本文選題：永久全護筒 + 嵌巖灌注樁�。� 參考：《廣州大學》2017年碩士論文

【摘要】：我國沿海城市以海相沉積平原地貌為主,這些地區(qū)會經(jīng)常遇到深厚的流塑狀軟土地質(zhì)條件,不利于其工程建設。以珠海市橫琴區(qū)某樁基工程作為例,該工程的中風化花崗巖層平均埋深約28m,軟土層平均厚度約24m左右,地質(zhì)條件尤為特殊。珠海市很多樁基礎工程通過改進普通嵌巖灌注樁得到了永久全護筒嵌巖灌注樁的新樁型。實踐表明,永久全護筒嵌巖灌注樁能不僅能滿足承載力要求還能保證施工質(zhì)量,很好地適用于這種深厚軟土地質(zhì)條件,解決了深厚軟土中的成樁難題。本文將深厚軟土中鉆孔或清孔、灌注混凝土時使用全護筒護壁,成樁后護筒不予拔出留在土中參與樁身受力且樁端嵌入巖層的鋼護筒—混凝土組合結(jié)構(gòu)定義為永久全護筒嵌巖灌注樁。本文先總結(jié)了永久全護筒嵌巖灌注樁的施工工藝,然后對其鋼護筒厚度選擇、承載力及沉降計算方法、承載性狀影響因素等展開了研究,其主要內(nèi)容及成果如下:(1)結(jié)合珠海市橫琴區(qū)某樁基工程實例,總結(jié)了永久全護筒嵌巖灌注樁的施工技術(shù)、施工要點、質(zhì)量控制要點及工程應用,并分析了其工程優(yōu)點。(2)基于靜力平衡理論進行施工過程中內(nèi)外環(huán)壓下鋼護筒穩(wěn)定性及強度分析,推導了確定永久全護筒嵌巖灌注樁的鋼護筒壁厚的計算公式,為工程中全護筒厚度的選擇提供了理論依據(jù)。(3)分析了永久全護筒嵌巖灌注樁荷載傳遞的影響因素,然后選擇合理的荷載傳遞模型推導了基于荷載傳遞函數(shù)法的荷載-沉降計算公式;并進一步推導了考慮深厚軟土中樁身的壓屈失穩(wěn)影響和強度的豎向極限承載力計算公式,最后以本文所依托的工程的靜載試驗數(shù)據(jù)作為依據(jù)論證了其合理性。(4)以本文所依托的珠海市橫琴區(qū)某樁基工程作為背景,通過MIDAS GTS NX有限元軟件建立永久全護筒嵌巖灌注樁的三維實體單元模型進行數(shù)值模擬,分析了不同樁徑、不同樁長、不同鋼護筒厚度、不同樁側(cè)土體地質(zhì)條件、不同嵌巖深度幾大主要因素對永久全護筒嵌巖灌注樁承載性狀的影響。
[Abstract]:The coastal cities in China are dominated by marine sedimentary plain landforms. These areas often encounter deep geological conditions of fluid-plastic soft soil, which is not conducive to its engineering construction. Taking a pile foundation project in Hengqin District of Zhuhai as an example, the average buried depth of weathered granite layer is about 28m, the average thickness of soft soil is about 24m, and the geological conditions are especially special. Through improving ordinary rock-socketed cast-in-place piles, a new type of permanent hold-in-situ cast-in-place piles has been obtained in many pile foundation projects in Zhuhai. The practice shows that the pile can not only meet the requirements of bearing capacity but also guarantee the construction quality. It is suitable for this kind of deep soft soil geological conditions and solves the problem of pile formation in deep soft soil. In this paper, the hole-hole is drilled or cleared in the deep soft soil, and the wall of the whole protective tube is used when the concrete is poured. The steel-concrete composite structure, which remains in the soil and embraces the rock layer at the end of the pile, is defined as the permanent cast-in-place pile. In this paper, the construction technology of permanent rock-socketed cast-in-place pile is summarized firstly, and then the selection of the thickness of steel retaining tube, the calculation method of bearing capacity and settlement, the factors affecting bearing characteristics, etc., are studied. The main contents and results are as follows: (1) combined with an example of pile foundation project in Hengqin District of Zhuhai City, the construction technology, construction key points, quality control points and engineering application of the cast-in-place pile with rock socketed in permanent retaining tube are summarized. Based on the static equilibrium theory, the stability and strength of steel retaining tube under internal and external ring pressure during construction are analyzed, and the calculation formula for determining the wall thickness of steel casing wall of permanent rock-socketed cast-in-place pile is derived. This paper provides a theoretical basis for the selection of the thickness of the whole retaining tube in engineering) and analyzes the factors affecting the load transfer of the permanent pile with rock-socketed cast-in-place. Then the load-settlement calculation formula based on load transfer function method is deduced by selecting a reasonable load transfer model, and the calculation formula of vertical ultimate bearing capacity considering the influence of buckling and buckling of pile in deep soft soil and the strength of pile is further deduced. Finally, based on the static load test data of the project relied on in this paper, the rationality of the project is demonstrated. (4) the pile foundation project in Hengqin District of Zhuhai City is taken as the background. The 3D solid element model of permanent rock-socketed cast-in-place pile is established by MIDAS GTS NX software, and the geological conditions of different pile diameter, pile length, different thickness of steel retaining tube and different soil around the pile are analyzed. The influence of several main factors of different rock socketed depth on the bearing behavior of permanent rock-socketed cast-in-place pile.
【學位授予單位】：廣州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU473.1

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