A Study On Methods Of AE Data Processing In Rock Mechanics Test

AE(Acoustic Emission) is an important technique in rock mechanics and experimental seismology. AE source locating and its relevant techniques are key to this method, because precise determination of AE sources is the basis for analysis of deformation and failure processes using AE data. Although there have been a great number of studies and progresses in this field, how to process profuse experimental data in an effective and precise manner remains to be further investigated, along with development of AE observations and increasing complication of rock sample structure. This work attempts to address this issue by some efforts. They include the following work : On the basis of previous development of the laboratory, a new AE data processing system is constructed to improve data processing efficiency. Using the methods such as: mimic sources, ball-dropping test and data analysis of rock deformation experiments, the accuracies of several availale locating methods are tested, and their advantages and applicabilities are evaluated. These work provide the basis for the further improvement, applications and choices of AE source locating methods.1.Construction of the AE data processing systemThe AE source locating includes three steps: arrival time picking up, locating calculation, and post-processing of location results. Among the original location programs, some are time consuming and can not process profuse data since they pick up arrival times by artificial identification. And the post-processing is difficult due to different formats of output of location ways. To solve these problems, this work develops the pre-processing and post-processing programs based on VC++ software plateform and the Matlab wavelet tool case. By integrating three available locating methods, a new AE data processing system is proposed, which has functions of signal pre-processing, location calculation, result post-processing and time process analysis. It can simplifies AE data handling and raise work efficiency of AE research in the laboratory.2.Tests of three AE locating methodsAt present the laboratory has three kinds of AE source locating methods which are developed on different requirement. This work makes a system comparison and analysis to their location precisions, advantages disadvantages, and applicabilities. The purpose is to help choose suitable location methods according to features of experiment samples.(1). Mimic sourcesA mimic source is placed in the assumed space. By calculating travel times, mimic location tests are performed. Using deviations of varied magnitudes, the calculated arrival time data are disturbed. Then three locating methods are introduced to test their location results. The location effects are as follows: Slowness deviation It has the best stability, although it cannot locate precisely and occasionally produces wrong locations. Its location precision always keeps in a small range of errors. Simultaneous Inverse It may reach precise location when the arrival time data are accurate. But with the increasing error disturbance, its location precision declines to some extent. Relative Location With increasing error disturbance , the location precision of the absolute locating method declines notably, with large errors in vertical direction and poor reliability. In comparison with the absolute locating method, the relative locating method has an raised precision which depends on the choice of the major event coordinates.(2). Ball-dropping testUsing small steel balls, dropping test is performed to the fixed points on the surface of intact rock samples. The viration signals produced by the collision between the balls and the rock are recorded and processed by different methods. Slowness deviation The source location tends to migrate toward the middle of the sample, and there is a "mislocation" area within the sample where errors are large. Simultaneous Inverse It has the highest location precision when the source depth and predicted wave velocity are given. And the location results do not migrate toward the middle of the...