Roadway Landslide Repair with Soil Nails

A state Department of Transportation in the Northeast had been self-performing slope stability monitoring for a failing fill slope along a rural road that served as the only access for a group of residents (and a large sod farm) since 2000. Once the failing slope began to threaten the road, the state knew slope stabilization measures were required to ensure the travel artery remained unaffected. Traditional repair methods, including sheet piling, slope flattening, a reinforced soil slope, and a Mechanically Stabilized Earth wall (MSE wall) either involved temporary road closure, right of way acquisition, encroachment onto an easement maintained by the state’s Society for the Protection of Forests, or were beyond the designated project funding levels.

Slope Failure Mitigation Through Soil Nailing Techniques

Over Mother’s Day Weekend in 2006, the area received over 10-inches of rain in a 24-hour period, causing the slope to drop more than six inches. GeoStabilization International®, leading soil nail wall contractors providing engineered soil repairs throughout the United States and Canada, visited the site and presented a soil nail wall solution that would not require easements, right of way acquisition, would maintain traffic in one lane throughout the repair, and could be completed in a fraction of the time and for a fraction of the cost of the “traditional” options. Since all these options were desirable to the state, GeoStabilization was awarded the landslide mitigation contract.

Soil Stabilization Technology with Launched Soil Nails

Once our crew arrived on site, they immediately began stabilizing the slope below the road by installing soil nails using our Soil Nail Launcher™, one of GeoStabilization’s soil stabilization innovations. Since this device dynamically shoots the soil anchors into the ground without the need for grouting, the nails can begin accepting load immediately, meaning the slope becomes stronger as the nails are installed. Also, launched soil nailing is installed much faster than traditional drilling methods, so the project’s duration is less, saving time and money. All the work was completed from the roadway platform above the slope to avoid altogether disturbing the forest below the slope with messy access roads.

Once the crews launched more than 200 galvanized and perforated soil nails into the slope, a high-tensile wire mesh was placed on the slope and then secured with bearing plates and nuts. This Galfan-coated wire mesh was tightened securely to the slope and acts as a soil retention system to engage the soil if it begins to move in the future. Topsoil was installed over the wire mesh to camouflage the mesh system’s existence completely and then seeded with native grass.

The site had been monitored by the state’s Geotechnical staff using inclinometers for over eight years and has shown no movement. Better yet, the entire area has been overgrown with vegetation to make the repair invisible to the naked eye.

A Leading Mitigation Company in the United States and Canada

For over twenty years, our teams have been providing residential slope stabilization, slope monitoring, slope protection, and landslide prevention services. Contact GeoStabilization International® at 855-579-0536 to learn how to utilize our geohazard mitigation services for your geotechnical application.