3次元不整形地盤の震動特性について

Abstract

Underground structures such as buried gas or water pipeline will be heavily damaged if the ground has locally large responses during an earthquake. These lifeline systems that extend for long distances along or below the ground are affected by the seismic response of layered media that have an irregular interface. If an irregular interface exists in a layered media, the ground motion above this interface may be amplified. The effects of surface waves generated from the edge of the interface can not be ignored.We here described the characteristics of seismic ground motion on irregular profile. The method used for simulating ground motion is the three dimensional (3D) discrete wave number method, which was devised to calculate the elastic wave field in a layer-over-half-space media with an irregular interface. Ground strain which affects on the seismic behaviour of underground structures was examined. The 3D wave field was investigated by changing the shape of basin and compared with the results from the 2D analysis.