Multi-mode Verlocity And Elliptical Polarization Dispersion Characteristics Of Rayleigh Waves In Horizontal Layered Media Physical Simulation Research

Rayleigh wave exploration method is an important method in engineering geophysical prospecting.It has the advantages of non-destructive,fast,economical,and effective.Using its dispersion characteristics,it can provide detailed and objective geological data of stratigraphic changes.As an important method for shallow formation exploration,the Rayleigh surface wave method has continuously made breakthroughs in theoretical research and practice.As far as the velocity and dispersion characteristics of Rayleigh waves are concerned,there are theoretically multiple modes of Rayleigh waves in layered media.Development,the exploration of multi-mode dispersion characteristics has always been the focus in the field of Rayleigh surface wave research.In addition,the multi-component dynamics of Rayleigh waves-elliptical polarization motion,has also attracted considerable attention from researchers.From the perspective of analytical solution and numerical simulation,the theory of Rayleigh wave is relatively extensive,while from another perspective,the research on physical simulation is relatively small.Physical simulation experimental research is an important method for laboratory research on underground geological structures,and has incomparable advantages over numerical simulation methods.Therefore,In order to strengthen the exploration of Rayleigh waves in the field of physical simulation,this article starts from the direction of physical simulation.Among them,the use of virtual instrument technology plays an important role in the experiment.Because of its high-precision and high-quality data acquisition technology,it provides a good way for the display of Rayleigh wave multi-mode dispersion and the acquisition of multi-component Rayleigh waves.Foundation and feasibility.In addition,the use of multi-component transducers to obtain seismic wave information from different directions provides strong data support for the study of Rayleigh wave elliptical polarization characteristics and helps reduce the ambiguity of seismic exploration.Based on this,this thesis uses ultrasonic seismic physics simulation experiments,based on model similarity theory,starting from the characteristics of ultrasonic and ultrasonic transducers,and establishing a variety of two-dimensional physical models for common geological structures in actual engineering surveys,using time domain Analysis,f-k domain wavefield transformation and H/V spectral ratio method,etc.,explore the morphological characteristics and elliptical polarization characteristics of multi-mode surface wave dispersion curves in horizontal layered media.The experimental research results show that there are multiple modes of Rayleigh surface waves in horizontal layered media.The judgment and separation of the dispersion information of multi-mode surface waves can help improve the exploration accuracy of shallow surface velocity structures,but for horizontal layers When the high-speed medium is overlaid on the surface of the high-speed medium,the experiment did not find the existence of high-order Rayleigh wave modes.In addition,other layered media in the study have multi-order Rayleigh wave modes.At the same time,experiments have found that the appearance of the "Zigzag"-shaped dispersion curve in the layered formation is related to the multi-order nature of the Rayleigh wave to a certain extent;through the study of the different modal characteristics of the Rayleigh wave,it is beneficial to the frequency Different modes of surface wave can be correctly identified in the energy dispersive map,which provides a basis for data processing and obtaining correct inversion results.In addition,the Rayleigh wave elliptical polarization calculated by the H/V spectral ratio method based on the experimental data is inversely proportional to the Poisson's ratio of the model medium,and its velocity dispersion characteristics reflect the formation information.This experiment The research results are consistent with related theoretical studies.Therefore,the elliptical polarization dispersion characteristics of Rayleigh waves can be used to distinguish the stratum velocity effectively.In this thesis,through physical simulation experiments,the multi-mode velocity dispersion,energy distribution,and elliptical polarization characteristics of Rayleigh waves in layered media have been deeply studied.The results of the research provide an in-depth understanding of the basic theories and extensions of Rayleigh waves.The scope of engineering application has important value and reference significance.