H-T聯(lián)合作用下基樁內(nèi)力位移理論分析及試驗研究
發(fā)布時間：2018-10-13 20:00
【摘要】：近年來,隨著我國沿海經(jīng)濟的快速發(fā)展,近海大型基礎(chǔ)建設(shè)(如海上橋梁、海上平臺、風力發(fā)電塔等)的規(guī)模不斷擴大。這類多采用樁基礎(chǔ)的海上結(jié)構(gòu)物時常承受由車輛制動、風、波浪、地震、船只或漂流物或撞擊等引起的水平受荷,且往往以水平偏心的形式傳遞至樁基礎(chǔ),造成復(fù)雜的結(jié)構(gòu)響應(yīng)。分解這種作用于樁身上的水平偏心荷載即表現(xiàn)為受水平力H和扭矩T的聯(lián)合作用,工程中若不考慮這種偏心作用,可能會使設(shè)計偏于不安全并導(dǎo)致災(zāi)難性后果。然而,現(xiàn)行基于疊加原理的常規(guī)方法不能考慮這種荷載耦合作用,存在不少尚需解決的問題。為此,本文結(jié)合已有相關(guān)研究工作,對水平受荷樁、受扭樁及H-T聯(lián)合受荷樁進行理論分析和室內(nèi)模型試驗研究,主要工作如下:首先,假定樁周土體滿足廣義Gibson地基分布特性,引入虛土樁理論,基于能量法獲得樁-土體系能量控制方程,通過變分原理分別建立出水平荷載作用下樁身和樁側(cè)土的控制方程,進而采用中心點差分法分別導(dǎo)得了樁-土的響應(yīng)值。在此基礎(chǔ)上,假定樁側(cè)土塑性區(qū)從地面開展并往下延伸,由此獲得樁側(cè)土處于塑性狀態(tài)時的下樁-土響應(yīng)值。其次,基于剪切位移法和平衡原理,考慮樁側(cè)土體剪切模量沿深度呈冪函數(shù)分布,同時假定樁側(cè)土的塑性變形隨樁頂荷載增加自上而下逐步開展,得到純扭矩作用下樁側(cè)土分別處于彈性、彈塑性和塑性狀態(tài)時的樁身內(nèi)力變形解析解。同時,針對工程中地基土的分層特性,引入土體彈塑性受扭荷載傳遞模型,給出了層狀地基中純受扭樁樁身扭矩-扭轉(zhuǎn)角的計算公式。第三,基于m法和改進有限桿單元法,將水平力H和扭矩T的耦合關(guān)系計入桿單元剛度矩陣,得到統(tǒng)一的桿單元剛度方程,并考慮不同邊界條件獲得H-T聯(lián)合作用時樁身的內(nèi)力位移解答。最后,采用自制砂箱和滑輪組加載裝置完成了砂土中單樁受純水平力H、扭矩T及H-T聯(lián)合作用的室內(nèi)模型試驗,獲得了相應(yīng)的樁頂荷載-變形曲線、樁身內(nèi)力-位移曲線。
[Abstract]:In recent years, with the rapid development of China's coastal economy, the scale of large-scale offshore infrastructure (such as offshore bridges, offshore platforms, wind power towers, etc.) is expanding. These types of offshore structures, which often use pile-foundations, are often subjected to horizontal loads caused by vehicle braking, wind, waves, earthquakes, ships or drifters or impacts, and are often transmitted to the pile foundation in the form of horizontal eccentricities. Resulting in complex structural responses. Decomposing this kind of horizontal eccentric load on the pile is expressed as the combined action of horizontal force H and torque T. if this eccentricity is not considered in engineering, the design may be unsafe and lead to disastrous consequences. However, the current conventional method based on the superposition principle can not take this kind of load coupling into account, and there are still many problems to be solved. Therefore, the theoretical analysis and laboratory model test of horizontal loaded pile, torsional pile and H-T bearing pile are carried out in this paper. The main work is as follows: firstly, it is assumed that the soil around the pile satisfies the distribution characteristics of generalized Gibson foundation. Based on the theory of virtual soil pile, the energy governing equation of pile-soil system is obtained based on energy method, and the control equations of pile body and pile-side soil under horizontal load are established by variational principle, respectively. Then the center point difference method is used to derive the pile-soil response value. On this basis, it is assumed that the plastic zone of the pile-side soil extends from the ground to the bottom, and the pile-soil response value is obtained when the pile-side soil is in plastic state. Secondly, based on the shear displacement method and equilibrium principle, considering the distribution of shear modulus along the depth of the pile, it is assumed that the plastic deformation of the soil on the side of the pile gradually develops from top to bottom with the increase of pile top load. The analytical solution of the internal force deformation of the pile is obtained when the pile side soil is in elastic, elastic-plastic and plastic state under pure torque. At the same time, according to the delamination characteristic of foundation soil in engineering, an elastic-plastic torsional load transfer model is introduced, and the calculation formula of torque-torsion angle of pure torsional pile in layered foundation is given. Thirdly, based on the m method and the improved finite member element method, the coupling relation of horizontal force H and torque T is taken into account in the stiffness matrix of the bar element, and the unified stiffness equation of the bar element is obtained. Considering the different boundary conditions, the displacement solutions of the internal force of the pile body under the combined action of H-T are obtained. Finally, a self-made sand box and pulley loading device was used to complete the laboratory model test of a single pile in sand under the combined action of pure horizontal force H, torque T and H-T. The corresponding load-deformation curve on the top of the pile and the load-displacement curve of the pile body were obtained.
【學位授予單位】：湖南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU473.1
本文編號：2269735
[Abstract]:In recent years, with the rapid development of China's coastal economy, the scale of large-scale offshore infrastructure (such as offshore bridges, offshore platforms, wind power towers, etc.) is expanding. These types of offshore structures, which often use pile-foundations, are often subjected to horizontal loads caused by vehicle braking, wind, waves, earthquakes, ships or drifters or impacts, and are often transmitted to the pile foundation in the form of horizontal eccentricities. Resulting in complex structural responses. Decomposing this kind of horizontal eccentric load on the pile is expressed as the combined action of horizontal force H and torque T. if this eccentricity is not considered in engineering, the design may be unsafe and lead to disastrous consequences. However, the current conventional method based on the superposition principle can not take this kind of load coupling into account, and there are still many problems to be solved. Therefore, the theoretical analysis and laboratory model test of horizontal loaded pile, torsional pile and H-T bearing pile are carried out in this paper. The main work is as follows: firstly, it is assumed that the soil around the pile satisfies the distribution characteristics of generalized Gibson foundation. Based on the theory of virtual soil pile, the energy governing equation of pile-soil system is obtained based on energy method, and the control equations of pile body and pile-side soil under horizontal load are established by variational principle, respectively. Then the center point difference method is used to derive the pile-soil response value. On this basis, it is assumed that the plastic zone of the pile-side soil extends from the ground to the bottom, and the pile-soil response value is obtained when the pile-side soil is in plastic state. Secondly, based on the shear displacement method and equilibrium principle, considering the distribution of shear modulus along the depth of the pile, it is assumed that the plastic deformation of the soil on the side of the pile gradually develops from top to bottom with the increase of pile top load. The analytical solution of the internal force deformation of the pile is obtained when the pile side soil is in elastic, elastic-plastic and plastic state under pure torque. At the same time, according to the delamination characteristic of foundation soil in engineering, an elastic-plastic torsional load transfer model is introduced, and the calculation formula of torque-torsion angle of pure torsional pile in layered foundation is given. Thirdly, based on the m method and the improved finite member element method, the coupling relation of horizontal force H and torque T is taken into account in the stiffness matrix of the bar element, and the unified stiffness equation of the bar element is obtained. Considering the different boundary conditions, the displacement solutions of the internal force of the pile body under the combined action of H-T are obtained. Finally, a self-made sand box and pulley loading device was used to complete the laboratory model test of a single pile in sand under the combined action of pure horizontal force H, torque T and H-T. The corresponding load-deformation curve on the top of the pile and the load-displacement curve of the pile body were obtained.
【學位授予單位】：湖南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU473.1
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