Pile Foundations Under Inertia and Liquefaction-Induced Lateral Spreading

惯性和液化引起的横向扩展下的桩基

• 批准号: 1761712
• 负责人: Arash Khosravifar
• 金额: $ 9.99万
• 依托单位: Portland State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1761712&HistoricalAwards=false
• 关键词: Pile; Foundations; Under; Inertia; Liquefaction

Past earthquakes indicate that liquefaction-induced lateral spreading is a major cause of collapse of pile foundations. Pile foundations in liquefiable soils should be designed to sustain both lateral spreading loads (kinematics) and structure loads during shaking (inertia). The past research on the consequences of liquefaction-induced lateral spreading are fairly new and in some cases contradict each other; specifically, on the combination of inertia and kinematic demands. This knowledge gap has both potentially un-conservative and over-conservative consequences. On one hand, it poses considerable public safety concerns in regions affected by long-durations subduction earthquakes, such as the U.S. Pacific Northwest, Japan, and the western coast of South America. On the other hand, we don't know if, and how, inertia and kinematics combine at large depths. The latter has resulted, in some cases, in excessively conservative, and costly, ground improvement solutions. This research project will use data from five centrifuge tests on pile-supported wharves in liquefiable soils combined with advanced numerical modeling to contribute in-depth understanding of the inelastic behavior of piles in multi-layer soil profiles with liquefiable soils for buildings, ports and wharfs, lifelines and bridges. The broader impacts of this project are diverse and include providing design recommendations for practitioners, developing advanced 3D numerical tools that will provide vertical steps for future research, and growing a diverse geotechnical graduate research program at Portland State University.The overall objective of this research is to understand the factors that affect how inertia and liquefaction-induced lateral spreading (kinematics) combine during earthquakes. The central hypothesis in this research is that this combination reduces with depth and increases with strong-motion duration and pile inelasticity. The objectives of this research will be pursued through three specific aims. First, the combination of inertia and liquefaction-induced kinematics will be evaluated with respect to depth by analyzing data from five centrifuge tests on pile-supported wharves that were conducted by Dickenson and coworkers at UC Davis large centrifuge between 1999 and 2000. Second, the effects of strong-motion duration on the combination of inertia and kinematics will be evaluated using 3D numerical models. The 3D models will be validated against centrifuge tests data and will be subjected to a suite of spectrally-compatible ground motions. The results of numerical analysis will be used to test the hypothesis that the combination of inertia and kinematics increases with earthquake duration. Third, the effects of combined inertia and kinematics on inelastic demands of piles will be evaluated using 3D numerical models updated with inelastic piles. This will allow assessing the hypothesis that inelastic demands of piles in laterally spreading grounds are amplified during long-duration motions. This research thereby integrates experiment-based data from physical models and advanced numerical analysis. The potential findings of this research will reduce uncertainties in evaluating pile behavior in laterally spreading grounds.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

过去的地震表明，液化引起的横向扩散是桩基础崩溃的主要原因。 应在液化土壤中设计的桩​​基础，以维持摇动（惯性）期间的侧向扩散载荷（运动学）和结构载荷。 过去关于液化引起的侧向扩散后果的研究相当新，在某些情况下相互矛盾。具体而言，关于惯性和运动学需求的结合。 这种知识差距既有潜在的不保守和保守性的后果。 一方面，它在长期俯冲地震影响的地区（例如美国太平洋西北，日本和南美西部海岸）提出了相当大的公共安全问题。 另一方面，我们不知道是否以及如何在大深处结合在一起。 后者在某些情况下导致过度保守和昂贵的地面改进解决方案。 该研究项目将使用五个离心测试的数据对液化土壤中的桩支撑码头结合使用高级数值建模，从而有助于对多层土壤中的桩的无弹性进行深入了解，并具有可用于建筑物，港口和warfs的液化土壤的多层土壤剖面。 ，生命线和桥梁。该项目的更广泛影响是多种多样的，包括为从业者提供设计建议，开发高级的3D数值工具，这些工具将为未来的研究提供垂直步骤，并在波特兰州立大学发展多样的岩土技术研究生研究计划。这项研究的总体目标是了解影响惯性和液化诱导的侧向扩散（运动学）在地震期间结合的因素。 这项研究的中心假设是，这种组合随着深度而减少，并随着强度持续时间和堆积的弹性而增加。 这项研究的目标将通过三个具体目标来实现。 首先，将通过分析狄更斯顿（Dickenson）和同事在加州大学戴维斯（UC Davis）进行的桩支持的码头上的五个离心测试的数据来评估惯性和液化引起的运动学的组合。强度持续时间对惯性和运动学组合的影响将使用3D数值模型进行评估。 3D模型将通过离心机测试数据进行验证，并将进行一系列频谱兼容的地面运动。 数值分析的结果将用于检验以下假设：惯性和运动学的组合随地震持续时间增加。第三，将使用与非弹性桩更新的3D数值模型评估组合惯性和运动学对桩非弹性需求的影响。 这将允许评估以下假设：在长期运动中，在侧向传播基础上的无弹性需求得到扩增。 这项研究从物理模型和高级数值分析中整合了基于实验的数据。 这项研究的潜在发现将减少在评估横向传播基础上的桩行为方面的不确定性。该奖项反映了NSF的法定任务，并认为使用基金会的知识分子优点和更广泛的影响审查标准，被认为值得通过评估。

项目成果

Development of Experimental P-Y Curves from Centrifuge Tests for Piles Subjected to Static Loading and Liquefaction-Induced Lateral Spreading

通过静载和液化引起的横向扩展桩的离心试验开发实验 P-Y 曲线

• DOI: 10.37308/dfijnl.20191120.212
• 发表时间: 2020
• 期刊: DFI Journal The Journal of the Deep Foundations Institute
• 作者: Souri, Milad

EXPERIMENTAL P-Y CURVES FROM CENTRIFUGE TESTS ON PILE FOUNDATIONS SUBJECTED TO LIQUEFACTION AND LATERAL SPREADING

液化和横向扩展的桩基离心试验的实验 P-Y 曲线

• 发表时间: 2019
• 期刊: 2019 44th Annual Conference on Deep Foundations
• 作者: Souri, Milad;Khosravifar, Arash;Schlechter, Scott;McCullough, Nason;Dickenson, Steve
• 通讯作者: Dickenson, Steve

Seismic Performance of Pile-Supported Piers and Wharves Subjected to Foundation Deformations

• DOI: 10.1061/9780784482612.058
• 发表时间: 2019-09
• 期刊: Ports 2019
• 作者: M. Souri;A. Khosravifar;S. Dickenson;S. Schlechter;N. Mccullough