Experimental Study of Ice-Rich Permafrost Cut Slope Protection

In Alaska and other permafrost regions, cut slopes are often required in order to achieve roadway design grades in ice-rich permafrost areas. However, excavation of a cut slope and subsequent exposure to sunlight destroy the existing thermal balance and result in degradation of ice-rich permafrost. Uncontrolled erosion and runoff, as well as slope failure of cut slopes, resulting from thawing ice-rich permafrost can cause environmental distress that is not acceptable by many environmental laws. This study investigates three potential environmentally acceptable thermal-erosion mitigation techniques to address the regulatory concerns raised by current practices. Four test sections, using 0.3 m wood chips, coconut blanket, coconut blanket and Tecco mesh, and 0.3 m crushed rock, respectively, were constructed at the Dalton Highway 9 Mile Hill in interior Alaska. Different sensors were installed to measure changes in the temperature and moisture in the four test sections with time and evaluate the effectiveness of the different thermal-erosion mitigation techniques. A weather station was also installed to monitor climate information at the test site. The thermal erosion of the cut slope was evaluated using a photogrammetric method. This paper presents results from the field monitoring period. The effectiveness of different thermal-erosion mitigation techniques is also discussed.