含软土夹层的场地及其地面结构的地震响应分析

发布时间：2018-04-28 09:33

本文选题：场地条件 + 软弱土夹层　；参考：《华中科技大学》2015年硕士论文

【摘要】：场地条件在地震动研究领域一直是重要的课题,场地条件中影响土层与结构地震响应的因素众多。场地中含有软土夹层是一种常见的地质现象。《建筑抗震设计规范》BG5011-2010(以下简称《抗规》)中对场地类别的划分方法并不适合于该类场地,且对该类场地没有提出明确的设计规定。本文以此为出发点,建立含有软土夹层的土层模型,结合地表面上的较短周期结构,采用时程分析法在基岩面处输入地震波,运用ABAQUS在考虑土的非线性因素影响下进行有限元分析。通过计算与分析发现:在含有软土夹层的场地中,基岩面上覆土对地震加速度的放大作用小于无软土夹层的场地;软土夹层在地震作用下的应变普遍大于其他土层,对地震能量的耗散更大;地面结构的地下室对加速度有一定程度的削弱,结构顶部的加速度峰值一般大于结构的底部;软硬土层弹性模量比值变化的影响较软土夹层厚度变化的影响要显著;软硬土层弹性模量差异越大,覆土对加速度放大作用越小,但两者之间不呈现为线性关系;当软硬土层弹性模量比值大于一定值后,覆土对加速度峰值反而起减小的作用。结合计算结果和理论分析,本文建议该领域可考虑采用以下方法,如采用反应谱法进行对比分析;以大容量的实际地震数据为样本用三维实体模型进行分析;选择更符合实际的土体本构关系;建立长周期的地面结构进行对比分析等,以期得到符合地震动、场地土和结构实际状况的研究成果。
[Abstract]:Site conditions have always been an important subject in the field of ground motion research. There are many factors that affect the seismic response of soil and structure in site conditions. It is a common geological phenomenon that soft soil intercalation is included in the site. The classification method of site category in BG5011-2010 (hereinafter referred to as "Anti-gauge") is not suitable for this kind of site, and there is no clear design regulation for this kind of site. In this paper, a soil layer model with soft soil intercalation is established. Combined with the short period structure on the ground surface, the seismic wave is input at the bedrock surface by time-history analysis method. The finite element analysis is carried out by using ABAQUS under the influence of nonlinear factors of soil. Through calculation and analysis, it is found that in the site with soft soil intercalation, the amplification of seismic acceleration by overlying soil on the bedrock surface is less than that in the site without soft soil intercalation, and the strain of soft soil intercalation under earthquake is generally greater than that of other soil layers. The ground structure basement weakens the acceleration to a certain extent, and the peak acceleration at the top of the structure is generally greater than that at the bottom of the structure. The effect of the ratio of elastic modulus of soft and hard soil is more significant than that of the thickness of soft soil intercalation, the greater the difference of elastic modulus of soft and hard soil is, the less the effect of overburden on acceleration is, but there is no linear relationship between them. When the ratio of elastic modulus of soft and hard soil is greater than a certain value, the soil overburden plays a role in decreasing the acceleration peak. Combined with the results of calculation and theoretical analysis, this paper suggests that the following methods should be adopted in this field, such as using the method of response spectrum to carry on comparative analysis, taking the actual seismic data of large capacity as the sample and using the three-dimensional solid model to analyze; A more realistic constitutive relation of soil is chosen, and a long-period ground structure is established for comparative analysis, in order to obtain the research results in accordance with the actual conditions of ground motion, site soil and structure.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU435

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