AASHTO Journal, 15 February 2013
Wyoming Department of Transportation solved a three-decade landslide issue on time and on budget by developing a new way to stabilize a landslide area using vertically installed micro-piles.
The Double Nickel Landslide (named after its location—milepost 55 on WYO 28) just south of Lander had caused WYDOT trouble since the 1980s, when WYO 28 was realigned. WYDOT tried several methods to fix the problem, but found that they only slowed movement of the landslide. Unusual amounts of water from heavy snow and rain in the spring of 2010 resulted in major slide movement and roadway damage.
WYDOT needed to come up with a completely new way to stabilize the landslide and traditional methods were not an option due to project constraints – there could be no additional right-of-way or major environmental regulatory work. WYDOT’s design consultant, HNTB, developed a stabilization technique using vertically installed micro-piles (or small steel casings with a reinforcing steel bar filled with cement grout) that included four rows of 80- to 100-foot-long shear piles installed through the soil and rock slide mass and embedded into the stable bedrock.
The project was bid on schedule and construction began in May 2012. The project was finished in September, on time and within the $5.8 million budget. Better yet, WYDOT has a new tool in its toolbox to remedy numerous ongoing landslides impacting highways throughout Wyoming.