Anchors transfer loads using grouted thread bars or strand tendons connected to a structure and bonding into stable soil or rock.

Keller rig installing micropiles

Common uses

Excavation support
Temporary or permanent slope stabilization
Tie down applications for permanent structures

Process

Anchors consist of full-length holes that are drilled vertical for uplift support or at angles for lateral support into the bond zone in soil or rock, using casing if necessary. Thread bar or strand tendon is inserted into the hole and the hole is filled with high-strength grout. Any casing used is then extracted. Bond breaker covers the length of bar or strand above the bond zone to eliminate load transfer there. Then, the anchor head is generally tensioned and connected to the structure requiring the support.

Ground anchors are also frequently utilized for lateral support of slurry diaphragm walls. Since the ground anchors provide intermediate points of support at one or more levels, they reduce bending moments and consequently reduce the need for thicker walls, reinforcement, and depth-of-toe requirements. Anchors eliminate the need for internal steel bracing and strutting within the excavation and leave it free of obstructions which reduce excavation costs and speeds up construction. This aspect can be particularly valuable in congested urban locations with limited surrounding space for equipment and materials. Anchors are used in soils or in rock and may be either permanent or temporary.

Advantages

Pre-stressing reduces movement of support structures
Installation in limited access areas and complex drilling conditions
Reduces pile diameter, length and distance
Cost effective bracing system for all soil conditions

Quality assurance

Keller has been installing anchors for many years, continually evolving the technique to achieve better performance. Testing and monitoring to ensure high quality execution.