本文關(guān)鍵詞：有孔錐—柱管樁開孔應(yīng)力集中系數(shù)及樁身極限承載力研究　出處：《南昌航空大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 有孔錐-柱管樁 孔徑 錐度 開孔方式 應(yīng)力集中系數(shù) 數(shù)值模擬 極限承載力

【摘要】：有孔錐形管樁具有傾斜側(cè)面,加大了樁土接觸面積,使其受力更合理,更能發(fā)揮樁側(cè)土體的側(cè)摩阻力;同時,作為復(fù)合地基豎向增強體,有孔錐形管樁上端尺寸變大,增大了復(fù)合地基面積置換率,從而可提高復(fù)合地基承載力。但在沉樁施工過程中,錐形管樁存在接樁不便、處理深度不足、擠土效應(yīng)明顯等缺點。現(xiàn)提出一種有孔錐-柱管樁技術(shù),在加大地基處理深度的同時,樁周土體中超孔隙水可通過樁孔主動進(jìn)入管樁內(nèi)腔,從而加速超孔隙水壓力消散,減小超孔隙水壓力最大值,減小錐-柱管樁的擠土效應(yīng)并提高土的抗剪強度。但開孔必將導(dǎo)致結(jié)構(gòu)的幾何連續(xù)性遭到破壞,產(chǎn)生明顯的應(yīng)力集中,從而降低結(jié)構(gòu)的承載能力和使用壽命。因此,本文圍繞有孔錐-柱管樁開孔方式、管樁側(cè)壁開孔所產(chǎn)生的應(yīng)力集中系數(shù)大小和分布范圍、樁身極限承載力折減規(guī)律等關(guān)鍵問題,采用模型試驗和數(shù)值模擬相結(jié)合的方法,研究單向、雙向和星狀開孔在樁身受力時,樁身應(yīng)力集中系數(shù)分布規(guī)律和極限承載力折減情況,為有孔錐-柱管樁技術(shù)的應(yīng)用推廣提供試驗基礎(chǔ)。主要研究成果如下:(1)有孔錐-柱管樁應(yīng)力集中系數(shù)試驗表明:在三種開孔方式中,星狀樁型應(yīng)力集中系數(shù)分布范圍最小,樁身受力均勻�？讖綖�5mm的各樁型應(yīng)力集中系數(shù)普遍低于孔徑為6mm各樁型,應(yīng)力集中系數(shù)的大小主要影響因數(shù)是孔徑直徑,錐度對應(yīng)力集中系數(shù)分布范圍和系數(shù)值影響不明顯。所有樁型中孔徑為5mm的星狀樁型受力性能最佳。(2)樁身極限承載力試驗表明:三種開孔方式極限承載力性能星狀樁型最優(yōu)�？讖綖�5mm的各樁型極限承載力折減情況明顯低于孔徑為6mm的各樁型,開孔孔徑越大樁身極限承載力折減越嚴(yán)重;有孔錐-柱管樁極限承載力性能最好的是開5mm孔徑錐度為1/80的星狀樁型。(3)樁身應(yīng)力集中系數(shù)數(shù)值模擬研究表明:有孔錐-柱管樁柱形段應(yīng)力集中系數(shù)值要高于錐形段;其樁身錐度的變化對其應(yīng)力集中系數(shù)影響不大;孔徑的大小是影響應(yīng)力集中系數(shù)大小的主要因素,應(yīng)力集中系數(shù)的分布范圍受開孔方式的影響。在三中開孔方式中,星狀有孔錐-柱管樁的應(yīng)力集中系數(shù)分布范圍最集中。開孔孔徑越小其應(yīng)力集中系數(shù)越小,其中孔徑為5mm的各樁型應(yīng)力集中系數(shù)值最小。所有樁型中孔徑為5mm的星狀樁型受力性能最優(yōu)。(4)由于試驗誤差的存在,試驗所得應(yīng)力集中數(shù)值小于數(shù)值模擬所得的數(shù)值;但應(yīng)力集中系數(shù)分布規(guī)律基本一致,柱形段應(yīng)力集中系數(shù)高于錐形段,開孔孔徑越大應(yīng)力集中系數(shù)越大;說明數(shù)值模擬管樁受壓時的應(yīng)力集中變化情況與試驗過程一致。
[Abstract]:A hole conical pipe with inclined side, increasing the pile soil contact area, the stress is more reasonable, more can play the side friction of pile side soil; at the same time, as the vertical reinforcement composite foundation, pore size at the upper end of the tapered pipe pile composite foundation, increasing the area replacement ratio, which can improve the composite foundation the bearing capacity of pile sinking. But in the process of construction, conical pipe pile connection exists inconvenience, depth insufficient, compacting effect and other shortcomings. In this paper a hole cone cylinder pile technology, to increase the depth of foundation treatment at the same time, the soil around the pile in pore water through the pipe into the active cavity of pile hole thus, accelerate the dissipation of excess pore water pressure, the excess pore water pressure decreases the maximum squeezing effect of taper column pile and improve the shear strength of soil. But the hole will cause the structure of geometric continuity is destroyed, produce significant stress concentration, In order to reduce the bearing capacity of the structure and service life. Therefore, this paper around the hole cone column pile holes, pile side holes caused by stress concentration coefficient and distribution range, capacity reduction key rule of ultimate bearing pile, one-way research method, model test and numerical simulation with the two-way and star shaped hole in the force of pile, pile stress concentration coefficient distribution and ultimate bearing capacity reduction, provide experimental basis for application of hole cone cylinder pile technology. The main research results are as follows: (1) a test showed that the stress concentration coefficient of cone hole column pile: in three holes, star shaped pile stress concentration coefficient distribution of minimum force of pile diameter is 5mm. The uniform pile stress concentration coefficient is generally lower than the diameter 6mm of each pile type, should be the main influence factor is the size of the coefficient of stress concentration Aperture diameter, taper on the stress concentration coefficient distribution and numerical aperture is not obvious. All type of pile for pile type 5mm star was optimized. (2) show that the bearing capacity of pile: three holes of ultimate bearing capacity of pile type. The optimal performance of star shaped aperture type pile the limit for 5mm capacity reduction of each pile is obviously lower than the pore size of 6mm, the diameter of the holes is more serious reduction of bearing capacity of pile hole limit; cone cylinder pile ultimate bearing capacity is the best 5mm hole taper star pile type 1/80. (3) pile should be set in the numerical simulation of the force coefficient showed that the hole cone cylinder pile column section of the stress concentration coefficient is higher than that of the conical section; the change of the pile taper on the stress concentration coefficient has little effect; the pore size is the main factor affecting the stress concentration coefficient, the coefficient of stress concentration distribution fan Around the affected holes. In third holes, star has the most concentrated hole cone column pile stress concentration coefficient distribution range. The hole diameter is smaller and the stress concentration coefficient is small, the aperture of each pile type 5mm stress concentration coefficient of the minimum aperture pile all. In the star like pile type 5mm best mechanical properties. (4) because of the testing errors, the experimental stress concentration value is less than the simulated values; but the stress concentration coefficient distribution are basically the same, the column section of the stress concentration coefficient is higher than that of conical section, hole diameter greater stress the greater the concentration coefficient; that the change and test process of stress concentration in numerical simulation of pile compression.

【學(xué)位授予單位】：南昌航空大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU473.1

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