【作者】 胡安峰；

【导师】 谢康和；

【作者基本信息】 浙江大学 ， 岩土工程， 2002， 博士

【摘要】 桩基的水平动力特性已受到工程界越来越普遍的重视，但关于水平动力受荷桩的理论和性状至今仍处于研究阶段。本文建立了一整套考虑桩体剪切变形的桩基水平振动分析理论，并较系统地研究了桩的长径比、桩土刚度比、激振频率等因素对桩基水平动力响应的影响。 首先，基于动力Winkler模型(BDWF)对粘弹性地基中有限长桩的水平动力响应问题进行求解，得到了单桩在桩顶受水平简谐荷载作用下的时域解析解，并在此基础上通过叠加原理得到了半正弦激振条件下的瞬态解析解。同时，对上述同一问题在频域内进行求解，得到了各种边界条件下的有限长桩和无限长桩水平稳态振动解。 利用所得解，采用与频率相关的刚度系数和阻尼系数的近似表达式，对有限长桩和无限长桩的动力特性特别是对最大无量纲响应沿深度的变化曲线进行了参数研究，表明在常见桩土参数下，当长径比大于15时，可将有限长桩视为无限长桩以简化计算。 首次在桩基的水平振动分析中考虑了桩体的剪切变形，获得了单桩在均匀地基中更为精确的水平振动解。通过参数分析，提出在常见桩土参数情况下可以将剪切效应忽略不计的界限长径比约为8。在此基础上，进一步得到了成层粘弹性地基中考虑桩体剪切变形的单桩水平振动解析解，并分析了桩基剪切变形对水平动力响应的影响。 基于获得的考虑剪切变形的单桩水平振动解和Makris(1992)提出的双桩分析方法得到了横向相互作用因子的计算公式，并通过参数分析研究了横向相互作用因子的变化规律以及剪切变形对其的影响。在此基础上，利用叠加原理得到了考虑桩体剪切变形的群桩水平动力响应解，并分析了剪切变形和其他因素对桩顶水平位移以及桩顶剪力分布的影响。 本文所给出的从单桩到双桩再到群桩的一整套水平动力响应分析理论和解答，首次同时考虑了桩基水平振动时的弯曲变形和剪切变形，克服了现有解只能考虑弯曲变形的不足，从而完善了桩基水平振动理论。更多还原

【Abstract】 The horizontal dynamic behavior of pile foundation is becoming more and more attractive in geotechnical engineering. But the theory concerned with this is still in research stage. In this paper,the theory for lateral vibration of pile foundation with consideration of shear deformation of pile is established,and the influence of the ratio of pile length to its diameter,the ratio of pile stiffness to soil stiffness and dimensionless frequency were studied systemically.The Beam-on-Dynamic-Winkler-Foundation (BDWF) model was utilized to determine the lateral dynamic response of a pile with finite length in a viscoelastic soil. An analytical solution was obtained in the time domain for the vibration of a pile under a laterally cyclic force applied at the pile head. Based on the solution,the transient response of the pile loaded by semi-sine force was acquired with superposition principle. At the same time,the problem described above was solved in the frequency domain and the analytical solution for lateral steady response of single pile with finite length or with infinite length was developed under different boundary conditions.By using the solution developed and the frequency-dependent stiffness coefficient and damp coefficient,the dynamic behavior,especially the one concerned with the variation of the dimensionless maximum response along the depth,for the pile with finite length or with infinite length was studied. It was shown that to simplify computation a pile of finite length can be taken as the one of infinite length if the ratio of pile length to its diameter (i.e. lid) is greater than 15.A more rigorous analytical solution for lateral vibration of single pile in a homogeneous soil was developed,in which the shear deformation of pile was considered for the first time. Based on parameters studies,it was proposed that the critical value of lid is 8 beyond which the shear deformation can be ignored in common cases. Furthermore,the analytical solution for the lateral vibration of single pile embedded in layered soils was obtained,and the influence of the shear deformation on the lateral dynamic response was examined.On the basis of the developed solution for single pile considering shear deformation and the analysis method for two piles proposed by Makris (1992),the dynamic interaction factor between two piles was obtained and relevant parameter study made. The influence of shear deformation on the dynamic interaction factor was also studied. Accordingly,solution for the dynamic response of grouped piles taking consideration of shear deformation was developed by using superposition principle,and the effects of shear deformation and the other factors on the horizontal displacement and the distribution of shear forces at pile head were investigated.It is the work presented herein that for the first time gives analytical theories for the lateral vibration of single pile and grouped piles taking consideration of both bend deformation and shear deformation of pile. The shortcoming involved with the existed analytical theory which considered bend deformation of pile only is then overcomed. This makes the theory for lateral vibration of pile foundation more perfect.更多还原