飽和砂中鋁樁受側向載重之試驗與分析

The responses of load test on Aluminum pile in saturated sand

戴偉倫(Wei-Lun Tai)

指導教授 ： 陳正興

國立臺灣大學/工學院/土木工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.10417

摘要

為側向載重樁之行為，本研究進行模型樁試驗，以深入探討基樁承受側向力後的變形、受力及其與土壤之互制作用。
模型樁試驗於國家地震工程研究中心進行，將模型樁埋置於雙軸向多層剪力盒中，再配合反力牆與反力梁架設油壓制動器進行試驗，分別針對鋁製管樁於空箱與飽和砂土中兩種情況進行反覆側向載重試驗，此試驗採用位移控制，於樁頭施予單週之反覆側向位移，量取樁身之撓曲變形。
空箱單樁試驗之目的主要為量測鋁樁之撓曲剛度，並檢核量測儀器與假設邊界條件是否符合，以確認基樁參數。土壤中模型樁試驗利用應變計量測樁斷面的應變進而計算出各斷面的曲率大小，再由曲率乘上撓曲剛度則得各斷面之彎矩。進而採用多項式變形曲線法將各斷面彎矩值以曲線近似，利用Lagrange multiplier 法來限制邊界條件，則可得到最佳的彎矩函數，得到此函數後應用彈性梁理論，可推求出樁身轉角、側向變位、剪力、及土壤反力分佈函數，進而建立基樁受側向位移時周圍土壤之 p-y曲線。
利用所得到之 p-y 曲線，探討初始地盤反力模數隨有效覆土深度之關係、割線地盤反力模數隨側向位移之變化與等值地盤反力模數隨深度之關係，並歸納出簡化 p-y 特性曲線與各深度 p-y 曲線遲滯圈之阻尼比變化。最後則將試驗得到之p-y曲線代入SAP2000程式進行模擬分析，數值分析與試驗之分析結果相符。

關鍵字

模型樁 ； 側向載重試驗 ； 樁土互制 ； 回歸分析模式 ； p-y曲線

並列摘要

To investigate the behavior of a laterally loaded pile, a series of model pile tests were conducted at the National Center for Research on Earthquake Engineering (NCREE). An aluminum model pile in a box without and with soils was tested. Tests with the pile only were performed to determine the pile’s flexural rigidity while tests with the pile in saturated sands were conducted to record the pile-head load-deflection responses and the curvatures along the pile shaft.
To analyze the test data of this model test, the moment distributions of the pile were firstly computed by multiplying the curvatures with the flexural rigidity. Then, an optimization method with Lagrange multipliers was adopted to fit the moment curves to polynomials. Afterward, the displacement, slope and shear of the pile, as well as the soil reactions can be obtained through integration and differentiation of the moment function. Besides, the p-y curves can be thus constructed by relating the soil reactions to the displacements of the pile.
To understand the characteristics of the experimental p-y curves obtained, the initial subgrade modulus and the secant subgrade reaction modulus of the p-y curves were investigated. Simple empirical equations were further proposed to simplify the experimental p-y curves. Finally, numerical analyses with the experimental p-y curves were performed by SAP2000 for verification and give satisfactory results.

並列關鍵字

laterally loaded piles ； model pile test ； pile-soil interaction ； regressive analysis ； p-y curves

參考文獻

22. 邱俊翔，樁頭受側向力作用之側推分析模式，國家地震工程研究中心報告，報告編號:NCREE-07-012 (2007)。

30. 曾永成，飽和砂土中樁基受反覆側向荷重之行為，國立台灣大學土木工程研究所，碩士論文 (2008)。

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