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  本文選題：樁基礎 + 耦合效應��； 參考：《長沙理工大學》2015年碩士論文

【摘要】：近年來,大型建(構)筑在復雜的工作環(huán)境中的工作性狀與破壞形態(tài)受到了廣泛關注。與常規(guī)環(huán)境不同,復雜環(huán)境下結構物所受的組合荷載更為特殊,如風荷載或船舶撞擊等引起的扭轉荷載與水平荷載的耦合。工程上已有由于船舶撞擊而導致上部結構突然破壞,以及風載引起建筑物永久變形的案例。因此,對推扭耦合條件下群樁基礎的承載機理及相關計算理論進行研究十分必要。本文為此展開了一系列的研究,主要工作如下:(1)結合國內(nèi)外研究現(xiàn)狀,在已有的研究成果的基礎上,對推扭荷載下群樁基礎的荷載分配、位移模式以及破壞模式進行了初步的分析;(2)結合屈服接近度概念,分別對推扭荷載下單樁地表及樁中樁周土在荷載下的應力路徑進行分析,由結果可知:扭轉荷載下樁周土應力通常沿某一?平面上向屈服面接近;水平荷載下樁周土應力路徑與?平面呈一定角度;而推扭耦合作用會導致兩種應力路徑的組合。其應力路徑分析有助于定性分析推扭耦合效應對樁基水平和扭轉特性的影響;結合三維數(shù)值分析方法,對推扭荷載下樁基礎的響應特征及耦合效應進行分析,分析表明,土質以及偏心距的大小均對群樁基礎的受荷性狀有影響;水平荷載與扭矩荷載存在耦合效應,水平荷載對群樁扭轉剛度有增強的作用,扭矩荷載對群樁的水平向剛度有減弱的作用。(3)首先在分析推扭荷載下群樁基礎工作機理的基礎上,根據(jù)靜力平衡條件建立了以轉心為參照點的各基樁位移及轉角普適方程。其次,采用p-y曲線法以及單樁扭轉剛度計算理論分別確定各基樁的水平剛度與扭轉剛度,并提出了各計算參數(shù)的取值方法。然后,建立了推扭荷載群樁內(nèi)力與位移的解算流程,編制了相應的計算程序,與試驗數(shù)據(jù)的對比表明,本文方法計算結果與實測結果吻合較好,且計算過程簡單,具有工程實用性。最后,采用計算程序對推扭耦合作用下群樁基礎進行了失穩(wěn)破壞分析,結果表明:當荷載偏心距變大時,同等量級荷載下群樁轉角即隨之增大,偏心距對承臺轉角的影響更明顯;而影響群樁水平位移的主要因素則是水平荷載及樁頭水平剛度。(4)在對樁基礎基本設計原則、樁型選擇方法以及一般設計步驟進行初步總結分析的基礎上,建立了推扭荷載下群樁設計驗算流程。
[Abstract]:In recent years, extensive attention has been paid to the working characteristics and failure patterns of large-scale construction in complex working environment.Different from the conventional environment, the combined loads of structures in complex environments are more special, such as the coupling of torsional loads and horizontal loads caused by wind loads or ship impacts.There have been cases of sudden damage to superstructures caused by ship impact and permanent deformation of buildings caused by wind loads.Therefore, it is necessary to study the bearing mechanism and related calculation theory of pile group foundation under the condition of push-torsion coupling.In this paper, a series of studies have been carried out, the main work is as follows: (1) combined with the current research situation at home and abroad, based on the existing research results, the load distribution of pile group foundation under push-torsional load is discussed.The displacement mode and failure mode are analyzed preliminarily. Combined with the concept of yield approach, the stress paths of the ground surface and the soil around the pile under the load are analyzed, respectively.From the results, it can be concluded that the stress of soil around pile is usually along a certain one under torsional load.The stress path of the soil around the pile under horizontal load and the stress path of the soil around the pile are close to the yield surface on the plane.The plane is at a certain angle, and the coupling of push and torsion will lead to the combination of two stress paths.The analysis of stress path is helpful to qualitatively analyze the influence of the coupling effect of push and torsion on the horizontal and torsional characteristics of pile foundation, combined with the three-dimensional numerical analysis method, the response characteristics and coupling effect of pile foundation under push-torsion load are analyzed, and the results show that,Soil quality and eccentricity influence the behavior of pile group foundation, the coupling effect of horizontal load and torque load exists, and horizontal load can enhance the torsional stiffness of pile group.Firstly, on the basis of analyzing the working mechanism of pile group foundation under push-torsion load, the universal equations of pile displacement and rotation angle with reference point of rotation center are established according to the static equilibrium condition.Secondly, the horizontal stiffness and torsional stiffness of each pile are determined by the p-y curve method and the calculation theory of torsional stiffness of single pile.Then, the calculation flow of the internal force and displacement of the pile group under push-torsion load is established, and the corresponding calculation program is worked out. The comparison with the experimental data shows that the calculated results of this method are in good agreement with the measured results, and the calculation process is simple.It has engineering practicability.Finally, the instability failure analysis of pile group foundation under the coupling of push and torsion is carried out by using the calculation program. The results show that when the eccentricity of load increases, the rotation angle of pile group increases under the same order of magnitude.The influence of eccentricity on pile cap angle is more obvious, and the main factors influencing the horizontal displacement of pile group are horizontal load and horizontal stiffness of pile head.Based on the preliminary summary and analysis of the selection method of pile type and the general design steps, the flow of pile group design verification under push-torsion load is established.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU473.1

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