Rock Safety

Polyester end-anchored bolts were introduced around 1970. This bolt type is currently the most common for use in road tunnels. Pipe bolts were introduced in the 1980’s, but are mostly used for underwater tunnel construction. Pipe bolts have gradually been replaced by polyester anchored re-bar bolts. The polyester bolts are corrosion resistant from the GalvaCoat treatment.

A common principal is to utilize the rock’s ability for self-support, but there are different opinions on what safety measures should be used to achieve this. The stability measures are divided into three groups:

• Clean-up and bolting
• Spray cement combined with bolting
• Full cement casting