Collaborative Research: Salt Rock Microstructure and Deformation

合作研究：盐岩微观结构与变形

• 批准号: 1362004
• 负责人: Chloe Arson
• 金额: $ 20.01万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1362004&HistoricalAwards=false
• 关键词: Collaborative; Research; Salt; Rock; Microstructure

Salt rock is used for secure storage of oil, high-pressure gas, and nuclear waste because of its ability to creep and form barriers to gas and fluid flow. However, creep processes near subsurface storage facilities can lead to crack debonding, opening, closure and rebonding that compromise the integrity of flow barriers and stability of engineered structures. Mathematical descriptions of cracking and healing are incompletely developed. This award will support fundamental rock physics and mechanics research to link deformation by crack debonding, opening and rebonding to microstructures and mechanical variables that govern the time-dependent behavior of salt rock over geological space and time scales. Deformation of salt occurs rapidly at laboratory conditions making it a good analog to study damage and healing in other crystalline materials and porous media. Project findings are expected to advance quantitative relations enabling accurate modeling and prediction of behaviors in engineering projects. The work will advance fundamental understanding of cracking and healing in other rocks that deform by the same processes, especially around earthquake faults and zones of induced seismicity. The team of geoscience and engineering researchers will collaborate with other programs to broaden the participation of women and other under-represented groups in research and engineering.Most continuum damage models for salt are based on the concept of dilatancy boundary, and do not account for crack-induced anisotropy of elastic properties. Micro-mechanics and homogenization principles were successfully employed to model salt rock elastoplastic behavior, but were not used to test scale invariance of microstructure to transitions in deformation regimes. The goal of this project is to link salt deformation regimes and rheological behaviors with the density and orientation distribution of microstructures. Deformation regimes at the scale of a Representative Elementary Volume will be decomposed into independent processes (e.g., cracking), each related to different microstructure descriptors (e.g., grain aspect ratio). Macroscopic thermodynamic variables will be formally related to the microstructure descriptors to test the space and time scale invariance of transition points in deformation regimes. Specific research objectives are to: (1) Identify topological components and subcomponents of salt microstructure; (2) Determine the energy cost of intra- and inter-granular crack debonding, opening, closure and rebonding; (3) Compute energy thresholds associated with transitions between deformation regimes at the grain and REV scales; (4) Test the time and scale dependence of microstructure organization during transitions; (5) Design rock salt microstructural systems that optimize healing properties in subsurface storage environments.

盐岩用于石油、高压气体和核废料的安全储存，因为它具有蠕变能力，并对气体和流体流动形成屏障。 然而，地下储存设施附近的蠕变过程可能导致裂纹脱粘、打开、闭合和重新粘结，从而损害流动屏障的完整性和工程结构的稳定性。 对裂纹和愈合的数学描述还不完全。 该奖项将支持基础岩石物理和力学研究，将裂缝脱粘，打开和重新粘合的变形与微观结构和力学变量联系起来，这些变量控制着盐岩在地质空间和时间尺度上的时间依赖行为。 盐的变形在实验室条件下迅速发生，使其成为研究其他晶体材料和多孔介质中损伤和愈合的良好模拟物。 预计项目结果将推进定量关系，使工程项目中的行为准确建模和预测。 这项工作将促进对其他岩石中通过相同过程变形的开裂和愈合的基本理解，特别是在地震断层和诱发地震活动区周围。 地球科学和工程研究人员团队将与其他项目合作，以扩大妇女和其他代表性不足的群体在研究和工程中的参与。大多数盐的连续介质损伤模型都是基于非线性边界的概念，并且没有考虑裂纹引起的弹性属性的各向异性。细观力学和均匀化原理被成功地用于模拟盐岩弹塑性行为，但没有被用来测试变形机制中微观结构的尺度不变性。该项目的目标是将盐变形机制和流变行为与微观结构的密度和取向分布联系起来。在代表性基本体积的尺度下的变形机制将被分解成独立的过程（例如，开裂），每种都与不同的微结构描述符有关（例如，晶粒纵横比）。宏观热力学变量将正式相关的微观结构描述符，以测试变形制度的转变点的空间和时间尺度的不变性。具体的研究目标是：（1）确定盐微观结构的拓扑成分和子成分;（2）确定晶内和晶间裂纹脱粘、张开、闭合和再结合的能量消耗;（3）计算与晶粒和REV尺度下变形状态之间转变相关的能量阈值;（4）测试转变过程中微观结构组织的时间和尺度依赖性;（5）设计岩盐微结构系统，优化地下储存环境中的愈合性能。