Dynamic response of a stratified transversely isotropic half-space with a poroelastic interlayer due to a buried moving source

Response of a ground subjected to dynamic sources is a classical problem in many fields. This paper develops a transversely isotropic (TI) half-space ground model which considers the alternating distribution of different media: a TI elastic surface layer, a TI poroelastic interlayer and a TI elastic half-space from top to bottom. The model can consider soils with different properties and the existence of groundwater. Dynamic responses of the model subjected to a buried moving source are investigated. General solutions to the TI poroelastic interlayer in the wavenumber domain are derived by Fourier transform and a potential function method in a Cartesian coordinate system. The layered system with different media is solved adopting an ‘adapted stiffness matrix method’ for a buried source scenario. Dynamic responses in the time-spatial domain are obtained by inverse fast Fourier transform (iFFT) and numerical integration. The performance of the method in this study is first tested by comparison with existing research, and the influences of the existence of pore water in the interlayer, transverse isotropy, and source features are comprehensively investigated. The effect of pore water is more significant for a TI ground compared with isotropic ground, and the model in this study cannot be simplified by an ‘equivalent’ layered TI elastic model. Peak values of displacement and pore pressure exist with increasing source speed. Source speeds corresponding to them are related to the wave speeds of the medium and affected by transverse isotropy.