Collaborative Research: Multi-scale Modeling and Measurement of Clay Aggregate Behavior

合作研究：粘土骨料行为的多尺度建模和测量

• 批准号: 1702881
• 负责人: Guoping Zhang
• 金额: $ 26.47万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2021-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1702881&HistoricalAwards=false
• 关键词: Collaborative; Research; Multi; scale; Modeling; Collaborative; Research; Multi; scale; Modeling

The goal of this research is to advance the understanding of the mechanical behavior of clays as engineering materials. Clays comprise very fine ( 2 um), electrically charged, chemically active particles whose behavior and assembly are strongly affected by physico-chemical forces operating on individual particles at the smaller (i.e., molecular and interfacial) scales. Clay minerals of different varieties occur widely in natural geological environments and are generally found in the form of aggregates or clusters whose interactions control the macroscopic engineering properties of clay-rich soils used in the design and construction of infrastructure. While micromechanics-based experimental and computational research has advanced significantly the understanding of the behavior of sands (particle sizes greater than 75um), the importance of the particulate nature of clays has not been extensively investigated. This collaborative project aims to develop and validate a new multiscale framework for understanding the macroscopic (i.e., continuum scale) mechanical properties of clays by studying the microscale aggregation of elementary clay particles and the interactions between the resultant clay aggregates. The project will provide the fundamental understanding needed to develop the next generation of constitutive models for mechanical properties of clays that can be used for subsurface engineering, ultimately reducing risks and costs associated with the design of foundations, underground construction and use of geological energy resources (e.g., clay shales, etc.). The research will impact directly upon the education of future geotechnical engineering and geomechanics students through the creation of online modules related to the small-scale measurement and multiscale modeling of clay behavior. The research work comprises a closely-integrated program of multiscale experimentation, atomistic and coarse-grained multiscale simulations for one common clay mineral, illite. The research involves the following main tasks: 1) modeling and experimental validation of individual clay aggregate behavior under a range of porewater chemistry conditions; 2) development of new modeling techniques and experimental methods for investigating aggregate-aggregate interactions and fabric (i.e., quantitative measurement of particle orientation and of orientation distribution function); and 3) validation of multiscale model predictions through comparison with macroscopic measurements of clay properties. Experimental measurements will use existing laboratory facilities at the University of Massachusetts Amherst (UMass) as well as the analytical facilities at the Argonne National Laboratory, while numerical simulations at the Massachusetts Institute of Technology (MIT) will take advantages of NSF eXtreme Science and Engineering Discovery Environment (XSEDE) national supercomputing resources. By developing a framework for understanding particulate-based clay micromechanics, the research aims to provide an innovative multiscale perspective for explaining the underlying basis of continuum-based clay properties such as cohesion and creep, which have to date only been observed phenomenologically via macroscopic approaches. The long-term goal is to generalize the methodology to enable bottom-up prediction of mechanical properties for complex natural soils that comprise mixtures of different clay minerals with silt- and sand-sized particles as well as varying porewater chemistry.

这项研究的目的是提高人们对粘土作为工程材料的机械行为的理解。 粘土包含非常细的（2 um），电荷电荷的化学活性颗粒，其行为和组装受到在较小（分子和界面）尺度上在单个颗粒上运行的物理化学力的强烈影响。 不同品种的粘土矿物质在自然地质环境中广泛存在，通常以聚集体或簇的形式发现，其相互作用控制基础设施设计和建造中富含粘土土壤的宏观工程特性。 尽管基于微力学的实验和计算研究已经显着提高了对沙子行为（粒度大于75um）的理解，但尚未广泛研究粘土颗粒性质的重要性。 该协作项目旨在通过研究基本粘土颗粒的显微镜聚集以及所得的粘土聚合物之间的相互作用，来开发和验证一个新的多尺度框架，以理解粘土的宏观（即连续尺度）机械性能。该项目将为开发可用于地下工程的粘土机械性能的下一代构造模型提供基本理解，最终降低与基金会设计，地下建筑和地质能源的使用相关的风险和成本（例如，粘土页岩等）。 这项研究将直接影响未来的岩土工程和地质力学学生的教育，从而创建与粘土行为的小规模测量和多尺度建模有关的在线模块。该研究工作包括一个密集的多尺度实验，原子和粗粒的多尺度模拟程序，用于伊利特的一种常见粘土矿物。 该研究涉及以下主要任务：1）在一系列孔隙水化学条件下对单个粘土骨料行为进行建模和实验验证； 2）开发用于研究聚集 - 聚集的相互作用和织物的新建模技术和实验方法（即粒子取向和方向分布函数的定量测量）； 3）通过与粘土特性的宏观测量进行比较来验证多尺度模型预测。 实验测量结果将使用马萨诸塞大学阿默斯特大学（UMASS）以及Argonne国家实验室的分析设施的现有实验室设施，而马萨诸塞州技术研究所（MIT）的数值模拟将获得NSF极端科学和工程学环境（XSSEDE）国家超级配置资源的优势。 通过开发一个理解基于颗粒的粘土微力学的框架，该研究旨在提供创新的多尺度观点，以解释基于连续的粘土特性（例如凝聚力和蠕变）的基础，而这些粘土和蠕变只能通过宏观方法在现象学上观察到。 长期的目标是概括该方法，以使复杂自然土壤的机械性能自下而上预测，这些土壤包括不同粘土矿物质与粉砂和砂粒和砂粒颗粒以及变化的孔隙水化学的混合物。