CAREER: Inspiring a New Paradigm in Geotechnical Design and Education Through an Understanding of Biomimetic Load Transfer in Soils

这项教师早期职业发展计划（Career）资助将支持研究，这些研究将促进对载荷如何通过土壤转移的基本理解，以及生物机制和新建筑技术如何改善土壤作为建筑材料的使用。许多天然材料具有几何微结构，这使它们比其基材更坚固、更坚韧。这项研究将提供所需的知识，以便使用增材制造（即3D打印）技术将这些机制纳入土壤中，在这种技术中，土壤被“打印”成结构部件或细胞模式，以提高其承载能力。像蜂窝这样的仿生结构已经被研究用于金属和其他固体材料；然而，对这些载荷传递机制在土壤等颗粒材料中的有效性的理解是缺乏的。通过减少项目所需的混凝土和其他材料的数量，提高土壤的承载能力将导致更具可持续性和成本效益的岩土工程实践。在这个项目中获得的基本理解也将使增材制造进一步成为在偏远和欠发达地区、救灾或饱受战争蹂躏的地区建造避难所和其他基础设施的可行选择。此外，该项目旨在通过新课程促进跨学科教育，并通过诸如K-12外展活动，重点探索自然中的工程原理，视觉空间研讨会，以及通过大学的工程职业意识计划招募高质量的研究人员等活动来参与和保留不同的学生。层次化的微观结构赋予许多天然材料的强度，其强度比其组成成分大几个数量级。这项CAREER资助的研究目标是利用这些仿生学概念来推进对土壤负荷传递机制的基本理解。虽然研究人员已经观察到类似的生物启发金属和复合材料设计的好处，但需要对脆性颗粒材料（如土壤）中这些载荷传递机制的有效性有一个基本的了解。因此，本基金的重点是：(1)了解自然界的最佳承载机制，并在土壤中模拟这些机制；(2)利用实验测试和离散元法（DEM）模型对生物土在不同长度尺度上的行为进行评价；(3)研究增材制造作为在现场规模上构建细胞土壤结构和基础设施的手段。除了DEM模拟之外，基于拓扑的方法可以优化给定加载场景的模式，并捕获结果行为，从而为许多可能的岩土工程应用提供解决方案。还将对生物改良土壤进行实验室和中等规模的测试，以评估全面实施这一过程的可行性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development Program (CAREER) grant will support research that will advance the fundamental understanding of how loads are transferred through soils, and how biological mechanisms and new construction techniques can improve the use of soil as a building material. Many natural materials have geometrical microstructures which make them stronger and tougher than their base materials. This research will provide the needed knowledge so that these mechanisms can be incorporated in soils using additive manufacturing (i.e. 3D printing) techniques in which soils are "printed" into structural components or cellular patterns to improve their load carrying ability. Bio-inspired structures like the honeycomb have been studied for metals and other solid materials; however, an understanding of the effectiveness of these load transfer mechanisms in particulate materials like soils is lacking. Improving a soil's ability to carry load will result in more sustainable and cost-effective geotechnical practice by reducing the amounts of concrete and other materials needed for a project. The fundamental understanding gained in this project will also move additive manufacturing further towards becoming a viable option for building shelters and other infrastructure in remote and underdeveloped locations, and in disaster relief or war-torn areas. Additionally, this project seeks to promote interdisciplinary education through a new course and the participation and retention of diverse students through activities such as K-12 outreach focused on exploring engineering principles in nature, visual-spatial workshops, and recruitment of high quality researchers through the University's Engineering Career Awareness Program. Hierarchical microstructures give many natural materials strengths which are orders of magnitude greater than their constituents. The research goal of this CAREER grant is to leverage these biomimicry concepts to advance the fundamental understanding of load transfer mechanisms in soil. While researchers have observed benefits for similar bio-inspired designs of metals and composites, a fundamental understanding of the effectiveness of these load transfer mechanisms in brittle particulate materials like soils is needed. Therefore, this grant focuses on: (1) understanding the optimized load carrying mechanisms in nature and mimicking these mechanisms in soils; (2) evaluating the behaviors of bio-inspired soils across the length scales using experimental testing and discrete element method (DEM) modeling; and, (3) investigating additive manufacturing as a means to construct cellular soil fabrics and infrastructure at the field-scale. In addition to the DEM simulations, a topology-based method for optimizing the patterns for a given loading scenario and capturing the resulting behavior is necessary to provide a solution for the many possible geotechnical applications. Laboratory and mid-scale testing of bio-improved soils will also be conducted to assess the feasibility of full-scale implementation of the process.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.