Joint Inversion Of Love Wave And Rayleigh Wave In Layered Media

Surface wave exploration is widely used in nondestructive testing of roadbed,engineering geological exploration and other fields because of its advantages such as simple operation,high exploration efficiency,strong anti-interference ability and so on.Surface wave mainly includes Love wave and Rayleigh wave.Compared with Rayleigh wave,Love wave dispersion equation is simpler.So the results of inversion is more accurate and procedure fast.With the development of science and technology,computer simulation technology and detector have also been improved,which drive the research of Love wave in the material nondestructive testing,formation exploration and other aspects in detection.Firstly,in this paper,on the basis of the constitutive relation and wave equation of layered medium,the characteristics of frequency dispersion in Love waves are studied and analyzed,which provides a theoretical basis for using the Love wave to inverse the layered medium structure.Then ?-p transform is applied to obtain frequency dispersion curve of Love wave from the seismic records.Secondly,based on the damped least squares method and the frequency dispersion of Love wave,a nonlinear inversion objective function is established.I choose reasonable initial model and parameter to finish Love wave inversion by MATLAB program.On the basis of analyzing the characteristics of inversion in both Love waves and Rayleigh wave,weight coefficient of joint inversion in Love wave and Rayleigh wave is proposed guided by the thought of joint inversion.Then corresponding objective function is established and the MATLAB program is used to achieve joint inversion.At the same time,the degree of joint inversion dependence on initial model is analyzed.On account of theoretical model and finite element numerical simulation calculation,the joint inversion in Love wave and Rayleigh wave not only can perform accurate model parameters but can reduce dependence on the initial model.Finally,the correctness of the above method is verified by the measured data,which shows the potential of the joint inversion of Love wave and Rayleigh wave.