饱和土—地下结构非线性地震反应分析

发布时间：2018-02-14 17:36

本文关键词： 粘弹性人工边界自由场饱和土地铁车站结构土—结构动力相互作用　出处：《福州大学》2014年硕士论文　论文类型：学位论文

【摘要】：研究土-结构动力相互作用问题需要考虑波动能量向无限域地基的传播。自然界中饱和土由固体骨架和填充于空隙中的流体组成。在动力荷载下,固相与液相之间存在动力相互作用,因此同单相固体介质相比,按照饱和多孔介质的特性分析地基土更加合理。由于饱和多孔介质波动理论比较复杂,对于饱和多孔介质动力响应解析解的研究大多都仅局限于简单的边界情况。对于复杂的几何形状以及考虑近场区域介质的非均匀和非线性时,分析无限或半无限空间的时域动力问题通常采用有限元模型的数值方法进行分析,此时采用的有限域为了反映无约束域能量辐射效应影响,需引入虚拟的人工边界条件。不同的人工边界对模拟精度的影响较大。本文采用有限元分析方法,将结构周围的土体视为固-液二相介质,对地下结构地震反应进行数值模拟。总结了地下结构地震响应的一些规律。论文主要包括以下内容：(1)研究了考虑双相介质的人工边界,建立自由场模型,与广义解析解比较,分析了采用固定边界、粘性边界及粘弹性边界对计算的结果精度的影响,验证了粘弹性边界条件。(2)将输入地震动场转化为施加在人工边界节点上的等效荷载,采用辅助计算程序计算,实现了节点荷载在有限元软件上的施加,并建立二维自由场模型,分析了不同地震波作用下自由场的地震响应,比较了采用单相介质和双相介质模型进行计算的结果。(3)根据实际地铁车站工程,建立了地铁车站结构的二维有限元模型。对比分析了考虑饱和土情况下和采用单相介质土情况下地铁车站结构在水平地震作用下的地震反应,同振动台试验进行比较,分析地铁车站相应的内力分布规律及土动力反应,讨论了横向地震输入下车站结构的最不利位置和抗震措施。
[Abstract]:The study of soil-structure dynamic interaction needs to consider the propagation of wave energy to the infinite subgrade. The saturated soil in nature consists of solid skeleton and fluid filled in the void. There is a dynamic interaction between solid and liquid phase, so it is more reasonable to analyze the foundation soil according to the characteristics of saturated porous media than that of single-phase solid medium. The analytical solution of the dynamic response of saturated porous media is mostly confined to simple boundary case. For complex geometry and considering the nonuniformity and nonlinearity of near-field media, the analytical solution of the dynamic response of the saturated porous media is mostly confined to the simple boundary case. The numerical method of finite element model is usually used to analyze the time-domain dynamic problems in infinite or semi-infinite space. The finite domain is used to reflect the effect of energy radiation in unconstrained domain. It is necessary to introduce virtual artificial boundary conditions. Different artificial boundaries have great influence on the simulation accuracy. In this paper, the soil around the structure is regarded as a solid-liquid two-phase medium by using finite element method. Numerical simulation of seismic response of underground structure is carried out. Some laws of seismic response of underground structure are summarized. The main contents of this paper are as follows: 1) the artificial boundary of two-phase medium is studied, and the free field model is established, which is compared with the generalized analytical solution. The influence of the fixed boundary, viscous boundary and viscoelastic boundary on the accuracy of the calculation results is analyzed. It is verified that the viscoelastic boundary condition .2) transforms the input ground motion field into equivalent load applied on the artificial boundary node. The application of nodal loads on finite element software is realized by using the auxiliary calculation program, and the two-dimensional free field model is established, and the seismic response of the free field under different seismic waves is analyzed. The calculation results using single-phase medium model and two-phase medium model are compared according to the actual subway station project. The two-dimensional finite element model of subway station structure is established, and the seismic response of subway station structure under horizontal earthquake under the condition of saturated soil and single-phase medium soil is analyzed and compared with the shaking table test. The distribution law of internal force and soil dynamic response of subway station are analyzed, and the most disadvantageous position and seismic measures of station structure under lateral earthquake input are discussed.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU435

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