Climate Control Triaxial System for Strength Assessment of Frozen and Partially Frozen Soils

近四分之一的北半球，包括加拿大一半的陆地，被永久冻土覆盖。从本质上讲，永久冻土是指在摄氏零下至少两年内保持永久冻结的土地。气候变化导致的温度上升对永久冻土的强度和完整性产生了不利影响。这种变暖的后果包括浅层斜坡的不稳定性增加和管道等近地表基础设施的变形，并将影响矿山复垦框架内的景观设计。变暖允许孔隙空间中的冰将相变为水，这种水会导致部分冻结材料中的内部孔隙水压力增加。所提出的三轴系统将使我们能够在受控升温的情况下测量孔隙压力的增加，从而量化随后相对于温度剖面的强度降低。所要求的最先进的环境三轴测试系统能够在受控温度条件下测试冻结和部分冻结的土壤，以监测冻土融化时的孔压过渡变化。该系统将使我们能够编制一个独特的实验数据库，以开发和校准能够预测冻土在融化时强度变化的数值模型。虽然三轴试验在岩土工程中经常被用来测量土壤的强度，但很少被用来了解冻土和部分冻土中的有效应力。通过收购这一系统，我们的研究小组将在三个关键研究领域(采矿废物管理、建筑和铁路行业)的大力支持下，站在为加拿大北部发展做出重大基础贡献的前沿。此外，这将有助于在我们的HQP培训中创造优势，为他们提供独特的技能集，使他们能够在未来扮演有影响力的角色。

Nearly a quarter of the northern hemisphere, including half of Canada's landmass, is underlain by permafrost. Essentially, permafrost is ground that remains perennially frozen for at least two years below zero degrees centigrade. Rises in temperature due to climate change have detrimental impacts on the strength and integrity of permafrost. The ramifications of this warming include increasing instability of shallow slopes and deformation of near-surface infrastructures, such as pipelines, and will impact landscape design in mine reclamation framework. Warming allows ice in the pore space to change phase to water, and this water can result in increases in internal pore water pressures in the partially frozen material. The proposed triaxial system will enable us to measure pore pressure increase with controlled warming and therefore quantify the subsequent strength reduction relative to temperature profiles. The requested state-of-the-art environmental triaxial testing system is capable of testing frozen and partially frozen soil under controlled temperature conditions to monitor the pore pressure transitional changes as frozen soil thaws. This system will allow us to compile a unique experimental database to develop and calibrate numerical models capable of predicting the change in the strength of frozen soils as it thaws. Although triaxial tests are routinely used in geotechnical engineering to measure strength of soils, they are rarely utilized to understand effective stresses in frozen and partially frozen soils. By acquiring this system, our research group would be at the forefront of making significant and fundamental contributions to Canada's northern development in three key research areas with strong support: mining waste management, construction, and railway industries. Furthermore, it will help create an edge in our HQP training, providing them with a unique skillset to place them in impactful future roles.