SV和SH波垂直入射下二维盆地-子盆地共振对比研究  

Comparison of two-dimensional basin and sub-basin resonances under vertical incidence of SV and SH waves

作　　者：刘昇 刘启方 LIU Sheng;LIU Qifang(Key Laboratory of Structure Engineering of Jiangsu Province,Suzhou University of Science and Technology,Suzhou 215009,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215009

出　　处：《地震工程与工程振动》2024年第3期146-156,共11页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(51978434);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：盆地-子盆地中的子盆地除了底部直达的入射体波外,还存在大盆地产生的横向传播的面波入射,导致子盆地共振特性的变化。基于显式有限元法,对比分析了SH波和SV波垂直入射下,子盆地基底阻抗比、大盆地倾角和半宽对二维梯形盆地-子盆地的二维共振频率及其对应放大系数的影响。研究表明:受大盆地产生的横向传播面波的影响,子盆地的速度峰值PGV和累积能量Ex最大值均有明显放大,且SV波入射下的放大系数大于SH波;子盆地基底阻抗比对盆地-子盆地的PGV最大值、Ex最大值、二维共振频率及其对应放大系数影响较大,大盆地倾角和半宽的影响不大。SV波和SH波入射下子盆地二维共振频率较单一小盆地均有所增加,且同阻抗比下SV波入射的增幅大于SH波。SH波入射下二维共振频率下的放大系数基本大于单一小盆地,而SV波在低阻抗比下低于单一小盆地,高阻抗比下高于单一小盆地和SH波入射下的结果。SV波入射下盆地-子盆地的二维共振频率及其对应放大系数受大盆地的影响较SH波更大。In addition to the direct incident body wave at the bottom,the sub-basin in the basin and sub-basin also have laterally propagated surface waves generated by the large basin,which lead to the change of the resonance characteristics of the sub-basins.Based on the explicit finite element method,the effects of sub-basin impedance ratio,large-basin dip angle and half-width on the resonance frequency and amplification factor of two-dimensional trapezoidal basin and sub-basin under the vertical incidence of SH and SV waves are comparatively analyzed.The results show that:affected by the laterally propagating surface waves generated in the large basin,the maximum values of PGV and E x in the sub-basin are obviously amplified,and the amplification of SV waves is greater than that of SH waves.The sub-basin impedance ratio has a great influence on the maximum PGV,E x,resonance frequency and amplification factor of the basin and sub-basin,while the dip angle and half-width of the large basin have little effect.Compared with a single small basin,the resonance frequency of the sub-basin increases under the incidence of SV wave and SH wave,with the value of incidence of SV wave greater than that of SH wave under the same impedance ratio.The amplification factor of the sub-basin under the incidence of SH wave is basically larger than that of the single small basin,while the SV wave is lower than the single small basin under the low impedance ratio,but higher than the single small basin and the SH wave incidence under the high impedance ratio.The resonance frequency and amplification factor of the basin and sub-basin are more affected under the incident SV wave than that of SH wave.

关 键 词：盆地-子盆地 显式有限元法 二维盆地共振 阻抗比 

分 类 号：TU435[建筑科学—岩土工程]