- 學位論文
土層沉陷對路堤軌道系統振動特性影響
Influence of vibration due to embankment-rail foundation settlement
摘要
土層沉陷依地質環境與負載的條件而定。軌道下方土層因沖刷、鬆動、或受力不均勻，可能隨時間增加而造成軌道下方土層沉陷。軌道基部土層沉陷，可能造成路床的下陷，影響軌道版及鋼軌變形，為不可忽略的問題。路堤軌道系統基礎土層沉陷對於高速列車之營運影響很大，如增加軌道結構與列車之振動，影響乘客舒適性，甚至是造成行車安全上的疑慮。 本文重點進行鋼軌應變量測，軌道版與軌床振動量測與分析，以了解路堤段土層沉陷帶來軌道系統的影響。首先建立路堤軌道系統有限元素模型，分析其基本自然頻率與模態振形，探討車輪衝擊力與鋼軌應變(應力)之關係，再以LS-DYNA軟體進行高速列車行經路堤段，衝擊軌道引致軌道結構振動之暫態分析，比較土層無沉陷的軌道狀況與不同沉陷狀況軌道振動分析結果與輪軌衝擊力分析結果，並將動態分析結果與實際軌道系統量測結果進行比較，歸納土層下陷對軌道結構動態特性之影響。分析結果顯示地層沉陷導致軌床變形引致軌道版與軌床出現縫隙時將大幅增加鋼軌剪應變及軌道版振動量。
並列摘要
Subsidence is caused by geology and surface load conditions. The soil property under rail foundation should be investigated in the early design stage of track system usually, the geology condition of its environment still has uncertainty. The settlement of soil foundation under track may lead to roadbed settlement、deformation of slabs and rail. It’s a nonnegligible problem. The settlement of rail foundation increases vibration of track structure, influences the riding comfort, and may also causes safety problems. This paper focuses on the influences of rail dynamic characteristics due to settlement of embankment-rail foundation by strain measurement and vibration measurement. First, establishment of the embankment-rail finite element model；then, natural frequencies and mode shapes were calculated, and the relation between rail stress and the impact on rail were investigated. Finally, the finite element transient analysis for the dynamic response of track structure induced by high speed train were analyzed by LS-DYNA in order to compare the difference between different settlement conditions of soil foundation. The analyzed results were compared with the measurement results.