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（1 上?？辈煸O(shè)計(jì)研究院（集團(tuán)）有限公司， 上海 200093；2 上海環(huán)境巖土工程技術(shù)研究中心， 上海 200093）
［摘要］搜集軟土地區(qū)近二十項(xiàng)工程七十余組超長樁試樁資料，對其承載特性進(jìn)行深入研究，分析結(jié)果表明：樁側(cè)土層性質(zhì)和分布、施工因素、后注漿效果是影響承載特性的主要因素。根據(jù)單樁Q-S曲線特征，提出緩變型樁端后注漿超長樁極限承載力的確定標(biāo)準(zhǔn)； 超長樁在最大荷載下的樁頂回彈率與單樁剛度總體呈指數(shù)關(guān)系，單樁剛度均值約為550kN/mm； 超長樁混凝土單軸壓縮彈性模量隨荷載水平增大呈指數(shù)關(guān)系降低，提出考慮模量變化和承載性狀發(fā)揮的超長樁樁身壓縮量估算公式； 不同荷載水平下，側(cè)阻力沿樁身由菱形分布向梯形分布發(fā)展，工作荷載下可不考慮臨界樁長問題； 端阻比隨最大加載量的增大而線性增大，采用后注漿工藝后超長樁端阻力發(fā)揮值未顯著提高。
［關(guān)鍵詞］超長樁； 承載特性； 單樁極限承載力； 樁身壓縮量估算公式； 端阻比
中圖分類號：TU473文獻(xiàn)標(biāo)識碼：A文章編號：1002-848X(2020)21-0114-07
Field tests research on bearing characteristics of super-long piles in soft soil region
LI Tao1,2
（1 SGID Engineering Consulting (Group) Co., Ltd.， Shanghai 200093, China;2 Shanghai Engineering Research Center of Geo-Environment, Shanghai 200093, China）
Abstract:By collecting more than 70 sets of super-long pile test information in nearly twenty projects, bearing characteristics of super-long pile has been studied in-depth. According to the analysis results, soil properties and vertical distribution, construction factors and post-grouting effect are the main factors affecting the bearing characteristics. Through the characteristics of Q-S curve of a single pile, the determination criteria of ultimate bearing capacity was proposed in which the Q-S curve of a super-long base-grouting pile was changed slowly. The rebound rate of pile top under ultimate load is the exponential relationship with the stiffness of a single pile, which the average value of stiffness is above 550kN/mm. The uniaxial compressive elastic modulus of concrete for super-long piles decreases exponentially with the increase of load level, at the same time the estimation formula of super-long pile compression was taken to consider changes in modulus and load characteristics; Under different load levels, the shaft resistance develops from the diamond-shaped distribution to the trapezoidal distribution in which the critical pile length is not considered under the working load state. The share of base resistance increases linearly with the increase of the maximum loading, however the development of top resistance of super-long piles after using post-grouting process did not significantly improve.
Keywords:super-long pile; bearing characteristics; ultimate bearing capacity of a single pile; estimation formula of pile compression; share of base resistance
*上海市科學(xué)技術(shù)委員會工程技術(shù)研究中心建設(shè)專項(xiàng)（15DZ2251300）。
作者簡介：李韜，博士，高級工程師，Email:litao@sgidi.com。
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