RAPID: Liquefaction and Its Effects on Buildings and Lifelines in the February 22, 2011 Christchurch, New Zealand Earthquake

该快速反应研究（Rapid）赠款为2011年2月22日新西兰克赖斯特彻奇地震（Mw=6.1）和2010年9月4日新西兰达菲尔德地震（Mw=7.0）期间液化对建筑环境的影响提供了研究资金，目的是获取易损数据，从而开发增强的分析程序，以全面评估危害。克赖斯特彻奇地震造成强烈的地面震动和土壤液化，破坏了许多建筑物、生命线和工程系统。基督城的中央商务区（CBD）仍然是一片废墟。2月22日的事件尤其有意义，因为它发生在距离市中心约40公里的达菲尔德地震仅仅5个月之后。2月22日的事件造成近200人死亡，而9月的事件没有造成死亡。此外，尽管9月4日的地震在克赖斯特彻奇地区造成了广泛的液化引起的损害，但在CBD内并没有造成严重的液化引起的损害。通过比较这两次地震中不同程度的土壤液化，以及评估建筑物、生命线和工程系统在这两次地震中的不同抗震性能，我们可以学到很多东西。有机会了解相同的地面和基础设施如何应对两次大地震是极其罕见的。这两次地震的震级和距离是美国城市经常考虑的两种情况。获取横向扩散的细节和液化对良好建筑（如办公楼及其相互连接的地下公用设施）的影响是至关重要的。了解当地地质条件如何影响观测到的破坏模式也很重要。现场侦察的重点是捕获易腐烂的数据，并通过以下方式描述地下条件：(1)液化特征的挖沟，(2)进行动态锥形穿透测试，(3)测量横波速度（Vs）。christthurch地区土壤液化对建筑环境的影响十分普遍。新西兰的建筑规范与美国使用的类似，而且最近的建筑也有很多，可以学到很多直接适用于美国地震带的东西。这项研究由地球工程极端事件侦察协会（GEER）协调，并与坎特伯雷大学和新西兰政府合作。设计级地震后的观测记录和学习对于提高地震工程的实践水平是非常宝贵的。调查再次发生的液化，记录液化引起的地面运动的案例，评估液化对建筑物和生命线的影响，提供了宝贵的信息，这些信息将作为专业人士了解地震影响的基准。这些地震还涉及多种灾害的影响。两次地震期间液化造成的沉降使基督城的许多社区面临河流和海洋洪水的威胁，包括海啸。液化引起的地面运动数据的收集将构成洪水风险评估和地震脆弱性的基础。这项研究结合了几位主要研究人员的努力，从整体上考察了液化的影响。该团队还包括一名初级教员和研究生，他们正处于职业生涯的早期阶段，因此这将有助于发展他们在地震工程方面的能力，并使他们能够在新西兰建立研究联系。

This Grant for Rapid Response Research (RAPID) award provides funding to investigate the effects of liquefaction on the built environment during the 22 February 2011, Mw=6.1 Christchurch, New Zealand, earthquake and the 4 September 2010, Mw=7.0 Darfield, New Zealand, earthquake with the goal of capturing perishable data that would lead to the development of enhanced analytical procedures for evaluating the hazard holistically. The intense ground shaking and resulting soil liquefaction from the Christchurch earthquake damaged many buildings, lifelines, and engineered systems. The Central Business District (CBD) of Christchurch is still in ruins. The 22 February event is particularly meaningful, because it occurred just 5 months after the Darfield earthquake, the epicenter of which was approximately 40 km from the CBD. Whereas the 22 February event killed almost two hundred people, the September event resulted in no deaths. Additionally, although the 4 September event caused widespread liquefaction-induced damage in the Christchurch area, it did not produce significant liquefaction-induced damage within the CBD. There is much to learn from comparing the different levels of soil liquefaction from these two earthquakes and from evaluating the differing seismic performance of buildings, lifelines, and engineered systems during these two earthquakes. It is extremely rare to have the opportunity to learn how the same ground and infrastructure responded to two significant earthquakes. The magnitude and distances of these two earthquakes are two of the scenarios often considered in US cities. Capturing details of lateral spreads and the impacts of liquefaction on well-built structures, such as office buildings and their interconnecting buried utilities, are critically important. Understanding how local geologic conditions influenced the observed damage patterns is also important. Field reconnaissance is focusing on capturing perishable data and characterizing the subsurface conditions through: (1) trenching of liquefaction features, (2) performing dynamic cone penetration tests, and (3) measuring shear wave velocities (Vs).The effects of soil liquefaction on the built environment in the Christhurch area were pervasive. The New Zealand building code is similar to that used in the U.S., and with much recent construction, there is much that can be learned that is directly applicable to seismic regions across the U.S. This study is being coordinated through the Geoengineering Extreme Events Reconnaissance (GEER) Association and in collaboration with the Univ. of Canterbury and the New Zealand government. Documenting and learning from observations after design level earthquakes are invaluable to advancing the state-of-practice in earthquake engineering. Surveying the re-occurrence of liquefaction, documenting cases of liquefaction-induced ground movements, and evaluating the effects of liquefaction on buildings and lifelines provide invaluable information that will serve as benchmarks to the profession's understanding of the effects of earthquakes. These earthquakes involve also multi-hazard effects. The combined settlement caused by liquefaction during both earthquakes has exposed many Christchurch neighborhoods to increased threats from river and ocean flooding, including tsunami. Collection of data on liquefaction-induced ground movement will form the basis for flood risk assessment as well as earthquake vulnerability. The study combines the efforts of several leading researchers to examine the effects of liquefaction holistically. The team also includes a junior faculty member and graduate students who are in the early stages of their careers, so it will help develop their capabilities in earthquake engineering and allow them to establish research contacts in New Zealand.