Collaborative Research: Validation of Constitutive and Numerical Modeling Techniques for Soil Liquefaction Analysis

土壤液化是地震期间普遍存在的问题，对美国和世界其他地区的民用基础设施造成了重大而昂贵的破坏。 实践工程师和学者一直在使用计算模型和数值模拟工具的设计和分析的地质系统，涉及可液化土壤。 这些工具非常复杂和精致，但它们经常在过去的许多大地震后进行修改，以纳入从事后观察和调查中吸取的教训。 因此，这些工具的有效性尚未完全确定。 液化实验和分析项目（LEAP）是一个国际合作实验室，使用离心试验产生一组高质量的实验数据，然后使用这些数据来建立现有计算模型和模拟程序的有效性和适用范围，用于土壤液化分析。 合作实验室包括位于戴维斯的加州大学、伦斯勒理工学院、剑桥大学（英国）、京都大学（日本）、国立中央大学（台湾）、浙江大学（中国）、IFSTTAR（法国）、KAIST和KWater（韩国）以及香港科技大学（香港）的离心机设施。 该项目利用这些设施的实验资源，补充参与的美国机构的测试能力，以调查土壤液化发挥重要作用的一些具有挑战性的问题。（LEAP-2017，-2018和-2019）计划将用于解决三个重要问题：再现性和不确定性;土壤结构的影响;以及双向地震动对土壤液化的影响。 LEAP-2017将使用改进的质量控制措施来最大限度地减少不确定性，并将设计和执行广泛的测试计划，以表征相对简单的横向扩展离心机测试的灵敏度和不确定性。 LEAP-2018将产生高质量的离心数据，以评估计算工具对预测组构和分层影响的适用性。 LEAP-2019将评估数值工具对一系列双轴振动离心机实验的性能，这些实验使用合成和真实的地震运动。 在每次LEAP之后，将举行一次研讨会，讨论实验和数值模拟的结果。 将利用新的数据库公布机制对该项目产生的数据进行组织、存档和电子公布。 组织的数据将有助于（1）未来的验证工作，（2）其他正在进行的液化研究，（3）在岩土建模教育。一些研究生参与了该项目，并将获得独特的培训机会，超出了任何一个机构的能力。 将开发一个验证驱动程序框架（VDF），使建模人员和从业人员能够有效地验证其代码。

Soil liquefaction is a pervasive problem during earthquakes that has caused significant and costly damage to civil infrastructure in the US and other parts of the world. Practicing engineers and academics have been using computational models and numerical simulation tools in the design and analysis of geosystems involving liquefiable soils. These tools are highly sophisticated and refined, but they often have been revised following many major past earthquakes to incorporate the lessons learned from post-event observations and investigations. Thus, the validity of these tools is yet to be fully established. The Liquefaction Experiments and Analysis Projects (LEAP) is an international collaboratory to produce a set of high quality experimental data using centrifuge testing, and then to use these data to establish the validity and range of applicability of existing computational models and simulation procedures for soil liquefaction analysis. The collaboratory includes centrifuge facilities at the University of California at Davis, Rensselaer Polytechnic Institute, Cambridge University (UK), Kyoto University (Japan), NCU (Taiwan), Zhejiang University (China), IFSTTAR (France), KAIST and KWater (Korea), and HKUST (Hong Kong). The project leverages the experimental resources at these facilities to complement the testing capabilities in the participating US institutions for investigating a number of challenging problems in which soil liquefaction plays a prominent role.Three consecutive projects (LEAP-2017, -2018, and -2019) are planned which will be used to address three important issues: reproducibility and uncertainty; effects of soil fabric; and effects of biaxial ground motion on soil liquefaction. LEAP-2017 will use improved quality control measures to minimize uncertainties, and an extensive testing program will be designed and conducted to characterize the sensitivity and uncertainty for relatively simple lateral spreading centrifuge tests. LEAP-2018 will produce high quality centrifuge data to enable the assessment of the applicability of computational tools for predicting the influence of fabric and layering. LEAP-2019 will assess the performance of numerical tools against a series of biaxial shaking centrifuge experiments using synthetic and real earthquake motions. Following each LEAP, a workshop will be held to discuss the results of experiments and numerical simulations. The data resulting from this project will be organized, archived and publically released using a new database publication mechanism. The organized data will be useful for (1) future validation efforts, (2) other ongoing liquefaction research, and (3) in geotechnical modeling education. A number of graduate students are involved in the project and will receive unique training opportunities beyond the capabilities of any one institution alone. A Validation Driver Framework (VDF) will be developed to allow modelers as well as practitioners to efficiently validate their codes.