What is the difference between rock bolt and rock anchor?

An anchor is a system used to transfer tensile loads to the ground. Soil nails and rock bolts are bar anchors that are normally passive, although they can be active, or be prestressed with a small load.

How do rock anchor bolts work?

Rock bolts work by ‘knitting’ the rock mass together sufficiently before it can move enough to loosen and fail by unraveling (piece by piece). Unlike common anchor bolts, rock bolts can become ‘seized’ throughout their length by small shears in the rock mass, so they are not fully dependent on their pull-out strength.

What is rock bolting and anchoring?

An anchor is a system used to transfer tensile loads to the ground. Soil nails and rock bolts are bar anchors that are normally passive, although they can be active, or be prestressed with a small load.

How do rock anchor bolts work?

Rock bolts work by ‘knitting’ the rock mass together sufficiently before it can move enough to loosen and fail by unraveling (piece by piece). Unlike common anchor bolts, rock bolts can become ‘seized’ throughout their length by small shears in the rock mass, so they are not fully dependent on their pull-out strength.

What is rock bolting and anchoring?

Rock anchors are made of high tensile steel, and typically they are anchored in sound bedrock by means of high strength grouting. Ducts are placed in the concrete and holes will be drilled into the rock for post-tensioning application. The anchors may be bolts or cables.

What is active anchor?

Active anchors refers to pre-stressed anchors, in which the tensile force is established by tensioning a tendon free length against the anchor head. The anchoring force is established without further deformations in the ground.

What are rock anchors used for?

Rock anchors are used in civil and mining structures to counteract uplift forces acting on foundations and post-tension existing concrete structures.

What should be the distance between two lines of rock bolts?

In practise, the bolt pattern in systematic bolting is such that the in-row spacing and the distance between rows are equal. The bolt spacing, s, is recommended to be in the range from 1 m to 2.5 m. However, rock joint spacing should be also taken into account when the bolt spacing is determined.

How are rock anchors fixed?

A Rock anchor is a high strength steel tendon which is placed along with a stressing anchorage on one end, whereas a means for transferring force to the grout & rock on the other end. A hole is drilled of a proper length and diameter, after which the rock anchor tendon is inserted & fixed to the rock.

What are rock anchors made of?

Rock bolts are commonly used in tunnels or rock cuts. Rock bolts can either be anchored into the rock by mechanical or epoxy means. Rock bolts are made from steel or Fibre Reinforced Polymers (FRP). The most common FRP is fibreglass (GFRP), but other systems are available.

What is a passive anchor?

A Passive Anchor is not pre-tensioned. Applied loads are transmitted from the ground or ground structure directly. A passive anchor does not usually have a free (unbonded) length of tendon. A typical application for Passive Anchors is the stabilization of soil-covered slopes, which are constantly moving due to gravity.