Amplification of in-plane seismic ground motion by group cavities in layered half-space (Ⅱ): with saturated poroelastic soil layers

摘要

As the continuation study on amplification of in-plane seismic ground motion by underground group cavities in layered half-space, this study extends to the case of poroelastic half-space with dry poroelastic and saturated poroelastic soil layers. The influence of poroelastic layers on the amplification of seismic ground motion is studied both in frequency domain and time domain using indirect boundary element method (IBEM). It is shown that for the example of a saturated poroelastic site in Tianjin under the excitation of Taft wave and El Centro wave, the amplification of seismic ground motion in poroelastic case is slightly smaller than that in the elastic case, and the amplification of PGA (peak ground acceleration) and its PRS (peak response spectrum) can be increased up to 38.8% and 64.6%; the predominant period of response spectra in poroelastic case becomes shorter to some extent compared with that in the elastic case. It is suggested that the effect of underground group cavities in poroelastic half-space on design seismic ground motion should be considered.