Design Process

Proper site investigations, long-term planning, redundancies and the ability for adaptations are crucial for structures located in mountain permafrost environments. The actual degree mainly depends on the project and the sensitivity of the structure (Bommer et al., 2008). In-depth site investigations that include climate data and ground temperatures are critical for the determination of the actual ground thermal conditions as well as predictions for future ground temperature trends.

The design process must start with a thorough screening process. In Canada, the Panel on Research and Development (PERD) developed such a process (Hayley and Horne, 2008; PERD, 1998), that can be adopted for mountain permafrost infrastructure. Figure 6 shows the schematics that result in an assessment for the consequences and the sensitivity of the structure to be built. These two assessments are combined in a Consequence - Sensitivity matrix that forms the basis not only for the required design, but also for the required site investigation. Some examples are given in Figure 7. A temporary road, built mainly on permafrost bedrock, requires less thorough site investigations with specific laboratory tests to determine soil properties than a dam for a hydropower project that is partially founded on frozen ground. The latter should include possibilities for future adaptations of the structures as improved data of future climatic trends and structural response become available, based on a detailed monitoring programme. Structural reassessments should be made mandatory as part of the licensing process in such a case.

Failure Mode and Effects Analyses (FMEAs: Nahir et al., 2005; Robertson and Shaw, 2005) are an additional important pillar during a design process. The result of the analysis is to be incorporated into the screening process as it identifies sensitivities as well as consequences. This should be an unreserved process with various experts involved. The earlier an FMEA is carried out, the better it can be used to guide the project design.

Fischer and Huggel (2008) present a methodical design for stability assessments of permafrost affected rock walls that provides additional information when dealing with structures in rock.

Risikobeurteilung Baum

Sensitivity matrix

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