考虑地震波输入差异的二维兰州盆地地震效应研究  

Study on seismic effect of two-dimensional Lanzhou basin considering the difference of seismic wave input

作　　者：田浩 于彦彦[1] 丁海平[1] 章旭斌[2] TIAN Hao;YU Yanyan;DING Haiping;ZHANG Xubin(Key Laboratory of Structure Engineering of Jiangsu Province,Suzhou University of Science and Technology,Suzhou 215011,China;Key Laboratory of Earthquak Engineering and Engineering Vibration.Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China)

机构地区：[1]苏州科技大学江苏省结构工程重点实验室,江苏苏州215011 [2]中国地震局工程力学研究所地震工程与工程振动重点实验室,黑龙江哈尔滨150080

出　　处：《世界地震工程》2024年第2期123-135,共13页World Earthquake Engineering

基　　金：国家自然科学基金青年基金项目(51808371);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(2021EEEVL0001)。

摘　　要：利用谱元法和多次透射边界相结合的数值模拟方法,探讨了不同地震波输入时,具有大盆地内嵌小盆地特征的二维兰州盆地构造对地表地震波传播、地表峰值加速度(PGA)及其放大系数,以及频域放大特征等影响,分析了地表地震动的放大特征与盆地横向不均匀构造之间的关系。结果表明:1)当输入波的卓越频率接近小盆地最深处的一阶自振频率时,小盆地发生整体共振现象,进而显著改变地震动或放大系数的分布特征。大盆地边缘形成的次生面波在进入更为松散的小盆地时分化为波速差别显著的两阶面波,且盆地较陡一侧边缘形成的面波强度更大。2)无论何地震波入射,盆地内的最强烈地震动集中于小盆地边缘区域,大盆地较陡一侧边缘上方的区域是次强烈地震动放大区,而盆地基底倾角较缓的一侧边缘区域基本无边缘效应。3)兰州盆地基底形状对地震动的分布特征影响强烈,盆地地表地震动的放大系数受输入波的影响明显。4)水平和垂直分量的地震动及放大系数分布特征差别显著,垂直分量上在大盆地较陡一侧边缘及小盆地内形成两个显著放大区,最强烈放大效应区域靠近小盆地中心,而水平分量上的强烈放大区域主要出现在小盆地内的边缘区域。此外,地表不同位置处的频域放大特征也存在明显差别。By using the spectral element method and the numerical simulation method of multiple transmission boundary,the effects of the two-dimensional structure of Lanzhou basin,which has the characteristics of large basin embedded with small basin,on the surface seismic wave propagation,the surface peak acceleration(PGA)and its amplification coefficient,as well as the amplification characteristics in the frequency domain,under different seismic wave input are discussed.The relationship between the amplifying characteristics of ground motion and the lateral uneven structure of the basin is analyzed.The results show that:1)when the dominant frequency of the input wave is close to the first natural frequency in the deepest part of the small basin,the global resonance phenomenon of the small basin will be induced,and then the distribution characteristics of the ground motion or the amplification coefficient will be significantly changed.The secondary surface waves formed at the edge of a large basin transform into two-order surface waves with significant difference in wave velocity when entering a smaller,looser basin,and the intensity of surface waves formed at the edge of the steeper side of the basin is higher.2)No matter where the seismic wave incident occurred,the most intense seismic motion in the basin concentrated on the edge of the small basin,the area above the edge of the steeper side of the large basin was the subintense seismic amplification area,and the edge area of the side with the lower dip Angle of the basin had no edge effect.3)The basement shape of Lanzhou basin has a strong influence on the distribution characteristics of ground motion,and the amplification coefficient of ground motion is obviously affected by the input wave.The distribution characteristics of ground motion and amplification coefficient of horizontal and vertical components are obviously different,on the vertical component,two significant amplification regions are formed on the steeper edge of the large basin and within the small basin,t

关 键 词：谱元法 透射边界 兰州盆地 平面波入射 地震效应 

分 类 号：P315.9[天文地球—地震学]