【摘要】：局部復(fù)雜場(chǎng)地條件對(duì)地表地震動(dòng)的影響一直以來是地震工程中較受重視的研究課題之一。由于計(jì)算尺度及人工邊界條件的限制,需要求解方程組的隱式計(jì)算方法往往無法完成分析,而時(shí)域顯式方法結(jié)合吸能邊界因具有時(shí)空解耦、時(shí)間域上步步遞推及合理匹配局部人工邊界的顯式計(jì)算特征,常常用于這類問題的分析。本文基于傳統(tǒng)的時(shí)域顯式有限元方法,結(jié)合粘性人工邊界,在ABAQUS中成功實(shí)現(xiàn)了邊界項(xiàng)的處理,分析了經(jīng)典場(chǎng)地反應(yīng)中的內(nèi)外源問題,并將計(jì)算結(jié)果與解析解對(duì)比,研究分析了計(jì)算的精度和解的可靠性。時(shí)域顯式有限元法空間離散采用線性插值,因而只具備一階精度,為了能更好地模擬分析問題,本文主要還采用了另一種近些年才被引用到地震工程領(lǐng)域中的數(shù)值計(jì)算方法—譜元法。此方法具有空間計(jì)算精度高、數(shù)值模擬收斂快及易于實(shí)現(xiàn)并行運(yùn)算等優(yōu)點(diǎn),因此目前已成為大尺度模型及復(fù)雜地質(zhì)結(jié)構(gòu)計(jì)算模型等地震動(dòng)數(shù)值模擬分析的重要工具。同樣基于顯式譜元法并加載粘性邊界模擬分析了典型的波動(dòng)內(nèi)外源問題,并與顯式有限元法或參考解進(jìn)行了對(duì)比,研究兩類數(shù)值方法的差異。最后本文還采用顯式有限元法研究了實(shí)際工程中的二維復(fù)雜場(chǎng)地條件下,不同分析模型的影響,得到了若干對(duì)實(shí)際工程有意義的建議。主要的工作如下：1、在內(nèi)域中首先從理論上介紹了顯式有限元法及顯式譜元法的的幾個(gè)重要理論點(diǎn),并分析了顯式譜元法的高精度優(yōu)點(diǎn)及內(nèi)在原因,在邊界上建立了粘性邊界的具體表達(dá)式,同時(shí)實(shí)現(xiàn)了粘性邊界和外源散射問題中地震動(dòng)輸入在計(jì)算機(jī)上的加載。2、基于顯式有限元法及顯式譜元法并加載粘性邊界分別建立了均勻彈性全空間內(nèi)源、均勻彈性半空間內(nèi)源問題這兩個(gè)規(guī)則模型,對(duì)比分析了兩種顯式方法的精度差別及粘性邊界的吸能效果。3、基于顯式有限元法及顯式譜元法并加載粘性邊界分別建立了圓弧形凹陷、圓弧形凸起及圓弧形凹陷覆蓋土層這三個(gè)典型非規(guī)則場(chǎng)地模型,在時(shí)域中對(duì)比分析了兩種顯式數(shù)值方法的模擬結(jié)果,并在頻域中分析了入射波傳播方向、入射頻率、入射角度及圓弧形寬度對(duì)圓弧形凹陷及凸起場(chǎng)地地表地震動(dòng)的影響。4.基于顯式有限元法建立了新西蘭惠靈頓區(qū)場(chǎng)地的不同位置處的二維復(fù)雜場(chǎng)地計(jì)算模型,從場(chǎng)地地形、基巖及其上覆蓋土層介質(zhì)同時(shí)作用時(shí)對(duì)比各計(jì)算模型結(jié)果的差異,研究了計(jì)算模型的合理建立方式。5、對(duì)本文的研究工作進(jìn)行了總結(jié),并在此基礎(chǔ)上對(duì)本文所采用的兩種顯式數(shù)值方法在模擬分析地震工程波動(dòng)問題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.
【學(xué)位授予單位】：廣東工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P315.9

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本文編號(hào)：2147215