CAREER: Multiphysics Damage and Healing of Rocks for Performance Enhancement of Geo-Storage Systems - A Bottom-Up Research and Education Approach

这项教师早期职业发展（Career）计划将加强工程师对地下能源和废物储存系统中岩石裂缝形成和愈合的理解，同时为来自不同背景的本科生提供研究和国际合作经验。在地下岩层中安全储存能量或废物依赖于对岩体中存在的裂缝和流体流经裂缝系统的理解。目前，工程师们对如何利用裂缝形成和裂缝愈合的微观理论来开发岩体行为模型还不完全了解。因此，CAREER奖的目标是：了解和预测岩石裂缝的变化；建立裂缝网络的数值模型；制定和评估骨折损伤和愈合的创新模型；并解释岩石变形和流体流动不稳定造成的破裂损伤和愈合。除了防止下沉、钻孔不稳定和污染物泄漏外，所提出的模型还将适用于优化地质材料的密封和屏蔽性能，以及评估能源地质技术对环境的影响。研究和教育活动将整合起来，培养本科生的设计和研究能力，让研究生参与指导和公共讨论，并促进长期的国际合作。PI将与佐治亚理工学院的一些教育和推广项目合作，以评估活动的有效性，并提高学生的参与度，特别是那些来自代表性不足群体的学生。该CAREER计划的具体研究目标是了解和预测岩石在化学-力学损伤和愈合过程中微观结构和孔隙力学行为的演变。盐和碳酸盐的地质储存被用作研究以下基本科学问题的说明性问题：为什么孔隙和裂缝会愈合？机械和液压回收需要多长时间？治疗需要多少能量？该项目的一个主要预期成果是为岩石力学建立一个新的连续损伤和愈合理论框架，该框架使用了一组最小的解释耗散变量，定义为微观结构描述符的概率矩。最初的贡献包括：在多物理场损伤和愈合过程中预测孔隙几何演化的理论；用控制损伤和愈合的几何变量来描述孔隙网络拓扑的创造性数学模型；孔隙尺度愈合时间与宏观力学恢复时间的基本关系——连接孔隙力学与损伤力学的重要一步创新的计算方法，以预测损伤和愈合时的机械不稳定性和渗透阈值，与领先的实验家合作验证；与行业合作伙伴合作，对地质储存进行逼真的多物理场模拟。拓扑学、热力学、孔隙力学和连续介质力学的严格整合将改变损伤和愈合力学理论，并提供一个从拓扑描述符解释岩石应力路径历史的框架。研究结果将有助于推荐必要的湿度和温度条件，以尽量减少损害和/或增强岩石的愈合，并设计安全和可持续的地质储存系统。本职业计划的教育目标是吸引国际和跨学科的本科生和研究生参与能源岩土技术研究和工程。研究、教育和推广活动将通过以下方式整合：与地球科学家合作，培训地球系统学生如何设计和进行岩石力学实验；让学生的思维在本科课堂中可见，实施方案设计策略；让研究生参与能源岩土技术的公开讨论；管理垂直整合实验室，建立跨代、跨学科和国际学者网络，提高本科生的学习成果，激励学生学习地质力学；并在乔治亚理工学院和包括法国巴黎理工学院在内的欧洲顶级院校之间建立了一个可持续的学生交换项目。

This Faculty Early Career Development (CAREER) Program grant will enhance engineers' understanding of the formation and healing of rock fractures as it pertains to underground energy and waste storage systems, while providing undergraduate students from a diverse background with both research and international collaboration experiences. The safe storage of energy or waste products in underground rock formations relies on an understanding of the fractures that exist within the rock mass, and the fluid flow through the fracture system. Currently, engineers have an incomplete understanding of how microscopic theories of fracture formation and the healing of fractures can be used to develop models of rock mass behavior. Therefore, the objectives of this CAREER award are to: understand and predict changes in rock fractures; develop numerical models of fracture networks; formulate and assess innovative models of fracture damage and healing; and interpret rock deformation and fluid flow instabilities resulting from fracture damage and healing. In addition to preventing subsidence, borehole instabilities and contaminant leakage, the proposed models will be applicable for optimizing containment and shielding properties of geomaterials and assessing the environmental impact of energy geotechnologies. Research and education activities will be integrated to train undergraduate students in design and research, engage graduate students in mentoring and public deliberation, and foster long-term international collaborations. The PI will collaborate with a number of educational and outreach programs at Georgia Tech in order to assess the effectiveness of the activities and improve the participation of students, especially those from under-represented groups.The specific research goal of this CAREER plan is to understand and predict the evolution of rock microstructural and poromechanical behavior upon chemo-mechanical damage and healing. Geological storage in salt and carbonates is used as an illustrative problem for investigating the following fundamental scientific questions: why do pores and cracks heal? how long do mechanical and hydraulic recovery take? how much energy does healing require? A major expected outcome of this project is a new continuum damage and healing theoretical framework for rock mechanics, which uses a minimal set of explanatory dissipation variables defined as moments of probability of microstructure descriptors. Original contributions include: a theory to predict pore geometry evolution upon multi-physics damage and healing processes; creative mathematical models to describe pore network topology with geometric variables that control damage and healing; fundamental relationships between pore-scale healing time and macroscopic mechanical recovery time - a step forward to bridge poromechanics and damage mechanics; innovative computational methods to predict mechanical instabilities and percolation thresholds upon damage and healing, verified in collaboration with leading experimentalists; and realistic multi-physics simulations of geological storage, in collaboration with industry partners. The rigorous integration of topology, thermodynamics, poromechanics and continuum mechanics will transform the theory of damage and healing mechanics and provide a framework to interpret rock stress path history from topology descriptors. Research findings will be useful to recommend the conditions of moisture and temperature necessary to minimize damage and/or enhance healing in rocks and to design safe and sustainable geological storage systems. The education goal of this CAREER plan is to engage an international and cross-disciplinary community of undergraduate and graduate students in energy geotechnology research and engineering. Research, education and outreach activities will be integrated by: collaborating with geoscientists to train geosystems students on how to design and conduct rock mechanics experiments; making students' thinking visible in undergraduate classes to implement solution design strategies; engaging graduate students in public deliberations on energy geotechnology; supervising a Vertically Integrated Laboratory that will build a trans-generational, cross-disciplinary and international scholar network, improve undergraduate students' learning outcomes and inspire students in geomechanics; and creating a sustainable student exchange program between Georgia Tech and top European institutions including Ecole des Ponts Paris Tech (France).