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).

本研究的目标是推进对界面物理性质的基本理解（即，接触角和毛细管应力）的不饱和粘土-水系统在分子尺度上通过广泛的计算实验。 非饱和粘土-水系统在地质灾害中起着重要作用，如垃圾填埋场边坡破坏、干燥开裂、地下污染物运移以及能量收集和储存。非饱和粘土-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具有显著影响。 虽然过去的研究在连续介质尺度上推进了对非饱和粘土热-水-力学行为的理解，但在原子尺度上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。本计画旨在透过全尺度分子动力学模拟，研究非饱和黏土之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，用于在三相多孔材料中建模多物理过程，这些材料在岩土工程和地质环境工程，石油工程，环境工程和科学，生物物理学，地质科学，化学工程和制药工业中具有广泛的工程应用。 该项目将通过设计分子动力学模型的新课程模块，以及让学生参与计算机集群上的计算非饱和土力学，朝着招募科学和工程人才迈出重要一步。这项研究工作的重点是非饱和粘土界面物理性质的计算研究（即，高岭石）-水系统通过分子动力学建模在0和99摄氏度之间的温度。 研究任务包括：（1）在佛罗里达大学的超级计算机HiPerGator 2.0上，通过全尺度分子动力学模拟，模拟了不同温度下的非饱和粘土-水体系;（2）定量分析了温度对接触角和水弯月面曲率的影响;（3）比较了经典宏观理论和分子动力学模拟得到的粘土颗粒上的毛细应力。本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管应力？(2)如何准确测定高温下的接触角？以及（3）经典宏观理论（即，杨拉普拉斯方程，包括线张力）准确量化毛细应力粘土颗粒在一个广泛的温度范围内的一般三维的情况下？ 这些科学发现也可用于开发和验证中尺度非饱和粘土的粗粒度分子动力学模型（即，从纳米到微米）。这一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，用于研究非饱和土中的局部和扩散不稳定性以及多物理过程，通过利用直接从创新计算实验（即，分子动力学模拟）。

项目成果

Dynamic Localized Failure of Soils via Nonlocal Poromechanics Model: A Case Study of the Lower San Fernando Dam Failure

通过非局部孔隙力学模型进行土壤动态局部破坏：圣费尔南多下游大坝溃决案例研究

• DOI: 10.1061/9780784483701.002
• 发表时间: 2021
• 期刊: ASCE Geo-Extreme 2021
• 作者: Menon, Shashank;Song, Xiaoyu
• 通讯作者: Song, Xiaoyu

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
• 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
• 期刊: Computers and Geotechnics
• 影响因子: 5.3
• 作者: Zhang, Zhe;Song, Xiaoyu
• 通讯作者: Song, Xiaoyu

Nanoscale crack propagation in clay with water adsorption through reactive MD modeling

• DOI: 10.1002/nag.3507
• 发表时间: 2022-09
• 期刊: International Journal for Numerical and Analytical Methods in Geomechanics
• 影响因子: 4
• 作者: Zhe Zhang;Xiaoyu Song

Soil–Water Retention Surface of Unsaturated Clay Incorporating Capillary Interface Area through Molecular Dynamics

通过分子动力学研究包含毛细管界面面积的不饱和粘土的土壤-保水表面

• DOI: 10.1061/9780784484050.034
• 发表时间: 2022
• 期刊: ASCE Geo Congress 2022
• 作者: Zhang, Zhe;Song, Xiaoyu
• 通讯作者: Song, Xiaoyu