Pore Pressure Response to Loading of Warm Permafrost

这项研究的重点是加强加拿大多年冻土工程师对控制多年冻土区浅层斜坡稳定性和近地表基础变形行为的因素的了解。由于气候变化，该近地表多年冻土的温度正在逐渐变暖，这种升温正在影响该近地表多年冻土的强度和变形行为。这种变暖会导致这些与斜坡稳定性和地基变形相关的材料的有害行为。 这项研究将建立部分冻土中内部产生的孔压对这一变暖多年冻土的强度和变形的控制影响。气候变化对多年冻土表以下(活跃层以下)的近地表冻结物质有重大影响。这块温暖的永久冻土富含冰的成分，这对设计工程师在评估其稳定性时是一个挑战。在低于冰点的温度下，温暖的永久冻土中可能存在大量未冻结的水，这些水的数量随着温度的小幅上升而增加。变暖允许冰在孔隙空间中改变相，这些水可能会导致部分冻结材料中的内部孔隙水压力增加。这些变化的孔隙水压力会降低有效应力，从而导致变暖的永久冻土的抗滑性降低。这项研究的重点是确定这些孔压是如何变化的，并在温度和应力的情况下测量这些变化。了解这些孔压是如何发展的，将允许在未来对温暖的永久冻土进行分析时使用有效应力原理。由于缺乏能够准确预测部分冻土中的内部孔压的能力，这一概念至今还没有被使用。 还将对冻结锋在土壤中推进时形成的孔隙水压力的行为进行研究。这是为了提高该行业对冻胀的基本原理以及控制冻胀量的冻结推进速度的影响的理解。 研究结果将减少道路和机场地基的短期和未来成本，以及与这项基础设施相邻的地基和斜坡的稳定性。

The research focuses on enhancing Canadian permafrost engineers' understanding of the factors that control both stability of shallow slopes and deformation behavior of near surface foundations in permafrost regions. The temperature of this near surface permafrost is gradually warming due to climate change, and this warming is impacting the strength and deformation behavior of this near surface permafrost. This warming can lead to detrimental behavior of these materials related to stability of slopes and deformation of foundations. The research will establish the controlling influence of internally generated pore water pressure in partially frozen soils on the strength and deformation of this warming permafrost. Climate change has its major impact on the near surface frozen material at and just beneath the permafrost table (below the active layer). The ice rich composition of this warm permafrost is a challenge for the design engineer when evaluating their stability. Significant amounts of unfrozen water at below freezing temperatures can exist in warm permafrost, and the amount of this water increases with a small increase in temperature. Warming allows ice to change phase in the pore space, and this water can result in increases in internal pore water pressures in the partially frozen material. These changing pore water pressures can reduce the effective stresses, thus leading to a decrease in the resistance to sliding of the warming permafrost. The research is focused on determining how these pore pressures can change and measuring these changes with both temperature and stress. Understanding how these pore pressures develop will allow use of the effectives stress principle in future analysis of warm permafrost. This concept has not been used to date because of a lack of being able to accurately predict the internal pore water pressures in partially frozen soils. Research will also be carried out on the behavior of the pore water pressure developed during advancement of the freezing front in soils. This is being undertaken to improve the profession's understanding of the fundamentals of frost heave and the impact of rate of freezing advancement that control the amount of heave. The research findings will reduce the near term and future costs of road and airport foundations, and foundations and stability of slopes adjacent to this infrastructure.