Simplified models for axial static and dynamic analysis of pile foundations
Simplified models for axial static and dynamic analysis of pile foundations
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桩基轴向静力和动力分析的简化模型
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
J. Crispin
中科院分区：
文献类型：
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作者：
G. Mylonakis;J. Crispin
本文提出了水平荷载作用下桩基静动力分析的简化方法。首先，简要回顾了弹性Winkler地基梁的经典模型和相关弹簧和阻尼器的模量公式。该模型（1）导致了一个特征（“机械”）桩长，包括桩刚度和细长度，这在问题的连续体公式中没有对应物;（2）将控制响应的无量纲组的数量减少了一个。其次，推导了均质土和非均质土条件下的单桩刚度解。这些解决方案是基于能量的原则，使用复值形状函数类似于那些在频谱有限元法，占在不同的海拔下的桩的响应的相位差。使用这些功能在现有的配方的基础上实值（静态）的形状函数，大大提高了在动态政权的解决方案的准确性。本文还指出，长桩静刚度单项表达式中的指数受刚度矩阵的静态凝聚条件的约束，而文献中的一些公式不满足这个条件。第三，利用Poulos的叠加法推导了群桩的解。为此，一个家庭的相互作用因素占桩-土-桩相互作用进行了审查。结果以无量纲图形和图表的形式呈现，阐明了问题的关键方面。提供了更严格的数值连续解的详细比较。
Simplified methods for static and dynamic analysis of pile foundations under lateral loading are presented. Firstly, the classical model of a Beam on an elastic Winkler Foundation (BWF) and a number of formulas for the moduli of the associated springs and dashpots are briefly reviewed. This model (1) leads to a characteristic (“mechanical”) pile length, encompassing both pile stiffness and slenderness, which has no counterpart in continuum formulations of the problem; (2) reduces the number of dimensionless groups governing the response, by one. Secondly, solutions for stiffness of single piles are derived for both homogeneous and inhomogeneous soil conditions. These solutions are based on energy principles obtained using complex-valued shape functions analogous to those used in spectral finite-element methods, which account for phase differences in the response at different elevations down the pile. Use of these functions over existing formulations based on real-valued (static) shape functions, greatly improves the accuracy of the solution in the dynamic regime. It is also shown that the exponents in monomial expressions for the static stiffness of long piles, are constrained by a condition associated with the static condensation of the stiffness matrix, and that this condition is not satisfied in a number of formulae in literature. Thirdly, solutions for grouped piles are derived using the superposition approach of Poulos. To this end, a family of interaction factors accounting for pile-soil-pile interaction is reviewed. Results are presented in the form of dimensionless graphs and charts that elucidate critical aspects of the problem. Detailed comparisons with more rigorous numerical continuum solutions are provided.