The Application Of The Finite Difference Method In The Numerical Simulation Of Rayleigh Wave

With the acceleration of modernization process, China’s investment in theinfrastructure construction is more and more big, the roads and especially the changeof the construction of residential housing.Especially in March2014to hold the12thmeeting of the National People’s Congress, prime minister li keqiang, turnshantytowns into new housing areas, and put forward by the high-speed railwayconstruction. the exploration is very important for the construction of the foundation,because it is directly related to the safety of the engineering construction.A lot ofgeophysical methods currently used in engineering exploration, there are mainly highdensity resistivity method, Transient Electromagnetic method,refraction wave seismicexploration method and Rayleigh wave method,etc.The Rayleigh wave method hasmany advantages,such as the shallow high resolution, small damage to constructionsite,strong anti-jamming capability,high construction efficiency.However,because ofthe complexity of the actual engineering sites,acquisition of data is not ideal.forexample,it contains the low-velocity layer and hole collapse ofgeology.Therefore,how to theoretically discusses medium model for these specialcases become very important.Finite difference method as an effective numerical simulation method,it not onlycan reflect the kinematics of seismic wave information,also can reflect the dynamicinformation of seismic wave,can comprehensively reflect the wave field ofinformation.The finite difference method is applied to the numerical simulation of theRayleigh wave.this method broke the dispersion equation can only study thelimitation of the simple layered medium model.For more complex geological model(including empty) can also be numerical simulated and analyzed.In this paper,the high order staggered grid finite difference method is used,andproblems is solved,include the numerical simulation of dispersion problems, PMLboundary condition problem,free boundary condition problem.then, the actualengineering exploration and empty contains of weak intercalations, model issimulated, and the wave field snapshot, seismic records, dispersion curve is discussed and analyzed.For practical engineering exploration,Some regular conclusions, andtheoretical guidance provided.In addition,because of the complexity of the actual explorationmedium,especially contains empty geology,through a traditional method of extractionof dispersion curve,do not have access to reflect the underground geologic profile ofmedium condition.Therefore,in this paper,a different approach,"backscatter"analysismethod is proposed,from seismic records,through the seismic data processing(including f ktransformation,LMO,etc),in the end,get the position of the holes onthe surface,avoid the defects of the extraction of dispersion curve method itself.