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In anticipation of inevitable climate-induced changes in permafrost, additional consideration is required when designing and constructing new infrastructure in dynamic northern environments.  What about existing infrastructure? The degree to which it will be affected is often poorly understood; the design criteria of yesterday, in some cases, may not be sufficient to handle expected landscape changes of today and tomorrow.

The extent that infrastructure in arctic regions may be affected by thawing permafrost is shown below Hinkel et al.(2003) . Population centers are represented by red dots, while the pink shading delineates areas of human settlement.  For comparison, the distribution of arctic permafrost can be seen in a previous posting.

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Accounting for the variety of factors that may affect permafrost distribution over large geographic scales is difficult, given the large variability in physiography, as well as soil characteristics and types of land cover.

Further, areas underlain with ‘warm’ permafrost (permafrost that is very near the freezing point), are likely to experience widespread thaw and subsequent settlement, much sooner.

Let’s look at another image from Hinkel et al. to see specifics related to transportation infrastructure.  Here, yellow lines indicate winter trails, blue lines are railroads, and red dots are airfield locations.

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Routes for Mitigation

  1. Enhanced Design Criteria
    1. Geotechnical design should consider the latest methods when approaching new construction and retrofitting in zones of warm and/or discontinuous permafrost:
      • Active/passive refrigeration and/or deeper piles on building foundations
      • Scaled embankments
      • Adequate insulation
      • Blow-through spaces
      • Water drainage
  2. Improved Data Coverage
    1. The acceptable design life of a structure may also need to address unexpected, local thaw and settlement. Updated thermal and mass balance models, with appropriate boundary conditions and driven by adequate data, are critical tools to assess uncertainties in a structure’s design life under global warming conditions.
    2. “While yesterday’s baseline may or may not be valid today, it will definitely not be valid tomorrow.”  Hans Christian Krarup, Golder Associates, Inc.

Following Han’s lead, more data is required to maintain context on the bigger picture.  This not only means more baseline data in order to establish new benchmarks, but also operational monitoring throughout all project phases to gauge how conditions are changing over time, in order to respond quickly and appropriately. More data, both spatially and temporally, provides better context to help adapt current design and guide future design and construction. This will save time, money and resources, resulting in higher efficiency with better, longer-lasting results.

 

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