RAPID: Pile Downdrag Behavior Based on Blast Liquefaction Testing

由于基督城遭受了广泛的液化破坏，新西兰地震委员会（EQC）正在赞助一项数百万美元的研究，以确定最具成本效益的液化缓解策略，用于修复工作和随后的重建。 根据这一测试计划，政府批准的方法将有资格获得地震保险赔偿。 将进行爆炸液化试验，以评估全尺寸条件下的地基加固技术。 我们将与EQC合作，安装仪器测试桩基础，并测量液化引起沉降后的负表面摩擦力和桩性能。 这些液化引起的地面沉降，桩沉降和桩荷载分布的全尺寸测量将提供桩下拉现象的基本理解。 现场测量的缺失导致了相互矛盾的设计建议，根据实际的桩行为，这些建议可能是不安全的或不经济的。 由于深基础是在可液化砂中支撑桥梁和建筑物的常用方法，因此可靠的设计方法对于防止未来的地震破坏至关重要。 饱和松散砂土的液化在几乎所有的地震事件中都会对民用基础设施造成重大破坏。 液化造成的直接和间接经济损失是社会的巨大成本。新西兰基督城地震序列造成的巨大财产损失和间接经济损失，生动地说明了未能正确设计液化危害的广泛社会影响。 地震发生多年后，这座城市的大部分地区仍然无人居住，经济正在努力恢复。 这项在新西兰进行的合作研究将为桥梁和高层建筑物的典型深桩基础在液化时的性能提供基本的了解。 这些测试的结果将使工程师能够评估现有设计程序的准确性，并进行修改，以产生与测量行为更好的一致性。 这些结果将有助于工程师设计安全，但成本效益的基础解决方案。 这项研究的结果将使新西兰和美国的工程界受益，并促进国际合作。 利用两国的资金扩大了工作范围，超出了两国单独完成的范围。 考虑到与地基液化诱发荷载相关的试验数据的缺乏，这些试验结果可能对世界各地地震活跃地区的设计实践产生强烈影响。

As a result of the extensive liquefaction damage in Christchurch, the New Zealand Earthquake Commission (EQC) is sponsoring a multi-million research study to determine the most cost-effective liquefaction mitigation strategies for repair work and subsequent reconstruction. Based on this test program, government approved approaches will be eligible for earthquake insurance reimbursements. Blast induced liquefaction trials will be performed to evaluate the ground improvement techniques under full-scale conditions. In collaboration with EQC we will install instrumented test pile foundations and measure negative skin friction and pile performance following liquefaction induced settlement. These full-scale measurements of liquefaction induced ground settlement, pile settlement and pile load distribution will provide fundamental understanding of the pile downdrag phenomenon. The absence of field measurements has led to contradictory design recommendations which may be either unsafe or uneconomical depending on the actual pile behavior. Because deep foundations are a common approach for supporting bridges and buildings in liquefiable sands, reliable design approaches are critical to preventing future earthquake damage. Liquefaction of loose saturated sands results in significant damage to civil infrastructure in nearly every earthquake event. Direct and indirect economic losses resulting from liquefaction are substantial costs to society. The tremendous damage to property and the indirect economic loss resulting from the Christchurch New Zealand earthquake sequence dramatically illustrate the broad social impacts of failure to properly design for liquefaction hazards. Large sections of the city are still uninhabited years after the earthquakes and the economy is struggling to recover. This collaborative research study in New Zealand will provide fundamental understanding of the performance of typical deep pile foundations for bridges and high-rise structures when subjected to liquefaction. The results from these tests will allow engineers to evaluate the accuracy of existing design procedures and develop modifications to produce better agreement with measured behavior. These results will help engineers to design safe, yet cost effective foundation solutions. Results from this research will benefit both New Zealand and US engineering communities and foster international collaborations. Leveraging funding from both countries expands the scope of work beyond what either country could accomplish independently. Considering the paucity of test data relative to liquefaction induced loads on foundations, these test results are likely to have a strong impact on design practice in seismically active areas around the world.