基于KiK-net记录的PGA与Sa场地影响因子分布研究  

Research on the distribution of site influence factors for PGA and Sa based on KiK-net records

作　　者：王祥祺 王自法[2,3] 赵登科 李兆焱 WANG Xiangqi;WANG Zifa;ZHAO Dengke;LI Zhaoyan(School of Civil Engineering and Architecture,Henan University,Kaifeng 475000,China;Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China;CEAKJ ADPRHexa Inc,Shaoguan 512000,China)

机构地区：[1]河南大学土木建筑学院,河南开封475000 [2]中国地震局工程力学研究所,黑龙江哈尔滨150080 [3]中震科建(广东)防灾减灾研究院,广东韶关512000

出　　处：《地震工程与工程振动》2023年第4期204-215,共12页Earthquake Engineering and Engineering Dynamics

基　　金：中国地震局工程力学研究所基本科研业务费专项资助项目(2021B09);国家自然科学基金面上项目(51978634)。

摘　　要：场地条件对地震动有着重要的影响,它一般通过地表峰值加速度PGA或者谱加速度Sa在不同场地条件下的放大系数表示。以往的相关研究中缺少大量的实测地震动数据分析;没有明确给出PGA和Sa在不同场景下的适用性;较少赋予其放大系数分布概率含义。选取KiK-net台网1997—2019年记录的210多万条地震动信息,通过PGA与Sa放大系数的分布分析了其在不同场景下的适用性,然后基于控制变量法和回归方法对每个台站的PGA放大系数进行拟合分析,最后对不同场地类别的PGA放大系数进行了概率分布函数拟合。研究结果表明:场地条件不变情况下,地震动放大系数的分布有很好的规律性;Sa较PGA放大系数分布离散程度更小,且随着Sa周期增加,其离散程度呈现逐渐减小趋势,在建筑物周期确定的情况下,Sa具有更高的适用性;Ⅰ、Ⅱ类场地且周期大于1.0 s的Sa放大系数具有较高的稳定性;相同场地条件下,PGA放大系数呈非线性分布,随着基岩PGA(PGA R)的增加逐渐减少;PGA放大系数趋于指数正态分布。研究结果可用于未来更加准确地估计损失与描述场地条件对地震动的影响。Site conditions have an important influence on ground motion,and the influence is generally expressed by the amplification factor of the Peak Ground Acceleration(PGA)or Spectral Acceleration(Sa).Previous related research results have shown the following shortcomings including without the support of analysis based on a large number of observed ground motion data,no explicit specification of the applicability of PGA and Sa in different scenarios,and lack of distribution probability of the amplification factor.This paper selects more than 2.1 million ground motion datasets recorded by the KiK-net network from 1997 to 2019,to analyze the amplification factor and its distribution for both PGA and Sa.Two regression methods are used to fit the PGA amplification factor of each station,and the probability distribution function for each site category is subsequently fitted using different functions.The results show that within the same site category,the distribution of ground motion amplification coefficients has a good concentration around the mean value.Compared to PGA,the distribution of Sa amplification coefficients has a smaller degree of dispersion,and with the increase of the Sa period,the degree of dispersion decreases.When the natural period of building is determined,Sa has better applicability than PGA.The Sa amplification factor ofⅠandⅡsite categories is less disperse when the natural period is greater than 1.0 s.For the same site conditions,the PGA amplification factor is nonlinearly distributed and gradually decreases with the increase of bedrock PGA.The PGA amplification factor distribution tends to follow an exponential normal function.These results can be used to estimate the loss more accurately and quantify the impact of site conditions on ground motion in the future.

关 键 词：场地条件 地震动 场地放大系数 线性拟合 概率分布 

分 类 号：P65[天文地球—地质学]