橋梁樁基礎與沉箱基礎耐洪能力分析之研究

Study on flood-resisting capacity analysis of Bridge with pile foundations and caisson foundations

陳晨(Chen Chen)

指導教授 ： 宋裕祺

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00136

摘要

近年來台灣每逢颱風豪雨常出現橋梁倒塌、斷裂沖毀，2000 年碧利斯颱風過後高屏大橋無預警的塌毀，2008 年辛樂克颱風時后豐大橋斷裂等等災害事件頻傳，造成不少生命財產的損失。過去河川係依水位高做為封橋標準，顯然只單單依據此種決定封橋時機的方式不足以達到預警避免災害的功能。 本研究主要針對橋梁樁基礎與沉箱基礎的耐洪能力進行分析與探討，首先以張有齡側向荷重基樁理論、莫爾庫倫土壤破壞準則等為理論基礎，得到各種不同排列之基樁承受側向荷重之樁體內力解析解，再利用有限元素軟體Midas GTS 建立三維分析模型模擬土壤與樁基礎、沉箱基礎間的互制作用求得數值解，並比較二者之差異，驗證Midas GTS 分析所得結果之精確性。繼而利用Midas GTS 建立樁基礎與沉箱基礎之耐洪能力分析模式，考量各種不同的沖刷深度、水流流速和水位高作用下之基礎安全係數。並根據我國公路橋梁設計規範、建築物基礎構造設計規範、日本道路橋示方書等規範標準做為限定條件，建立警戒值、行動值等指標提供橋梁管理之用。

關鍵字

耐洪評估 ； 沖刷 ； 基礎穩定性

並列摘要

In the past decades, the heavy rain frequently caused the scoured bridges collapse during typhoon period in Taiwan. The observation of water lever serving as the unique criterion of traffic-close for the bridges has been proven as fail in alarming of flood disaster. To get a better warming system, this thesis first concluded three fundamental parameters including the water level, the scoured depth of the bridge foundation and the flood velocity sensitive to the failure of the bridges and proposed an analysis process in determining the safety level.
In this thesis, various possible failure modes of the pile-foundation and caisson-foundation were classified and employed as the check-point of the governed issue during the analysis. In which, the shear capacity as well as the interaction between axial force and bending moment of the foundation body is taken into account as the body strength. Besides, the maximum shear capacity as well as bearing capacity of the soil at the bottom of foundation is considered as the soil strength. Through the 3D finite
element software of MIDAS-GTS, the stresses concerned during various situations of scoured riverbed are able to be determined and, accordingly, the most possible failure
mode of the bridge foundation can be detected through the choice of minimum ratio of capacity to stress. As a result, different kinds of safety level represented by the surfaces
composed of the parameters could benefit the bridge engineers a good making decision on management of the scoured bridges.

並列關鍵字

pile ； caisson ； foundation ； scour ； flood-resisting

參考文獻

[3] U.S. Department of Transportation, FHWA, Hydraulic Engineering Circular

No.20, “Bridge Scour and Stream Instability Countermeasures”,2001.

[4] U.S. Department of Transportation, FHWA, Hydraulic Engineering Circular

No.23, “Stream Stability at Highway Structures”,2001.

[5] U.S. Department of Transportation, FHWA, Hydraulic Engineering Circular