半无界分层介质表面任意面源激发的弹性波场

Elastic wave excited by a plane source on the surface of a multilayered medium

研究了半无界层状介质自由表面任意形状的面源产生的弹性波场。首先,我们将层状介质中的传递矩阵理论从二维推向三维空间,在频率域研究了任意面源激发的三维弹性波理论问题。然后,深入研究了Rayleigh波和Love波的激发与传播特性,发现Rayleigh波和Love波的传播速度在与自由表面平行的平面内与传播方位角θ无关,但其激发强度却强烈地依赖于传播方位角θ。最后,我们具体研究了矩形源、无穷长条形源和圆盘激励出的弹性波场,并通过数值计算给出了Rayleigh波和Love波的位移指向性分布图。

Elastic waves excited by a plane source with an arbitrary shape on the surface of a multilayered medium have been studied. At first, 2D elastic wavefield in a multilayered medium is extended to 3D space, and the propagation of elastic wave is studied in the frequency domain. Then, the excitation and propagation of the Rayleigh and Love waves are analyzed further. It is found that the propagation velocity of the Rayleigh and Love waves does not depend on the propagation azimuth θ in the plane parallel to the free surface of the multilayered medium while the displacement amplitude of the Rayleigh and Love waves is strongly dependent on the azimuth θ. Finally, the elastic fields excited by a rectangle source, strip source with infinite length, and circular disk source are studied, and theoretical representation and numerical results of the displacement directivity distribution both of the Rayleigh and Love waves are obtained.