Collaborative Research: A Fundamentals-based Paradigm for Expansive Soil Classification

仅在美国，每年在膨胀土上建造建筑物、道路和桥梁的损失和诉讼费用总计数十亿美元，但目前的减灾实践仍然严重依赖于过时的、不确定的和高度经验性的场地表征方法。需要一个更系统和根本上健全的方法来进行膨胀土分类，以减轻这些材料造成的严重经济和社会负担。该项目的土壤分类新范式被视为解决当前全球社会和环境挑战的核心，包括能源和资源需求、基础设施建设、环境保护和改善以及自然灾害的保护和恢复。该框架将允许设计人员更有效地量化网站的可变性，允许在短时间内测试更大，更多样化的样本套件。对膨胀性粘土的基本了解的提高将影响它们已被发现使用的极其广泛的应用，包括环境应用，如废物容纳，过滤和膜，以及作为工业吸附剂。活动将与研究相结合，以利用该项目的协作性质，包括在威斯康星州（UW）和矿业（CSM）和教育/多样性倡议实施通过现有的计划在UW和CSM的科罗拉多学校的学生夏季交流计划。将组织一个实践培训研讨会，向岩土工程界传播新的土壤分类系统。该项目的目标是通过开发基于基本土壤性质和行为的膨胀土表征新范例，实现岩土工程实践的现代化。负责粘土膨胀行为的两种不同的物理化学机制-结晶膨胀和渗透膨胀-将形成新框架的基础。本项目的方法明确区分了这些机制，以收集有关基本粘土性质（包括比表面积和阳离子交换容量）的具体信息，并使用独立的矿物学和孔隙流体化学标准对膨胀性粘土进行分类。现代实验方法，包括水蒸气吸附等温线和土壤收缩曲线的自动测量，将取代新的膨胀土分类系统中的历史指标测量（例如Atterberg极限）。该奖项反映了NSF的法定使命，并被认为值得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来支持。

Damage and litigation costs from construction of buildings, roads, and bridges, on expansive soils total billions of dollars each year in the US alone, yet the current state of mitigation practice still heavily relies on antiquated, uncertain, and highly empirical site characterization methods. A more systematic and fundamentally sound approach for expansive soil classification is required to alleviate the severe economic and social burden of damages resulting from these materials. The new paradigm in this project for soil classification is viewed as central to solving current global societal and environmental challenges, including energy and resource needs, infrastructure development, environmental protection and enhancement, and protection and recovery from natural disasters. The framework will allow designers to more effectively quantify site variability by allowing a larger and more diverse suite of samples to be tested in a short amount of time. Improved basic understanding of expansive clays will impact the tremendously broad range of applications where they have found use, including environmental applications such as waste containment, filtration and membranes, and as industrial adsorbents. Activities will be integrated with the research to capitalize on the collaborative nature of the project, including a summer exchange program for students at the University of Wisconsin (UW) and the Colorado School of Mines (CSM) and education/diversity initiatives implemented through existing programs at UW and CSM. A hands-on training workshop will be organized to disseminate the new soil classification system to the practicing geotechnical engineering community.The goal of this project is to modernize geotechnical engineering practice by developing a new paradigm for expansive soil characterization based on fundamental soil properties and behavior. Two distinct physicochemical mechanisms responsible for clay swelling behavior - crystalline swelling and osmotic swelling - will form the basis of the new framework. The approach in this project explicitly differentiates these mechanisms to glean specific information about fundamental clay properties including specific surface area and cation exchange capacity and to classify expansive clays using independent mineralogy and pore fluid chemistry criteria. Modern experimental approaches, including automated measurements of water vapor sorption isotherms and soil shrinkage curves, will replace historical index measurements (e.g. Atterberg Limits) in the new expansive soil classification system.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.