Research On Reflected Wave Tomography Method For Hazard Diagnosis Of Dam

With the nation paying more attention to reinforcement and diseases harnessing ofHydraulic Engineering, the diagnosis of dam hidden defectiveness is more and moreurgent needed to be updated with better technology. Under this background, this articleattempted to use the reflection wave imaging and analyzing for dam hiddendefectiveness. This master graduate dissertation relies on the project of National NaturalScience Foundation of China (NSFC)-The research of diagnosis technology in view ofDam hidden trouble based on the three-dimensional wave to electric field coupling bythe holographic imaging.The research is from two sides: the isotropic and transverseisotropic in this master graduate dissertation.We have developed the wave velocity imaging software which based on the theory ofwave velocity imaging, meanwhile we also have builted mathematical model which isin order to verify the accuracy of the imaging software and carry on the error analysis,in the case of isotropic. The reflection wave procedure is used for studying dam hiddendefectiveness in forward modeling, when the dam medium is transverse isotropic.In this dissertation, the main works are as follows:(1)Analyzed the types and the causes when dam hidden defectiveness analysis. Itmainly includes the dam foundation hidden defectiveness and the dam body hiddendefectiveness. The hidden defectiveness includes two types which are seepage channeland Imperfect areas. The research of wave propagation characteristics is from twoaspects separately. The one is the soil medium and the other is earth-stone compositemedium. Then, putting forward the dam hidden defectiveness of generalized model andcombinating with the engineering practice from two types of dams which arehomogeneous and core wall.(2)Established the forward and inversion theory calculation model with respect to thedam hidden defectiveness of isotropic dams medium by using the reflection wave. Theprogramming and its implementation process are given in this article. The forwardtheories in this programming are Huygens Principle, Snells law, Fermat’s principle,reciprocity principle, radon transform, the improved shortest path ray tracing algorithmand so on. They are combine with the Least-squares orthogonal decomposition methodto solve linear equations inversion theory constitute the theoretical foundation of thisentire article. (3) Built numerical calculation for homogeneous dam and core wall dam by using theprogram under the conditions of no defectiveness, seepage channel and imperfect area.Then we verify the feasibility and reliability of the forward model and inversion modelby analyzing the differences between the inversion image and the theoretical model,comparing channel homogeneous dam with channel core wall dam, comparing differenthidden defectiveness in the same type of dam, contrasting between the section andelevation in the same hidden defectiveness, also the difference travel time betweenkinds of hidden defectiveness.(4)Maked forward analysis for hidden defectiveness in transversely isotropic damsmedium based on Ray tracing principle and the wave theory of anisotropy by usingreflection wave.We also analysis the elastic wave equation of anisotropic medium andthe Thomsen parameter characterization of transversely isotropic medium. Then weused two types of methods which are nonlinear inversion and joint inversion for inverseanalysis in transversely isotropic media.(5)Established forward theoretical model to calculate. We have based on thereflection wave imaging technology under the transversely isotropic media. We alsocarried out the dams forward calculation analysis on hidden defectiveness under theconditions that are the same waveform at different incident angles and the differentwaveform in the same incidence angle in homogeneous dams and core wall dam.