Permanent ground anchors are applied for carrying high tensile forces onto the load bearing soil stratum in a longer period of time (over 2 years). A permanent ground anchor is made of: root length, rod (free anchor length) and anchorage.
Permanent anchors are primarily applied for:
• supporting various types of permanent retaining walls, incl. sheet pile walls, permanent Berliner walls, diaphragm wall pile walls;
• carrying high tensile forces resulting from the upper parts of constructions (e.g. mast stays) or buoyant forces (e.g. bottom plates) onto the ground,
• strengthening slopes and embankments (incl. protection of landslides). We offer the installation of permanent ground anchors with outer diameters of 133m or 152mm. The anchors are drilled with a gimlet bit in pipe casing with air/water/grout etc. flush, depending on the design. Upon making a borehole, grout injection is carried out and then the anchor bearing element is installed (such as a set of wires or a bar with double corrosion protection (DCP) to ensure prolonged lifespan, equipped with spacers, injection hoses and separator(s). Some 12 hours afterwards anchor injection is executed (single or double) and 7 days later the anchors are tested, compressed and stabilized with anchorage.
Due to the character of anchor performance – carrying tensile forces – and related risk, each anchor, before being put to use, is tested for load carrying capacity at least equal to the design load. Anchors used for supporting retaining structures are installed in one or more levels. The upper anchor level is usually located above the ground water level. Bottom levels are often installed below the ground water level (underwater anchors) with the use of watertight heads. In permanent ground anchors the heads are usually left accessible for inspection.
For very demanding structures, as well as in non-standard soil conditions or/and before application of a new anchoring technology, preliminary tests are performed before commencement of anchor installation in order to check applicability of anchoring and/or usability tests in order to define requirement for working anchor (for more info see PN-EN 1537 and PN-EN 1997-1).
Permanent ground anchors are installed in accordance with the requirements of PN-EN 1537: Execution of special geotechnical works – Ground anchors