1. Introduction
The Arctic is usually considered the base for climate change since arctic air temperatures hike at around double the rate compared to the whole world. But the diverse features of arctic climate change influence the built environment to more than one might consider depending on warming air temperatures alone. These facets include hydrologic changes, sea ice loss, and permafrost thaw. The effects include altered river dynamics, erosion of arctic shorelines, and increased wildfire risk.
Climate change in the Arctic of Alaska shows many expected outcomes as it does globally. These outcomes may be ecological disturbances, community displacement, and profound economic disruption. However, a prominent feature unique to cold regions is the influence of a warming climate on permafrost.
2. Arctic Infrastructure and Permafrost
Infrastructure is built with permafrost as a ground zero in much of the Arctic. Thawing of those soils can decrease their bearing capacity. Therefore, one discriminating consequence of climate change is that engineers must consider more to protect permafrost beneath built structures. Protecting the underlying permafrost from thawing is essential to survive the structures in these areas. Plus, the temperature of permafrost is also significant for infrastructure stability since the bearing capacity of frozen soil is immensely declined as permafrost temperatures hike towards the melting point. Hence, arctic engineering has advanced to protect the soil in its frozen state as well as to forecast the impacts of localized thaw. With arctic engineering, one can find solutions to maintain foundation stability.
Engineering Challenges and Mitigation Techniques
An important engineering challenge related to permafrost infrastructure is providing an enduring and solid foundation for structures. Even ice-rich permafrost can offer an appropriate foundation for most infrastructure if one can prevent thawing.
Heated Structures
Warm structures, for instance, warm pipelines or heated buildings, should be separated from ice-rich permafrost. It is so that these warm structures do not induce thawing with their heat. Generally, these kinds of structures are separated from the base by ventilated space. They are located on a foundation with pilings that are frozen into the permafrost. Thermal piles are usually used in the warmer discontinuous permafrost zone. They include a gravity-assisted heat pipe (Thermosiphon) cooling system. It improves the wintertime cooling of the piling and the surrounding permafrost. This helps to keep the permafrost frozen and improves the frozen soil-piling surface bond strength. It offers vertical support for the piling as well as its load.
Unheated Structures
Linear structures, for instance, airports, railways, roads, or other unheated structures, can often be situated in permafrost areas with just minimal protective considerations of the permafrost from the thaw. Mainly, this is true in the continuous permafrost zone, where there are lower chances for unheated structures to cause enough warming and induce thawing. In such spaces, it is practical to design linear structures with the height of a barrier. It will ensure the annual summer thaw will not pierce through the permafrost. The discontinuous permafrost areas usually have warmer conditions; thus, it may require more evolved mitigation techniques.
Water and Wastewater Services
Historically, providing piped community water or wastewater services in permafrost-prone regions has been challenging. This challenge is aggravated in a warming Arctic. Communities having buried pipes must thermally protect the surrounding permafrost from the flowing warm liquid by pipe insulations. One can diminish this challenge with the help of heavily insulated utilidors or insulated arctic pipe over the ground surface.
Warm Permafrost
Besides the type of infrastructure, the thermal balance between infrastructure and permafrost foundation soils is complicated. The permafrost temperatures are generally within 1°C of the melting point in the discontinuous permafrost areas. Because of the construction disruptions, surface disturbances tend to move that balance to permafrost thawing. Some amount of climate warming can be addressed through more conservative designs. Adjusting to an extensive permafrost regime shift may be impossible or difficult in some situations.
Conclusion
Vamsi Kukkapalli an arctic engineer working on new evaporator constructs to efficiently improve the thermal performance of thermosyphons installed in roadway embankments. The impact of climate change in the Arctic encounter most of the same challenges as engineers globally, these challenges are interlinked with flooding, erosion, rising sea levels, social displacement, and wildfire. But the higher potential of structural damage associated with warming permafrost is distinctive to the Arctic and related cold regions.
Temperature distribution at optimum width for two-bifurcation level Y-shaped
Since permafrost thaw can be the outcome of different disturbances, locating the cause of thawing is usually difficult. Arctic engineers have established several techniques to mitigate or prevent infrastructure damage associated with permafrost thaw. Progress in remote sensing, design support systems, modelling, and imaging techniques can help engineers now and in the future.
References:
Kukkapalli, V.K., Kim, JH. & Kim, S. Optimum design of thermosyphon evaporators for roadway embankment stabilization in the arctic regions. J Mech Sci Technol 35, 4757–4764 (2021). https://doi.org/10.1007/s12206-021-0941-1
