Helical tiebacks are used to secure retaining walls or to secure shoring of excavations. Multi-helix screw anchors are used because they enable the tiebacks to remove the performance uncertainties and costs associated with a grouted anchor when used in loose, sandy and low-shear-strength clay soils. When screwed into the soil, the helical anchor acts as a deep, end-bearing tension member to secure the retaining wall.
Other advantages to tiebacks for retaining walls and shoring include:
- Tiebacks may be installed with conventional rotary drilling equipment.
- Screw anchors are quick to install. Typical installing time per tie back is 20-30 minutes with no spoils removal necessary.
- Elimination of grout allows for immediate loading or testing.
- In some cases the screw anchors can be withdrawn and reused.
How Tiebacks Work for a Retaining Wall
The lead section of the tie back anchor can be equipped with one or more helical bearing plates ranging from 6” to 16” diameters. Plates are welded onto a steel shaft, each one acting as a separate anchor for maximum holding capacity. The lead section is followed by extension rods as it is drilled through the no load zone directly behind the wall and into the load zone.
If you have a project that may require installation of helical tiebacks, contact us.