Earthquake Surface Fault Rupture Interaction with Building Foundations

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。研究地震地表断层破裂对建筑物地基的影响，目的是开发合理的分析方法来评估危险，为活动断层附近建筑的有效设计概念提供指导，并提出有前景的地基加固技术来减轻这种危险。最近的地震提供了许多地震地表断层破裂对建筑物的破坏性影响的例子。几个主要城市都建在含有活动断层的地区，这些断层可能会打破地面(例如洛杉矶、盐湖城、圣地亚哥、旧金山和西雅图)。伴随着经常壮观的破坏观察，也观察到了令人满意的结构性能的例子。这些性能令人满意的例子表明，与其他形式的地面故障类似，可以开发有效的设计策略来解决与地表断层破裂相关的危险。为了应对地表断层破裂的危害，需要一个合理的分析、设计和缓解框架。这项研究的重点是评估不同建筑基础在不同相对密度和厚度的砂土场地上受到反向或正向断层运动的反应。地表断层破裂问题是一种土-结构-土相互作用现象，采用非线性有效应力UBC-砂土模型，采用显式有限差分方法进行研究。目前正在利用记录充分的实地案例和两项全面的离心机研究来了解情况并为分析确立基准。在对分析模型进行校正后，对地震地表断层破裂对建筑物基础的影响进行了全面的数值研究。几种有希望的缓解技术也在探索之中。分析结果将提供基本的见解和以实践为导向的建议。几个政府机构和专业委员会正在重新审查现有政策或制定新的政策来解决地表断层破裂的危险。由于过度依赖于避免，地表断层破裂灾害缓解方面的进展落后于其他形式的地面故障。然而，并不是所有的断层都可以避免，如果能够证明缓解技术在处理与微小断层运动相关的地面变形方面是有效的，那么也不是所有的断层都需要严格避免。有效的缓解和设计程序是必需的，而它们的使用需要强大的分析程序。这一研究项目的结果通过帮助工程师和城市规划者解决这一危险，满足了社会的迫切需求。此外，由于现象的复杂性，在理解土的破坏和土-结构-相互作用方面正在取得重要进展。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The effects of earthquake surface fault rupture on building foundations are investigated in this research with the goals of developing sound analytical procedures for evaluating the hazard, providing guidance regarding effective design concepts for buildings that are built near active faults, and advancing promising ground improvement techniques for mitigating this hazard. Recent earthquakes have provided numerous examples of the devastating effects of earthquake surface fault rupture on structures. Several major cities are built in areas containing active faults that can break the ground surface (e.g., Los Angeles, Salt Lake City, San Diego, San Francisco, and Seattle). Along with the often spectacular observations of damage, examples of satisfactory performance of structures have been observed. These examples of satisfactory performance indicate that similar to other forms of ground failure, effective design strategies can be developed to address the hazards associated with surface fault rupture. A rational analytical, design, and mitigation framework for addressing the surface fault rupture hazard is required.This research focuses on evaluating the responses of different building foundations at sandy soil sites with different relative densities and thicknesses that are subjected to reverse or normal fault movements. The surface fault rupture problem is investigated as a soil-structure-interaction phenomenon using the explicit finite difference method with the nonlinear effective stress UBC-SAND soil model. Well-documented field case histories and two comprehensive centrifuge studies are being used to gain insight and to establish benchmarks for the analysis. After calibrating the analytical model, a comprehensive numerical investigation of the effects of earthquake surface fault rupture on building foundations is performed. Several promising mitigation techniques are also being explored. The analytical results will provide both fundamental insights and practice-oriented recommendations.Several government agencies and professional committees are re-examining existing policies or developing new policies to address the surface fault rupture hazard. Advancements in surface fault rupture hazard mitigation lag behind those for other forms of ground failure, because of the overreliance on avoidance. However, not all faults can be avoided, and not all faults require strict avoidance if mitigation techniques can be shown to be effective in handling the ground deformation associated with minor fault movements. Effective mitigation and design procedures are required, and their use requires robust analytical procedures. The results of this research project meet a critical need in society by helping engineers and urban planners address this hazard. Additionally, due the complexity of the phenomena, important advances in the understanding of the failure of soil and of soil-structure-interaction are being made.