發(fā)布時(shí)間：2018-01-14 14:45

  本文關(guān)鍵詞：Gibson地基中V-T聯(lián)合受荷樁承載力分析與試驗(yàn)研究　出處：《湖南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 樁基礎(chǔ) Gibson地基 聯(lián)合加載 荷載傳遞函數(shù) 剪切位移法

【摘要】：樁基礎(chǔ)因其承載力高、沉降小、施工方便以及能適應(yīng)復(fù)雜地質(zhì)環(huán)境等優(yōu)點(diǎn)在基礎(chǔ)工程中被廣泛使用。對(duì)于城市立交橋、跨江跨海大橋、海上鉆井平臺(tái)或風(fēng)力發(fā)電塔等結(jié)構(gòu)物中的樁基礎(chǔ),除承受豎向荷載V外,又由于樁頂?shù)牟痪鶆蚧蚱乃搅�、�?cè)向沖擊荷載或地震等因素的影響而作用有較大扭矩�，F(xiàn)有的常規(guī)設(shè)計(jì)方法難以考慮這種豎向力V與扭矩T的共同作用,導(dǎo)致難以合理地評(píng)價(jià)樁身承載力,有時(shí)甚至使設(shè)計(jì)偏于不安全而危及上部結(jié)構(gòu)。為此,本文基于已有研究工作和成果,結(jié)合國(guó)家自然科學(xué)基金項(xiàng)目(51378197),針對(duì)廣義Gibson地基中的V-T聯(lián)合受荷樁進(jìn)行了理論分析與室內(nèi)模型試驗(yàn)研究,主要工作如下:首先,針對(duì)Gibson地基中的豎向受荷樁與受扭樁,視樁身和樁周土分別為彈性體和理想彈塑性體,基于剪切位移法和樁身荷載傳遞函數(shù)建立出樁身位移控制方程,并考慮樁-土接觸面上的位移非協(xié)調(diào)性,引入樁底力和位移邊界條件后,推導(dǎo)出由Bessel函數(shù)表示的樁周土處于不同受力階段時(shí)的樁身內(nèi)力位移解答,并將其計(jì)算結(jié)果與已有研究成果進(jìn)行了對(duì)比分析,驗(yàn)證本文方法的可行性。其次,基于獲得的豎向受荷樁與受扭樁解答,針對(duì)樁周土體分別處于彈性→彈性、彈性→彈塑性及彈塑性→彈塑性三個(gè)不同階段,同時(shí)考慮V-T聯(lián)合受荷樁的不同加載路徑(V→T與T→V),導(dǎo)得了V-T聯(lián)合受荷樁的內(nèi)力位移解答,并求解出不同加載路徑下的樁身極限聯(lián)合承載力。然后,基于Mathcad編制出相應(yīng)的計(jì)算程序,由此完成的參數(shù)分析探討了樁身長(zhǎng)徑比L/D、樁土彈性模量比λ、樁側(cè)土體的剪切模量和極限側(cè)阻力分布常數(shù)比n對(duì)樁身承載力的影響規(guī)律,進(jìn)而獲得了不同加載路徑下的樁身承載力包絡(luò)線。最后,通過(guò)自制砂箱和滑輪組加載裝置,完成了砂土中單樁分別在純扭矩荷載與V-T聯(lián)合荷載作用下的室內(nèi)載荷模型試驗(yàn),獲得了相應(yīng)的樁頂荷載-變形、樁身內(nèi)力位移及樁身極限承載力,并將試驗(yàn)結(jié)果與本文理論分析值進(jìn)行了對(duì)比分析和驗(yàn)證。
[Abstract]:Pile foundation is widely used in foundation engineering because of its high bearing capacity, small settlement, convenient construction and can adapt to complex geological environment. The pile foundation in offshore drilling platform or wind power tower is not only subjected to vertical load V, but also due to the uneven or eccentric horizontal force on the top of pile. Due to the influence of lateral impact load or earthquake, the existing conventional design method is difficult to consider the interaction of vertical force V and torque T, which makes it difficult to evaluate the bearing capacity of pile body reasonably. Sometimes even the design is unsafe and endangers the superstructure. Therefore, this paper based on the existing research work and results, combined with the National Natural Science Foundation Project 51378197). The theoretical analysis and indoor model test of V-T combined loaded pile in generalized Gibson foundation are carried out. The main work is as follows: first. In view of vertical loaded pile and torsional pile in Gibson foundation, the pile body and surrounding soil are regarded as elastic body and ideal elastoplastic body, respectively. Based on the shear displacement method and the load transfer function of the pile body, the displacement control equation of the pile body is established. Considering the disharmony of the displacement on the pile-soil interface, the boundary conditions of the pile bottom force and displacement are introduced. In this paper, the displacement solutions of the internal force of the soil around the pile under different loading stages are derived by Bessel function, and the calculated results are compared with the existing research results. The feasibility of this method is verified. Secondly, based on the solutions of vertical loaded pile and torsional pile, the soil around pile is elastic respectively. 鈫扙lasticity. 鈫扙lastoplasticity and elastoplasticity. 鈫扵hree different stages of elastoplasticity and consideration of different loading paths of V-T combined loaded piles. 鈫扵 and T. 鈫扵he internal force displacement solution of V-T combined loaded pile is obtained, and the ultimate joint bearing capacity of pile body under different loading paths is solved. Then, the corresponding calculation program based on Mathcad is worked out. The influence of the ratio of length to diameter of pile, the ratio of elastic modulus of pile to soil, the shear modulus of soil around the pile and the distribution constant ratio of ultimate lateral resistance to the bearing capacity of pile are discussed. Then the envelope of pile bearing capacity under different loading paths is obtained. Finally, the self-made sand box and pulley loading device are used. The indoor load model tests of single pile in sand under the combined load of pure torque and V-T have been completed, and the corresponding load-deformation of pile top, displacement of internal force and ultimate bearing capacity of pile body have been obtained. The experimental results are compared and verified with the theoretical analysis in this paper.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU473.1

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