Cable Bolts
The Wedge Anchorage of the Cable Bolt
The anchorage of most cable bolts consists of a wedge barrel and a 2- or 3-part wedge. The wedge segments grip the cable by means of tooth shaped threads which are forced into the surface of the cable wires. Warning: If friction increases (due to corrosion), a larger F will reduce the clamping force. As V increases, all other forces can only increase if the wedge can seat deeper into the barrel. If the wedge is restrained to do so (i.e. by corrosion or dirt accumulation), the clamping force can not increase with the pulling force causing slippage when the load on the cable bolt gradually increases during service life. To avoid slippages during use, it is important that the cable bolt is fully stressed at time of installation to a force equal to 0.5 Fu. (ie. 50% of the capacity of the cable)
The clamping force W is highly dependent on the friction between wedge and wedge hole. For normal friction conditions, the clamping force W is more than 4 times the cable pulling force V and it adjusts with the pulling force V.
When a wedge is properly seated, radial cracks may develop indicating adequate seating.
The wedge can be supplied with a rubber O-ring or a metal spring ring holding the wedge segments together.
The wedge can be supplied with a rubber O-ring or a metal spring ring holding the wedge segments together.