本文選題：有孔管樁　切入點(diǎn)：群樁　出處：《南昌航空大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：對(duì)于高速公路、高速鐵路等工程的深厚軟土地基,目前國(guó)內(nèi)外很多都是通過(guò)選用合適的豎向增強(qiáng)體形成復(fù)合地基進(jìn)行地基處理,以達(dá)到減少建筑物沉降、提高地基承載力的目的。帶帽管樁復(fù)合地基適合于較為深厚的軟土地基處理,但在靜壓管樁沉樁過(guò)程中所產(chǎn)生的擠土效應(yīng)可能會(huì)造成鄰樁樁身移位、上浮、傾斜,甚至斷樁等不良后果。為此,課題組提出了帶帽有孔管樁復(fù)合地基技術(shù)。當(dāng)前對(duì)帶帽有孔管樁復(fù)合地基技術(shù)的研究主要集中在有孔管樁單樁承載性狀,對(duì)有孔管樁群樁的工作性狀研究尚處于一片空白,但實(shí)際工程中使用更多的卻是群樁。因此,對(duì)帶帽有孔管樁群樁復(fù)合地基的工作性狀研究,具有一定的必要性和實(shí)踐意義。本文通過(guò)室內(nèi)模型試驗(yàn)和數(shù)值模擬兩種方法,對(duì)帶帽有孔管樁群樁復(fù)合地基的工作性狀進(jìn)行了研究與探討。主要研究?jī)?nèi)容及成果如下:(1)對(duì)有孔管樁群樁沉樁時(shí)引起的超孔隙水壓力進(jìn)行了室內(nèi)模型試驗(yàn)研究。結(jié)果表明,有孔管樁群樁沉樁產(chǎn)生的超孔隙水壓力不是單樁沉樁產(chǎn)生的超孔隙水壓力簡(jiǎn)單疊加,而是單樁相互影響的累積和消散的綜合結(jié)果,且有孔管樁群樁測(cè)點(diǎn)產(chǎn)生的超孔隙水壓力與沉樁方向有關(guān),當(dāng)沉樁方向趨向測(cè)點(diǎn)時(shí),有孔管樁群樁產(chǎn)生的超孔隙水壓力上升,當(dāng)其背向測(cè)點(diǎn)時(shí)超孔隙水壓力下降。另外,星狀布孔方式的有孔管樁群樁沉樁產(chǎn)生的超孔隙水壓力峰值最小、消散速率最快,最有利于減小沉樁擠土效應(yīng),沉樁效應(yīng)最佳。樁壁開(kāi)孔方式為管樁群樁施工時(shí),如何減小沉樁擠土效應(yīng)提供了一種新的途徑。(2)對(duì)豎向荷載下帶帽有孔管樁群樁復(fù)合地基的工作性狀進(jìn)行了室內(nèi)模型試驗(yàn)研究。結(jié)果表明,帶帽有孔管樁群樁復(fù)合地基沉降量小于帶帽無(wú)孔管樁群樁復(fù)合地基沉降量,即帶帽有孔管樁群樁復(fù)合地基的控沉能力比帶帽無(wú)孔管樁群樁復(fù)合地基的控沉能力強(qiáng);群樁樁身軸力隨深度的增加而減少,且隨豎向荷載的增大,軸力減少的速率逐漸增大;在加載初期,荷載主要由樁體承擔(dān),隨荷載繼續(xù)增加,荷載由樁土共同承擔(dān),直至達(dá)到樁土共同工作的穩(wěn)定狀態(tài)。另外,隨荷載等級(jí)逐漸加大,帶帽有孔管樁群樁復(fù)合地基樁土應(yīng)力比始終小于帶帽無(wú)孔管樁群樁復(fù)合地基樁土應(yīng)力比,這進(jìn)一步說(shuō)明了樁身開(kāi)孔能增強(qiáng)管樁群樁復(fù)合地基土體承載力。(3)采用ABAQUS軟件,對(duì)帶帽有孔管樁群樁復(fù)合地基的工作性狀進(jìn)行了數(shù)值模擬分析,并與室內(nèi)試驗(yàn)研究結(jié)果進(jìn)行對(duì)比,結(jié)果證實(shí)了室內(nèi)模型試驗(yàn)結(jié)果是正確的。
[Abstract]:For the deep soft soil foundation of expressway, high-speed railway and other projects, at present, many of the domestic and foreign foundation are treated by selecting suitable vertical reinforcement to form composite foundation, so as to reduce the settlement of buildings. The purpose of improving the bearing capacity of foundation is that the composite foundation with cap pipe pile is suitable for deep soft soil foundation treatment, but the squeezing effect of static pressure pipe pile in the course of piling may result in the displacement of adjacent pile body, the floating, and the inclination of pile body. For this reason, we put forward the technology of composite foundation with cap and perforated pipe pile. At present, the research on the composite foundation technology of pipe pile with cap is mainly focused on the bearing behavior of single pile with hole pipe pile. The study on the working behavior of the pile group with holes is still blank, but it is more often used in practical engineering. Therefore, the working behavior of the pile group with cap is studied. It has certain necessity and practical significance. This paper adopts two methods: indoor model test and numerical simulation. In this paper, the working behavior of pile group foundation with cap is studied and discussed. The main research contents and results are as follows: 1) the laboratory model test of excess pore water pressure caused by pile group pile with hole pile is carried out. The results show that, The excess pore water pressure caused by pile group piling with holes is not a simple superposition of excess pore water pressure produced by single pile driving, but a comprehensive result of accumulation and dissipation of single pile interaction. And the excess pore water pressure produced by the pile group pile group is related to the direction of piling. When the pile driving direction tends to the measuring point, the excess pore water pressure of the pile group increases, and the excess pore water pressure decreases when the pile is measured in the back direction. The maximum value of excess pore water pressure and the fastest dissipation rate of the pile-driven pile with holes in the star-arranged hole mode are the minimum and the quickest, which is most helpful to reduce the pile-squeezing effect and the pile-driving effect is the best. The hole opening mode of the pile wall is the pipe pile group pile group construction. How to reduce the compaction effect of pile-sinking is a new way to study the working behavior of pile-group composite foundation with cap hole pile under vertical load. The results show that the experimental results are as follows: (1) the experimental results are as follows: (1) A new way to reduce the compaction effect of pile-driven piles is provided. The settlement of pile group with cap is smaller than that of pile group with cap, that is, the control ability of pile group with cap is better than that of pile group with cap. The axial force of group pile body decreases with the increase of depth, and with the increase of vertical load, the rate of axial force decrease increases gradually, at the beginning of loading, the load is mainly borne by pile body, and with the increase of load, the load is shared by pile and soil. In addition, with the increasing of load grade, the pile-soil stress ratio of pile with cap pile group pile group composite foundation is always smaller than that of pile soil composite foundation without hole pile group pile group foundation with cap, and the pile-soil stress ratio of pile and soil composite foundation with cap hole pile group pile group foundation is smaller than that with cap hole pile group pile group pile composite foundation. This further shows that the hole opening of pile body can enhance the bearing capacity of soil in the composite foundation of pipe pile group pile group. Using ABAQUS software, the numerical simulation analysis of the working behavior of the composite foundation of pipe pile group pile with cap is carried out, and the results are compared with the results of laboratory test. The results show that the results of indoor model tests are correct.
【學(xué)位授予單位】：南昌航空大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TU473.1

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