JOINING OF TUBE-FORMED EXPANSION BOLT

ELEMENT POUR ANCRAGE FORME DE PIECES TUBULAIRES JOINTES

English Abstract

Tube-formed rock bolt intended for expansion into contact with the wall in a
bore hole without stretching the periphery of the rock bolt. The rock bolt
comprises an elongated tube (12) with closed cross section. The tube is
provided with a longitudinal depressed part (13). End pieces (14, 24) are
secured to the ends of the tube. Rock bolts according to the invention can be
connected to arbitrary length through screwing them together. The end pieces
are provided with axial channels (15, 35) whose peripheries sealingly
cooperate through deformation of the material when the rock bolts are screwed
together. Through connecting one end (30) of the assembled rock bolt to a high
pressure pump (39) the entire assembled rock bolt can be expanded at the same
time.

French Abstract

L'invention concerne un élément pour ancrage dans la roche, formé de pièces tubulaires et capable de se dilater et de venir en contact avec la paroi d'un trou de forage, sans étirage de sa périphérie. Chaque pièce comprend un tube allongé (12) à section transversale fermée. Le tube a une partie longitudinale en creux (13). Des embouts (14, 24) sont fixés aux extrémités du tube. Les pièces selon l'invention peuvent être assemblées jusqu'à une longueur quelconque, en les vissant ensemble. Les embouts ont des canaux axiaux (15, 35) dont les périphéries coopèrent d'une manière étanche par déformation du matériau quand les pièces sont vissées ensemble. En reliant une extrémité (30) de l'élément d'ancrage à une pompe à haute pression (39), on peut provoquer la dilatation simultanée de tout l'élément.

Claims

Claim:
1. Tubeformed rock bolt comprising an elongated tube (12) with closed cross
section and provided with a longitudinal depressed part (13) which at expansion of the rock
bolt increases in diameter without stretching the periphery of the tube and an end piece (14)
provided with an axial channel (15) in connection with a room (16) defined by said tube
(12), c h a r a c t e r i z e d in that said end piece (14) is provided with a thread (17) for
connection with a further rock bolt (10) or a termination piece (18) and that the periphery
(19) of said channel (15) is formed to sealingly cooperate through deformation with a
channel periphery (20) on said further rock bolt or termination piece (18).

Description

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Joining of tube-formed expansion bolt
The present invention relates to a lul~folllled rock bolt. More specifically the invention
concerns a tubeforrned rock bolt which is formed for being Joined to a l,.l~ r Iength.
In a previously known rock bolt of the above mentioned kind, see US-A-4 509 889, one
can achieve a long rock bolt through cntering a rock bolt into a bore hole and exp~n~ling it.
Then a further bolt is entered on a tube ç~nrling from the inner rock bolt and is expanded
so that it is fixed on the eYIe~ tube. A d~awlJ&ck when setting a long rock boltcomprising several short rock bolts is that one needs a long tool which norm~lly must be
bendable in order to set the rock bolt which is to be innermost in the bore hole. Another
d.~l,acl; is that the rock bolt at the joints beco.~P~ subsPti~lly weaker since the
comle.,lion is obtained through friction. This force beco...cs small because the extPn~ling
tube has small di~mrtPr and thus a small outer surface.
The present invention, which is defined in the subsequent claim, aims at achieving a rock
bolt which can easily be joined to ~lihaly length and which has perfect skength along the
whole length after assel..bly.
An embodiment of the invention is described below with l. f~ ce to the aaconl~ ying
dMwings in which fig 1 scl~ ... ;r~lly shows setting of a rock bolt. Fig 2 shows a section
through one of the ends of a rock bolt P ~,car~il.g to the invention. Fig 3 shows a section
Ihrvugh the other end of the rock bolt a r~ g to ~e invention. Fig 4 shows a section
according to 4-4 in fig 2. Fig 5 shows a section a~ord;-~g to 5-5 in fig 2. Fig 6 shows a
section accol.lillg to 6-6 in fig 3. Fig 7 shows a section acco.til.~; to 7-7 in fig 3. Fig 8
shows two bolt ends accor~g to fig 2 and fig 3 screwed tog-.t!lPn Pig 9 shows on a larger
scale a detail from fig 8. Fig 10 shows the upper ent of a top bolt for coopeMtion with a
rock bolt according to the invention. Fig 11 shows a lower end of a rock bolt for
coopeMtion with a rock bolt according to the invention. Fig 12 shows an end sleeve which
can be used instead of the top bolt according to fig 10.

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In fig 1 is shown schematically the setting of a rock bolt 10 which comprises a number of
rock bolts connected with one another. The rock bolt, which is described more in detail
below, is set by e~cr~n.1in~ the rock bolt against the bore hole wall 11 by suplying high
ples~le liquid, preferably water, from a high ,~leSD~ pump 39 via a valve 42, a tube 59, a
hose 41 and a chuck 21 to a room in the rock bolt. The chuck can be made as described in
US-A-4 423 986. In figs 2 and 3 two different ends of a rock bolt 10 according to the
invention are shown. The bolt ends 14,24 which are shown in these figures can ~ sclll
either two ends of the same rock bolt or two ends of two different bolts which are to be
co~...r~;led with one another. The rock bolt cull.l~.;3es an elongated tube 12 which along the
major part of its length is provided with a dcl,..,ssed part 13. A sleeve 22 is by means of
welding secured to one end of the tube 12. An end piece 14 is welded to the sleeve 22. A
sleeve 23is welded to the other end ofthe tube 12. An end piece 24 is welded to the sleeve
23. Both l~ ches25,26 ofthe d~le~3ed part 13 are at both ends ofthe tube 12 pressed
together and by means of welds sealingly co..l-e~l~A with one another. Through this the
tube 12 defines a room 16 whose only comleclion with the surro~n~ling.~ is con.~titl~ted by
the channels 15 and 35 through the end pieces 14 and 24. The end piece 14 is provided
with an intemal thread 17 and the end piece 24 with an external thread 37 by means of
which two rock bolts can be connected with one another. In the shown example the end
piece 14 is provided with a raised l~c~ h~l y 19 about the channel 1~. This raised peli~uhely
is intentle~l for cooperation with a ch~nnel ,~ hcl~ 20 on the end piece 24. Through
deformation of the material sealing cooperation is obtailled as shown in fig 9. The r.h~nnel
35 has a somewhat larger ~ neter than the channel 15. It is, of course, possible to form the
sealing parts in an ;~ y way within the scope of the claim.
In fig 10 the upper end of a rock bolt int~nrled for use at the bottom of the bore hole is
shown. The tube 12 is provided with a sleeve 28 which by means of a weld 29 is sealingly
connected with the tube 12. The not shown end is provided with a thread accor~lillg to any
of the above described embodiments.
In fig 11 is shown the lower end of a rock bolt which is int~.nr1ed for use at the bore hole
mouth for comle.;lion to the chuck 21 and thus to the high ples~ purnp 39. The tube 12

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is provided with a sleeve 31 which by means of a weld 32 is sealingly connected with the
tube 12. A radial hole 33 extends through the sleeve 31 and the outer surface oftube 12 so
that the room 16 can be pressurized via the chuck 21. The other end of ~e rock bolt is as
above provided with a thread. As an ~Itern~tive to this rock bolt one can use a thick-walled
tube at the mouth of the hole if it is desired that the joined rock bolt shoould not extend all
the way to the mouth of the bore hole. One can then after the rock bolt has been set fix
different fittings in the threaded end piece. Another advantage, which is obtained if one lets
the rock bolt end in the bore hole, is that the rock bolt does not extend beyond the rock
surface. Through this large amounts of concrete can be saved if the rock surface is to be
covered by means of spraying.
~n fig 12 is shown a termin~tion piece 18 which can replace the rock bolt according to fig
10. The termination piece 18 is provided with a thread 34 for corulection to a rock bolt
according to the above.

Representative Drawing