Based On The Theory Of Rayleigh Wave Inversion Dynamic Rock Mechanics Parameters

Rayleigh wave exploration which is applied widely in near-surface geophysicalproject is an advanced seismic exploration technique. It has some advantages, such ashigh resolution in shallow layer, non-destruction, fast detection. Furthermore, It is notaffected by the velocity relations of layers. The characteristic of Rayleigh wave isfrequency dispersion when this wave propagates in horizontal sub-layered media.This propagation characteristic includes abundant underground geologic information.After inversion and analysis of measured dispersion curve, underground mediaparameters can be obtained and the changes of structures and properties can berevealed in underground media.The transfer matrix method is often used in the calculation of Rayleigh wavetheoretical dispersion curve when this wave propagates in multilayer media. In thispaper, the transfer matrix method defined in rectangular coordinate system is appliedin forward calculation of Rayleigh wave dispersion curve. The method which is calledKNOPOFF can improved the calculation speed and cutoff upper limit frequency.Measured dispersion curves are obtained after original seismic records aretransformed by two-dimensional Fourier transform and seismic signals are analyzedin frequency-wavenumber domain. The damped least square method is used whenmeasured dispersion curves are inversed in this paper. The density, S-wave velocity,P-wave velocity and depth values are obtained after inversion. Furthermore, dynamicrock mechanics values are computed. In order to automate the calculation of rockmechanics parameters, rock mechanics parameters processing software is developedby using Delphi language. Real seismic records are processed by using this software,and then a set of dynamic rock mechanics parameters values are obtained. Shallowgeological structure features are well reflected by these mechanics parameters profiles.A fast, efficient and economic method and technique of calculating dynamic rockmechanics parameters values is formed based on this paper research.