Why Soil Nail Walls?
Soil nail walls consist of a grid of "nails" drilled anywhere from 10-50 ft horizontally into the wall of an excavation. A facing is installed on the wall and held into place with washers and nuts on each nail.
Soil nail walls are the preferred shoring solution when the situation allows. If shoring is required, due to poor soil or inability to slope excavations back, a soil nail wall can be installed to ensure that the dirt stays in place. A soil nail wall can be installed as long as there is relatively cohesive soil, no groundwater, and no utility or right-of-way issues with the nails.
How it's done
Either grouted-in-place hollow bars or helical piers are typically used as the nails for soil nail wall shoring. Nails are drilled horizontally into the ground and a facing is installed through the nails with washers to hold the facing in place. A shotcrete permanent facing can be installed if necessary.
Soil nail walls are typically quicker and easier to install than other shoring methods. There is no disruptive vibration during installation. Once a soil nail wall is installed, the nails and most of the facing are sacrificial. Only the washers and nuts are typically recovered, instead of the entire system, saving more time during shoring removal.
Chris-Hill has installed a number of soil nail walls over the past decade.