Note: Descriptions are shown in the official language in which they were submitted.
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WO 99/56001 PCT/SE99/00626
1
DEVICE FOR A ROCK WALL
TECHNICAL FIELD
The invention relates to a device for sealing a rock wall, which device
comprises an
injection tube adapted to be introduced into a bore hole in the rock wall,
into which bore
hole a filling material is intended to be injected through the injection tube.
According to one aspect of the invention, the device may also comprise a
reinforcement
rod, e.g. a conventional reinforcement bar, so that both a sealing effect and
a reinforcing
effect is achieved through the use of the device. The invention is utilized in
the
construction of tunnels and other rock cavities.
PRIOR ART
On working in rock walls, e.g, for constructing tunnels or rock cavities,
reinforcement of
the rock wall is most often required to increase the strength, and sealing of
cracks and
the like to prevent damp and water from penetrating the tunnel or cavity.
Known
methods of reinforcement consist in providing the rock wall with evenly
dispersed bore
holes, which can have a diameter of about half a decimetre and a depth of
about 1-6
metres.
One method of reinforcing rock walls has been and continues to be the
insertion into the
bore holes of two concentrically arranged tubes of different diameter. The
space
between the walls of the tubes is filled with cement or concrete, following
which the
tubes are taken out before the filling material has hardened and a
reinforcement bar can
be stuck into the central hole. A major disadvantage of this method is that
the filling
material and reinforcement bar fall out of the hole again relatively
frequently, for which
reason the reinforcement often has to be repeated several times before it
succeeds. If in
addition water leaks out of the rock into cracks which lead into the bore
hole, the filling
material can be washed away before it manages to harden. In this case, the
rock must
instead be sealed in a first stage, a rubber plug or tap normally being
arranged in the bore
hole opening and the hole being filled with concrete or cement which is then
allowed to
solidify. Following this, a hole is drilled in the concrete/cement which is
reinforced in the
same way as described above. As is clear, the method comprises several stages
and it is
nevertheless not entirely certain that the reinforcement remains in place.
In a more modern known system, a long bolt is introduced into each bore hole,
which
bolt is provided at the top with an expander for anchoring in the bore hole.
Arranged in
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the eiid of the bolt which sticks 6ut of the berrtbote ks a washer wbich iies
iike a cover
cve~r tbe bore hole and in tbe: ccntre ofwhich a bemispbere is ar.rangcd. The
bolt sticks a
distan.ce out afthe heFnisphere and is stirrounded. there by a nut wtdcb i's
tightsn.ed when
the expander in the bolt top is to be Anchored Ãn, the rock. Fcliokving,
ancboring, cement
paste is inl'ccteI into tb.e hemisphere to proceed inwards into tbe bbre hole,
first inside a
plastic tu:be whicb surrounds the b0it; and then outside tids plastic
tub~iuntii the cement
paste emerges throtigh a hole in the washer. This system certaraty provides
reinforcement ofthe rock watls but no appreciable sealing of water beareng
cracks and
the like. Problems of corrosion at. the bolt can also acmrif air bubbles are
formed in th,~
1tJ cement closest to this.
In connection ivith the sealing of a rtrri, wall, using cernent or concrete
which is filled
into bore holes, tber6 is a problem in connection ivith water ieai~agge
tluough cracks in
the rock wall. As to cur knowle:d.ge there is no existing dMice which can be
used to fill
bore holes under a pQsitive pressure ofthe filling material.
Con.venticnal methods of sea[ina the rock wall ramprise e.~. IabO~~ inte~nsive
and
expen:sive so-calted "Irnbtg" of the rack wall, i:e. cladding with concrete.
Anatb.er
known metliQCi utilizes a seatiqg mater'taI which is injected into the rock
wall. This has
been found to lead to very great envitonmcntil disadwsnt~,es, as tbe~ sealirg,
material
contains the toxic substance actyhvmideT which can be dispersed in the
groundwater:
SB-A-609 139 (V7QE 9.9{45,575) shGws a device frrr rcinforcing aad sealing a
rock walL
which devi'ce comprises a reinfibmement bar ada:pted to be iatoduced into a
bore hole in
the rock wall, .intc which bcrrc imle a filling material is intended to be
injected. The
de-vice aZso comprisea a norrretum valve far.thc filrmg materiaL The device
requires
several operational steps for the irdmdttctian into a bore hole and fiffing of
the same.
Accordmgly, an in,jection nozzlo must first:be applied, where aftcr= the bolt
kwIfis
inserted via a hole in the inj:ection nozzle:.
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2.1
BRIEF ACCC)~CJNT t3F TF-M INVENTION
In the follovfing, the inventib.n is m.at'nIy described in connectivn with a
device which is
25 adapted. to both seal and reinforce a rock wall. It is however to be
understood that the
invention aiso relates to a device whi.eh'is adapted to seal but not to
reinforce the rock wall, in which case ttre: device does not comprise a
reitiforce~ent, rod-or anchoring
means.
30 The aim of the present invention is to offer a deVice for reinforcing and
sealing a rock
wati; by means of which device the aforementioned disadvantages are avoided or
at least
manim. ized, it being possible to carry ou.t reinforcement and seaFtn; c~ftbe
rt~ek wall in
just a.few: stages, meanin.g that the reinforcement rern.ains securely iit
Pf.ace at the same
time as sealing ofwater :bear'tn~~:g~ cracks leadi;ng iota the bore hoies iS
ach's.eved. and air
35 bubbles in the cement are avoid:eÃI.
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3
This is. achieved by means of a device for reitiforcirtc, aad segiitg a rock
wail, which
device comprises a reirfOroeirient: rod, e.g. a conventional reinforcementbar
intended to
be introd.uced into a-txore hole in the rouk cvaii, iot;o which bore hole a
fitiing, material is
then injecte.ti, said device a:tso cortipris'tng a non: retut-iz valve for the
fiIlirp material. The
non-return valve is adapted to uritlseand a pQsitive pressure of the fAIing
material in the
bore hote. The filiin; material is thiis injected uiid.er positive pressure,
at w1ich anX
cracks in the rock leading into the bcare hole are sealed. Said ncyzt-retttrn
valve A
consists of a 1sleeve which enclos:es an in.}eotYott tube provided with outlet
Qpedinggs, which injeeti.on. tube is preferably joined to said reinforcement
bar or
I.o equivalent.
Further features and aspects of the irivention are evident frorri ti'ie
following cla ims and
the detailed descriptiart ofthe invention.
i5 BRiEF I3ESCR.TPTI4N OF DRAWINGS
Reference r~~Rill be made L-1 the detailed description of the inventian to the
enclosed
drawings, of which
Fig. I represents a lateral view, garety in cross-section, of the part of the
sealinb and.
20 reinforcing device which is positioned adjacent to the opening of the bore
hole
and which oonta%Ãts the non-returrn valve.
Fi3. 2 represents a lateral view, partly in cross-section, of the pact afthe
tievice which is
positioned fuiti=zest in in the bore hole and -whioh conta'tns an expander for
25 anchoring in tlierock.
Fig. 3 repFesezits a tesp view of a icok- washer for the expander in.Fig. 2,
before the lock
washer is fÃsrmed fcr appiication.
30 Fij. 4 represents a lateral Yieiv, partly in cross-section, of the bore
hole and the
reinforcement during the hardening phase of the f llinj material.
Ficy: S represents a lateral view, partly in cross-section, of the fmished
reinforcement in
the rock.
Fia,. 6 represents a lateral view, p~irtiy in cross-sectian of the embatliment
of the
invention which is a sealiog device vr'rthout: a reinfa:rceinent rod, the
figure
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WO 99/56001 PCT/SE99/00626
4
showing the device inside the bore hole during the hardening phase of the
filling
material.
DETAILED DESCRIPTION OF THE INVENTION
With reference first to Fig. 1, a reinforcement bar which forms part of the
device is
described by the number 1. For technical drawing reasons the reinforcement bar
in the
figure is cut away at the top but in reality has a length of about 0.5-10 m,
preferably 1-7
m and even more preferredly 2-5 m. In Fig. 1 and 2 the device is shown as it
is arranged
in a vertical, upwardly directed bore hole in the roof of the tunnel or rock
cavity, which
position is used in the further description. However, it is to be understood
that the
device can just as well be used in a horizontal hole, an angled hole or in a
vertical,
downwardly directed hole. The reinforcement bar I has a strongly profiled
surface for
fastening securely in the cement or concrete, henceforth termed filling
material, which
will enclose the same. Joined as an extension of the reinforcement bar
arranged at the
bottom, via a coupling sleeve 2 welded firmly at both ends, is an injection
tube 3 which
accordingly has an inner longitudinal cavity and is open at the bottom for the
connection
of hosing for filling with the filling material.
Arranged a distance below the coupling sleeve for the reinforcement bar 1 and
the
injection tube 3 is a non-return valve 4. This non-return valve 4 is adapted
to withstand
a positive pressure of the filling material when this is injected under
positive pressure into
the bore hole via the non-return valve. Thanks to this non-return valve, the
filling
material does not run out of the bore hole before it solidifies, in spite of
the positive
pressure. The non-return valve 4 preferably comprises a rubber sleeve 5 which
encloses
a part of the injection tube 3. In the area of the rubber sleeve the injection
tube has a
number of outlet openings 6 for the filling material. The rubber sleeve, which
can of
course also be manufactured from another, to some extent elastic, strong
material, is
suitably formed as an envelope of a truncated cone, having a first diameter at
the bottom
and a second, smaller diameter at the top. At the first diameter, the rubber
sleeve 5 is
3 0 vulcanized firmly at an internally threaded eye nut 7, which in turn is
screwed firmly on
an externally threaded ring fastener 8. The ring fastener 8 encloses the
injection tube 3
and is welded firmly to the same. The ring fastener 8 also has a flange 9 at
the bottom,
on the upper surface of which flange the eye nut 7 rests. The upper, smaller
diameter of
the rubber sleeve 5 is adapted to end sealingly around the injection tube 3.
For this
purpose the nose is suitably provided with a few, e.g. two, internal lip seals
consisting of
0-rings which are set into the rubber sleeve, or by a few continuous
projections on the
inside of the rubber sleeve in the tip part.
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WO 99/56001 PCT/SE99/00626
Below the flange 9, the injection tube is enclosed by a narrow tube 13 with an
upper
flange 14 which lies close to the lower surface of the flange 9. Resting
against the lower
surface of the flange 14 is the upper short end of a seal in the form of a
sleeve 10 which
suitably also consists of rubber. This rubber sleeve 10 encloses a part of the
lower
5 section of the injection tube surrounded by the narrow tube 13, its lower
short end
resting against a washer i l which in turn rests against a nut 12. In the area
of the nut 12
and a distance up under the rubber sleeve 10 the injection tube 3 and/or the
narrow tube
13 are threaded externally with the same thread size as the nut 12.
Arranged in the upper part of the device, suitably at its top, is a top piece
forming an
expander. The expander is shown in Fig. 2, which forms a continuation of the
device
shown in Fig. 1, a longer piece of the reinforcement bar 1(only partly shown)
connecting
the part according to Fig. 1 to the part according to Fig. 2. The expander is
joined to the
reinforcement bar by means of a sleeve-shaped spacing piece 21 which is welded
firmly
at the bottom on the end of the reinforcement bar and which at the top
contains an
internal thread. Screwed into this thread is a coupling pin 22 which consists
of a straight
pin provided with external thread at least a distance at the bottom and a
distance at the
top. At the top, the coupling pin 22 is partly screwed - in the unexpanded
state - into a
hole provided with an internal thread in a core part 23. The hole here is
sufficiently long
2 0 to permit further screwing in when anchoring of the device into the rock
is to be
executed, which will be described in greater detail. The core part 23 tapers
off at the top
into a short conical piece 24 and is threaded externally above this conical
piece, a top
cone 25 enclosing the conical piece 24 and a part of the upper section of the
core part
23. The top cone 25 has an internal bevel at the bottom which is adapted
according to
the conical piece 24 of the core part 23. Arranged above the top cone is a top
nut 26 to
hold the top cone firmly. Between the internal bevel of the top cone and the
conical
piece 24 of the core part, a number, preferably 1-10, suitably 2-6, of lock
washers 27 are
fastened around the core part 23. A lock washer of this kind is shown in its
level state in
Fig. 3 and consists of a washer provided with a number of slits 41, preferably
2-10,
3 0 suitably 4-7. When these lock washers are fastened over the conical piece
24 of the core
part, they assume the form of an envelope of a truncated cone. Arranged under
these
lock washers, surrounding the upper part of the coupling pin 22 and the lower
part of the
core part 23 is a loose sleeve 28 with an inwardly facing flange 29 arranged
at the
bottom. This flange 29 rests against the upper short end of the spacing piece
21.
Unless otherwise indicated, the details described are manufactured preferably
of so-called
cam steel-, which can be hot-galvanized or surface-protected in another way.
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WO 99/56001 PCT/SE99/00626
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Fig. 3 shows as stated a lock washer 27 in its level state. The slits start
out from the
washer's circumference, extending almost, but not completely, in towards the
inner bore
diameter of the washer and suitably having a certain, inwardly tapering width
and a
radius furthest in. The inner bore diameter of the washer is suitably provided
with a
shorter straight piece 42, to prevent the washer from rotating when it sits on
the core
part 23. The lock washers are suitably manufactured from cold-rolled, hardened
steel of
a thickness of 0.1 - 1 mm, preferably 0.2 - 0.7 mm and even more preferredly
0.3 - 0.45
mm. In a preferred embodiment, the washer has an outer diameter of about 60 mm
and
an inner bore diameter of about 20 mm.
The function of the device is as follows. A hole 30, Fig. 4, is bored into the
rock wall, of
at least the same length as the length of the device. The device is introduced
into the
bore hole so far that the washer l 1 and nut 12 will be located at the mouth
of the bore
hole. After this, the injection tube 3 is rotated a number of revolutions,
suitably by
means of a hydraulic device which grips the part of the injection tube
sticking out of the
bore. The rotation thereby extends to the reinforcement bar 1 and further to
the sleeve-
shaped spacing piece 21 which is joined to the upper part of the reinforcement
bar. As a
consequence of this, the upper part of the coupling pin 22 is screwed further
into the
threaded hole in the core part, at which the upper short end of the spacing
piece presses
on the lower flange 29 of the sleeve 28 so that the sleeve is pressed upwards
against the
lock washers 27. The sleeve 28 will then act as a pressing device on the lock
washers so
that their shape of an envelope of a truncated cone is at least flattened out
somewhat.
The circumference of the lock washers will hereby be pressed firmly into the
walls of the
bore hole so that the entire device is anchored in the rock. The next stage is
to seal the
bore hole with the device contained therein at the bottom by tightening the
nut 12 so that
the rubber sleeve 10 is compressed in an axial direction, at which it expands
in a radial
direction to seal between the injection tube 3 and the lower walls of the bore
hole, Fig. 4.
A pipe (not shown) can now be connected to the injection tube and the filling
material
3 lA is injected under positive pressure, at which the filling material flows
out of the
outlet openings 6 in the injection tube and penetrates into the bore hole at
the upper
diameter of the rubber sleeve 5. The rubber sleeve 5 acts here as a non-return
valve
integrated into the device so that the filling material, in spite of being
under positive
pressure, cannot run back out of the bore hole before it manages to harden.
Beneficially,
there is also arranged a small diameter conduit 35, e.g. of a hydraulic tube
type, which
mouths in the most distant region of the bore hole 30. Preferably it ends
upstream of the
spacing piece 21. The conduit 35 is adapted to act as a degassing conduit
which leads air
and gasses out of the bore hole as the filling material is introduced. During
introduction
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of the filling material, the open end, adjacent the entry of the bore hole, of
the conduit 35
is sealed when filling material starts to continuously come out of the
conduit, whereafter
the introduction of filling material into the bore hole can proceed under a
positive
pressure.
Due to the positive pressure, filling material is also caused to penetrate any
cracks 32
leading into the bore hole, in spite of the fact that these cracks may be
water-bearing.
When the desired positive pressure, which may reach about 100 bar positive
pressure or
suitably about 50-80 bar positive pressure, has been attained, the pipe
connection can be
detached, at which the filling material 31 A can be left to harden under
positive pressure,
thanks to the non-return valve 4 and the rubber sleeve 10. When the filling
material has
hardened, the nut 12 is unscrewed, the washer 11 removed and the rubber sleeve
10 is
taken out of the hole by means of the narrow tube 13 provided with a flange.
The space below the flange 9 is then filled with filling material 31B (Fig. 5)
by providing
the opening of the bore hole with a larger washer (not shown) with a hole in
one side for
filling with filling material, air being made to evacuate the hole via an air
pipe. If the risk
of corrosion is not great, however, the narrow tube 13 provided with a flange
can be left
out of the device, in which case the rubber sleeve 10, washer 11 and nut 12
can instead
remain permanently in place after the device has been applied to the bore
hole. The
opening of the bore hole and its immediate surroundings are then covered in a
conventional manner with a plate, disc or washer 33, which is pressed against
the rock
wall by means of a nut 34, which is screwed on to the protruding part of the
injection
tube.
By means of the invention a relatively simple and cheap construction is
achieved for
sealing and a non-return valve function which thus permits filling material to
be injected
into a bore hole and allowed to harden under a favourable positive pressure.
The
relatively simple and cheap construction also allows the seal, non-return
valve and
expander to be cast in the bore hole and thereby form an admittedly permanent
but
nevertheless disposable material without incurring costs which are too great.
Corrosion-
promoting air bubbles close to the reinforcement bar are counteracted due to
the positive
pressure. A further advantage of the device according to the invention is that
it can be
used for filling material of varying viscosity or dry content according to the
circumstances and preference.
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Referring now to Fig. 6, it is seen that the embodiment of the invention,
which is a device
for sealing the rock wall without reinforcing it, corresponds fully to the
lower part of the
device shown in figures 1, 4 and 5. Accordingly, the device of the embodiment
in Fig. 6
does not comprise a reinforcement rod nor anchoring means. Instead, the
injection tube 3
ends just downstream the non-return valve 4 with a blind end wall 3A. By means
of the
device according to the embodiment in Fig. 6, filling material can be
introduced into the
bore hole under a positive pressure, and be allowed to harden under a retained
positive
pressure, thus achieving a good seal of cracks 32 that mouth in the bore hole.
This
embodiment of the invention is preferably used in rocks that are relatively
strong, but
water leaking.
The invention is not restricted to the embodiment described above but can be
varied
within the scope of the following patent claims. The expert thus easily
perceives that e.g.
the expander for anchoring the device in the rock can be executed in a number
of
different ways, some of which belong to the prior art. The sealing and
reinforcing device
can possibly even be used entirely without anchoring. The non-return valve 4
and the
rubber sleeve 10 can also be conceived to be executed in other ways and in
other
materials.
