Multiscale Meshfree Analysis of Failure in Geostructures Founded on or Containing Liquefiable Soils

路堤边坡液化失稳破坏分析是岩土地震工程中的一个重要问题。虽然各种基于经验和/或简化的方法已被开发和应用于实践，但目前对可液化土应力-应变-强度行为的认识状况，在最近几年中观测到的大量土坡和路堤的响应，以及近年来在工程结构数值模拟方面的重大进展，为更严格、更现实地分析液化引起的失稳和破坏奠定了基础。该项目将开发一种多尺度方法，允许使用统一的本构模型在破坏前和破坏后阶段捕捉土体响应。此外，由于传统的土的完全耦合有效应力分析方法在处理岩土系统的近破坏响应和破坏后响应方面存在严重的局限性，提出了一种无网格方法来克服有限元方法的已知困难，并在液化分析的所有阶段产生可靠和健壮的解。该项目的智力价值在于发展和引入了两种非常强大的本构和数值方法来分析土壤液化。所提出的方法将在公共领域开源代码中实现，可供研究人员和实践者使用。开发的计算工具将通过一系列关于土坡和路堤响应的实验和现场观测进行验证和验证。该项目的更广泛影响包括将本研究开发的技术潜在地应用于其他工程领域，如生物孔洞力学和金属和合金的热轧工艺。在本项目课程中接受培训的研究生将有很好的机会深入了解液化和液化引起的变形和破坏所涉及的机制，以及使用工程力学中两种最先进的分析和建模方法对岩土系统进行建模的专业知识。这种研究培训的深度和广度应该对岩土工程实践具有重要价值。

Analysis of liquefaction-induced instability and failure in slopes and embankments is an important problem of geotechnical earthquake engineering. While various empirically-based and/or simplified approaches have been developed and used in practice, the current state of knowledge of stress-strain-strength behavior of liquefiable soils, the wealth of observed response of soil slopes and embankments during recent earthquakes, and the significant progress in numerical modeling of engineering structures in recent years, have prepared the ground for a more rigorous, yet realistic, approach to the analysis of liquefaction-induced instability and failure. This project is to develop a multiscale approach, which allows the soil response to be captured in both pre- and post-failure stages with a unified constitutive model. Moreover, since the traditional finite element (FE) approach for fully-coupled effective stress analysis of soils is severely limited in handling the near- and post-failure response of a geotechnical system, a meshfree method is proposed to overcome the known difficulties of an FE approach, and to produce reliable and robust solutions in all stages of a liquefaction analysis. The intellectual merit of the project lies in the development and introduction of two very powerful constitutive and numerical methods in the analysis of soil liquefaction. The proposed methods will be implemented in a public domain open source code, which can be used by researchers and practitioners. The developed computational tool will be validated and verified against a series of experimental and field observations on the responses of soil slopes and embankments.The broader impacts of the project include the potential use of the techniques developed in this research in other fields of engineering such as bio-poromechanics and hot rolling processes in metals and alloys. The graduate students trained in the course of this project will have an excellent opportunity to develop a thorough understanding of the mechanisms involved in liquefaction and liquefaction-induced deformation and failure as well as an expertise in modeling of geotechnical systems using two of the most advanced methods of analysis and modeling in engineering mechanics. The depth and breadth of such research training should be of significant value to geotechnical engineering practice.