SGER: Nanoscale Modeling and Macroscopic Homogenization of the Behavior of Rock Minerals and Interfaces

摘要：岩石是地球表面分布最广、种类最多的物质，其力学性质和流体输运性质在许多领域发挥着重要作用。岩石的宏观行为通常由在连续介质力学框架内建立的本构模型来表示，这些本构模型是由元素试验建立的。在许多情况下，只有在校准模型的条件范围内才能保证模型的可靠性。物候学模型很难预测岩石在高应力、高温和极慢或极快加载的极端环境下的行为。这项探索性研究小拨款(SGER)的主要目标是：1)开发模拟岩石矿物及其界面的纳米尺度行为的计算模型；2)开发岩石矿物及其界面纳米尺度响应的均匀化方案；3)在岩石宏观模型中实现纳米尺度响应。用于岩石建模的方法包括将岩石细分为多尺度组分。基于原子尺度有限元和虚拟内键(VIB)模型的分子动力学模拟将在纳米尺度上分析形成单个颗粒的矿物的行为和矿物之间的接触特性。纳米和微米尺度的行为将使用与不同元素模拟验证的涂抹裂纹模型进行均质化。这项工作的主要学术价值来自于先进的和尖端的纳米到宏观尺度表征、建模和计算能力的开发、使用和集成，以及对岩石力学中突出问题的应用。这些能力正在发展，尚未在地球工程和地球科学界得到充分利用。这些能力的发展将大大推进地质力学建模的最先进水平。更广泛的影响包括改进在极端环境和广泛的时间和空间尺度下的岩石、矿物和界面行为的预测。这种能力将对国土安全和环境产生影响，例如在弹丸侵彻问题和核废料处理方面。在纳米尺度上对岩石矿物结构和力学行为的更好理解，以及纳米尺度响应与宏观行为的相互作用，也可以导致新的和创新的“地质启发纳米材料”。在令人兴奋的纳米机械和纳米技术领域培训今天和未来的工程师，将确保美国劳动力的竞争力。该项目将通过积极鼓励少数群体和妇女参与，促进提案研究活动的多样性。积极及时地在期刊、会议和万维网上传播研究成果，将确保研究产生立竿见影的效果。

Abstract:Rocks are the most ubiquitous and most diverse materials on the earth's surface, and their mechanical and fluid transport properties play important roles in many different fields. The macroscopic behavior of rocks is conventionally represented by constitutive models that are formulated within the framework of continuum mechanics, and are phenomologically established from element tests. In many cases, model reliability can only be guaranteed over the range of conditions in which the model is calibrated. Phenomological models have difficulty in predicting the behavior of rocks under extreme environments involving large stresses, high temperatures, and extremely slow or fast loading.The main objectives of this Small Grant for Exploratory Research (SGER) research are: 1) to develop computational models for simulating the nanoscale behavior of rock minerals and their interfaces, 2) to develop homogenization schemes for nanoscale response of rock minerals and their interfaces, and 3) to implement nanoscale response in macroscopic models of rock masses.The approach to be used for modeling of rock masses involves subdividing rock into its multiscale components. The behavior of the minerals forming an individual grain and the contact properties between minerals will be analyzed at the nanoscale using Molecular Dynamics simulations based on the Atomistic-Scale Finite Element Method and Virtual Internal Bond (VIB) Model. The nano- and micro-scale behavior will be homogenized using the Smeared Crack Model validated against Distinct Element simulations. The primary intellectual merits of this work stem from the development, use and integration of advanced and cutting edge nano- to macro-scale characterization, modeling and computational capabilities, and applications to outstanding problems in rock mechanics. These capabilities are evolving and have not been fully exploited in the geoengineering and geoscience community. Development of these capabilities will significantly advance the state-of-the-art in geomechanical modeling.Broader impacts include improved prediction of rock mineral and interfacial behavior under extreme environments and under wide temporal and spatial scales. Such capability will have homeland security and environmental implications, for instance in projectile penetration problems and nuclear waste disposal. Improved understanding of rock mineral structures and mechanical behavior at the nanoscale and the interaction of nanoscale response with macroscopic behavior can also lead to new and innovative "geo-inspired nanomaterials." Training of today's and future engineers in the exciting area of nanomechanics and nanotechnology will ensure the competitiveness of the US workforce. The project will promote diversity in the research activities of the proposal by actively encouraging the participation of minorities and women. Active and timely dissemination of research results in journals, conferences and via the world-wide-web will ensure immediate impact of the research.