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Study On Rayleigh Wave Dispersion Curves Forward Modeling And Inversion Under Karst Geological Condition

Posted on:2014-01-23Degree:MasterType:Thesis
Country:ChinaCandidate:W Z ZhouFull Text:PDF
GTID:2250330425470955Subject:Geological Engineering
Abstract/Summary:PDF Full Text Request
In our country,there are many karst areas,such as GuangXi, GuiZhou, and YunNan province.In recent years, with the rapid development of economy, more and more engineering projects are built in the karst areas, in order to avoid the damage,it is very important for us to make a survey of caves before the construction.In the actual industry engineering also urgently need more economic exploring methods to check and seek this geology disease.To fit this engineering request one of the exploring methods is the Rayleigh wave need to strengthen.Extraction accurately dispersion curves and effective inversion of the dispersion curves have been the focus of the study. In order to avoid multi-trace comprehensive effect, which is produced by computing dispersion curves of multi-trace seismograms with traditional method and weak abnormal effect, we particularly use S transform to compute dispersion curve of adjacent two trace seismograms and then use the least square method for the inversion of the dispersion curves.In the paper,we researched the wave field characteristic of Rayleigh wave in karsts, simulated the communication process of Rayleigh wave in the models of different fillings,different shapes and adjacent cave, comparing and analysing the snaps at50millisecond,100millisecond,150millisecond and seismograms.Using S transform to compute dispersion curve of adjacent two trace seismograms in the model of single karst,we analysis the influence of dispersion curves/which made by karst, at different locations.By using the least square method for the inversion of the extracting dispersion curves and using fifty dispersion curves to draw the inversion of shear velocity contour map to determine the size and depth of the karst and compare with the initial model, we can obtain correct inversion results.
Keywords/Search Tags:Rayleigh Wave, karst, dispersion curves, cross-correlationmethod, S transform, least square method
PDF Full Text Request
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