本文選題：大直徑樁 + 橫向慣性�。� 參考：《蘇州科技學(xué)院》2015年碩士論文

【摘要】：大直徑樁因其更高的承載力和更小的沉降變形等特性而廣泛應(yīng)用于高層建筑、道路和橋梁等大型工程中。但由于樁身特殊的幾何尺寸,其工作性狀無法簡單地應(yīng)用和借鑒以往的樁基理論。目前,相比靜載作用下大直徑的工作性狀研究,對于大直徑的縱向動力特性的研究比較匱乏。鑒于此,本文一方面在理論上對大直徑樁的樁身、樁側(cè)土與樁身的相互關(guān)系、樁端土對樁身的支承作用做了簡化模型的處理,采用解析方法較系統(tǒng)地研究了均質(zhì)地基和非均質(zhì)地基中大直徑樁的樁-土耦合縱向振動問題。另一方面采用ANSYS/LS-DYNA對大直徑樁-土耦合縱向振動問題進行有限元數(shù)值模擬,驗證數(shù)值分析的可行性。論文的具體研究內(nèi)容有以下幾個方面：(1)基于平面應(yīng)變模型和Rayleigh-Love桿模型,研究粘彈性支承條件下均質(zhì)土中大直徑樁的縱向振動問題。采用積分變換法,解析推導(dǎo)得到激振脈沖作用下樁頂動力響應(yīng)的理論解。并基于所得的理論解,研究大直徑樁身的特性參數(shù)——泊松比、樁徑、樁長和縱波波速等對樁頂振動特性(速度時域曲線、速度頻域曲線、動剛度和動阻尼曲線)的影響。(2)將樁端土粘彈性支承模型替換為類似于一維桿的擴散虛土樁模型,研究徑向非均質(zhì)士中大直徑樁的縱向振動問題。采用積分變換方法和阻抗函數(shù)遞推法,推導(dǎo)得到激振脈沖作用下樁頂頻域響應(yīng)的解析解和時域響應(yīng)半解析解。并基于所得的理論解,研究擴散虛土樁的特性參數(shù)——劃分精度、虛土樁長度、擴散角和虛土樁縱波波速等對樁頂振動特性的影響。(3)結(jié)合考慮大直徑樁成樁效應(yīng)引起的樁側(cè)土體施工軟(硬)化和樁側(cè)土縱向成層性,基于擴散虛土樁模型和復(fù)剛度傳遞的多圈層平面應(yīng)變模型建立樁側(cè)土體雙向非均質(zhì)情況下大直徑樁縱向振動的定解問題。利用環(huán)向剪切復(fù)剛度傳遞法和阻抗函數(shù)傳遞法,推導(dǎo)得到樁頂動力響應(yīng)的理論解。通過參數(shù)分析法,研究徑向擾動程度、擾動范圍、縱向軟(硬)夾層厚度、樁身密度等因素對樁頂振動特性的影響機理。(4)利用ANSYS/LS-DYNA建立樁-土耦合模型,分別建立理論求解時樁徑的變化、虛土樁樁長變化、樁側(cè)土縱向存在軟(硬)夾層和樁側(cè)土徑向施工軟(硬)化對應(yīng)的有限元模型,進行數(shù)值計算,并和相同工況下的理論解進行對比分析,驗證兩種方法的正確性和可行性。(5)總結(jié)本文的研究成果和需要改進的地方,并對大直徑樁-非均質(zhì)土縱向耦合振動的后續(xù)研究提出展望。
[Abstract]:Large diameter piles are widely used in high-rise buildings, roads and bridges because of their higher bearing capacity and smaller settlement and deformation. However, because of the special geometric size of the pile body, its working characteristics can not be simply applied and used for reference to the previous pile foundation theory. At present, compared with the study of working characteristics of large diameter under static load, the study on longitudinal dynamic characteristics of large diameter is relatively scarce. In view of this, on the one hand, this paper theoretically deals with the relationship between the pile body, the side soil and the pile body of the large diameter pile, and the supporting effect of the pile end soil on the pile body. The pile-soil coupling longitudinal vibration of large diameter piles in homogeneous and heterogeneous foundations is studied systematically by analytical method. On the other hand, the finite element numerical simulation of large diameter pile-soil coupling longitudinal vibration problem is carried out by using ANSYS/LS-DYNA to verify the feasibility of numerical analysis. Based on the plane strain model and the Rayleigh-Love rod model, the longitudinal vibration of large diameter piles in homogeneous soil with viscoelastic support is studied. By using the integral transformation method, the theoretical solution of the dynamic response of the pile top under the action of the exciting pulse is derived analytically. Based on the theoretical solutions obtained, the vibration characteristics of pile top (velocity time domain curve, velocity frequency domain curve), such as Poisson's ratio, pile diameter, pile length and longitudinal wave velocity, are studied. The influence of dynamic stiffness and dynamic damping curve. (2) replacing the viscoelastic support model of pile end with the model of diffusion soil pile similar to one dimensional rod, the longitudinal vibration of medium and large diameter pile with radial heterogeneity is studied. By using the integral transformation method and the impedance function recursive method, the analytical solution and the semi-analytical solution of the pile top response in frequency domain and in time domain are derived. Based on the theoretical solution, the characteristic parameter of diffusion virtual soil pile, the partition precision, the length of virtual soil pile, is studied. The influence of diffusion angle and longitudinal wave velocity of virtual soil pile on the vibration characteristics of pile top. (3) considering the soft (hard) construction of pile side soil and longitudinal stratification of pile side soil caused by pile formation effect of large diameter pile. Based on the diffusion fictitious soil pile model and the multilayer plane strain model of complex stiffness transfer, the solution of longitudinal vibration of large diameter pile under bidirectional heterogeneity of soil on the side of pile is established. The theoretical solution of the dynamic response of the pile top is derived by using the toroidal shear complex stiffness transfer method and the impedance function transfer method. Through parameter analysis, the influence mechanism of radial disturbance degree, disturbance range, longitudinal soft (hard) interlayer thickness and pile density on the vibration characteristics of pile top is studied. (4) the pile-soil coupling model is established by ANSYS/LS-DYNA. The finite element models corresponding to the variation of pile diameter, the length of fictitious soil pile, the longitudinal soft (hard) intercalation of pile side soil and the soft (hard) soft (hard) construction of pile side soil are established respectively, and the numerical calculation is carried out. And compared with the theoretical solution under the same working conditions to verify the correctness and feasibility of the two methods. The future research on longitudinal coupling vibration of large diameter pile-heterogeneous soil is presented.
【學(xué)位授予單位】：蘇州科技學(xué)院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU473.1

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