Molecular Dynamics Modeling of a Partially Saturated Clay-Water System

部分饱和粘土-水系统的分子动力学建模

• 批准号: 1659932
• 负责人: Xiaoyu Song
• 金额: $ 7.08万
• 依托单位: University of Florida
• 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: 2017-05-15 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1659932&HistoricalAwards=false
• 关键词: Molecular; Dynamics; Modeling; Partially; Saturated

The goal of this research is to advance the fundamental understanding of interfacial physical properties (i.e., the contact angle and capillary stress) of unsaturated clay-water systems at the molecular scale via extensive computational experiments. Unsaturated clay-water systems play a substantial role in geohazards such as landfill slope failures, desiccation cracking, and contaminant transport in the subsurface, and energy harvesting and storage. Unsaturated clay-water systems are three-phase porous media comprised of plate-like clay particles, water, and air. Among those three phases, the interfacial physical properties (i.e., the contact angle and water meniscus curvature) have a significant impact on the hydro-thermal-mechanical behavior of unsaturated soils. While past research has advanced the understanding of the thermo-hydro-mechanical behavior of unsaturated clays at the continuum scale, the interfacial physical properties at the atomistic scale and their potential impact on the thermo-hydro-mechanical behavior have not yet been thoroughly investigated. This project aims to study the interfacial physical properties of unsaturated clays and their temperature dependence via a full-scale molecular dynamics modeling. The project will provide a fundamental understanding needed to build a physics-based multi-scale computational framework for modeling multi-physical processes in three-phase porous materials that have a broad spectrum of engineering applications in geotechnical and geoenvironmental engineering, petroleum engineering, environmental engineering and science, geophysics, geologic sciences, chemical engineering, and the pharmaceutical industry. The project will allow significant steps toward the recruitment of a talented workforce in science and engineering through the design of new course modules in molecular dynamics modeling, and the involvement of students in computational unsaturated soil mechanics on computer clusters.This research work is focused on the computational investigation of interfacial physical properties of unsaturated clay (i.e., Kaolinite)-water systems via molecular dynamics modeling at temperatures between zero and 99 degrees Celsius. The research tasks involve: (1) modeling an unsaturated clay-water system at different temperatures via the full-scale molecular dynamics modeling on the HiPerGator 2.0, a supercomputer at the University of Florida; (2) quantifying the impact of temperature on the contact angle and water meniscus curvature; and (3) comparing the capillary stress on clay particles obtained by classic macroscopic theory, and molecular dynamics modeling respectively. The research aims to answer the following fundamental questions: (1) how does temperature impact the capillary stress on clay particles? (2) how can the contact angle at the elevated temperature be accurately determined? and (3) does classic macroscopic theory (i.e., the Young-Laplace equation including the line tension) accurately quantify capillary stress on clay particles over a wide temperature range for a general three-dimensional case? The scientific findings can also be utilized to develop and validate the coarse-grained molecular dynamics model for unsaturated clays at a mesoscale (i.e., from nanometer to micrometer). The long-term goal of this line of research is to formulate the bottom-up multi-scale multi-physical computational technique for studying localized and diffusive instabilities and multi-physical processes in unsaturated soils through utilizing the interfacial physical information such as the capillary stress on clay particles obtained directly from the innovative computational experiment (i.e., molecular dynamics simulations).

这项研究的目标是通过广泛的计算实验，在分子尺度上增进对不饱和粘土-水系统界面物理性质（即接触角和毛细管应力）的基本理解。 不饱和粘土-水系统在垃圾填埋场边坡破坏、干燥开裂、地下污染物迁移以及能量收集和储存等地质灾害中发挥着重要作用。不饱和粘土-水系统是由板状粘土颗粒、水和空气组成的三相多孔介质。 在这三个相中，界面物理性质（即接触角和水弯月面曲率）对非饱和土的水热力学行为有显着影响。 虽然过去的研究增进了对连续尺度不饱和粘土热水力学行为的理解，但原子尺度的界面物理性质及其对热水力学行为的潜在影响尚未得到彻底研究。该项目旨在通过全尺寸分子动力学建模研究不饱和粘土的界面物理性质及其温度依赖性。 该项目将提供建立基于物理的多尺度计算框架所需的基本理解，用于对三相多孔材料中的多物理过程进行建模，这些材料在岩土工程和地球环境工程、石油工程、环境工程等领域具有广泛的工程应用以及科学、地球物理学、地质科学、化学工程和制药业。 该项目将通过设计分子动力学建模的新课程模块以及让学生参与计算机集群上的计算非饱和土力学，在招聘科学和工程领域的人才方面迈出重要一步。这项研究工作的重点是通过在 0 到 99 摄氏度之间的温度下进行分子动力学建模，对不饱和粘土（即高岭石）-水系统的界面物理性质进行计算研究。 研究任务包括：（1）通过在佛罗里达大学超级计算机HiPerGator 2.0上进行全尺寸分子动力学建模，对不同温度下的不饱和粘土-水系统进行建模； (2)量化温度对接触角和水弯月面曲率的影响； (3)比较分别通过经典宏观理论和分子动力学建模获得的粘土颗粒上的毛细管应力。该研究旨在回答以下基本问题：（1）温度如何影响粘土颗粒的毛细管应力？ (2) 如何准确测定高温下的接触角？ (3) 经典宏观理论（即包括线张力的杨-拉普拉斯方程）是否能够在一般三维情况下在较宽的温度范围内准确量化粘土颗粒上的毛细管应力？ 这些科学发现还可用于开发和验证介观尺度（即从纳米到微米）不饱和粘土的粗粒分子动力学模型。该研究方向的长期目标是制定自下而上的多尺度多物理计算技术，通过利用毛细管应力等界面物理信息来研究非饱和土中的局部和扩散不稳定性和多物理过程。直接从创新计算实验（即分子动力学模拟）获得的粘土颗粒。

项目成果

Modeling Cracks in Clay at the Nanoscale through Molecular Dynamics

通过分子动力学模拟纳米尺度粘土中的裂缝

• DOI: 10.1061/9780784484692.001
• 发表时间: 2023-03
• 期刊: Geo-Congress 2023 GSP 342
• 作者: Zhang, Zhe;Song, Xiaoyu
• 通讯作者: Song, Xiaoyu

Nanoscale creep mechanism of clay through MD modeling with hexagonal particles

通过六方颗粒 MD 建模研究粘土的纳米级蠕变机制

• DOI: 10.1002/nag.3651
• 发表时间: 2023-04-29
• 期刊: International Journal for Numerical and Analytical Methods in Geomechanics
• 影响因子: 4
• 作者: Zhe Zhang;Xiaoyu Song
• 通讯作者: Xiaoyu Song

Molecular dynamics modeling of a partially saturated clay‐water system at finite temperature

有限温度下部分饱和粘土-水系统的分子动力学建模

• DOI: 10.1002/nag.2944
• 发表时间: 2019-07
• 期刊: International Journal for Numerical and Analytical Methods in Geomechanics
• 影响因子: 4
• 作者: Song, Xiaoyu;Wang, Miao‐Chun
• 通讯作者: Wang, Miao‐Chun

Nanoscale soil-water retention mechanism of unsaturated clay via MD and machine learning

基于 MD 和机器学习的非饱和粘土纳米级土壤保水机制

• DOI: 10.1016/j.compgeo.2023.105678
• 发表时间: 2023-11
• 期刊: Computers and Geotechnics
• 影响因子: 5.3
• 作者: Zhang, Zhe;Song, Xiaoyu
• 通讯作者: Song, Xiaoyu

Determination of clay-water contact angle via molecular dynamics and deep-learning enhanced methods

通过分子动力学和深度学习增强方法测定粘土-水接触角

• DOI: 10.1007/s11440-021-01238-1
• 发表时间: 2021-06-07
• 期刊: Acta Geotechnica
• 影响因子: 5.7
• 作者: Xiaoyu Song;Zhe Zhang
• 通讯作者: Zhe Zhang