摘要
基于多次透射边界和有限元数值模拟方法,研究了SV波垂直入射下,山体高度、盆地深度、以及山体与盆地剪切波速变化对盆山耦合场地位移峰值放大系数、位移频谱及谱比的影响。结果表明:(1)盆地与山体均对地震波有放大作用,从坡底到坡顶位移放大效用逐渐增大,从盆地外边缘到盆地中心位移放大效应逐渐增大,但盆地内放大系数分布特征受盆地深宽比的强烈影响。(2)山体测点位移峰值放大系数AF随山体高度增大而增大;山体的存在减弱了盆地的地表地震动放大效应,导致盆地远离山体一侧的放大更强烈,反之亦然。(3)随盆地波速的减小或山体波速的增大,盆地AF最大值增大,且最大AF出现的位置向远离山体一侧偏移,而山体各测点的AF值受此影响较小。(4)山顶处谱比峰值主要受山高、盆地深度及盆地波速影响,但最大放大频率及分布特征基本不变;山体波速对山顶处谱比分布影响显著。盆地中点处谱比受各参数影响均较显著,但规律较复杂。盆山复合场地的地震动分析中需考虑二者的耦合效应对地震动的影响。
The seismic ground motion of coupled basin-mountain terrain under vertical SV waves was studied using the numerical simulation method and the transmission boundary theory,and the effects caused by mountain height,basin depth,and basin-mountain shear wave velocity were also discussed.The results show that:(1)Both the basin and the mountain have amplification effect on seismic wave,the peak amplification coefficient of displacement increases gradually from the bottom to the top of the slope,and the peak amplification coefficient of displacement increases gradually from the outer edge of the basin to the center,however,the distribution characteristics of amplification coefficient for the basin are strongly affected by the aspect ratio of the basin.(2)The amplification factor AF of peak displacement increases with the increase of mountain height;The amplification effect on the seismic ground motion of the basin is reduced due to the existence of the mountain,which results in a stronger amplification effect on the side of the basin away from the mountain.(3)With the decrease of wave velocity for the basin or the increase of wave velocity for the mountain,the maximum value of AF for the basin increase and the location of the maximum AF shifts away from the mountain,however,the AF value of each surface point for the mountain is less affected.(4)The peak value of spectral ratio at mountain top is mainly affected by the height of the mountain,the depth and the wave velocity of the basin,but the maximum amplification frequency and distribution characteristics of spectral ratio are basically the same;The distribution of spectral ratio at the center of the mountain top is significantly affected by the shear wave velocity of the mountain;The spectral ratio at the center of the basin is significantly affected by each parameter,but the regularity is complex.The influence on the ground motion of the coupling effect should be considered in the ground motion analysis of basinmountain composite site.
作者
高严
于彦彦
GAO Yan;YU Yanyan(Research Institute of Structure Engineering,Hohai University,Nanjing 210098,China;Key Laboratory of Structure Engineering of Jiangsu Province,Suzhou University of Science and Technology,Suzhou 215011,China)
出处
《防灾减灾工程学报》
CSCD
北大核心
2022年第1期100-110,共11页
Journal of Disaster Prevention and Mitigation Engineering
基金
国家自然科学基金项目(51808371)
江苏省高校自然科学研究面上项目(18KJB560017)
江苏省结构工程重点实验室开放研究课题(ZD1703)资助。
