Struts (wire struts, line struts, tensioning etc.) are mainly used to anchor sheet piling to rock. The usual method is to fit the strut to the back of the sheet piling at a 45 degree angle, but other angles may be used.
The components of the rock strut are the anchor head, a length of strut through a drilled casing tube and a length into the rock for anchorage. The power is obtained by embedding one or more laces into the rock.
The difference between temporary and permanent struts is in the actual steel used and the specified corrosion protection requirement. Struts with a design life of more than two years are normally counted as permanent.
All types of anchor heads with wedge locking of tension cable give a lock displacement. This is often about 5-6 mm. This means that the tension cables must have a minimum free length in order to achieve the defined lock load, depending on the difference between trial load and lock load. The minimum free length is normally 5.0 metres. Anchorage lengths vary with rock quality.
Our anchorages in stock are based on Ø15.24 mm (0.6″) tension cable of area = 140 mm2, produced according to prEN 10138-3 and ASTM A416 with yield strength, fy (S0.2)=1670N/mm2 and breaking point, fu=1860 N/mm2.
The lace has weight = 1.1 kg/m and consists of seven cords Ø5 mm.
Drilling system and diameter must be adjusted to the angle and length of strut, as well as any requirement for covering between strut and drill hole. Water loss measurements etc. ref special description.