中国仪器地震烈度增量与场地放大系数的关系研究

相对于基岩的中国仪器地震烈度增量可以作为地震小区划的一个重要指标，也可以作为研究区建（构）筑物差异抗震设防的可靠依据。使用2021年2月13日福岛地震期间日本KiK-net台网120个台阵记录的地震动数据，根据18种地震动参数的定义和《中国地震烈度表》中中国仪器地震烈度的算法，分别计算了相对基岩的、土层上的中国仪器地震烈度增量和这些地震动参数的放大系数，然后用一元、二元回归分析方法分别建立它们之间的经验关系式。结果表明:（1）一元回归分析中，中国仪器地震烈度增量与持时超过0.3秒的加速度阈值（a_0.3）的放大系数的相关系数最高且为0.918，与峰值地面加速度（PGA）、水平向最大谱烈度（SI）的放大系数的相关系数均在0.870以上；（2）从中国规范的II类场地到III类场地（或美国规范的C类场地到E类场地），中国仪器地震烈度增量的均值逐渐增大；（3）相比于一元回归结果，二元回归分析中的中国仪器地震烈度增量与18种地震动参数放大系数两两组合的相关系数普遍有所提高，其中中国仪器地震烈度增量与PGA和SI放大系数组合的相关系数最高且为0.9261。

Study on the relationship between Chinese instrumental seismic intensity increments and site amplification factors

The Chinese instrumental seismic intensity increment relative to bedrock can be used as an important index for seismic microzoning, but also as a reliable basis for different seismic fortification of structures in the study area.Using the ground motion data recorded by 120 arrays from the KiK-net network in Japan during the Fukushima earthquake on February 13,2021,and according to the definition of 18 kinds of ground motion parameters and the algorithm of the Chinese instrumental seismic intensity in The Chinese Seismic Intensity Scale,the Chinese instrumental seismic intensity increments and the amplification factors of these ground motion parameters relative to the bedrock are calculated,and then the empirical relationships between them were established by means of univariate and binary regression analysis methods respectively.The results show as follows.(1)For unary regression analysis, correlation coefficient between the Chinese instrumental seismic intensity increment and amplification factor of the acceleration threshold(a_0.3)with duration more than 0.3 seconds is the highest and 0.918,and the correlation coefficients of the Chinese instrumental seismic intensity increments with amplification factor of peak ground acceleration(PGA),and with amplification factor of horizontal maximum spectrum intensity(SI)are greater than 0.870. (2)From Class II to Class III(or from Class C to Class E),the mean value of the Chinese instrumental seismic intensity increments in different site categories gradually increases(. 3)The correlation coefficients between the Chinese instrumental seismic intensity increments and the amplification factors of any two ground motion parameters are generally improved compared with the results of unitary regression,and the correlation coefficient between the Chinese instrumental seismic intensity increments and the amplification factors of both PGA and SI is the highest and 0.9261.