Wicking Geosynthetic Used for Frost Heave Prevention Pioneer Mountain Scenic Byway

摘要

Problem The Pioneer Mountain Scenic Byway, located just 30 miles West of Dillon Montana, seasonally experiences frost heave over a 20 mile stretch of roadway. The road is closed to winter traffic and typically opened in May. Longitudinal cracks are commonly found. The Moose Park location experiences the most dramatic problems and had been recently repaired in 2004. Solution & Design Federal Highways subsurface investigations indicate a high water table and a variable subgrade strength consisting of silts and pit run materials. The preference is to minimize over excavation and looked to geosynthetics as an option. The new wicking geosynthetic provided by TenCate was recently used on an Alaska DOT project with early indications of success. Three design solutions were proposed and presented to the county for review. The dual layer solution was selected to minimize the cross section depth and keep the wicking geosynthetic above the water table to mitigate the frost heave effects. Construction In the fall of 2013, the site was excavated to the required depth finding a mix of materials to include 4 drain tiles and miscellaneous geosynthetics used in previous repairs. The first layer of wicking geosynthetic was installed and covered with select pit run aggregate. Early wicking was witnessed shortly after installation. The project was put on hold as snow started falling and temperatures dropped at this 7625 foot elevation. The final installation will be completed in early summer of 2014.