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Studies On Dispersion Curve In Numerical Simulation Of Transient Rayleigh Wave Method

Posted on:2014-08-10Degree:MasterType:Thesis
Country:ChinaCandidate:Y S WanFull Text:PDF
GTID:2250330422964828Subject:Architecture and Civil Engineering
Abstract/Summary:PDF Full Text Request
As a new method of shallow seismic exploration, Rayleigh wave exploration isdeveloped in recent twenty years. This method is convenient to operate, low cost.Therefore it is widely used in engineering geological investigation and nondestructivetesting field. By using finite element software to establish the axisymmetric model oflayered soil under different soil conditions and MATLAB software to analysis datapost-processing, This paper focuses on the characteristics of transient Rayleigh wavedispersion curves in the soil foundation, as well as some factors affected the accuracy ofdispersion curves.First of all, discuss the finite element model of transient Rayleigh wave method todetermine the model calculation parameters such as size, mesh size and boundaryconditions. And demonstrate the appropriate selection of seismic source function. Extractthe dispersion curves in uniform medium and compared with the theoretical results toverify the reasonableness of the finite element method.Secondly, based on the dispersion curves extracted calculation process, discuss theimpact of transient Rayleigh wave dispersion curves related factors such as interferencewave, offset and receiver spacing, and give some recommendations in the extractionaccuracy high-frequency dispersion curves.Finally, get the wave response of multi-layer soil medium model under circular loadby the finite element method. Analyze and extract the relevant dispersion curves. Comparethe reflects of dispersion curve in aspects of layer thickness and layer velocity with thecalculation simulation settings, demonstrate the rationality of dispersion curve extractedby the transient Rayleigh wave method in shallow exploration, and do further study of therelevant characteristics of the dispersion curves including the so-called half wave theory incomplex formation such as weak interlayer.
Keywords/Search Tags:Rayleigh wave, dispersion curve, finite element, Spectral Analysis ofSurface Wave(SASW), half wavelength
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