Helical Soil Nails in North Carolina

To avoid the performance uncertainties and costs associated with grouted soil nails, Tar Heel Foundation Solutions prefers the faster and more cost-effective method of helical soil nails. A helical soil nail wall is a gravity composite soil structure in which an excavated slope or vertical cut is internally reinforced through the placement of closely spaced linear helical soil nails. An Earth Contact Products (ECP) helical soil nail consists of a shaft fabricated from either 1-1/2″ or 1-3/4″ solid square steel bar. Welded along the entire length of the helical soil nail shaft are identically sized helical plates measuring six or eight inches diameter with a plate thickness of 3/8″.

Soil nails are passive structural elements and are not tensioned after installation. The soil nail gains pullout resistance from within the sliding soil mass in front of the slip plane and the stable soil mass located behind the slip plane. The geometric system of soil nail placements creates an internally reinforced soil mass that is stable. Soil nails may be the product of choice in applications where the vibrations from installing sheet piling or “H” piles may cause structural distress to nearby structures. Soil nails are generally installed to a shallower depth than tiebacks, which might be an advantage if deeply installed tiebacks have to cross property lines and/or terminate under structures owned by other parties.

Helical Soil Nail Installation in Charlotte, NC

Tar Heel Foundation Solutions installs the helical soil nails in an evenly spaced close geometric pattern. When installing a helical soil nail stabilization project, the soil nail installations and the excavation must be accomplished in incremental depths of 4 to 6 feet until the final depth of cut is accomplished. Usually, only one increment can be completed per day. Immediately following the incremental excavation of the soil and the soil nail installations, the vertical face of the soil is covered with a steel-reinforced coating of shotcrete. Soil nails are passive structural elements and are not tensioned after installation. The soil nail gains pullout resistance from within the sliding soil mass in front of the slip plane and the stable soil mass located behind the slip plane. The geometric system of soil nail placements creates an internally reinforced soil mass that is stable.