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Journal of Applied Sciences

Year: 2009  |  Volume: 9  |  Issue: 19  |  Page No.: 3491 - 3501

Surface Wave Analysis Using Morlet Wavelet in Geotechnical Investigations

Z. Chik, T. Islam, M.M. Mustafa, H. Sanusi, S.A. Rosyidi and M.R. Taha

Abstract

This study addresses wavelet transform for multichannel surface wave method to overcome the limitations of conventional seismic signal analysis. Seismic surface wave method is familiar nondestructive seismic test to reveal the soil profile in geotechnical engineering. The spectral analysis surface wave method using two receivers is constraint due to interferences of other signals and various types of noises. To reduce these problems, the multichannel analysis of surface wave method is developed as more reliable surface wave technique with the performance of mode discrimination. But this method is tedious and slower for phase velocity extraction using Fourier transform. However, because of characteristic of fourier transform used in the conventional phase extraction method, dispersion curve is sensitive to background noise and body waves in the low frequency range. Furthermore, under some field conditions such as pavement site, the phase extraction method can lead to erroneous dispersion curve. To overcome these problems, a new method of determining the group velocities and phase velocities using time frequency analysis based on Complex Morlet wavelet transform is highlighted with the algorithm in this study. To estimate the applicability of the proposed method, the dispersion curve at soil layer profile is revealed and the dispersion curve by proposed method is more reliable than those by the usual phase extraction method. The significance of this study is to obtain a robust and consistent performance with noise reduction for surface wave analysis regarding multichannel and Morlet wavelet transform.

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