Department of Civil Engineering and Water Engineering, Université Laval
1065 avenue de la Médecine
Quantitative risk analysis of linear infrastructure on permafrost: geotechnical properties to social impacts
Qualitative analysis processes are currently used to design, and allocate maintenance monies for, linear infrastructure on permafrost. The routing is generally selected using a qualitative process with risks and their associated consequences evaluated using a scalar rating system, generally 1 to 5 or 1 to 10. The values of risk and consequence are multiplied to determine an importance factor. Risks are ranked and analyzed based on the value of the importance factor. Climate change vulnerability assessments for highways in permafrost regions of Canada utilized this methodology. While these analysis methods have been used in practice for many years, there is a push within the engineering community towards analysis methods based on probability theory, quantifying the analysis process. Specifically, probabilistic methods have been used to determine the reliability of geotechnical factors of safety, and statistical updating methods have been presented to refine geotechnical investigations.
The goal of this project is to develop a tool for quantitative risk assessment for embankment infrastructure (roads and airstrips) built on permafrost. The tool will be objective, removing the human factor from the risk assessment; this tool could be used to prioritize maintenance monies or select infrastructure routes to reduce risk. The analysis method will be calculated on a landform basis, utilizing input values including: climate factors (present or future depending on the needs of the user), geotechnical properties (in-situ soil and fill material properties), and site geometry. A landform is an area defined in surficial geologic mapping, formed by a specific geological process; thus, the underlying soil conditions and surrounding land features should be similar. Weighted averaging of the greatest risk along an alignment should be used to determine an overall infrastructure risk. A landform calculation basis will also allow a risk analysis map to overly the landform maps commonly used in infrastructure development and management.
The objective tool will determine the vulnerabilities of existing infrastructure and aid in determining the risk associated with climate warming. Since a risk analysis includes both an analysis of failure probability and a consequence of failure analysis, the socio-economic costs, both direct and indirect, can be added to the analysis; helping communities to use limited resources in an effective manner.
Since the roadway and airstrip infrastructure is of upmost importance in rural communities, a quantitative risk assessment tool will also aid the public sector in hazard assessments.
Brooks, H., Doré, G., Smith, S., 2018. Permafrost geotechnical index property variation and its effect of thermal conductivity calculations. Cold Regions Science and Technology, 148: 63-76. DOI: 10.1016/j.coldregions2018.01.004.
Doré, G., Niu, F., Brooks, H., 2016. Adaptation methods for transportation infrastructure built on degrading permafrost. Permafrost and Periglacial Processes, 27(4 - Special Issue: Transactions of the International Permafrost Association): 352-364. DOI: 10.1002/ppp.1919.