不整形地盤上の地震動の空間分布特性とそのモデル化

Abstract

Lifeline systems such as buried gas or water pipelines will be heavily damagedduring an earthquake if the relative displacement between two points on the groundis large. These long underground structures are affected by the profile of thesurface ground. In particular, if an irregular interface exists in the layered media, ground motion above this interface may be amplified. The mean powers of wavesobserved on the points at surface ground are not constant and an assumption of thestationary process does not hold true.We first simulated the surface ground motion of layered media that had anirregular interface by the Discrete Wave Number Method. The mean powers andcross correlations were examined with simulated waveforms, and the shape of theirregular interface was identified.The relative displacements between two observation points were modeled by theuse of spatial correlation and autocorrelation functions by replacing a simple basinwith two sets of layered media.