Constitutive modeling of post-liquefaction cyclic response of sands

砂土液化后循环响应的本构模型

• 批准号: 508036-2016
• 负责人: Taiebat, Mahdi
• 金额: $ 1.59万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=618059
• 关键词: Constitutive; modeling; post; liquefaction; cyclic

Large post-liquefaction deformation is a major cause for seismic induced hazards in soil foundation and geotechnical structures, and has been a subject of extensive research since its observations in several well documented earthquakes. While there has been advances in constitutive modeling of granular materials, particularly within the platform of critical state soil mechanics and with the use of bounding surface plasticity, significant challenge is still remaining in modeling the shear strains in the post-liquefaction regime. The objective of this project is to extend the formulation of the SANISAND family of models. Despite of the elegant mathematical formulation of the SANISAND up to the point of initiation of liquefaction (nearly zero mean effective stress), the predicted shear strain accumulation at low mean confinement pressure is not in agreement with laboratory experiments, and the model predictions in the post-liquefaction regime significantly differ from those observed in the experiments. The complexity of the mechanisms involved, and experimental limitations on measurement of the involving components such as micro-mechanical fabric and stiffness, justify the use of mathematical and computational tools in accordance with physical postulates, such as discrete element modeling (DEM), for understanding the involved mechanisms. The research proposal has 4 well-defined parts. The first part is to study the nature of the problem from a particle-to-particle perspective using DEM simulations. The second part deals with the extension of the formulation of SANISAND model, where the model extension will be inspired from the DEM simulation results, and incorporated to an existing model implementation in 2- and 3-dimensional continuum based finite difference platform. In the third phase the resulting developed and implemented constitutive model will be verified and validated, to ensure about its performance and robustness, so the compiled model can be made accessible as a Dynamic Linked Library (DLL) to other modelers in the field. Finally, the developed tool will be used in modeling the liquefaction response in the foundation of a tailings dam during a seismic event.

大的液化后变形是土基和岩土结构地震诱发灾害的主要原因，自从在几次有据可查的地震中观察到后，它一直是广泛研究的课题。虽然颗粒材料的本构建模取得了进展，特别是在临界状态土力学平台内并利用边界表面塑性，但在液化后状态下的剪切应变建模方面仍然存在重大挑战。该项目的目标是扩展 SANISAND 系列模型的制定。尽管 SANISAND 的数学公式在液化起始点（平均有效应力几乎为零）很优雅，但在低平均约束压力下预测的剪切应变累积与实验室实验并不一致，并且后面的模型预测也不一致。 -液化状态与实验中观察到的明显不同。所涉及机构的复杂性以及微机械织物和刚度等相关组件测量的实验限制，证明根据物理假设使用数学和计算工具（例如离散元建模 (DEM)）来理解是合理的所涉及的机制。该研究计划有 4 个明确的部分。第一部分是使用 DEM 模拟从粒子到粒子的角度研究问题的本质。第二部分涉及 SANISAND 模型公式的扩展，其中模型扩展将从 DEM 模拟结果中得到启发，并结合到基于 2 维和 3 维连续体的有限差分平台中的现有模型实现中。在第三阶段，将验证和确认所开发和实现的本构模型，以确保其性能和鲁棒性，因此编译后的模型可以作为动态链接库（DLL）供该领域的其他建模者访问。最后，开发的工具将用于模拟地震事件期间尾矿坝地基的液化响应。