以數值方法模擬傾斜入射波造成之地盤反應

Abstract

藉由前人的研究我們可以知道當地震波傳達至建築物基礎下方土壤時大多數情況下是以非垂直的入射方式進入，然而在工程問題上，為了計算的方便，地震波入射土壤時常常被簡化為垂直入射，不過隨著近年來計算機設備的進步，模擬非垂直的地震波入射已成為可行的分析方法，因此本研究透過數值軟體FLAC來找出地震波入射角度對於土壤剪切模數、輸入運動頻率、土層厚度、時間延遲方法以及地下土層分布情況之影響。 分析結果顯示，垂直入射所得之水平方向地盤反應皆大於傾斜入射分析，但垂直方向的地盤反應分析中傾斜入射之角度對於其結果具有相當大的影響。

In conventional one-dimensional site response analysis, the waves are assumed to be vertically propagating. However, in reality (especially for shallow earthquakes), when the seismic waves travel from the earthquake source to the sites, the incidence may not be vertical. In this study, two oblique incidence specification methods, which are the vector decomposition method and the time delay method, are considered. These methods are implemented in the numerical software FLAC2D to simulate the oblique incidence of seismic waves and to investigate its impact on seismic site response. In addition, different model geometries, material properties, halfspace condition and predominant frequencies of the input motions would be considered.