地下捷運引致之地表振動

Abstract

隨著都市人口的增加，現有的大眾運輸工具已不敷使用，因此能提供快速且便捷的捷運系統，即成為現今各國改善交通運輸的首要選擇，然而，無論是地上或地下捷運列車行駛所引起的干擾性振動，對鄰近建物與居民所造成的衝擊，亦於近年來因人們對生活品質要求的提高，而產生越來越多的抱怨與批評，因此如何提供快速且方便的大眾運輸，且能同時兼顧環境的品質，亦即降低列車行駛所引致之振動，已成為國內外學者與專家研究的重要課題。有鑑於此，本文之目的即希望藉由有效的數值分析方法與列車與軌道的模擬，針對地下捷運列車所引致之振動作深入的探討。 本文分別運用由Yang 和 Hung (2001a)所發展出的土壤與結構互制之數值分析方法：2.5維有限元素與無限元素混和分析法，與一針對較簡單的彈性半無限域問題的解析解(洪，2000)，並加入考慮車輛、軌道與鋼軌粗糙度之特性，分析土壤受一完整之地下捷運列車之行進，對地表造成之振動反應的影響，其中車輛及軌道分別以懸浮質量系統與單層連續彈性支承梁模擬，而鋼軌之粗糙度則以一較簡單之餘弦函數模擬。並進一步探討土壤、車輛與軌道的幾何及材料參數，對移動列車引致之波傳效應的影響。另外為了驗證此一數值分析方法之可靠性，本文分別將分析結果與瑞典(Sweden)、北京(Beijing)及倫敦(London)之實際試驗結果作比較，同時並考慮於軌道平版之下面，安置一較軟的彈性支承，研究其對列車引致之振動波傳的阻隔效應，而此一形式之軌道平版又稱為浮動式道床版(floating slab track)。

The congested ground traffic has been a serious problem for both the government and citizens living in densely populated metropolitan areas. To relieve this problem, mass rapid transit systems that are built underground have provided an effective alternate. However, most highly developed modern cities have encountered the problem that transportation lines inevitably come across or close to some buildings. This often results in perceptible vibrations on the building floors whenever an underground train passing by. Although vibrations of these magnitudes may not cause the collapse of buildings as earthquakes do, residents living alongside the transportation lines will never feel comfortable. This is a new environment problem facing the city planners and engineers. How to reduce the ground-born vibrations induced by trains moving inner the underground tunnel has gained increasingly attention in recent years. To this end, this thesis is focused on the ground-born vibration induced by underground mass rapid transit system. The analytical technique developed by Hung in 2000 and the numerical technique proposed by Yang and Hung in 2001 have both been applied to the analysis of ground-born vibration due to underground railway traffic. The analytical procedure is based on the Fourier transform technique. The numerical simulation method is based primarily on the 2.5D coupled finite/infinite element approach. Both of the analytical and numerical techniques will be combined to simulate the train, rail and soils, with the geometric irregularities taken into account. Using the analytical method, the effects of different parameters are investigated. The results obtained serve as the benchmark for verifying the results obtained by the numerical method. Moreover, to confirm the accuracy of the results calculated by the numerical method, comparisons will be made with the experimental data collected in Sweden, Beijing and London. Finally, the performance of vibration countermeasures, like the elastic foundation, for reducing the train-induced vibrations will be evaluated.