Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Process for setting anchors and anchor
usable in the process
The invention relates to a process for the setting of anchors such as ground
anchors and rock
anchors, with the features of the introductory part of claim 1.
The invention relates furthermore to an anchor which can be used in the
process in
accordance with the invention.
US 4,459,067 A discloses a process of the initially named type.
In this known process an anchor (rock bolt or rock anchor) which has a
longitudinally
inwardly folded pipe is placed in a drilled hole and expanded by increasing
the pressure within the
folded pipe, so that the outside surface of the pipe comes to rest against the
inside surface of the
drilled hole and thus fixes the anchor in the drilled hole.
In the known rock anchor, the front end of the pipe is closed and the back end
of the pipe,
therefore the end which is adjacent to the opening of the drilled hole (the
outer end of the drilled
hole) is connected to a hose or pipe via which the pressurized fluid
(especially water) can be
introduced into the interior of the pipe for expanding it.
It is a disadvantage of the known process and rock anchor that the latter is
fixed in the
drilled hole exclusively by friction and positive locking, but that the
beneficial side effects of an
injection anchor, such as solidification of the soil or rock surrounding the
drilled hole, are not
provided.
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The object of the invention is to provide a process of the initially mentioned
type and an
anchor which can be used in this process which does not have the described
disadvantages, and
allows for the quick achievement of a permanently reliable retention of the
anchor.
This object is achieved with respect to the process with the features of the
main process
claim, and with respect to the anchor, with the features of the independent
claim directed to the
anchor.
Preferred and advantageous embodiments of the invention are the subject matter
of the
dependent claims.
An anchor set according to the process of the invention sticks securely and
permanently
since it is rests securely against the inside surface of the drilled hole, not
only because the wall of
the expanded pipe of the anchor provides a positive locking and friction by
deforming into gaps,
crevices and/or areas with softer material, but also has the advantage that
the rock or soil into to
which the anchor is inserted is solidified in the area of the deepest end of
the drilled hole by the
added settable mass, so that any gaps or cracks present deep in the drilled
hole are filled with the
mass.
The anchor as claimed in the invention is a development of known friction pipe
anchors, as
are known for example from the aforementioned US 4,459,067 A and which are
also called
"Swellex". In the anchor in accordance with the invention, force transferred
into the substratum
takes place both by means of friction and also by means of a mechanical
(positive locking-type)
connection to the substratum.
The anchor in accordance with the invention also has the advantage that the
anchor can also
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be used as an injection lance for soil improvement. Soil improvement at
certain depths or starting
from a certain depth is especially important where the soil layers overlying
the open surface or the
rock layers ahead in tunneling would be negatively affected by the compaction
pressure, such that
under certain circumstances the entire stability of the structure could be
endangered.
Within the framework of the invention, anchor mortar, Portland cement and
other cements
with small enough grain sizes, but also synthetic resins and other injection
material can
fundamentally be used as the settable mass (injection material).
The settable mass used in the process in accordance with the invention can
also be a
hydraulically setting mass such as grout (essentially a mixture of water,
cement and optionally fine
aggregate such as fly ash, for example) or a mortar (essentially a mixture of
water, cement and
aggregate with small grain size). In this case the process in accordance with
the invention further
has the advantage that the interior of the anchor is protected against
corrosion by the hardened
mass.
The settable mass can also be plastics which are added for example in molten
liquid form
and which solidify by cooling or harden after placement by chemical reaction.
In general words the procedure used in the process in accordance with the
invention can be
described as follows:
A drilled hole of the length and diameter required for respectively used
product (anchor) is
produced. The expandable anchor is placed in this drilled hole. The anchor is
then connected to a
pump, especially by way of an adaptor, filled with water and pressurized until
the profile of the
anchor unfolds and the pipe rests snugly against the drilled hole wall.
Subsequently, the profile
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expands such that irregularities in the drilled hole diameter are filled in.
In crevices or cavities, the
profile expands up to its largest possible diameter, whereby relative to the
limited expansion in a
regular drilled hole a mechanical (positive locking-type) anchoring is also
created. After this is
achieved, the pressure is further increased until the tip, especially in the
area of a groove provided
for this purpose, opens and is separated at the bottom of the drilled hole. At
this point the adapter
used previously, via which the water was introduced, is replaced by an
injection adapter and the
injection material is delivered into the ground through the separated tip of
the anchor. The grouting
material (injection material) is also introduced under pressure, whereby the
pressure is absorbed,
because of friction and mechanical anchor-substratum bonding of the anchor
which is dimensioned
accordingly, such that the anchor is not pressed out of the drilled hole in
the manner of a piston.
The anchor which can be used in the process in accordance with the invention
on its front
end, which means the end with which it is introduced into the drilled hole,
has an end piece which
is attached, for example, to a sleeve provided there and connected to the
pipe, the end piece opening
at a pressure which is higher than the pressure applied during expansion of
the pipe for placement
against the inside of the drilled hole, so that a settable mass can be pressed
through the pipe and the
then open end piece and into the drilled hole.
The anchor in accordance with the invention can bear on its end which lies in
the drilled
hole an anchor plate which is supported on the soil or rock side on the outer
end sleeve of the
anchor.
Anchors as claimed in the invention can also be combined with injection drill
anchors. This
has the advantage that the anchor as claimed in the invention ensures prompt
loadability and the
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injection anchor ensures long-term loadability.
Other details, features and advantages of the invention will become apparent
from the
following description with reference to the attached drawings.
Figure 1 schematically shows in an oblique view a rock anchor, Figure 2 shows
the pipe of
the rock anchor in cross-section in the middle region, Figure 3 shows the pipe
of the rock anchor in
cross-section in the region of one of its ends, Figure 4 shows the end piece
on the front end of the
rock anchor in a first embodiment, Figure 5 schematically shows the pipe of a
rock anchor
expanded to make contact with the inside surface of the drilled hole, Figure 6
shows the end piece
of the rock anchor in a second embodiment, Figure 7 shows an adapter receiving
piece provided at
the rear end of the rock anchor adjacent the open end of the drilled hole,
Figure 8 shows an adapter
for the introduction of a pressure medium for expansion of the rock anchor
pipe, Figure 9 shows an
adapter for the introduction of the settable mass into the drilled hole,
Figure 10 shows an anchor
partially in a section, and Figure 11 shows another embodiment of an anchor
partially in cross-
section.
Although the invention is described in the following primarily using the
example of rock
anchors as also shown in the drawings, it should be stressed that the
invention can be used
fundamentally for all types of anchors, predominantly those of the initially
named type, therefore
also for use in soils and similar soft substratum.
The rock anchor shown in Figure 1 has a pipe 1 which has in its middle area
the cross
sectional shape shown in in Figure 2. The pipe 1 therefore has a longitudinal,
inwardly directed fold
3, whereby the part of the wall of the pipe 1 folded inward in the middle area
(Figure 2) appears
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somewhat omega-shaped, whereas in the area of the ends of the pipe 1 the
lengthwise fold 3 folded
to the inside has two wall parts 5 which run essentially parallel to one
another (Figure 3).
The ends of the pipe 1 which as mentioned have the cross sectional shape shown
in Figure 3
are connected to sleeves 7 and 9 placed over these ends. In particular, the
sleeves 7, 9 are connected
to the ends of the pipes 1 by welds 11.
An end piece 13 is connected to the inner end of the pipe 1, especially to the
sleeve 9
connected to this end of the pipe 1.
The end piece 13 is closed, but made such that at a certain pressure (a
pressure higher than
the pressure required for expanding the pipe 1 ) it opens and clears access to
the interior of the end
piece 13 or the pipe 1. Possible embodiments for end pieces 13 are shown in
Figures 4 and 6 as
well as 10 and 11.
In the embodiment shown in Figure 4 the end piece 13 has a tapered end 15
which is
connected to the tubular part of the end piece 13 by a groove 17, therefore a
weakening point. When
a certain pressure is reached within the pipe 1, the wall of the end piece 13
breaks in the area of the
groove 1? so that the end of the pipe 1 connected to the sleeve 9, for example
by a weld l0, is open.
In the embodiment shown in Figure 6, the end piece 13 is made as a pipe with a
free end 19
which is provided with an internal thread. A plug 21 is screwed into the
internal thread so that the
end piece 13 of the embodiment shown in Figure 6 is initially closed . When a
certain internal
pressure is reached in the pipe 1 or in the sleeve 9, the plug 21 is pressed
out of the end 19 of the
end piece 13 which is made as a plug holder, so that in this embodiment the
interior of the pipe 1 is
connected to the vicinity, therefore to the interior of the drilled hole.
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An adapter receiving piece 31 is connected via the sleeve 7 to the other end
of the pipe 1
which is shown in Figure 7 and which is opposite the inner end of the pipe 1
with the sleeve 7 and
the end piece 13. For example, the adapter receiving piece 31 is connected to
the sleeve 7 by a weld
33. The adapter receiving piece 31 is located in the area of the open end of
the drilled hole in which
the rock anchor is to be fixed. The adapter receiving piece 31 can be equipped
with a check valve
34 which opens into the pipe 1 only in the flow direction and thus prevents
the pressurized fluid and
settable mass from emerging from the rock anchor.
Either [sic] the adapter 35 shown in Figure 8 for feeding the pressurized
fluid, especially
water, into the interior of the pipe 1 can be connected to the adapter
receiving piece 31.
Alternatively the adapter 37 which is shown in Figure 9 and which is used for
forcing in the settable
mass, especially hydraulically binding mass, such as grout or mortar, can be
placed on the adapter
receiving piece 31.
The adapter 37 from Figure 9 can be equipped with a quick-release coupling 38
so that a
hose coming from a pump which delivers the settable mass can be quickly
connected.
The adapters 35 and 37 can be provided with an outside thread 39 which can be
screwed
into the internal thread 41 of the adapter receiving piece 31.
Components such as for example eye bolts (DIN 580) can be attached to the
adapter
receiving piece 31, after the rock anchor has been fixed in a drilled hole, as
is described above.
To fix the described rock anchor in a drilled hole, the procedure is as
follows:
First of all, the rock anchor is inserted with its end piece 13 first into a
previously prepared
drilled hole . As soon as this has taken place, a pressurized fluid (for
example, water with a pressure
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of roughly 100 - 500 bar) is fed into the interior of the pipe 1 via the
adapter 35 which is attached to
the adapter receiving piece 31 by screwing it in. Under the action of the
pressure prevailing within
the pipe 1, the pipe 1 expands as its lengthwise fold 3 is opened so that it
is pressed with its outside
surface tightly against the inside surface of the drilled hole (Figure 5). As
soon as this has
happened, the adapter 35 can be removed from the adapter receiving piece 31 by
unscrewing and
replaced by the adapter 37 (Figure 9) whereby this adapter 37 is screwed into
the adapter receiving
piece 31. At this point the settable mass, especially grout or mortar, which
is delivered from a
corresponding pump under pressure is forced in through the adapter 37 (Figure
9. The pressure in
the settable mass is thereby higher than the previously prevailing pressure
during expansion of the
pipe I so that the end piece 13 opens, by either (Figure 4) the tip 15 being
separated from the end
piece 13 by breaking the wall in the area of the groove 17 or (Figure 6) by
the plug 21 being forced
out of the plug holder 19. As soon as this has happened, first the fluid which
has been used to
expand the pipe 1, especially water, and then the settable mass emerge from
the pipe I via the
sleeve 9 and the end piece 13 into the drilled hole. The settable, especially
hydraulically binding
mass now fills the space 8 remaining after expansion of the pipe 1 between the
remainder of the
fold 3 and the inside surface of the drilled hole (Figure 5). In addition, the
settable mass penetrates
into the cracks or fractures which proceed from the front end of the drilled
hole and thus solidifies
the material (rock, stone, or the like) into which the rock anchor has been
set, mainly in the area
which surrounds the drilled hole bottom.
In one modified procedure, one proceeds such that first a pressure is produced
with the fluid
fed via the adapter 35 from Figure 8 which is sufficient for expanding the
pipe 1 as its fold 3 opens,
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so that the pipe 1 with its outer surface rests against the drilled hole
(Figure 5), whereupon the
pressure in the fluid is then raised so that the end piece 13 opens and only
then is the adapter 35
from Figure 8 replaced by the adapter 37 from Figure 9.
In addition, the described procedure offers the advantage that the interior of
the rock anchor
which consists especially of steel is protected against corrosion. In the case
in where a hydraulically
binding mass based on cement is used, an alkaline environment is additionally
ensured , whichis
advantageous.
With the procedure as claimed in the invention and the use of the rock anchor
as claimed in
the invention in combination with injection drill anchors (so-called "hybrid
anchors") the
advantages of rock anchors which can be expanded using internal pressure
(quick strength and solid
seating) are combined with the advantages of injection drill anchors fixed by
a settable, for example
hydraulically binding mass, since the settable mass fills possible free spaces
in the area of the
drilled hole between the outside of the injection drill anchor and also
penetrates into cracks or gaps
which proceed from the drilled hole, and thus compacts the rock, the soil or
quite generally the
substratum around the drilled hole.
In the embodiment shown in Figure 10, the anchor again consists of a profiled
pipe 1 and
the two sleeves 7 and 9 provided at its ends. The sleeves 7 and 9 are
connected to the profiled pipe
1 of the anchor by pressure and welding. An end piece 31 is welded to the
sleeve 7 in the
embodiment shown in Figure 10, and the adapters shown in Figures 8 and 9 can
be selectively
screwed into the end piece 31. For this purpose, the end piece 31 has an
inside thread via which the
coupling piece shown in Figure 8 for expanding the profiled pipe 1 can be
screwed in. Water is
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injected under pressure via this coupling in order to expand the profiled pipe
1 and then to blow off
the tip of the anchor.
The injection adapter as shown in Figure 9 with the anchor can be connected
(screwed onto)
the end piece 31 after the coupling as shown in Figure 8 has been removed.
On the front end of the anchor, via the sleeve 9 the end piece 13 is connected
to the tip 15
by a weld 10. An outwardly open groove 14 is provided in the wall of the end
piece 13 in the
vicinity of the base of the tip 15. Material fracturing is then induced by way
of this groove 14 after
the expansion pressure is exceeded whereby the tip 15 is subsequently blown
off so that the mass
binding the substratum can then be injected through the anchor.
In the embodiment shown in Figure 11, the anchor again has the profiled pipe
l, the
sleeves? and 9 which are attached to the ends of the profiled pipe 1 by
pressing andlor welding and
the end piece 31 which is connected (welded) to the sleeve 7. A coupling piece
54 which is
provided with an outside thread is connected to the front sleeve 9 via a weld
55. Via this coupling
piece 54 a coupling piece 53 which is provided with an inside thread is
screwed, to which the weld,
the end piece 13 with the tip 15 is connected [sic]. In the embodiment shown
in Figure 11, the
groove 17 on the base of the tip 15 is open toward the inside of the end piece
13
The tip 15 in contrast to the embodiment shown in the drawings can be made
with different
angles. End pieces 13 with an arched front end (bomb-shaped) or with a flat
front end can also be
used.
In summary, one exemplary embodiment of the invention can be described as
follows:
An anchor with a longitudinally folded pipe 1 and with an end piece 13 which
can be
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opened under pressure and which is provided on the end of the anchor lying
inside the drilled hole
is introduced into the drilled hole, and by applying internal pressure is
expanded as the pipe 1
unfolds until the pipe 1 with frictional locking andlor positive locking
engages the drilled hole,
whereupon the pressure in the anchor is raised so that the forward tip 15 of
the end piece 13 is
separated. Then the settable mass is pressed through the anchor into the
drilled hole in order to fill
cavities in the area of the anchor end located at the bottom of the drilled
hole and the substratum
(soil, rock) in which the anchor is fixed, and cavities or cracks located in
the bordering substratum.
A hydraulically binding, cement-based mass can be used especially as the
settable mass.
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