Earthquake Deformations of Subway Infrastructure

[9714859]李在美国和世界其他国家的大多数大都市已经或正在计划建设地下基础设施系统，作为城市交通的另一种方式。了解与地下工程有关的损伤特征，找出引起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作用下结构变形放大的影响具有重要意义。以往地震的经验表明，在一些地区记录到的运动幅度比预期的要大。这些地区通常具有深度较大的冲积沉积物以及靠近地表的相对较软的土壤沉积物。大型民用基础设施（水坝、高速公路网络、桥梁和现在的地下地铁）对强烈的地震地面运动做出反应，这些运动高度依赖于当地的地表和地下地形。本项目旨在研究地铁、多重结构基础和当地地质之间相互作用的影响，探讨所有这些关键因素将如何影响基础运动的放大。该方法基于弹性固体介质中的波传播。解决这个问题的挑战将是在非正交的压缩和剪切势耦合的边界条件下。这将通过波势的扩展级数和积分表示来克服。这些研究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审议问题的正确建模的指导方针。通过正确理解地表（建筑和高速公路）和地下（地下地铁）结构在强震中的表现，未来新建筑的结构设计和现有结构的改造计划可以通过包括这些局部场地效应来改进，以提供正确的设计强度和加固。然后，它将有助于在未来的地震中减少财产损失和生命损失。＊＊＊

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. ***