CAREER: Micromechanical Model of Undrained Cyclic Soil Behavior

摘要本研究的目的是扩展现有的离散元建模（DEM）技术，以明确地解释饱和土壤中的孔隙流体响应。DEM方法通过考虑作用在土体内单个土壤颗粒上的力而起作用，特别适合于预计会发生大颗粒变形的问题。近年来计算能力的快速增长使DEM在计算颗粒土特性方面得到了广泛的应用。然而，在计算土体的响应时，很难明确地考虑连续孔隙流体的响应。在本研究中，将建立流体饱和无粘性土的三维数值细观力学模型。土相离散单元模型将与流体连续体的有限元表示相结合。流体模型是从众所周知的两相多孔介质的运动方程发展而来的。由此产生的模型将能够对土壤样品进行广泛的数值测试，包括经验数据不足的土壤，以校准连续体模型。由于DEM的微观力学性质，所获得的数据将比通过实验室或实地研究获得的分辨率高得多。由此建立的数值模型将提供一个强大的工具，以扩大现有的分析和经验土壤响应数据数据库。潜在的应用领域包括路面板下的细颗粒迁移、地震液化和环境运输现象。学生在整个学习过程中的参与将在研究生和高级本科阶段实施。没有直接参与研究的学生将受益于在研究生计算力学课程中增加的DEM课程模块。与工程兵工程队土力实验室路面及机场部建立有意义的伙伴关系，可确保研究结果的适用性。最后，将研究结果传播给更遥远的研究人员，将通过出版研究结果，通过传统的

9875334 Thomas E. Price Mississippi State University CAREER: Micromechanical model of undrained cyclic soil behavior Abstract The objective of this study is to extend existing Discrete Element Modeling (DEM) technologies to explicitly account for pore fluid response in saturated soils. DEM methodologies act through consideration of the forces acting on individual soil particles within the soil mass, and are particularly well suited to problems in which large particle deformations are expected to occur. The rapid growth in recent years of computing power has popularized the use of DEM in calculating the behavior of granular soils. However, it has proven difficult to explicitly account for the response of the continuum pore fluid in computing the response of the soil mass. In this study, a three-dimensional numerical, micromechanical model of fluid-saturated cohesionless soil will be developed. The soil-phase discrete element model will interface with a finite element representation of the fluid continuum. The fluid model has been developed from the well-known equations of motion for two-phase porous media. The resulting model will enable extensive numerical testing of soil samples, including soils for which insufficient empirical data is available to calibrate continuum models. Because of the micromechanical nature of DEM, the data obtained will be of significantly higher resolution than is possible through laboratory or field studies. The numerical model thus developed will provide a powerful tool to augment the existing database of analytic and empirical soil response data. Potential application areas include fines migration beneath pavement slabs, earthquake-induced liquefaction, and environmental transport phenomena. Student participation throughout the course of the study will be enacted at both the graduate and senior undergraduate level. Students not directly involved in the study will benefit by means of a course module on DEM to be added to the curriculum of a graduate computational mechanics course. Meaningful partnering with the Pavements and Airfields Division of the Corps of Engineers Geotechnical Laboratory will ensure applicability of the study findings. Finally, dissemination of the study results to more distant researchers will be achieved through publishing of the study results, through both conventional