DYWI® Drill Hollow Bar System
DYWI® Drill Injection Anchors provide an effective temporary anchor that can be readily installed into loose or collapsing ground without the need for a casing. Rotary percussive drilling, combined with simultaneous grouting, ensures that the grout penetrates the surrounding ground to provide an increased level of bond.
All ground anchors should incorporate a fixed length (bonded in the stable zone) and a free length (debonded with a sleeve, in the wedge zone) to enable the anchor to be prestressed. The prestress provides an active restraint, enabling the anchor to resist service loadings without additional elongation.
DYWI® Drill Hollow Bar Systems (irrespective of threadform) are recommended for temporary anchors. Special caution should be taken when considering their use for permanent anchors as corrosion protection and long term steel relaxation may be a concern. Rotary installed bars cannot provide the level of corrosion protection necessary for permanent anchors working in tension as outlined in current anchor standards. For permanent anchors, use of properly protected prestressing steels are recommended. Refer to DYWIDAG THREADBAR® and Strand Anchors with Double Corrosion Protection, and the Post-Tensioning Institute’s Recommendations for Prestressed Rock and Soil Anchors.