AIDC project number: 309032R

• Start Date: Oct 1, 2010
• End Date: Dec 31, 2011

Project Documents

Final Report

Project Summary

The failure mechanisms of unstable soil slopes in permafrost areas are not well understood. Analysis of these slopes requires consideration of soil temperatures, ice content, and their effects on soil strength, which is not part of typical slope stability analysis. These unstable slopes may vary in depth, affecting only the active layer or having a more deep-seated nature. Additionally, the subsurface conditions may be a complex mixture of frozen and unfrozen areas, which affects the groundwater flow and overall slope stability. Whatever their configuration, these unstable slopes possess characteristics that are unique to permafrost regions. Several unstable soil slopes in frozen ground exist along highways in Alaska's Northern Region. These areas of instability require ongoing maintenance and monitoring until possible mitigation strategies are developed. Without understanding the intricacies of these unstable slopes in frozen ground, the engineers from the Alaska Department of Transportation and Public Facilities (AK DOT&PF) may be at a disadvantage when developing mitigation strategies.

The research objectives of this project are:

1. to provide a comprehensive review of literature on unstable soil slopes in permafrost areas, including an overview of both successful and unsuccessful mitigation strategies that were applied previously,
2. to summarize case studies of key historic and/or ongoing unstable soil slopes in AK DOT&PF's Northern Region, and
3. to develop a training product for AK DOT&PF engineers that categorizes typical unstable soil slopes in permafrost areas within AK DOT&PF's Northern Region, and appropriate mitigation strategies. This training product will provide background and guidance to engineers at AK DOT&PF who will need to develop mitigation strategies for similar slopes in the future.