Over 80 years of experience in structural stabilization and foundation work, including engineering and contractor services related to drilling and grouting, anchor and tieback systems, installation of instrumentation, and cellular concrete and fly ash placement.

Rock Bolt Anchoring

What is Rock Bolt Anchoring?

Anchors are durable, reliable, economical tension supports used in a wide variety of situations to stabilize, secure, and augment structures. Made of high strength steel bars or strands, rock bolt anchoring bonds these steel bars and strands to rock, concrete and many types of soil. Rock bolt anchoring is used to counteract external, overturning, uplift, and seismic forces, and are used actively (prestressed) or passively (non-stressed). Stranded tendons can be fabricated for extremely high capacity load.

Rock bolt anchoring uses soil and Rock Anchors or “Nails” that are fully grouted passive, or non-tensioned anchors used to resist uplift or failure forces for earth retention, slope or rock face stabilization. Rock bolt anchoring also utilizes these nails for tunnel roof supports. The nails are situated for the best possible advantage of residual forces in soil or rock (broken or solid) for load transfer. Passive anchors are utilized where prestressing is neither possible nor desirable, as in fragile rock conditions where movement of the medium in situ should be avoided.

The main step in rock bolt anchoring is where soil and rock nails are fully grouted, passive (non-tensioned) anchors are used to resist uplift forces and failure forces on slopes or excavations. The nails take advantage of residual stresses in soil or excavations. In the process of rock bolt anchoring the nails utilize residual stresses in soil or rock (broken or solid) for load transfer. However, passive rock bolt anchoring is generally used where prestressing is either not possible or desirable. Rock and concrete anchors are prestressed tendons can be bars or multiple strands. A portion of the length is bonded to rock or concrete by cement grout, resin, or fixed by a mechanical anchor. The upper portion, or free length, is left ungrouted for prestressing, but is grouted afterwards to lock in tension and protect against corrosion.