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|Title: ||橋梁抗洪能力之整合性診斷與提昇技術-子計畫四-橋梁基礎系統抗洪評估( II )|
Stability Analysis of Bridge Foundation Subjected to Scouring
|Contributors: ||NTOU:Department of Harbor and River Engineering|
bridge scouring;permanent strains analysis;failure envelope
|Issue Date: ||2012-04-13T01:20:05Z
|Abstract: ||摘要:台灣地區河川大都具有短且急的特性，當颱洪來襲易造成橋墩基礎裸露與造成橋台與墩基損壞，甚或導致橋面崩塌。依據交通部運輸研究所公路防救災資訊系統1998~2009 年資料顯示，臺灣過河段橋梁於颱洪作用下橋梁基礎沖刷累計達278 橋橋基裸露，因此對橋梁的耐洪安全評估尤其是颱洪作用期間橋梁安全的判別實為重要課題。本研究為建立橋梁基礎系統抗洪評估的分析模式，並考量沖刷深度、水流流速及水位高度變化三因素的影響，分別依據現行「公路橋梁設計規範(98) 」採用的極限法分析方式與本研究建立的二維與三維數值分析模式，進行橋梁耐洪安全計算，最後並提出分析沖刷深度、水流流速、水位高度與累計應變對橋梁穩定之靈敏度，提供橋梁災前潛勢評估、災中應變決策與災後維修支援利用。|
abstract:Performance of a cross river bridge is influenced by scouring. Several meters thick of the river bed have been found to be eroded away in many key rivers in Taiwan after heavy rainfall or typhoon in the past decade. Some cases were worsened for the excessive river course dredging or gravel plundering in the years leading up to the storm. Consequently, many bridges collapsed due to scouring of pier foundations. One of the famousexamples is the typhoon Morakot struck Taiwan one year ago. It was one of the deadliest typhoons in Taiwan’s history and caused billions of dollars in property losses. Included in the damage were tens of bridges that were washed away by the storm. Between 1998 and 2009, investigation by the government has found that the foundations of the 308 bridges in Taiwan need some other grade-control structures to reduce scour depth. Among these bridges, 59 of them were in fact damaged or failed before the protection structure was installed.In this research, four analytical models which are limit state analysis model, two and three dimension finite element analysis model and the permanent strains analysis model are established. And a failure envelope considered scouring depth, river flow velocity and water level effect is used in analysis the bridge stability subject to scouring. Through the model, the mechanism of the failure of the bridge system due to the scourcan then be analyzed and the guideline of the disaster monitoring and precaution procedure can then be established, and also the maintanence of the bridge after the severe foundation erosions can be evaluated.
|Appears in Collections:||[河海工程學系] 研究計畫|
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