Permafrost Degradation and Coastal Erosion and Their Potential Impacts on Civil Infrastructure in the Arctic

open_access
Open Access
Author:
Liew, Min
Graduate Program:
Civil Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 15, 2022
Committee Members:
Patrick Fox, Major Field Member
Chris McComb, Outside Unit & Field Member
Ming Xiao, Chair & Dissertation Advisor
Richard Alley, Outside Field Member
Tieyuan Zhu, Outside Unit Member
Patrick Fox, Program Head/Chair
Keywords:
permafrost
erosion
degradation
thermo-hydro-mechanical
infrastructure
thaw
consolidation
Arctic
coastal
settlement
Abstract:
Degradation and erosion of permafrost have induced irreversible damage to civil infrastructure across the Arctic. These unprecedented changes are now threatening indigenous Arctic communities, urging them to consider community-wide relocations. It is therefore important to understand the geotechnical implications of permafrost affected by the changing climate. In this dissertation, a comprehensive research framework is developed to understand the effects of permafrost degradation and permafrost coastal erosion and their potential impacts on civil infrastructure in the Arctic. This dissertation aims to facilitate a physics-informed, culturally relevant, and inclusive infrastructure planning process for the Arctic community by bridging the experience of indigenous Arctic communities and the expertise of multidisciplinary scientific communities. A community survey is first designed and conducted to understand the effects of permafrost degradation and coastal erosion on civil infrastructure. Observations were collected from residents in four Arctic coastal communities: Point Lay, Wainwright, Utqiaġvik, and Kaktovik. The types, locations, and periods of observed permafrost thaw and coastal erosion were elicited. Survey participants also reported the types of civil infrastructure being affected by permafrost degradation and coastal erosion and any damage to residential buildings. This study shows a useful approach to coproduce knowledge with Arctic residents to identify locations of permafrost thaw and coastal erosion at higher spatial resolution as well as the types of infrastructure damage of most concern to Arctic residents. Then, the state-of-practice of coastal erosion control measures in permafrost regions are synthesized. The study shows the challenges in constructing the current erosion control measures and the escalating cost of the measures over the last four decades. Emerging solutions and research gaps are also identified and discussed so that these measures may be upscaled for full-scale applications in the future. In this dissertation, the physical processes of permafrost degradation are synthesized and presented in a geotechnical context. Geophysical and geomechanical properties of permafrost that are critical for the assessment of foundation performance under permafrost degradation are identified, collected, and analyzed. While the data collected are highly scattered, regression analysis shows that most of the geomechanical and geophysical properties have strong associations with temperature. These associations highlight that the ongoing warming can greatly affect the performance of civil infrastructures in the Arctic. Finally, a three-dimensional fully coupled thermo-hydro-mechanical (THM) model is developed to simulate permafrost degradation. Physical processes such as heat conduction, phase change, thermal convection, fluid flow due to pore water pressure, elevation, and thermal gradient, and force equilibrium based on effective stress theory are considered in this model. The THM model is validated using thaw settlement results from the literature. A parametric study is also conducted to investigate the influences of various input parameters on the thermo-hydro-mechanical behaviors of permafrost with temperature.