Evaluation of Earthquake-Induced Liquefaction Damage Potential to Infrastructure

最近在新西兰、智利和日本发生的地震突出了地震引起的液化对自然环境和建筑环境的破坏性影响。例如，2010-2011年新西兰坎特伯雷的地震序列给基督城的地下公用设施、道路、建筑物和其他基础设施造成了大约350亿美元的损失，其中大部分损失是液化的直接后果。“将灾难转化为知识”，该奖项支持开发一个框架来评估液化对基础设施的潜在损害，该框架使用了来自最近地震的丰富现场性能数据，以及来自记录良好的历史液化案例历史和补充计算机模拟的数据。本研究项目的动机是需要在尊重其基本差异的框架内适当地解释触发和破坏，系统地分类液化的严重程度并将其与整个土壤剖面的响应联系起来，消除用于开发触发曲线的液化案例历史解释中的大部分主观性，并避免重复计算影响液化破坏潜力的因素。该奖项的结果将通过改进目前的液化风险评估方法，帮助最大限度地减少地震造成的损失。此外，教育方面的影响不仅来自对主题的技术理解的增加，还来自与新西兰、智利和日本同事的国际合作。在目前用于开发液化“触发”曲线的方法中，由于主观性的原因，液化触发和由此造成的损害之间的区别模糊不清。其原因是液化“触发”曲线主要基于观测到的地表表现数据的严重程度。因此，所谓的简化液化“触发”曲线实际上是“触发”曲线和“表面表现”曲线的结合。因此，在当前的液化损伤潜力指数框架中使用这些曲线，本质上重复计算了影响液化损伤潜力的因素。对于可靠地评估液化风险来说，这是一个特别重要的问题。该合同支持在一致的框架内开发液化触发曲线和潜在损害指数，该框架提供了液化触发和液化损害潜力的明确分离和适当计算。最值得注意的是，该框架避免了将液化发生与剖面内的特定层联系起来的需要；相反，该框架集成了来自每个病例历史的整个概要文件的信息。表现严重程度的分类将遵循详细的规则，以便形成统一和客观的液化危害评估方法。现场性能数据将使用贝叶斯更新技术进行分析，以开发基于概率的“真实”液化触发曲线。该技术还将用于确定与不同液化严重程度概率相对应的潜在损害指数值，其中液化严重程度被用作潜在损害的代表。然而，该框架将保留简化的液化触发评估程序和液化潜力指数公式的优雅和简单性，因为它们为实践工程师所熟悉。

The recent earthquakes in New Zealand, Chile, and Japan highlight the damaging effects of earthquake-induced liquefaction on both the natural and built environments. For example the 2010-2011 Canterbury, New Zealand, earthquake sequence resulted in approximately $35 billion in damage to buried utilities, roads, buildings, and other infrastructure in Christchurch, with much of the damage being a direct consequence of liquefaction. "Turning disaster into knowledge," this award supports the development of a framework to assess liquefaction damage potential on infrastructure using the wealth of field performance data from the recent earthquakes, as well as data from well-documented historic liquefaction case histories and supplemental computer simulations. This research project is motivated by the need to properly account for triggering and damage within a framework that respects their fundamental differences, systematically classifies the severity of liquefaction and relates it to the response of the entire soil profile, removes much of the subjectivity in interpreting liquefaction case histories used to develop triggering curves, and avoids the double counting of factors that influence liquefaction damage potential. The results of this award will help minimize losses from earthquakes by improving the current methods for liquefaction risk assessment. Furthermore, the educational impacts will not only result from the increased technical understanding of the subject matter, but will also result from the international collaborations with colleagues in New Zealand, Chile, and Japan.The distinction between liquefaction triggering and the resulting damage is blurred by subjectivity in current approaches used to develop liquefaction "triggering" curves. The reason for this is that liquefaction "triggering" curves are primarily based on observed severity of surface manifestation data. As a result, the purported simplified liquefaction "triggering" curves are actually combined "triggering" and "surface manifestation" curves. Consequently, the use of these curves within current liquefaction damage potential index frameworks inherently double counts factors that influence liquefaction damage potential. This is particularly an issue for reliably assessing the risk due to liquefaction. This award supports the development of a liquefaction triggering curve and damage potential index within a consistent framework that provides a clear separation and proper accounting of liquefaction triggering and liquefaction damage potential. Most notably, this framework avoids the need to tie liquefaction occurrence to a specific layer within a profile; instead, this framework integrates information from the entire profile for each case history. The classification of manifestation severity will follow a detailed rubric such that a unified and objective approach for liquefaction hazard assessment is formed. The field performance data will be analyzed using the Bayesian updating technique to develop a probabilistically based "true" liquefaction triggering curve. This technique will also be used to determine the damage potential index values that correspond to different probabilities of liquefaction severity, where liquefaction severity is used as a proxy for damage potential. However, this framework will preserve the elegance and simplicity of the simplified liquefaction triggering evaluation procedure and Liquefaction Potential Index formulation because of their familiarity to practicing engineers.