CAREER: Coupled Hydrology and Mechanics of Fine-Grained Soils and Sedimentary Rocks

细粒岩石（页岩、泥岩）作为一系列地下水、能源和碳资源的盖层、寄主岩和源岩而存在。 它们还代表着对碳捕获和储存、高放射性废物储存、地下水源和储存以及页岩碳氢化合物开采的控制。细粒土壤在农业和土壤碳储存中发挥着同样重要的作用。富粘土介质的重要性主要来自其独特的水文和机械特性（超低渗透性、膨胀收缩和开裂）。这些特性在控制地下流体流动方面具有独特的重要性（其中细粒岩石约占沉积岩体的三分之二），但它们仍然是地下水水文学中的一个很少绘制的前沿研究领域。该项目将发展细粒土壤和沉积岩水文特性的一般理论。这一目标需要了解多孔介质在多个尺度上的耦合水文，机械和化学性质，从纳米尺度（粘土颗粒的聚集和膨胀发生）到控制岩石的整体机械和流动性质的10- 100米。拟议的研究依赖于一个适合于每个感兴趣的长度尺度的模拟方法的组合，沿着在每个尺度上进行严格的实验验证。预计的主要成果包括对细颗粒介质的中尺度和纳米尺度性质的详细基本理解，以及描述这些介质的耦合水文-机械-化学性质的新本构关系。主要的教育和推广目标是开发分子动力学模拟的使用，作为一种教学工具，可以直观地说明重要的科学概念和现象的基本基础，动手的方式。该工具将为环境工程本科课程的第一年开发，并作为基于网络的界面（科学网关）的一部分，使更广泛的社区（例如，该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Fine-grained rocks (shale, mudstone) exist as caprocks, host rocks, and source rocks for a range of subsurface water, energy, and carbon resources. They also represent a control on carbon capture and storage, high-level radioactive waste storage, groundwater sources and storage and shale hydrocarbon extraction. Fine-grained soils play an equally important role in agriculture and soil carbon storage. This importance of clay-rich media derives largely from their distinct hydrologic and mechanical properties (ultra-low permeability, swelling-shrinking and cracking). These properties are of singular importance in controlling fluid flow in the subsurface (where fine-grained rocks constitute roughly two-thirds of the sedimentary rock mass), yet they remain a sparsely charted frontier research area in groundwater hydrology. This project will develop a general theory of the hydrologic properties of fine-grained soils and sedimentary rocks. This goal requires understanding the coupled hydrologic, mechanical, and chemical properties of porous media on multiple scales, from the nanometer scale (where aggregation and swelling of clay particles takes place) to the 10-100s of meters that control the bulk mechanical and flow properties of the rock. The proposed research relies on a combination of simulation methodologies adapted to each length scale of interest, along with rigorous experimental validations at each scale. Key projected outcomes include detailed fundamental understanding of the meso- and nanoscale properties of fine-grained media and new constitutive relations describing the coupled hydrologic-mechanical-chemical properties of these media. The major education and outreach goal is to develop the use of molecular dynamics simulations as a pedagogical tool that can illustrate the fundamental basis of important scientific concepts and phenomena in an intuitive, and hands-on manner. This tool will be developed for both first year of the Environmental Engineering undergraduate curriculum and as part of a web-based interface (a Science Gateway) that will enable the broader community (e.g., high school students and teachers) to visualize and explore simulation results stored on the high-performance data storage systems at the National Energy Research Scientific Computing Center (NERSC).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.