocity model obtained by the PRM can significantly improve the accuracy of AE source location in the heterogeneous rock material with unknown inclusions.