STUDIES ON SEISMIC RESPONSE OF EXTENDED STRUCTURES IN IRREGULAR SITE AND THE RATIONAL DESIGN CONSIDERATIONS

首先给出了冲积层的瞬时地震反应，考虑了入射波的类型和长度，以及与下垫层远伸展基础的刚度对比，考虑了冲积层的形状和大小。对结构复杂、材料分布不规则的近场用有限元(FE)模拟，远场用边界元(BE)模拟。为了对地震波的散射和传播有一个清晰的解释，采用了时间域边界元-有限元混合计算。其次，讨论了在不规则场地上修建的盾构隧道结构的地震反应，充分考虑了冲积层的形状、大小以及与下垫层远伸展基础的刚度对比。边界元-有限元混合…为了考虑由于字母的存在而引起的地震波散射，对整个土体和结构体系进行了更多的表述。对不同入射角度的SV波、P波的不同入射波长进行了参数研究。对盾构隧道的结构内力和变形进行了研究。第三，针对盾构隧道的实际设计过程，提出了一种简化的三维温克勒型弹簧支承结构模型。对冲积层中延伸埋藏构造的行为进行了解释，并对场地地形给予了应有的关注。这是通过与上面精心设计的边界元-有限元混合解的比较来检验的。最后，从设计的角度出发，提出了对围堰土体进行加劲处理的建议，以避免产生过大的地震反应，减少地震反应。较少

Presented first is the transient seismic response of alluviums with due account for the configuration and the size in view of incident wave types and the lengths, besides the stiffness contrast to the underlain far extening base. Discretization is made such that the near field of complex configuration and irregular material distribution is modeled by the finite elements (FE) and the extending far field by the boundary elements (BE). The time domain BEM-FEM hybrid computation is taken in order to give a clear interpretation to the seismic wave scattering and propagation. Parametric studies are performed aiming at aquiring the relevant soil amplification which is useful information for the structural design on irregualar allumivums.Secondly, discussed is the seismic response of an extended shield tunnel structures to be constructed at irregular sites with due account for the alluvium configuration and size and the stiffness contrast to the underlain far extending base. The BEM-FEM hybird … More formulation is taken for the total system of soil and structure in order to account for the seismic wave scattering due to the presence of the letter. Parametric studies are performed for various wave lengths of the incident SV wave, P wave with different incident angles. The structural internal forces as well as deformation are investigated.Thirdly, for the purpose of practical design procedure of shield tunnels, a simplified 3-dimensional structural model supported by Winkler type springs.is proposed. The behavior of extended buried structures in alluvium deposits with is interpreted due care to the site topography. This is examined from the comparison with the above elaborate BEM-FEM hybrid solution. The matching between these different methods is achieved when an appropriate modification factor is made to the spring constant.Finally, from the design point of view, stiffening of the surrounding sofft soil is proposed in order to avoid excessive response and for the seismic response redunction. Less