【摘要】：為克服內河碼頭建設中大水位差對施工的影響,鋼護筒-鋼筋混凝土結構樁基已經廣泛應用于內河高樁碼頭工程實踐。本文結合交通運輸部建設科技項目“在役高樁碼頭結構整體安全性評估技術”,依托重慶果園港碼頭結構二期工程,通過室內模型試驗及理論分析的方法,對大直徑鋼護筒-鋼筋混凝土樁的承載性能及長期工作性能進行研究,主要的研究內容及相關的研究結論為:(1)結合果園港碼頭二期工程,完成了模型設計。開展了6組不同參數(shù)的模型樁基的承載力試驗研究。研究發(fā)現(xiàn):對于D/δ≥20薄壁鋼護筒-鋼筋混凝土樁基,在應力水平低于0.45的軸向荷載作用下,鋼護筒與內部鋼筋混凝土的縱向應變大小基本相同,此時鋼護筒對內部鋼筋混凝土的約束作用并不明顯,而在應力水平高于0.45的軸向荷載作用下,鋼護筒將對鋼筋混凝土施加側向約束作用。此側向約束作用可延緩微裂縫的開展,從而增強樁基的延性及極限承載能力;鋼護筒對核心混凝土的側向約束作用隨鋼護筒厚度的增加而增大;(2)對不同鋼護筒厚度下的鋼護筒-鋼筋混凝土模型樁基的橫向純彎構件性能進行研究。研究發(fā)現(xiàn):對于長細比L/D小于8的模型樁,在三分點加載方式下,相比于鋼筋混凝土模型樁基,鋼護筒的存在可有效增大破壞時的跨中撓度,避免脆性破壞;同時,鋼護筒的存在可極大提高此類構件的極限彎矩。(3)對鋼護筒-鋼筋混凝土模型樁基在長期荷載作用下核心混凝土徐變規(guī)律進行了研究,主要變量參數(shù)為鋼護筒厚度。并將試驗結果與混凝土徐變理論模型計算結果比較,研究發(fā)現(xiàn):在應力水平低于0.45的軸向荷載作用下,鋼護筒-鋼筋混凝土構件核心混凝土的徐變規(guī)律與混凝土結構徐變規(guī)律相同,均是前期發(fā)展較快而后期發(fā)展逐漸緩慢;鋼護筒-鋼筋混凝土樁的徐變值及徐變系數(shù)均小于同齡期時理論計算值且鋼護筒厚度越大,同齡期下混凝土的徐變值越小;(4)與混凝土典型徐變模型的比較發(fā)現(xiàn),在應力水平低于0.45的軸向荷載作用下,采用混凝土徐變的MC90模型計算的結果與試驗結果偏差相對較小。同時,用有限元軟件LINK3D對長期性能進行數(shù)值模,結果與試驗結果較為吻合。
[Abstract]:In order to overcome the influence of large water level difference on the construction of inland river wharf, the pile foundation of steel tube-reinforced concrete structure has been widely used in the engineering practice of inland river high pile wharf. In this paper, combined with the construction of science and technology project of Ministry of Communications and Transport, "overall safety assessment technology of in-service high pile wharf structure", relying on the second phase of Chongqing Orchard Port structure Project, through indoor model test and theoretical analysis method, The load-bearing performance and long-term working performance of large-diameter steel sheet-reinforced concrete pile are studied. The main research contents and related conclusions are as follows: (1) combined with the second phase of Orchard Port Wharf, the model design has been completed. The bearing capacity of six groups of model pile foundations with different parameters was studied. It is found that the longitudinal strain of steel retaining tube and internal reinforced concrete is basically the same when the stress level is less than 0.45 for D / 未 鈮，

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