Study On Methods Of Rayleigh Surface Wave Data Processing

Rayleigh wave exploration is a new elastic wave exploration method. It has many advantages,such as high resolution, small space affection, simple equipment has been widely used in geotechnical Engineering Investigation and high working speed. So rayleigh wave exploration has been widely used in geological disaster survey and nondestructive testing in shallow. Dispersion characteristic of Rayleigh wave is closely related to the underground media parameters, which is the physical basis of Rayleigh wave exploration. Therefor,it is how to extract accurate dispersion curve from the original seismic records and invert the underground medium parameters from the dispersion curve that is the key problem. In this paper, surface wave data processing are systematically studied from surface wave purification, dispersion curve extraction and inversion.At first ,Ï„-p transforms are used topurify surface wave data. These transforms can separate Rayleigh wave data from the whole wave data. The transforms is linear and reliable because of their good fidelity. In addition,the transforms can be easily realized with computer.Ï„-p transforms is proofed to be feasible and effective by examples.To extract the dispersion curve of Rayleigh wave, crosscorrelation method, phase-shist method and wavelet analytical method are introduced and compared in this paper. The effect of crosscorrelation method is the most unsatisfactory. The effect wavelet analytical method is not better than phase-shist method,while wavelet analytical method cost more time than phase-shist method. So the phase-shist method is more effective than the others.This paper introduced Genic Algorithm , using the scalar transmission algorithm to forward the frequency dispersion curve. Genic Algorithm is global optimization algorithm .Genic Algorithm simulates Genetic and biological evolution In the natural environment .Compared with generalized counter algorithm and the least squares method inversion, this method has higher accuracy , does not lay on the initial model and does not require partial derivatives.Overall,this paper researched each step of Surface wave data processing, found the best method in every step and got optimal surface wave data processing flow.