ROCK BOLTS

TUNNEL STEEL COMPONENTS PRODUCTS & INSTALL

A Rock Bolt is a long anchor bolt, for stabilizing rock excavations, which may be used in tunnels or rock cuts. It transfers load from the unstable exterior, to the confined (and much stronger) interior of the rock mass.

Rock Bolts are almost always installed in a pattern, the design of which depends on the rock quality designation and the type of excavation. As with anchor bolts, there are many types of proprietary rock bolt designs, with either a mechanical or epoxy means of establishing the set.

Rock Bolts work by ‘knitting’ the rock mass together sufficiently before it can move enough to loosen and fail by unravelling (piece by piece). Rock Bolts may be used to support wire mesh, but this is usually a small part of their function. 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.

SPECIFICATIONS

As there are many different sizes of Rock Bolts, we shall be manufactured different variety sizes which mean you can customize them depending your usage. Hence, please contact us for your requested dimensions at technic@momentum-metal.com

ASSEMBLING

Rock Bolts are mechanically point anchored within the rock using 3 leaf bail-type expansion shells attached to the inserted end of the bolt. Expansion shells are supplied screwed to the end of the rock tendon and are inserted into the hole. When tension is applied to the tendon the tapered plug within the shell forces the leaves to move outwards, thus wedging them against the walls of the borehole. This means that the mechanical bolt is functional immediately on installation. In many applications the installation is post-grouted for additional stability.

The complete Rock Bolt assembly includes the threaded bar, bearing plate (washer), nut, seat and expansion shell. Numerous combinations are available to suit individual strata control requirements.

These include: Bar Type, Bar Diameter, Thread Type, Expansion Shell Size, Washer Profile and Washer Dimensions.

We present Bernold Type Sheets and Rock Bolts to all contractors worldwide.

EVENTUALLY

In terms of many other practices for tunnel constructions (parallel to the insfrastructure investment increasing lately), Bernold Type Sheet and Rock Bolts are much easier in respect of not being applicability but also being reliability.

Beginning from the day it started to practice till to nowadays, both systems have been carried out and the tests have demonstrated that bonding between concrete and Bernold Type Sheet is absolutely perfect without having any minor problem; including applying Rock Bolts for tunnels and all other rock surfaces. MOMENTUM METAL BERNOLD TYPE SHEETS and ROCK BOLTS provide more security, more efficiency and even better costs.