Hilbert-Huang Transform Theory And Its Application In Geotechnical Engineering Signals Analysis

The geotechnical engineering information processing refers to signals transformation,filtration and analysis in the hope of getting engineering structures'performance information. Besides,signals analysis refers to the study of signals'basic properties. Geotechnical engineering signals are so complicated,changeable,nonlinear and non-stationary that the feature which is based on the traditional stable signals is hard to acquire the ideal effects. Therefore,the difficulties-geotechnical engineering signals analysis,identification and feature extraction are still urgent to work out. Aimed at the aforementioned problems,the author put forward a new studying subject on HHT analysis of the geotechnical engineering signals analysis theory and its applications,funded by program of the National Natural Science Foundation of China(No.50678028 , 51078043). The author conducted an in-depth research in geotechnical engineering signals analysis through taking advantage of MATLAB programming language working platform and reviewing a great deal of domestic and foreign relevant references and engineering practices.(1) After introducing the principle and algorithm of HHT,the author brought in HHT and analysed geotechnical engineering testing signal. The preliminary results confirmed that HHT method has both adaptability and superiority in geotechnical engineering signal analysis.(2) According to the inherent characteristics of the test signal,EMD method was used to decompose signals into a great number of IMF components with different time scale characteristics. what's more,After IMF components is transformed by using the Hilbert-Huang transformation , we got the instantaneous phase , instantaneous amplitude and instantaneous frequency,the most of which could reflect its physical meaning. Time-frequency diagrams could quantitatively describe the time-frequency relations. In addition, Hilbert spectrum could clearly depict the signals energy distribution with the development of time and frequency.(3) In the light of acoustic emission signal'instantaneity and diversity,the author adopted HHT and analyzed rock acoustic emission signals energy characteristics distribution from the angle of energy under impact loading. Moreover,the author summarized rock acoustic emission signals correlation between the energy and physical properties and related coefficient. Both Wavelet method and HHT can perfectly analysis nonlinear and non-stationary signals and extract the signals energy characteristics. However,EMD method don't need preinstall basis functions and have the adaptive and efficient characteristics.(4) Tunnel advance geological forecast detected the original radar profile image,EMD method was used to decompose image into a great number of IMF components,then we could get the instantaneous amplitude,instantaneous phase and instantaneous frequency through HHT,and finally formed three parameters independent profile image which could better explain geological radar profile. Therefore,HHT method used to tunnel advance geological forecast detection signal analysis and processing could effectively improve the accuracy of advance geological forecast.Based on the frontier research work,this paper adopted a series of advanced mathematics methods and means,and studied the geotechnical engineering signals. It has a high value in their theoretical and practical aspects,and also provides an academic and practical foundation for systematically researching geotechnical engineering signals analysis.