受沖刷之橋梁樁基礎側向反應行為探討

Effect of scour on lateral response of deep foundation for bridge pier

刁繼堃(Ji-Kun Diau)

指導教授 ： 陳皆儒

國立暨南國際大學/科技學院/土木工程學系/碩士(2013年)

https://doi.org/10.6837/NCNU.2013.00312

摘要

橋梁在沖刷作用下造成基礎系統承載能力降低及變形量增大，是洪流期間危害橋梁安全之重要原因。因此了解沖刷效應對橋梁基樁或基礎系統承載與變形行為之影響，是橋梁基礎沖刷危害探討的一個基本並關鍵課題。本研究以模型樁側向載重試驗(依照不同模型樁之材質、樁徑和砂土相對密度規劃8組試驗)成果進行沖刷對單樁側向承載行為影響之系統化探討，提出採用側向承載能力折減率和樁身最大彎矩放大率為沖刷效應評估之指標，並探討土壤勁度、樁細長比及沖刷深度比等因素對其影響。分析結果顯示，側向承載能力之折減率與有效深度比可建立一個簡化關係，透過此關係並配合評估之沖刷深度，可進行基樁殘餘承載力之初步估算。而從樁身最大彎矩放大率與有效深度比建立之關係可觀察出基樁的覆土深度為影響沖刷後樁身最大彎矩放大率之重要因素，其關係趨勢可作為工程設計上之參考。

關鍵字

沖刷 ； 基樁 ； 側向承載力 ； 彎矩

並列摘要

The reduction in capacity and increase in deflection of the foundation system as a result of scouring are factors affecting safety of bridges encountering flood current. Understanding the effect of scour on lateral capacity of foundation is an essential element in addressing mitigation of this adverse effect. In this study, the effect of scour on a single pile is investigated systematically through results of model pile tests. It is founded that the reduction ratio R (of the lateral capacity) and the amplification ratio A (of the maximum bending moment) are useful indexes to quantify the scour effect. Effect of soil stiffness, pile slenderness ratio, and scour depth ratio on the value of R and A are examined. Simple yet rational correlations between R and scour depth ratio as well as A and scour depth ratio are established. Used of the developed correlation in design and disaster prevention also are discussed.

並列關鍵字

scour ； pile ； lateral capacity ； bending moment

參考文獻

1. Bolton, M. D. (1986), “Strength and Dilatancy of Sands,” Géotechnique, 36(1), 65-78.

2. Broms, B. B. (1964), “Lateral Resistance of Piles in Cohesionless Soils,” Journal of the Soil Mechanics and Foundations Division, ASCE, 90(SM3), 123-156.

3. Chang, Y.L. (1937). Discussion on “Lateral Pile-Loading Tests” by L.B. Feagin,Trans., ASCE, Vol.102, pp. 272~278.

4. Kishore, Y. N., Rao, S. N., and Mani, J. S. (2008), “Influence of the Scour on Laterally Loaded Piles,” Proceedings, 12th International Conference of International Association for Computer Methods and Advances in Geotechnics, Goa, India, 3283-3288.

5. Kishore, Y. N., Rao, S. N., and Mani, J. S. (2009), “The Behavior of Laterally Loaded Piles Subjected to Scour in Marine Environment.” KSCE Journal of Civil Engineering, 13(6), 403-408.