时域显式方法模拟二维复杂场地地震反应的实现及其应用
发布时间：2018-07-26 20:34
【摘要】：局部复杂场地条件对地表地震动的影响一直以来是地震工程中较受重视的研究课题之一。由于计算尺度及人工边界条件的限制,需要求解方程组的隐式计算方法往往无法完成分析,而时域显式方法结合吸能边界因具有时空解耦、时间域上步步递推及合理匹配局部人工边界的显式计算特征,常常用于这类问题的分析。本文基于传统的时域显式有限元方法,结合粘性人工边界,在ABAQUS中成功实现了边界项的处理,分析了经典场地反应中的内外源问题,并将计算结果与解析解对比,研究分析了计算的精度和解的可靠性。时域显式有限元法空间离散采用线性插值,因而只具备一阶精度,为了能更好地模拟分析问题,本文主要还采用了另一种近些年才被引用到地震工程领域中的数值计算方法—谱元法。此方法具有空间计算精度高、数值模拟收敛快及易于实现并行运算等优点,因此目前已成为大尺度模型及复杂地质结构计算模型等地震动数值模拟分析的重要工具。同样基于显式谱元法并加载粘性边界模拟分析了典型的波动内外源问题,并与显式有限元法或参考解进行了对比,研究两类数值方法的差异。最后本文还采用显式有限元法研究了实际工程中的二维复杂场地条件下,不同分析模型的影响,得到了若干对实际工程有意义的建议。主要的工作如下：1、在内域中首先从理论上介绍了显式有限元法及显式谱元法的的几个重要理论点,并分析了显式谱元法的高精度优点及内在原因,在边界上建立了粘性边界的具体表达式,同时实现了粘性边界和外源散射问题中地震动输入在计算机上的加载。2、基于显式有限元法及显式谱元法并加载粘性边界分别建立了均匀弹性全空间内源、均匀弹性半空间内源问题这两个规则模型,对比分析了两种显式方法的精度差别及粘性边界的吸能效果。3、基于显式有限元法及显式谱元法并加载粘性边界分别建立了圆弧形凹陷、圆弧形凸起及圆弧形凹陷覆盖土层这三个典型非规则场地模型,在时域中对比分析了两种显式数值方法的模拟结果,并在频域中分析了入射波传播方向、入射频率、入射角度及圆弧形宽度对圆弧形凹陷及凸起场地地表地震动的影响。4.基于显式有限元法建立了新西兰惠灵顿区场地的不同位置处的二维复杂场地计算模型,从场地地形、基岩及其上覆盖土层介质同时作用时对比各计算模型结果的差异,研究了计算模型的合理建立方式。5、对本文的研究工作进行了总结,并在此基础上对本文所采用的两种显式数值方法在模拟分析地震工程波动问题的下一步研究工作提出了展望。
[Abstract]:The influence of local complex site conditions on ground motion has been one of the most important research topics in seismic engineering. Due to the limitation of computational scale and artificial boundary conditions, implicit calculation methods which need to solve equations are often unable to complete the analysis, while the explicit time-domain method combined with energy-absorbing boundary has spatio-temporal decoupling. The explicit computational characteristics of step by step recursion and reasonable matching of local artificial boundaries in time domain are often used to analyze this kind of problems. Based on the traditional explicit finite element method in time domain and the viscous artificial boundary, the boundary term is successfully processed in ABAQUS. The internal and external source problems in classical site response are analyzed, and the calculated results are compared with the analytical solution. The accuracy and reliability of the calculation are studied and analyzed. The explicit finite element method in time domain uses linear interpolation in spatial discretization, so it has only the first order precision. In order to better simulate and analyze the problem, In this paper, another numerical method, spectral element method, which has been used in the field of seismic engineering has been mainly used in recent years. This method has many advantages, such as high precision of spatial calculation, fast convergence of numerical simulation and easy to realize parallel operation, so it has become an important tool for numerical simulation of ground motion such as large scale model and complex geological structure calculation model. Also based on explicit spectral element method and loaded viscous boundary the typical wave internal and external source problems are analyzed and compared with explicit finite element method or reference solution to study the difference between the two numerical methods. At last, the influence of different analysis models on the actual engineering is studied by using explicit finite element method, and some meaningful suggestions are obtained. The main work is as follows: 1. In the inner domain, several important theoretical points of explicit finite element method and explicit spectral element method are introduced theoretically, and the advantages of explicit spectral element method and its intrinsic reasons are analyzed. The concrete expression of viscous boundary is established on the boundary. At the same time, the loading of ground motion input on computer in viscous boundary and external scattering problem is realized. Based on explicit finite element method and explicit spectral element method and loaded viscous boundary, the uniform elastic full space inner source is established, respectively. The two regular models of the endogenetic problem in uniform elastic half-space, The accuracy difference of the two explicit methods and the energy absorption effect of the viscous boundary are compared and analyzed. Based on the explicit finite element method and the explicit spectral element method and loaded viscous boundary respectively, the circular arc depression is established. The simulation results of two explicit numerical methods are compared and analyzed in time domain for three typical irregular site models of circular arc bulge and circular arc sag covering soil layer. The direction of incident wave propagation and incident frequency are analyzed in frequency domain. The influence of incidence angle and arc width on ground motion of circular arc depression and uplift. Based on explicit finite element method, a two-dimensional complex site calculation model at different locations in Wellington District, New Zealand, is established. The results of these models are compared in terms of site topography, bedrock and overlying soil media acting simultaneously. In this paper, the reasonable way of establishing the calculation model is studied, and the research work of this paper is summarized. On the basis of this, two explicit numerical methods used in this paper are put forward for the further research work of simulating and analyzing the wave problem of seismic engineering.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.9
本文编号：2147215
[Abstract]:The influence of local complex site conditions on ground motion has been one of the most important research topics in seismic engineering. Due to the limitation of computational scale and artificial boundary conditions, implicit calculation methods which need to solve equations are often unable to complete the analysis, while the explicit time-domain method combined with energy-absorbing boundary has spatio-temporal decoupling. The explicit computational characteristics of step by step recursion and reasonable matching of local artificial boundaries in time domain are often used to analyze this kind of problems. Based on the traditional explicit finite element method in time domain and the viscous artificial boundary, the boundary term is successfully processed in ABAQUS. The internal and external source problems in classical site response are analyzed, and the calculated results are compared with the analytical solution. The accuracy and reliability of the calculation are studied and analyzed. The explicit finite element method in time domain uses linear interpolation in spatial discretization, so it has only the first order precision. In order to better simulate and analyze the problem, In this paper, another numerical method, spectral element method, which has been used in the field of seismic engineering has been mainly used in recent years. This method has many advantages, such as high precision of spatial calculation, fast convergence of numerical simulation and easy to realize parallel operation, so it has become an important tool for numerical simulation of ground motion such as large scale model and complex geological structure calculation model. Also based on explicit spectral element method and loaded viscous boundary the typical wave internal and external source problems are analyzed and compared with explicit finite element method or reference solution to study the difference between the two numerical methods. At last, the influence of different analysis models on the actual engineering is studied by using explicit finite element method, and some meaningful suggestions are obtained. The main work is as follows: 1. In the inner domain, several important theoretical points of explicit finite element method and explicit spectral element method are introduced theoretically, and the advantages of explicit spectral element method and its intrinsic reasons are analyzed. The concrete expression of viscous boundary is established on the boundary. At the same time, the loading of ground motion input on computer in viscous boundary and external scattering problem is realized. Based on explicit finite element method and explicit spectral element method and loaded viscous boundary, the uniform elastic full space inner source is established, respectively. The two regular models of the endogenetic problem in uniform elastic half-space, The accuracy difference of the two explicit methods and the energy absorption effect of the viscous boundary are compared and analyzed. Based on the explicit finite element method and the explicit spectral element method and loaded viscous boundary respectively, the circular arc depression is established. The simulation results of two explicit numerical methods are compared and analyzed in time domain for three typical irregular site models of circular arc bulge and circular arc sag covering soil layer. The direction of incident wave propagation and incident frequency are analyzed in frequency domain. The influence of incidence angle and arc width on ground motion of circular arc depression and uplift. Based on explicit finite element method, a two-dimensional complex site calculation model at different locations in Wellington District, New Zealand, is established. The results of these models are compared in terms of site topography, bedrock and overlying soil media acting simultaneously. In this paper, the reasonable way of establishing the calculation model is studied, and the research work of this paper is summarized. On the basis of this, two explicit numerical methods used in this paper are put forward for the further research work of simulating and analyzing the wave problem of seismic engineering.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.9
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相关期刊论文 前3条
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3 杨微;陈可洋;;加权吸收边界条件的优化设计[J];石油物探;2009年03期
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