橋墩沖刷之高科技即時監測系統研發、整合與應用

Abstract

受台灣氣候、地形與地質特性之影響，暴雨期間河流水位高漲且流速極高，在上游區域則經常觸發土石流使得河川洪水具有高泥沙含量。此高泥沙含量洪水可將巨石浮起，順溪流向下沖刷，造成更大之衝擊與破壞力。現有橋梁與橋墩基礎沖刷深度監測的方法，不易滿足自動化即時監測之要求，或以電子式感測器為基礎在台灣常有之颱風洪水情況下很容易受雷擊或水流衝擊破壞以致於無法發揮功能。而光纖感測技術相對於傳統電子感測技術的優點包括體積小、耐久性高、訊號可長距離傳輸而不受電磁波干擾與可以在同一光纖上做多點分佈式的監測。所以若能對光纖感測器加以適當之包裝保護，將可作為橋梁安全與橋梁基礎沖刷即時監測系統。 本研究計畫為橋墩沖刷即時監測之高科技術研發，並整合與應用目前現有之橋墩沖刷即時監測技術。計畫主要內容為在大甲溪選定二座橋墩進行感測器安裝與安全監測，感測器包括孔隙水壓計、傾斜儀、漂浮式流速量測儀、水位即時監測設備及讀取系統。將本計畫二座橋墩所得資料進行統合、整理與分析後，對大甲溪橋墩的安全監測，提供一實用而經濟的橋墩沖刷監測與安全判試方法。藉由整合橋梁安全監測與分析結果，橋梁主管機關可以更有效的在確保用路人安全與便利的條件下對橋梁封閉與否做出合宜的決策。

Because of the climate, terrain and other geological characteristics, the flow rate and water level in rivers are very high. The debris flow in the upstream induced by heavy rainfall results in high soil content in the water. The high soil content water has enough buoyancy to float boulders which in turn create more pounding and damaging forces. The current technologies are not suitable to meet the challenge for automated and real-time bridge foundation scouring monitoring. The electronic sensors are prone to lightening and other damages by the strong current in river. The fiber optic sensors have the advantages of being small, durable and capable of transmitting signals for long distances. Multiple sensors can be connected by a single optic fiber for distributive sensing. These sensors can include the fiber optic accelerometers attached to the bridge piers for integrated bridge safety monitoring. This research aims at development of high technology monitoring methods integrate and apply the existing bridge foundation scouring monitoring technologies. The objectives of the project include the selection of two bridges along the Dajia river as targets for field installation of various sensors. The sensors to be installed include pore water pressure transducers, inclinometers, suspended flow rate sensors, water levels sensors and an automated data logging system. Data collected at the two bridges will be compiled and analyzed. Effective and practical monitoring schemes will then be proposed. Through the integrated monitoring and interpretation schemes, the bridge governing agencies can be more effective in assuring the security of bridge users and in their decision process to close the bridge in case of emergency.