强度包络函数参数不确定性对土层地震反应影响研究

发布时间：2018-04-30 07:07

  本文选题：地震安全性评价 + 强度包络函数　； 参考：《中国地震局工程力学研究所》2015年硕士论文

【摘要】：人造地震动是工程场地地震安全性评价工作的重要组成部分,目的是为土层地震反应分析提供基岩地震动输入。对于同一目标反应谱而言,利用不同的强度包络函数参数人工合成出的地震动时程是有一定差别,这势必影响土层地震反应分析结果以及基于此结果确定出的设计地震动参数。因此,研究强度包络函数参数的不确定性对土层地震反应分析结果的影响具有很强的工程应用价值。本文采用三段式的强度包络函数模型,结合近年来在实际工程场地地震安全性评工作中广泛应用的几种地震动时程强度包络函数参数确定公式,讨论了该模型中两个主要参数(上升段截止时间T1和相对平稳强地震动持续时间Td)在不同震级和震中距下的取值范围,研究了T1与Td变化对土层地震反应分析结果的影响。完成了以下主要工作:1.简要阐述了强度包络函数参数研究在地震安全性评价工作中的重要作用,系统介绍了强度包络函数研究的发展历程和近年来研究成果。2.采用俞言祥博士中国东部地区基岩峰值地震动加速度和地震加速度反应谱衰减关系,计算得到了人工合成地震动所需的目标谱,采用四种常用的强度包络函数参数计算公式确定了不同震级和震中距组合下的参数取值范围。3.以典型的6级和7级地震为例,针对每一种震级和震中距工况,在参数取值范围内,调整T1和Td,人工合成一系列地震动时程,并将其折半作为基岩地震动输入,针对四种典型场地类别的土层地震反应进行了分析。4.对土层地震反应计算结果进行了统计分析,结果表明:(1)总体而言,Td值变化对地表水平向峰值加速度和地表水平向加速度反应谱的影响程度较T1值变化更为显著;(2)近场地震动情况下,Td和T1的变化对土层反应分析结果影响较大,而远场地震动情况下影响较小;(3)Ⅰ类场地的放大系数受参数变化影响较小,Ⅱ、Ⅲ、Ⅳ类场地的放大系数受参数影响程度较大。(4)强度包络函数参数变化对不同场地类别的影响程度不同,Ⅰ类场地受影响程度较小,Ⅱ、Ⅲ、Ⅳ类场地受影响程度稍大。
[Abstract]:Artificial ground motion is an important part of seismic safety evaluation of engineering site. The purpose of this work is to provide ground motion input for seismic response analysis of soil layer. For the same target response spectrum, the time history of ground motion synthesized by using different parameters of intensity envelope function is different, which will inevitably affect the seismic response analysis results of soil layer and the design ground motion parameters based on these results. Therefore, it is of great value to study the influence of the uncertainty of intensity envelope function parameters on the results of soil seismic response analysis. In this paper, a three-segment strength envelope function model is used to determine the parameters of time-history intensity envelope function of ground motion, which has been widely used in the seismic safety assessment of practical engineering sites in recent years. The values of two main parameters (the cutoff time T _ 1 and the duration of relatively stationary strong ground motion T _ d) under different magnitude and epicentral distance in the model are discussed. The influence of the variation of T _ 1 and T _ d on the results of soil seismic response analysis is studied. Completed the following main work: 1. This paper briefly describes the important role of the study of the parameters of the intensity envelope function in the evaluation of seismic safety, and systematically introduces the development course of the study of the intensity envelope function and the research achievements in recent years. By using the relationship between peak ground motion acceleration and seismic acceleration response spectrum attenuation of the bedrock in eastern China, the target spectrum required for artificial synthetic ground motion is calculated. Four commonly used formulas for calculating the parameters of the intensity envelope function are used to determine the range of values of the parameters under different magnitude and epicenter distance combinations. Taking a typical earthquake with M 6 and M 7 as an example, according to each magnitude and epicentral distance, adjusting T1 and Td within the range of parameters, synthesizing a series of earthquake time history artificially, and taking it as the input of ground motion. The seismic response of soil layer of four typical site types is analyzed. The calculation results of soil seismic response are statistically analyzed. The results show that the variation of Td value has a more significant effect on the response spectrum of horizontal acceleration and horizontal acceleration than T1.) the variation of Td and T1 in near-field ground motion has a more significant effect on soil layer response. The results of the analysis have a great influence on, However, the magnification factor of type 鈪，

本文编号：1823574