DYWIDAG Multi-Stage Strand Anchor System
Enables higher anchor loads in weak ground through improved load distribution.
- Retaining Wall Tieback
- Uplift Restraint
- Excavation Support
The DYWIDAG Multi-Stage Strand Anchor comprises multiple strands with each bonded length placed at different levels within the borehole. This system ensures a more effective load distribution over the fixed length when compared with conventional anchors.
Conventional anchors typically have a maximum bonded length of 10 meters due to the risk of progressive debonding. Multi-Stage Anchors have no such limitations, enabling the achievement of the required anchor loads in weak ground. Through the use of multiple bonded lengths staggered at different depths within the borehole, the collective fixed length can be tailored to suit the ground conditions.
As a result of the bonded lengths being located at different levels within the borehole, each free length has a different length. To accommodate the differential extensions of the free lengths during stressing, a system of multiple pressure-synchronized jacks is required. A single jack is required for each free length, connected to a common manifold. This system enables the pressure in each jack to be synchronized whilst accommodating different extension of each strand, as the oil flows to the path of least resistance.
Staged bonded lengths ensure improved load distribution even in weak ground.
Unlimited bonded length enables the required anchor loads to be achieved despite poor ground conditions
Bonded lengths typically range from 3 to 5 meters, as greater lengths lose their efficiency
Available as temporary, semi-permanent, or permanent systems to suit all applications
Available as a partially or fully removable strand system when access is required for subsequent works or in temporary situations
Main standards for steel nuances
Europe/ Asia/ Latin America: Steel Strand Ø 15,2mm (0.6 in) and Ø15,7mm (0.62 in) – 1 to 22+ strands
UK: Steel Strand Ø 15,2mm (0.6 in) – 1 to 27+ strands
North America: 7-wire, low relaxation 270 ksi Steel Ø 0.6 in (15,2mm) – 1 to 61 strands
Bearing plates with angle compensation, different finishes.
Borehole spacers : lantern or skid
Tremie tubes for borehole grouting (bottom up)
Post-grouting tubes complete with TAM (tube à manchette) valves for bond stress enhancement