摘要
所描述的工作聚焦于大延伸非均匀介质中非均匀弹性地震波散射问题的研究.应用Born近似及等效源原理,推出了来自连续横向无界非均匀层的弹性散射波的通解.这一工作是解决大延伸非均匀介质的弹性地震波多次散射问题的基础.在上述通解的基础上,建立了适用于大延伸非均匀介质的全弹性散射理论.该理论可包容小尺度非均匀体、大延伸非均匀介质全弹性波单次弱散射理论及标量波单次弱散射理论,因此可视其为一个更为广义和统一的弱散射理论.
The focal point of the work described in this paper is the investigation of elastic seismic scattering by heterogeneous continua of large extent. For mathematical convenience, the incident waves are considered as time harmonic waves and the study works in the frequency domain. Elastic scattering from a continuous and laterally unbounded heterogeneous layer is formulated using the Born approximation. A general solution for the scattered waves for the above-stated medium is given in terms of a Fourier integral over plane waves. On this basis, far-field asymptotic expressions for weak elastic scattering by a finite, continuous and inhomogeneous layer are presented which agree with earlier results. For the case where perturbations of the two elastic parameters and the density have the same form of spatial variation, the spectrum of plane waves scattered from a heterogeneous layer is expressed as a product of an 'elastic scattering factor' and a 'distribution factor'. As in earlier results for small-scale heterogeneity, the scattering pattern depends on various combinations of perturbations of elastic parameters and density. The work described in this paper is a basis for solving the problem of multiple scattering of elastic seismic waves for extended and heterogeneous media.In this paper, a theory of full elastic scattering for heterogeneous media of large extent has been established, which can be considered as a more general and unitive theory of weak scattering that can contain the theory of full elastic scattering for heterogeneous media of large extent, the theory of full elastic scattering for small-scale heterogeneities and the theory of scattering of scalar waves in the case of weak and single scattering.
出处
《力学学报》
EI
CSCD
北大核心
2002年第4期559-568,共10页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家杰出青年科学基金(40025412)
中国科学院"百人计划"(10010120)
中国科学院知识创新工程重大项目(KZCX-07)
中国科学院研究基金(1980338)
中国科学院地球物理研究所
英国大学正副校长委员会
剑桥大学海外基金会联合资助
关键词
地震波
全弹性散射理论
大延伸非均匀介质
弹性波
theory of full elastic scattering, heterogeneous media of large extent, small-scale elastic heterogeneities, elastic waves, scalar wave approximation, scattered waves.
