岩溶场地地震反应分析研究

发布时间：2018-04-16 15:39

本文选题：岩溶场地 + 地震反应　；参考：《广西大学》2015年硕士论文

【摘要】：岩溶场地地震反应的研究对确定岩溶区工程结构的地震动参数、分析场地及结构的地震响应具有重要意义。由于岩溶场地的复杂性,常规场地的解析分析方法较难适应,而实验室又难以实现对岩溶场地的整体分析,这些导致岩溶场地进行工程建设时地震动参数较难确定。为实现对岩溶场地地表地震动参数变化规律的研究,进而在合理范围内确定单一土洞岩溶场地地表主要地震动参数的计算公式,在动力有限元的理论基础上,首先从岩溶场地与非岩溶场地地震响应的对比分析入手,利用ABAQUS软件建立两种场地的计算模型,研究岩溶场地由于土洞的存在对地震响应的差异,随后确定影响岩溶场地地震动响应的主要因素及其合理范围,在正交试验的基础上确定各主要因素的水平值,利用MATLAB对试验值进行二次回归分析,研究岩溶场地地表主要地震动参数变化规律,进而在合理范围内确定单一土洞岩溶场地主要地震动参数计算公式。主要包括以下几个方面的内容：(1)研究了岩溶场地的特点、场地地震反应分析的基本方法,归纳了土体动力本构研究现状和人工边界的研究现状,针对选取的地震波进行了反演计算,对场地地震反应的基本理论进行研究。(2)应用ABAQUS软件建立了岩溶场地和非岩溶场地的场地模型,计算由于土洞的存在对地表地震动参数的影响,得出岩溶场地由于土洞的存在对速度和位移影响相对较小,对加速度影响较大,计算中应重视岩溶场地土洞的影响。(3)阐述了正交试验的基本理论和实现的方法步骤,通过正交试验设计,分析影响场地地表地震动的主要因素,选取了L16(45)正交表安排数值试验的试验方案,确定合理的水平值,安排了5因素4水平的有限元正交试验。并且确定了32组场地试验的模型参数,通过ABAQUS建立32组400×400m的场地有限元模型,并进行计算分析。(4)运用MATLAB软件对上述32组有限元试验计算结果进行二次回归分析,得到场地地表地震动与各主要影响因素的关系式,误差分析效果良好。并对放大系数λ进行深入分析得出,当仅有一个自变量时λ分别随着土洞直径d、覆盖层厚度H和土体的动弹性模量E变化时为开口向下的二次函数,当仅有一个白变量h时λ随着土洞中心点的深度h变化时为开口向上的二次函数。在正交试验水平值取值范围内对λ关于d的二次函数进行试算发现,在水平值取值范围内存在极大值点,即土洞的直径对地表峰值加速度的影响在某一范围为增函数,在另一范围内为减函数。
[Abstract]:The study of seismic response of karst site is of great significance to determine the seismic parameters of engineering structure in karst area and to analyze the seismic response of site and structure.Because of the complexity of karst site, it is difficult to adapt to the analytical analysis method of conventional site, and it is difficult to realize the overall analysis of karst site in laboratory, which leads to the difficulty in determining the parameters of ground motion during the construction of karst site.In order to study the variation law of ground motion parameters in karst site, and then determine the calculation formula of main ground motion parameters in a single soil cave karst site within a reasonable range, on the basis of the theory of dynamic finite element,Starting with the comparative analysis of seismic response between karst site and non-karst site, this paper establishes the calculation model of two kinds of sites by using ABAQUS software, and studies the difference of seismic response between karst site and non-karst site due to the existence of soil cave.Then, the main factors affecting the response of karst ground motion and their reasonable range are determined. Based on the orthogonal test, the horizontal values of the main factors are determined, and the quadratic regression analysis of the test values is carried out by using MATLAB.The variation law of the main ground motion parameters of karst site is studied, and the calculation formula of the main ground motion parameters of a single soil cave karst site is determined within a reasonable range.The main contents are as follows: (1) the characteristics of karst site, the basic method of site seismic response analysis, the present situation of soil dynamic constitutive research and the research status of artificial boundary are summarized.The inversion calculation of selected seismic waves is carried out, and the basic theory of site seismic response is studied. (2) the site models of karst site and non-karst site are established by using ABAQUS software.Because of the influence of soil hole on ground motion parameters, it is concluded that karst site has relatively little influence on velocity and displacement, and greater influence on acceleration because of the existence of soil cave.The basic theory of orthogonal test and the method steps of its realization are expounded in this paper. Through orthogonal test design, the main factors affecting the ground motion of the site are analyzed.In this paper, we select the test scheme of L1645) orthogonal table to arrange the numerical test, determine the reasonable horizontal value, and arrange the finite element orthogonal test with 5 factors and 4 levels.The model parameters of 32 groups of site tests were determined, and 32 groups of finite element models of 400 脳 400m were established by ABAQUS, and calculated and analyzed. (4) using MATLAB software, the results of the 32 groups of finite element tests were analyzed by quadratic regression analysis.The relationship between the ground motion and the main influencing factors is obtained, and the error analysis results are good.By analyzing the magnification factor 位, it is concluded that when there is only one independent variable, 位 is a quadratic function with the change of soil hole diameter d, the thickness of overburden H and the dynamic elastic modulus E of soil, respectively.When there is only one white variable h, 位 is a quadratic function with an opening upward when the depth h of the center point of the soil hole changes.The quadratic function of 位 about d is calculated in the range of horizontal value of orthogonal test. It is found that there exists a maximum point in the range of horizontal value, that is, the influence of the diameter of soil hole on the peak acceleration of the earth surface is an increasing function in a certain range.In another range is a subtraction function.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.9;P642.25

【参考文献】