Tieback (geotechnical)

For other uses, see Tieback (disambiguation).

A tieback is a horizontal wire or rod, or a helical anchor used to reinforce retaining walls for stability. With one end of the tieback secured to the wall, the other end is anchored to a stable structure, such as a concrete deadman which has been driven into the ground or anchored into earth with sufficient resistance. The tieback-deadman structure resists forces that would otherwise cause the wall to lean, as for example, when a seawall is pushed seaward by water trapped on the landward side after a heavy rain.

Tiebacks to reinforce a slurry wall at Ground Zero, NY

Grouted tiebacks can be constructed as steel rods drilled through a concrete wall out into the soil or bedrock on the other side. Grout is then pumped under pressure into the tieback anchor holes to increase soil resistance and thereby prevent tiebacks from pulling out, reducing the risk for wall destabilization.

Helical anchors are screwed into place. Their capacity is proportional to the torque required during installation. This relationship is in accordance with the equation Qt = kT where Qt is the total tensile resistance, k is an empirical constant and T is the installation torque. These anchors are installed either for small loads in short sections or for larger loads and in long continuous lengths.

External links

California Department of Transportation tieback document

Geotechnical engineering

on-site	Cone penetration test Standard penetration test Monitoring well piezometer Borehole Crosshole sonic logging Nuclear densometer test

laboratory	Atterberg limits California bearing ratio Direct shear test Hydrometer Proctor compaction test R-value Sieve analysis Triaxial shear test Hydraulic conductivity tests Water content tests

Soil

Clay Silt Sand Gravel Peat Loam Loess

properties	Soil classification Hydraulic conductivity Water content Void ratio Bulk density Thixotropy Reynolds' dilatancy Angle of repose Cohesion Porosity Permeability Specific storage

mechanics	Effective stress Pore water pressure Shear strength Overburden pressure Consolidation Compaction Shear wave Lateral earth pressure

Stability

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