沉桩的离散—连续耦合数值分析

发布时间：2018-06-23 14:05

本文选题：耦合数值分析 + 桩贯入机理　；参考：《福州大学》2013年硕士论文

【摘要】：桩基础由于具有承载力高、刚度大、沉降小、稳定性好、适用性强等优点而在国内外土木工程实践中得到广泛的应用。现有的沉桩方法中,人们越来越多地使用静力压桩机及高频振动锤进行沉桩以减少在施工过程中产生的噪音、振动和空气污染。无论是静压沉桩还是高频振动沉桩,沉桩过程中桩对邻近土体的影响一直是学者们重点研究的内容。目前,沉桩机理的数值分析大多采用有限元方法,以小应变连续性假定为基础。然而,土体作为一种非连续散体材料,采用以非连续介质力学为基础的颗粒离散单元法进行分析无疑更有利于揭示沉桩机理。当利用颗粒离散元对大比尺模型进行分析时,由于需生成较多数量的颗粒,因此对计算机计算性能要求较高,计算时间较长,这已成为颗粒离散元的一个瓶颈问题。为此,不少学者们提出并发展了离散-连续耦合分析技术,这样既能充分利用各个数值计算方法的优点同时又降低了对计算资源的要求。本文以此为背景,通过利用颗粒离散元软件PFC2D和有限差分软件FLAC之间的内置接口程序实现二维离散和连续耦合分析,并建立起沉桩的连续-离散耦合数值模型,从宏细观两方面研究沉桩机理。本文的第一部分是文献综述,重点阐述了利用高频振动锤进行沉桩的基本原理,并对高频振动沉桩的发展和研究概况做了简要介绍,同时还对颗粒离散元在岩土工程中的发展和应用做了概括性总结。在对研究背景和现有文献进行回顾后,本文简要地介绍了FLAC/PFC2D耦合数值模拟计算方法的相关理论和方法,就耦合数值模拟中离散-连续交界面的处理方法进行了详细说明,同时对耦合计算程序的实现和整个耦合计算框架做了介绍。本文利用连续-离散耦合计算方法进行的沉桩数值分析主要包括两个部分内容即静压沉桩分析和高频振动沉桩研究。在对沉桩机理的分析中,主要研究沉桩过程中桩端阻力和桩侧摩擦阻力随深度的发展规律,并对包括桩周土体应力、桩周土体颗粒运动、桩周土孔隙率和配位数在内的桩周土体性状进行考察。一系列的研究成果均表明沉桩使得桩周附近土体的性状发生了复杂的变化。
[Abstract]:The pile foundation has been widely used in civil engineering practice at home and abroad because of its advantages of high bearing capacity, large stiffness, small settlement, good stability and strong applicability. In order to reduce the noise vibration and air pollution in the construction process the static piling machine and the high frequency vibration hammer are more and more used in the existing piling methods. Whether static pressure pile or high frequency vibration pile, the influence of pile on adjacent soil is always the focus of scholars. At present, the numerical analysis of piling mechanism mostly adopts finite element method, based on the assumption of continuity of small strain. However, as a discontinuous bulk material, the particle discrete element method based on discontinuous medium mechanics is used to analyze the soil mass, which is undoubtedly more helpful to reveal the piling mechanism. When the particle discrete element is used to analyze the large scale model, due to the need to generate a large number of particles, the computational performance of the computer is higher and the calculation time is longer, which has become a bottleneck problem for the discrete particle element. For this reason, many scholars have proposed and developed the discrete-time coupled analysis technique, which not only makes full use of the advantages of various numerical methods, but also reduces the requirements for computing resources. In this paper, two-dimensional discrete and continuous coupling analysis is realized by using the built-in interface program between particle discrete element software PFC2D and finite-difference software FLAC, and the continuous discrete coupling numerical model of piling is established. The mechanism of piling is studied from macro and micro view. The first part of this paper is a literature review, focusing on the basic principle of piling with high-frequency vibration hammer, and briefly introduces the development and research situation of high-frequency vibration piling. At the same time, the development and application of particle discrete element in geotechnical engineering are summarized. After reviewing the research background and existing literatures, this paper briefly introduces the relevant theories and methods of FLAC / PFC2D coupling numerical simulation, and describes in detail the processing method of discrete-time and continuous interface in coupled numerical simulation. At the same time, the implementation of the coupled computing program and the whole coupled computing framework are introduced. In this paper, the numerical analysis of piling with continuous and discrete coupling method mainly includes two parts: static pressure piling analysis and high frequency vibration piling analysis. In the analysis of pile-sinking mechanism, the development law of pile-tip resistance and pile-side friction resistance with depth is studied, and the soil stress around pile and the movement of soil particles around pile are studied. The properties of soil around piles, including soil porosity and coordination number, were investigated. A series of research results show that the behavior of soil around the pile is complicated by piling.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.1

【相似文献】