D-Bolt ©0 pages

Technical data sheet
February 2014

©

D-Bolt

General description
The D-Bolt is a rock reinforcement element comprised of a smooth steel bar with a number of deformed sections that
act as anchor points along its length. The collar end of the D-Bolt is threaded and is designed to be used with a face plate,
spherical washer and a nut that fastens the bolt. The bolt is fully encapsulated in a borehole, but it is only constrained to
the grout or resin along the anchor points. This allows the smooth sections of the bolt, between the anchor locations, to
deform without constraints and absorb energy as the rock mass dilates.

Functionality
The D-Bolt reinforces the rock mass by constraining the dilation between the anchor points. When the rock mass dilates,
the anchor points assume the load and the smooth sections between the anchor points stretch. The load on the smooth
sections increases quickly with a small increase in the dilation, until the yield load is reached. Once the yield load is
reached the smooth sections undergo plastic elongation until failure. The D-Bolt absorbs the dilation energy by fully mobilising the strength and deformation capacities of the bolt material. The smooth sections of the D-Bolt provide localised
and independent reinforcement to the surrounding rock mass. This has the important advantage whereby failure of one
section of the bolt would not affect the reinforcement function of other sections along the length of the bolt.
The anchor points are designed to mix two-component cartridge resins when the D-Bolt is spun into the borehole.
The D-Bolt steel is manufactured using micro-alloyed, engineered carbon steel using specific properties that result in
an optimal combination of yield strength, ultimate tensile strength and elongation. D-Bolt is also available with a hot dip
galvanized (HDG) and/or powder coating that provides further resistance to corrosion.

Typical applications
The D-Bolt can be used as an effective rock reinforcement element in underground excavations. As a result of its unique
ability to both withstand high static load and absorb dynamic energy, it is particularly suited in areas prone to large deformations in the rock mass, including rock burst and squeezing rock areas. D-Bolt can be installed with standard mechanized bolting equipment, as well as manually, in both cementitious grout and resin.

Normet reserves the right to change this specification without further notice.
Normet International Ltd.

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Tel: +41 41 768 52 00
Fax: +41 41 768 52 11
info@normet.com