Thermal-mechanical response of frozen clay soil and the impact on soil-structure interaction

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In northern Canada, frozen clay soil is very abundant in permafrost regions, where new infrastructure needs are being created as a result of heightened demand for resources. Long term records indicate an on-going global warming has resulted in thawing of portions of the permafrost area, which leads to extensive settlement of the ground surface and causing damage to infrastructures. Understanding the behavior of frozen soil under thermal-mechanical impact is the fundamental of studying on the soil-structure interaction, which is of significant importance to the development of safe and economical designs of infrastructures in cold regions. Currently, very little theoretical work on thermally induced strength weakening in frozen clay soil can be found, and numerical simulation on the temperature-dependent failure behavior in frozen clay soil is not available. There remains a significant knowledge gap in terms of understanding the underlying mechanisms of thermally induced mechanical degradation (weakening) of frozen clay soil and how those affect the performance of infrastructures. Consequently, very few companies would like to take into account of thermally induced failure of frozen clay soil in their designs.******This research program is proposed to put a step toward solving thermally induced problems in frozen ground engineering. The long-term scope of this program is to study thermal-hydro-mechanical-chemical coupled processes in frozen clay soils and the impact on soil structure interaction. The short-term scope (in 5 years) of this program is aimed at investigating the physics of thermally induced weakening in water-saturated frozen clay soil and the impact on soil-structure interaction. It has three objectives: (1) to perform laboratory tests to measure mechanical properties of frozen clay soil at different temperatures (2) to propose theoretical models for temperature-dependent mechanical properties and use the models in a numerical simulation tool (3) to propose an approach to simulate the soil-structure interactions in permafrost area with consideration of the temperature increase in frozen clay soils. The completion of this 5-years research program is the first part of the program's long-term scope.******The proposed research program will enrich the development of soil mechanics in the discipline of temperature related topics. The deliverables from this proposed research program will promote the interests of engineers to proactively consider thermal-mechanical impacts on designs and operations of buried structures in permafrost regions. Once the thermal impact on such soil-structure interaction is understood, it will be possible to upgrade the regulations for the design of infrastructures to account for the thermal impact. It will be very beneficial for engineering projects such as pipeline construction and natural resource exploitation in Canadian's permafrost regions.**