The Coal Rock Acoustic Emission Source Localization Based On HHT

Coal energy accounts for the largest proportion in China’s energy structure,which makes a significant contribution to all of our daily lives. However, water inrush leads the issue of casualties accidents as a result of the mine face and other damages in mine happens frequently, these coal workers’ lives who pay for the public life do not get effective protection. For this reason, many scholars were put themselves into mine water inrush prediction research, and them put forward many effective methods,including the application of acoustic emission technique to predict the water inrush,which is a good feasibility way. In many cases, coal mine water inrush caused due to the rock-like material deformation or damage under pressure, in the process of formation of this destruction inside material, will produce an elastic wave, acoustic emission technology is receiving such elastic waves through the sensor, and analyzing it to obtain emission source of elastic waves in order to forecast the possible water inrush point.Although the acoustic emission technology can forecast for the water inrush point effectively, but due to the non-stationary and complexity nature of acoustic emission signals, some of the existing signal analysis method are difficult to conduct a comprehensive and effective interpretation of them, thus positioning accuracy are poor. The paper carry out research for the analysis of coal rock acoustic emission signal and source localization based on Hilbert-Huang Transform, it has theoretical significance and practical value for application of acoustic emission technology in coal mine water inrush forecast and improvement of the acoustic emission source location accuracy.Author makes a research of Hilbert Huang transform(HHT) method for signal analysis and the algorithm of initial estimate Geiger AE source location based on the material properties of coal rock and acoustic emission signals characteristic combining theoretical analysis with simulation approach, obtains a high precision positioning point, effectively improves the prediction accuracy of coal rock acoustic emission technology. The main research focus on the following four areas:(1) In aspect of signal analysis, for the complexity of coal rock acoustic emission signals, the paper discusses the basic theory and basic characteristics of wavelet transform with a development perspective, compares wavelet transform with HHT for the level of non-stationary signal analysis, proves that HHT method is applied toanalyze the coal rock acoustic emission signals.(2) For the problems such as endpoint effect and modal aliasing occurred during analysis process with HHT, the paper makes a research of some common suppression methods, proposes dual-end optimization endpoint extension and preset wavelet filter modified methods on the basis of the current techniques according to the characteristics of coal rock acoustic emission signals, and effectiveness of these improvements are verified through simulation experiments.(3) According to the principle of three-dimensional positioning, author studies the velocity measurement of AE signal, get Hilbert spectrum and Hilbert marginal spectrum using the improved HHT methods to determine the analysis frequency, find out the same frequency waves of different sensor received, get TDE from peak time comparison of them, make the localization algorithm of initial estimate Geiger for the practical problems of coal rock acoustic emission source location.(4) A uniaxial loading experiment with coal rock samples is carried out. In the experiment, acoustic emission instrumentation and the coal rock acoustic emission source locate method based on improved HHT are used to locate the coal rock damage respectively, the results show that the improved method cannot only locate the source of acoustic emission,but also get high precision positioning point. It demonstrates the effectiveness of the method.The study is based on the actual coal rock acoustic emission signal, it provides strong evidence that improving the effectiveness using HHT method to analysis acoustic emission signal. Some of the improvements in the study are succeeded in raising the acoustic emission source location accuracy. The study promotes the application of HHT in the field of acoustic emission, and it has a very important practical significance in disaster prevention of coal rock water inrush.