| 摘要: | 近年來，颱風造成的暴雨、洪水強度更甚以往，斷橋事件頻傳更是讓管理單位及相關的研究人員更加重視橋梁耐洪的問題。在高屏大橋斷橋事件發生後，交通部針對損毀的橋梁進行複查，複查後發現損毀的橋梁中有82%是因沖刷而受損，由此可見橋墩局部沖刷實為橋梁結構安全最重要的影響因素之一。當橋墩裸露過於嚴重時會造成結構的承載力不足，當側向作用力超過橋墩基礎所能承受的力量時，橋墩可能會下陷、傾斜、側移，更嚴重者可能會倒塌。因此，在地處於亞熱帶且幾乎年年有颱風侵襲的台灣，橋墩局部沖刷的監測成為日漸重要的課題。本研究旨在開發一套具耐久、可靠且經濟的橋墩局部沖刷監測系統，為改善現有的沖刷監測計多需開挖河床、無法量測回淤變化以及造價昂貴的問題，發展出一套無需開挖河床、可量測回淤變化、造價便宜且數據處理簡單的沖刷監測計-重力式壓電片沖刷監測計。重力式壓電片沖刷監測計係利用壓電片薄膜作為主要的感測裝置，其安裝時將一探測桿上端連接一電阻尺並於桿上佈設數個壓電片薄膜製成的感測器，探測桿於安裝完成時置於固定在橋墩上的滑軌內，探測桿的底部則放置於河床上。當河床高程下降時探測桿會隨著下滑，可由電阻尺拉伸長度計算其下滑距離；當河床回淤後則藉由壓電片感測器判斷回淤高程。本沖刷監測系統所量測的數據搭配無線網路的傳輸可將資料即時傳回遠端的控制電腦，管理人員僅需經由遠端電腦便能掌握現地的狀況，並判斷該橋墩是否需進行修復甚至封鎖橋梁。 In recent years, the strength of rains and floods caused by typhoon are much stronger than ever, serial of bridge failure events made the bridge managements and researchers start to pay much attention to this problem. After the Kao-Ping Bridge broken, the Ministry of Transportation and Communications surveyed all the damaged bridges in Taiwan, than discovered that 82% bridges were damaged by scour. That is to say, scour is the primary threat to structure health of the bridges. When the pile foundation begin to expose, the bearing capacity of bridge structure will decrease. While the lateral force acts on the bridge structure is greater than the bearing capacity, the bridge pier will sink, tilt, and even collapse. Because there are several typhoons invading Taiwan every year, the government should pay more attention to the problem of bridge scour. The study subject is to develop a durable, reliable and cheap scour monitoring system- Piezoelectric Film Mounted Gravity Type Scour Monitoring System. This system improves the most existing problem and it has a cheap building cost, able to measure the back silting and installation without digging the river bed. A Piezoelectric Film Mounted Gravity Type Scour Monitoring System at least includes several piezoelectric films, a detection pole, two H beams, several fixing components, an encoder and a data logger. The detection pole is placed on river bed and links an encoder when finishing the installing. After the scour, the detection pole will go down with river bed, and then we can know the decreasing of elevation of river bed by the data from encoder. After the back silting, the piezoelectric films, which buried with silt or soil, will not send out the voltage because of the static situation. By this character, we can count how many piezoelectric films are buried with silt or soil. It can use the wireless network to achieve the real time monitoring. The manager can know the situation without going to the field in person and judge whether the bridge should do rush repair or not. |
