Earthquake Deformations of Subway Infrastructure

9714859李美国或世界其他地区的大多数大城市地区已经或正在计划建立地下基础设施系统，作为城市交通的替代方式。了解地下结构的破坏特征，找出岩土和结构变形的原因，以及研究结构附近的局部场地效应对强震引起的结构变形放大的影响是非常重要的。以往地震的经验表明，在一些地区记录到的运动幅度大于预期。这些地区通常有较大深度的冲积沉积物，以及靠近地表的相对松软的土壤沉积物。大规模的民用基础设施(水坝、高速公路网、桥梁和现在的地下地铁)对强烈的地震地面运动做出反应，而强烈地震地面运动高度依赖于当地场地的地表和地下地形。该项目旨在研究地铁、多个构造基础和局部地质相互作用的影响，探索这些关键因素如何影响基础运动的结果放大。该方法是基于波在弹性固体介质中的传播。解决这一问题的挑战在于边界条件，其中非正交的纵剪切势是耦合的。这将通过波势的展开级数和积分表示来克服。这些研究的结果将与以前地震记录的实际变形进行比较。这些比较将作为对所考虑问题的正确建模的指导方针。通过正确理解地面(建筑物和高速公路)和地下(地下地铁)结构在强震过程中的表现，可以通过考虑这些局部场地效应来改进未来新建筑的结构设计和现有结构的改造计划，以提供正确的设计强度和加固。这将有助于将未来地震中的财产损失和生命损失降至最低。***

9714859 Lee Most large metropolitan areas here in the United States, or countries in other parts of the world, already have or are planning to have underground infrastructure systems as an alternate way of urban transportation. It is important to understand the characteristics of damages associated with the underground construction and to find out the cause of both geotechnical as well as structural deformations, and also, to study the influence of local site effects in the vicinity of the structure on the amplification of structural deformations resulting from strong earthquake motions. Experiences from previous earthquakes suggest that the recorded motions in some areas had larger than expected amplitudes. These are usually areas with large depths of alluvial sediments together with comparatively soft soil deposits near the surfaces. Massive civil infrastructures (dams, freeway networks, bridges and now the underground subways) respond to strong earthquake ground motions that are highly dependent on the surface and subsurface topographies at the local sites. This project is to study the effects of the interactions among the subways, the multiple structural foundations and the local geology, to explore how all these key elements will affect the resulting amplifications of foundation motions. The proposed method is based on the wave propagation in elastic solid media. The challenge in solving the problem will be in the boundary conditions where the nonorthogonal compressional and shear potentials are coupled. This will be overcome with expanded series and integral representations of the wave potentials. Results from these studies will be compared with the actual deformations as recorded from previous earthquakes. The comparisons will serve as guidelines to the correct modelling of the problem under consideration. With proper understanding of how surface (buildings and freeways) and subsurface (underground subways) structures performed during str ong-motion earthquakes, future structural design of new buildings and retrofit plans for existing structures can be improved by including these local site effects to provide the correct design strength and reinforcement. Then it will help to minimize property damage and the loss of life in future earthquakes to come. ***