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.

盐岩用于固定油，高压气体和核废料的储存，因为它具有蠕变并形成气体和流体流动的障碍。 但是，地下存储设施附近的蠕变过程可能会导致破裂，打开，封闭和重建，从而损害流动障碍的完整性和工程结构的稳定性。 破裂和愈合的数学描述并非完全开发。 该奖项将支持基本的岩石物理和力学研究，以将裂纹，打开和重建与微观结构和机械变量联系起来，与控制盐岩在地质时空上的时间相关行为的机械变量联系起来。 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培养基的损害和愈合的好类似物。 预计项目发现将推进定量关系，从而实现工程项目中行为的准确建模和预测。 这项工作将提高对其他过程中的其他岩石中的破裂和愈合的基本理解，尤其是在地震断层和诱发地震性的区域周围。 地球科学和工程研究人员团队将与其他计划合作，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。盐的大多数连续性损害模型基于扩张边界的概念，并不考虑裂纹引起的弹性特性各向异性。微型力学和均质化原理已成功地用于建模盐岩弹性塑性行为，但并未用于测试微观结构的规模不变性到变形方案的过渡。该项目的目的是将盐变形制度和流变行为与微观结构的密度和方向分布联系起来。代表性基本体积尺度上的变形模式将分解为独立的过程（例如破裂），每个过程与不同的微观结构描述符（例如晶粒长宽比）相关。宏观热力学变量将与微结构描述符正式相关，以测试变形方案中过渡点的空间和时间尺度不变性。特定的研究目标是：（1）确定盐微结构的拓扑成分和亚组成部分； （2）确定颗粒内和粒间裂纹的能源成本剥离，开口，闭合和重建； （3）计算与谷物变形方案和转速量表之间的过渡相关的能量阈值； （4）测试过渡过程中微观结构组织的时间和规模依赖性； （5）设计岩盐微结构系统，可在地下存储环境中优化愈合特性。