Collaborative Research: Engineered Water Repellency to Mitigate Frost Susceptibility: Decoupling Osmotic and Matric Potential

霜冻对建筑物、道路、桥梁等民用基础设施影响显著。它会导致过大的沉降、地基失稳，甚至结构破坏。这项研究将调查防水添加剂(如有机硅烷)在多大程度上缓解冻胀，同时确定控制的物理和化学机制。这项研究有可能极大地延长民用基础设施的使用寿命，同时引入一种新的土壤和基础改良方法。这项研究为将工程排水性的概念扩展到岩土工程的其他领域提供了基础，包括在斜坡稳定、道路建设和固体/危险废物管理中的应用。更广泛地说，这项研究可能会增强我们对永久冻土在气候变化期间融化时的二氧化碳排放的理解。这项研究还可能让我们了解地球的月球、火星和其他地外天体上的霜冻形成。该项目为来自美国军事学院的学员提供独特的体验，与来自两个合作机构的退伍军人配对，在这些组织以及位于新罕布夏州汉诺威的美国陆军工程兵团工程师研究和开发中心寒冷地区研究和工程实验室(ERDC-CRREL)实验室体验。由首席调查员、学员、退伍军人和研究生组成的研究小组还将完成一场题为“以信任的速度领导”的以主动学习为基础的研讨会。这种培训强调信任和性格发展；随着工程师的工作将公众与大规模生产的产品和大型项目相结合，这两者都已成为关键属性。这项研究的主要焦点是渗透势和基质势对冰晶形成和生长的相对贡献，在有和没有工程防水性的情况下。这是动态热-水-机械(THM)系统中的一个关键环节。第二个重点是评估渗透势和基质势对这两个土壤系统(具有和不具有排水性)的净影响，这是通过直接物理测量(实验室和田间)解释的。多物理建模将通过参数和相关分析来补充这项工作。研究计划分为三个阶段(1)表征、(2)性能和(3)模型应用和现场测试。表征阶段的数据将量化渗透势/基质势作为拒水性的函数。性能阶段的实验将评估不同的电势和防水性如何影响冻胀，以及冻结和未冻结水含量之间的关系。描述冻结/未冻结水含量关系的参数将被修改，以反映渗透势和基质势的相对贡献，然后将用于模型，以预测在更广泛的气候条件下的行为。这些预测将与四个地点(密歇根州、新罕布夏州、北卡罗来纳州和阿拉斯加州)的现场数据进行比较，这些地点的霜冻暴露程度相差三个数量级。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Frost heaving has a significant effect on civil infrastructure such as buildings, roads, and bridges. It causes excessive settlement, foundation instability, and even structural failure. This research will investigate the extent to which water repellent additives (e.g., organo silanes) mitigate frost heaving while identifying the controlling physical and chemical mechanisms. This research has the potential to dramatically extend the service life of civil infrastructure while introducing a new approach to soil and foundation improvement. This research provides a basis to extend the concept of engineered water repellency to other areas of geotechnical engineering, including applications in slope stability, road construction, and solid/hazardous waste management. More broadly, this research may enhance our understanding of carbon dioxide emissions from permafrost as it thaws during climate change. The research may also inform our understanding of frost formation on the Earth's Moon, Mars, and other extraterrestrial bodies. This project supports a unique experience for Cadets from the U.S. Military Academy, to be paired with Veterans from both collaborating institutions for an experience at these organizations as well as at the U.S. Army Corps of Engineers Engineer Research and Development Center Cold Regions Research and Engineering Laboratory (ERDC-CRREL) Laboratory in Hanover, New Hampshire. The research team, inclusive of the Principal Investigators, Cadets, Veterans, and Graduate Students will also complete an active-learning based seminar entitled "Leading at the Speed of Trust." This training emphasizes trust and character development; both of which have emerged as critical attributes as the work of engineers intersects the public with mass produced products and mega-sized projects. The primary focus of this research is the relative contribution of osmotic and matric potential on ice lens formation and growth, with and without engineered water repellency. This represents a critical link in the dynamic thermo-hydro-mechanical (THM) system. A secondary focus evaluates the net effect of osmotic and matric potential on these two soil systems (with and without water repellency) as interpreted from direct physical measurements (in the lab and in the field). Multi-physics modeling will supplement this work via parametric and related analyses. The research plan is conceived to follow three phases (1) characterization, (2) performance and (3) model application and field testing. Data from the characterization phase will quantify osmotic/matric potential as a function of water repellency. Experiments in the performance phase will evaluate how varied potential and water repellency affect frost heave and the relationship between frozen and unfrozen water content. The parameters which describe the frozen/unfrozen water content relationship will be modified to reflect the relative contribution of osmotic and matric potential and will then be used in models to predict behavior under a wider set of climatic conditions. These predictions will be compared with field data from four sites (Michigan, New Hampshire, North Carolina, and Alaska) whose frost exposure varies by three orders of magnitude.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.