【作者】 刘金光；

【导师】 黄维平；

【作者基本信息】 中国海洋大学 ， 防灾减灾及防护工程， 2006， 硕士

【摘要】 桩基是一种历史悠久、且广泛采用的深基础形式,历次大地震中,均出现了各类桩基础的严重破坏现象。由于破坏的隐蔽性,使得破坏桩基的修复极为困难而且耗资巨大,因此,对地震作用下土-桩-结构动力相互作用进行数值分析具有重要的学术意义和较强的工程实用价值。本文在研读大量国内外文献的基础上,对前人的成果按地震波的反演分析、桩的分析模型、土-桩-结构动力相互作用的分析方法等几个方面进行了系统地分析和总结,并按下述思路开展了本文的研究工作:(1)推导了线粘弹性土体中垂直入射的剪切波的水平位移方程,根据波动理论,对地表地震加速度记录进行反演分析计算,得到地层某深度处(或基岩处)的地震加速度。结论表明,经过反演,地震波形没有根本性的变化,但土层对地震波的放大作用是很明显的;基岩深度不同,对加速度的影响亦不同,加速度最大幅值放大系数一般随基岩深度的增加而增加。(2)以动力Winkler地基上的梁模型为基础,以单调加载得到的单桩p-y曲线为骨干曲线,用修正的Ramberg-Osgood模型建立单桩在不规则循环荷载作用下的p-y曲线,从而可以方便地确定不规则循环荷载作用下土体的水平刚度,模拟土体的非线性,并考虑土体的材料和滞回阻尼特性,结合有限元思想建立土-桩-结构体系动力相互作用的控制方程,编制相应的计算程序。运用该模型对单桩支承的剪切性结构体系进行了较全面的参数分析。(3)基于Penzien提出的集中质量模型,将上部结构和桩基础离散为剪切型质点串,以弹簧和阻尼器模拟桩周围的土体,考虑了等价土体层间剪切和阻尼效应,给出了相互作用参数的确定方法,建立土-桩-结构动力相互作用的简化分析模型,通过对土体模量的等价线性迭代逼近体系的非线性动力响应。将该分析模型退化运用到单桩情况,并与前面单桩简化分析的结果进行比较,结果表明两种模型吻合较好。通过运用该模型对高柔结构以及相对刚性结构进行地震响应时程分析得出:对于高柔结构而言,相互作用对体系地震响应的影响不太显著,对相对刚性的结构则有显著的影响。更多还原

【Abstract】 Pile foundation has been used to consolidate soft ground for a long history, and it is also one popular means to be used to improve foundation today. Many pile foundations are damaged seriously during the past major earthquakes. Large amount of cost will be paid to remedy the defect of pile foundation undergoing earthquakes, so it is a significant value for both academic and concrete project to study the subject of numerical analysis of Soil-Pile-Structure Dynamic Interaction under seismic loading. Based on the review of past research work, a state-of-art with respect to Soil-Pile-Structure Dynamic Interaction, which includes inversion analysis, pile analysis models, analysis methods, is presented and analyzed firstly. Research work is conducted in light of the processes as follows:(1) The paper formulates horizontal displacement equation of upright shear wave in linear visco-elastic soil which is assumed to be horizontally layered, and makes an inversion analysis in frequency domain based on wave theory. Fourier transform is applied to transform the earthquake acceleration records measured from the ground surface from time domain to frequency domain and the earthquake acceleration records are made inversion computation in frequency domain, and the earthquake accelerations of any soil layer (or bed rock) below ground surface are gotten. Results indicate that, when the seismic wave passes through the soil layers, the wave shape don’t change basically, but the amplificatory effect on seismic wave of soil layer is evident. The effect on acceleration is different with the change of depth of rock. And the maximal value of acceleration will increase with the augmentation of depth of bed rock.(2) To model nonlinearity and hysteretic character of soil under seismic loading, the p-y curve of single pile under monotonic loading is used as the skeleton curve and modified Ramberg-Osgood model theory is employed to construct the hysteretic loop for single pile dynamic p-y curve. The improved model is used in the Dynamic Beam on Nonlinear Winkler Foundation method. Both material and hysteretic damping of soil are taken into consideration. The governing equation of motion is set up combining with theory of FEM, and a computation program is written based on above theory. A comprehensive parametric study is also done for shear type structure supported by a更多还原