Multi-helix screw anchors have established a consistent record of performance through extensive use in the tieback, electric-utility and petroleum industries. Construction applications for screw anchors in retaining-wall tiebacks continue to grow. They provide an excellent solution for failing retaining walls, bulkheads and basement walls. When these structures fail due to inadequate support or soil pressures, Carolina Foundation Repair can provide permanet and effective stabilization with tieback anchors.The screw anchor’s advantage is how it removes the performance uncertainties and costs associated with a grouted anchor when used in loose sandy soils and low shear-strength clay soils. When placed in the soil, the screw anchor acts as a bearing device. This is a fundamental difference compared to a grouted anchor formed in soil and reliant on friction between the soil and grout.
Screw Anchor Advantages
Several factors contribute to the lower installed costs of screw anchors:
- May be installed with conventional rotary drilling equipment used in grouted anchor tieback construction.
- Faster to install. No drilling or spoils removal. Typical installing time is 20 to 30 minutes.
- Immediate testing following installation since grouting is eliminated.
- Monitoring torsional resistance during installation gives an indication of soil strength that can relate to anchor-load capacities and help prevent overstress.
- Screw anchors can be withdrawn and reused.