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通过大型沉管隧道的实例分析和前期研究成果,重点讨论沉管隧道地震反应分析中建立局部三维精细化模型时所应关注的4个问题:1模型范围大小的问题;2上覆水体动水作用的简化;3时域分析中阻尼矩阵的合理建模及其影响;4地震输入方式的选择与影响等。文中通过工程算例验证局部三维精细化建模的合理方式,研究结果表明:考察某段沉管管节的地震反应时,应至少考虑该管节两端各三段相邻管节的影响和轴向5倍以上土层厚度范围的土层影响;上覆水体可近似采用等效附加质量的方式模拟;当沉管隧道-土层体系的基频低于输入地震波的卓越频率时,易采用基于体系基频的优化方法来确定Rayleigh比例阻尼矩阵的比例系数;沿沉管隧道轴向的多点地震输入对隧道地震反应有较大影响,应加以充分关注。
Through the analysis of large immersed tunnels and the previous research results, four problems that should be paid attention to in the establishment of local three-dimensional refinement model for seismic response analysis of immersed tunnel are discussed in detail: (1) the range of the model range; (2) The role of simplification; 3 time-domain analysis of the reasonable modeling of damping matrix and its impact; 4 Earthquake input options and effects. In this paper, a reasonable way of local three-dimensional refinement modeling is verified by engineering examples. The results show that when considering the seismic response of a sinking pipe joint, the influence of the adjacent pipe joints at each end and the axial 5 times more than the thickness of the soil layer; the overlying water can be approximated by equivalent additional mass; when the immersed tunnel-soil system has a lower fundamental frequency than the input seismic wave, it is easy to adopt the system based on the system The fundamental frequency optimization method is used to determine the proportional coefficient of Rayleigh proportional damping matrix. Multi-point seismic input along the tube axis of immersed tunnel has great influence on the seismic response of the tunnel, and should be fully concerned.