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Rock bolt

Inactive Publication Date: 2017-10-19
NORTHERN MINING PROD AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an embedded dynamic rock bolt that has a longer range of strain and higher energy-absorbing ability. This solution solves problems associated with conventional embedded dynamic rock bolts.

Problems solved by technology

This leads to increased rock tension and an increased risk of seismic activity.
If the degree of strain is large, the absorption of energy is also large.
A bolt with several anchors reduces the energy-absorbing ability of the bolt, since the stretch over which the bolt can be strained is reduced.
One disadvantage of dynamic embedded bolts arises if damage in the rock chamber reaches the region between the anchors, since in this case no counteracting forces are present to hold the rock in place.

Method used

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Embodiment Construction

[0026]FIG. 1 shows a rock bolt 1 according to the invention intended to be embedded in a borehole 2 in rock. The rock bolt 1 comprises an extended external tubular part 3 and an internal extended energy-absorbing part 4. In one preferred embodiment, the external part 3 has been given a length that is somewhat less than the length of the energy-absorbing part 4. The external tubular part 3 has a first end 5 and a second end 6, and a magnitude that allows the energy-absorbing part 4 to be surrounded by the external part 3. It is an advantage if the external part 3 has circular cross-section in the form of a circularly symmetrical metal tube, but it should be realised that also other forms and materials are possible. Square, elliptical or rectangular tubes, of metal, plastic or composite material can, for example, be used. Also other forms of the external tubular part 3 can be used.

[0027]The jacket 7 of the external tubular part 3 is, as is shown in FIGS. 6a-6c, arranged with a frictio...

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Abstract

A rock bolt to be embedded in a borehole and a method of manufacturing a rock bolt, the rock bolt including an extended energy-absorbing part, the first end of the energy-absorbing part including an anchor and the second end of the energy-absorbing part including a screw joint for prestressing the rock bolt. The rock bolt includes an extended tubular part with a jacket and a first end section and a second end section, with an internal dimension that is larger than the external dimension of the energy-absorbing part and arranged in such a manner that it surrounds the energy-absorbing part.

Description

[0001]The present invention concerns a rock bolt for the absorption of forces during the reinforcement of rock chambers in mines and during similar work with rock.BACKGROUND[0002]Mines in the world are being constructed ever deeper in order to reach minerals. This leads to increased rock tension and an increased risk of seismic activity. As the depth increases and in regions with large deformations, reinforcement with the ability to absorb energy, known as “dynamic reinforcement”, is used.[0003]There are principally two different types of energy-absorbing bolt. In one variant, the absorption of energy takes place through friction between the bolt and the grout or between the bolt and the borehole. The bolt glides and absorbs energy.[0004]A second method is to deform or strain the bolt. If the degree of strain is large, the absorption of energy is also large. The larger the degree of strain, the larger the absorption of energy.[0005]In order to achieve as large a degree of strain as ...

Claims

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Application Information

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IPC IPC(8): E21D21/00
CPCE21D21/0033E21D21/004E21D21/008E21D21/02E21D21/00
Inventor KREKULA, HAKANERIKSSON, LEIF
Owner NORTHERN MINING PROD AB
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