場鑄樁於卵礫石層之軸向及側向載重詮釋法及承載力評估

Evaluation of Interpretation Criteria and Capacity for Drilled Shafts in Gravelly Soils under Axial and Lateral Loading

朱祖宏(Tsu-Hung Chu)

指導教授 ： 陳逸駿

中原大學/工學院/土木工程研究所/碩士(2009年)

https://doi.org/10.6840/CYCU.2009.00870

摘要

本研究藉由大量之現地樁載重試驗資料，評估場鑄樁於卵礫石層之軸向及側向詮釋法及承載力。在詮釋法方面，以工程界常用的詮釋法為評估基準，探討各種詮釋法之相互關係及適用性。在軸向承載力方面，以一般建議之β法、底承力公式、及SPT-N經驗公式進行分析。側向承載力方面，則用Chang之簡易理論公式進行評估。
依分析結果，拉拔載重之L1約等於0.31%B及2.6 mm時之載重， L2約等於18.4 mm時之載重。於壓載方面，L1約等於0.54%B及7.2 mm時之載重， L2約等於52.1 mm時之載重。於所有軸向詮釋法，Davisson法所詮釋之破壞載重為最低，而Chin法為最高，可以當做各詮釋法之上下限值。於側向載重方面，Slack and Walker法所發生之位置大約為0.75%B及10.0 mm處，而Hirany and Kulhawy法所發生之位置大約為1.2%B及11.4 mm處。
在軸向承載力分析，一般β法分析之理論摩擦力易造成過於保守之評估，而一般底承力公式則過於高估。另外，不同規範所建議之SPT-N經驗值亦與量測值比較，驗證各規範建議之合理性。側向承載力分析方面，Chang之簡易評估法在位移愈大之情況下，其所推估之承載力則愈接近實測值。本研究最後針對場鑄樁於卵礫石層之詮釋及分析提出設計建議。

關鍵字

場鑄樁 ； 卵礫石層 ； 載重試驗 ； 詮釋法 ； 軸向載重 ； 側向載重

並列摘要

This study is a critical evaluation of drilled shafts under axial and lateral loading in gravelly soils. Both interpretation criteria and analysis methods are examined using field load test data. Available interpretation criteria are used to establish a consistent axial and lateral interpretation criterion. The β method, general bearing capacity equation, and SPT-N empirical equation are evaluated for axial capacity, while the simple Chang method is used for lateral capacity.
Based on these analyses, QL1 is close to load at 0.31%B with 2.6 mm and QL2 is close to load at 18.4 mm for uplift loading. QL1 is close to load at 0.54%B with 7.2 mm and QL2 is close to load at 52.1 mm for compression loading. Among all axial interpretation criteria, the Davisson method gives the lowest results and Chin method has the highest results. For lateral loading, QS&W is close to Q0.75%B and Q10.0mm, while QL is close to Q1.2%B and Q11.4mm.
For the analysis of axial capacity, the side resistance of β method is generally underestimated and the general bearing capacity equation is overestimated. The suggested SPT-N empirical equations were also evaluated using measured results. For lateral capacity, the statistical data show that the larger the lateral displacement, the closer the results between measurements and simple Chang method. Finally, specific design recommendations for the interpretation and capacity analysis are given.

並列關鍵字

lateral loading ； axial loading ； interpretation criteria ； load tests ； gravelly soils ； drilled shafts

參考文獻

1. 方顗忠，「場鑄樁樁身摩擦力及拉拔詮釋法之評估」，碩士論文，私立中原大

2. 李昀宣，「場鑄樁受側向載重之詮釋法評估」，碩士論文，私立中原大學土木

3. 張馨文，「場鑄樁樁身摩擦力及拉拔詮釋法之評估」，碩士論文，私立中原大

5. Chang, Y.L., Discussion on the paper “Lateral Pile-Loading Tests”, by LB Feagin,

Transactions, ASCE, Vol. 102, 1937.