Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Device for accommodating rock deformations in underground min-
ing, process for producing a fastening layer suitable for accom-
modating rock deformations in underground mining and use of a
polystyrene compression element, and process for producing such
a fastening layer
The present invention relates to a device for absorbing rock de-
formations in underground mining, a process for producing a fas-
tening layer suitable for absorbing rock deformations in under-
ground mining, the use of a polystyrene compression element and
a process for producing such a device.
In underground mining, the rock in which the excavation takes
place usually continues to deform for some time after the exca-
vation. For this reason, excavated cavities or tunnels are regu-
larly secured against deformation and/or at least partial col-
lapse with a shotcrete shell or segments. In principle, the
shotcrete lining or the segments do not deform as easily as the
secured surrounding rock. As a result, stresses and deformations
can occur in the shotcrete shell or in the segments, which can
cause damage. In order to avoid damage such as cracks or similar
in the shotcrete lining, it is common practice to equip the
shotcrete lining with compression elements which, in combination
with the shotcrete, ensure the intended, controlled flexibility
and deformability of the tunnel lining.
Compression elements made of various materials are known from
the prior art. Compression elements comprising concrete, plastic
or steel and containing reinforcing elements are known, for ex-
ample from EP 1564369 Bl. Compression elements are also known
which have tubes which are arranged with their longitudinal axis
either radially or tangentially to the shotcrete shell, such as
in EP 2918772 A2.
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The known compression elements according to the state of the art
have the disadvantage that they are heavy and bulky. At least
two persons are generally required for installation. This makes
installation time-consuming and expensive. In addition, the
known compression elements are composed of different bodies and
materials. The load transfer of the surfaces of the compression
elements resting on the shotcrete shell is not optimal with the
existing elements. Due to the composition of the known compres-
sion elements from different materials, which are also differ-
ently shaped (tube, cuboid, etc.), the known compression ele-
ments are also difficult for users on the construction site to
individually adapt their geometric shape to the existing instal-
lation conditions. Due to the composition of the previous com-
pression elements from different materials and different shapes,
the compression elements are also complex to manufacture and
therefore expensive.
It is therefore the object of the invention to overcome the dis-
advantages of the prior art and, in particular, to create a de-
vice for absorbing rock deformations in underground construc-
tion, a method for producing a fastening layer suitable for ab-
sorbing rock deformations in underground construction and a
method for producing such a device as well as a use of a poly-
styrene compression element for absorbing rock deformations in
tunnel construction, which can be easily installed and flexibly
adapted to the required dimensions and forces.
The object is solved with a device, a manufacturing process for
a fastening layer, a process for manufacturing a device and the
use of a polystyrene compression element according to the inde-
pendent claims.
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In particular, the object is solved by a device for absorbing
rock deformations in underground mining, in particular a damming
element, wherein the device has a base area, a height expansion
and a depth expansion and comprises polystyrene. The device
preferably comprises expanded polystyrene, in particular prefer-
ably high-strength expanded polystyrene.
Polystyrenes exhibit a non-linear, hyper-elasto-plastic defor-
mation behavior. Such a device enables optimum compression be-
havior and leads to a permanent bond between the aggregate and
the shotcrete lining.
Another advantageous property of polystyrene is its resistance
to environmental influences and its exceptional durability. Pol-
ystyrene is essentially rot-proof and insensitive to moisture.
Furthermore, polystyrene has a high resistance to chemical in-
fluences and a high resistance to corrosion. The devices can
therefore also be used under adverse conditions in underground
construction (e.g. moisture) and generally on the construction
site. Due to its chemical and corrosion resistance, polystyrene
can also be used in groundwater.
Due to the advantageous deformation behavior of polystyrene, the
tangential forces can be transferred to the entire surface of
the shotcrete shell. The uniform force transmission prevents ar-
eas with particularly high force transmission and areas with
particularly low force transmission. This means that the force
is essentially transferred evenly and thus gently into the shot-
crete and ranges with particularly high loads are avoided. As a
result, damage and spalling on the shotcrete shell can be re-
duced and an advantageous dimensioning of the shotcrete shell is
possible.
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The polystyrene can contain a polymeric flame retardant. The
polystyrene is then flame-retardant and therefore has an advan-
tageous fire behavior. As a result, there is essentially no
smoke formation.
The polystyrene can exhibit self-extinguishing behavior.
This means that the compression elements can also be used under-
ground and essentially no additional fire protection devices are
required when using the polystyrene.
Preferably, the devices contain essentially no reinforcing ele-
ments such as pipes or rods. This enables simple and therefore
cost-effective manufacture.
The device can be made of polystyrene.
Due to the simple construction of the devices from essentially a
single material, the devices are particularly cost-effective to
manufacture, easy to process and simple to use.
The devices can be essentially rectangular in shape.
Due to the cuboid shape, the devices can be stacked and are easy
to produce and install.
The longitudinal extension of the device can be greater than the
height extension and/or the depth extension.
This design means that the devices can be produced, stacked,
transported and installed simply and easily. For example, the
device can have a longitudinal extension of 80 cm, a height ex-
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tension of 30 cm and a depth extension of 25 cm. Of course, oth-
er dimensions are also possible.
The device can be composed of several element layers, whereby
the element layers are arranged on top of each other along the
height extension.
This advantageous design of the device makes it possible to pro-
duce the device in different height extensions or to quickly and
easily adapt the height extension of the device to the given
conditions on site. It is possible to cut off the element layers
of a compression element using means that are usually available
on the construction site (e.g. a saw) or to add further element
layers to a compression element. The added element layers can,
for example, be fixed with adhesive or mechanical fasteners such
as wires, screws or staples. The elements can be connected par-
ticularly easily using adhesive.
It is also possible to individually process the shape of the in-
dividual element layers or the compression element as a whole.
This is also possible with tools that are generally available on
a construction site, e.g. with saws or knives. As a result, the
upsetting element can be adapted to the given installation con-
ditions on the construction site. In practice, this means that
the upsetting element can be very easily adapted to different
conditions by the user. Of course, the devices can contain other
materials in small quantities, such as adhesive or fasteners.
The other materials added in small quantities do not essentially
change the deformation properties of the device. Further materi-
als are added to the device essentially to optimize the fabrica-
tion and/or installation of the device and not to influence the
deformation behavior of the device.
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The device may comprise at least two different densities, in
particular at least two, preferably three, element layers of
different densities.
The devices can thus contain polystyrene with different densi-
ties. By varying the density of the polystyrene, the deformation
behavior can be individually adapted to the expected rock defor-
mation. The polystyrene can have a deformation behavior that in-
cludes a linear-elastic zone, a flow zone and a compaction zone.
In the linear-ar-elastic zone, the stress increases essentially
in direct proportion to the compression. The linear-elastic zone
is essentially in a range between 2 percent and 5 percent of the
compression of the polystyrene. In the flow zone, the compres-
sion of the polystyrene increases, whereby the stress essential-
ly only increases moderately. The flow zone is essentially in
the range between 5 percent of the compression and 60 percent of
the compression of the polystyrene. In the compression zone, the
tension increases, while the compression essentially only in-
creases slightly. Compaction essentially takes place from a com-
pression of 60 percent of the polystyrene.
By designing the device with element layers of different densi-
ties, it is therefore possible to produce a device with special
deformation properties. This makes it possible to produce com-
pression elements that are specially adapted to the rock condi-
tions on site. Due to the standardized structure of the device
consisting of element layers, it is also possible to produce a
large number of devices with different deformation properties
using different essentially cuboid element layers with a few
different densities.
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A symmetrical arrangement of layers of different densities can
be formed so that two layers of the same density are formed in
one device. A single middle layer can be formed here.
By providing element layers in three different densities, the
construction of the device from several element layers makes it
particularly advantageous to produce a large number of devices
with different deformation properties.
This means that standardized element layers with different den-
sities can be used to produce a large number of compression bod-
ies simply and easily, which are adapted to the respective rock
conditions on the construction site. Production plants only need
to be designed for the production of element layers with a few
different densities, while the end products (compression ele-
ments), which comprise element layers with different densities,
can be produced with a variety of different deformation proper-
ties.
It is possible that the compression elements ordered from the
construction site are manufactured in a factory with the desired
properties. It is also conceivable that the element layers are
produced in several densities in one factory and delivered to
the construction site as element layers. Several element layers
with the same or different densities can then be assembled on
the construction site. It is therefore conceivable to manufac-
ture the compression elements in a factory as well as to manu-
facture element layers in a factory with subsequent delivery of
the element layers as semi-finished products to a construction
site and with subsequent assembly of the semi-finished products
to form a final product (compression element), which can then be
installed.
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In a further variant of the invention, the device can have a
lower density along the height extension on the outside than in
the central range.
Due to this advantageous embodiment of the invention, the device
fits snugly against the shotcrete along the height extension on
the outside, where the force is applied to the shotcrete. In
this way, unevenness, which regularly occurs with shotcrete, can
be compensated for. This enables an advantageous transmission of
force to the shotcrete essentially over the entire contact sur-
face of the compression element with the shotcrete. This means
that the force can be transferred from the compression element
to the shotcrete over the entire contact surface. This ensures a
large-area and gentle force transmission, which minimizes the
risk of damage to the shotcrete.
In a further advantageous embodiment of the invention, the de-
vice has a density in the range of 100 kg/m3 to 500 kg/m3. In
particular, the element layers essentially each have a density
of between 230 kg/m3 and 410 kg/m3.
At the specified density, the device is compressed before the
shotcrete is significantly damaged. At the same time, the device
is so rigid that the pressure of the surrounding rock can be ab-
sorbed in conjunction with the shotcrete. Thus, at the specified
densities, the device has the deformation properties required to
be able to act effectively in conjunction with the shotcrete
shell.
In a further advantageous embodiment of the invention, the de-
vice has a weight of less than 40 kg.
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Due to the weight of the device of less than 40 kg, the device
can be installed by a single user. This makes the installation
of the device less cost-intensive.
The object of the invention is further solved by a process for
producing a fastening layer suitable for absorbing rock defor-
mations in underground mining, wherein the fastening layer com-
prises an inner layer, in particular a shotcrete layer or a lay-
er of segments, and a device as described above is arranged in
the inner layer.
By installing the device in the inner layer, the device can be
easily installed by a user from the inside. In addition, the
correct installation and compression of the devices can always
be checked visually.
The device can first be placed on a radially arranged surface in
the range of the subsequent shotcrete shell and then fixed in
place. The device can also first be attached to a horizontal
fastening element or placed on a horizontal fastening element
and then fixed in place using fasteners. The horizontal fas-
tening element can be made of steel, plastic, a composite mate-
rial or another suitable material. The type of installation is
therefore extremely simple and flexible.
The fastening layer can comprise a fastening grid on the moun-
tain side, which is positioned between the inner layer and the
mountain.
The fastening grid can advantageously absorb the tensile forces
in the shotcrete and facilitate the installation of the device.
The fastening grid can comprise steel or plastic, for example.
The fastening grid can also be made of a composite material. The
device can be advantageously attached to the fastening grid.
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This can be done, for example, by tying straps, lines or other
fastening means around the device and looping them around one or
more elongated horizontal or vertical grid elements. It is also
conceivable that the device is attached to an essentially cylin-
drical fastening element with hooks. The hooks can be made of
steel. The hooks can be embedded in the device at one end and
have a substantially hook-shaped form at the other end, so that
the device can be attached to the fastening element with the
substantially hook-shaped ends of the hooks. It is conceivable
that the second end of the hooks is shaped like a segment of a
circle. Another shape of the hooks, for example with one or more
angles and/or bends, is also possible. Due to the advantageous
arrangement of the fastening element, the device can be trans-
ported extremely conveniently by a user. Furthermore, the fas-
tening element can be used for installation by attaching the de-
vice with the fastening element to the retaining grid or by
placing the device on a fastening element attached to the re-
taining grid. The device can then be attached to the fastening
grid using other fasteners, such as wires, straps or cable ties.
This type of installation is very simple and uncomplicated. As a
result, the device can be installed on construction sites with
the means usually available on construction sites.
The height extension of the device can be arranged tangentially
to the cavity. The base surface of the device can be arranged
radially to the cavity.
This arrangement of the device makes bending, tilting or twist-
ing buckling of the device extremely unlikely and the device is
highly likely to be compressed as intended. This ensures high
reliability of the device.
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The mounting layer can comprise at least two mounting arches,
with the device being positioned between the two mounting arch-
es. The device can rest on a fastening element or hang from a
fastening element that connects the fastening arches. In this
arrangement, the fastening element is arranged along the longi-
tudinal axis of the cavity created in the underground construc-
tion.
Due to the embodiment of the invention with fastening arches,
the device can be installed in a particularly advantageous man-
ner by installing a fastening element between the fastening
arches in a substantially horizontal direction. The fastening
element can be a rod made of steel or plastic, for example. The
device can be placed on the fastening element or attached to the
fastening element. The device can be installed in a particularly
advantageous manner by hooking the fastening element onto the
two hooks located on the device and then hooking it with the at-
tached device first into a first fastening bend and then into a
second fastening bend. The device can also be installed by first
hooking the fastening element into the first fastening bend and
then into the second fastening bend and then attaching the de-
vice to the fastening element with the hooks or placing it on
the fastening element. The device can then be fixed to the fas-
tening grid using wires, straps, cable ties or other fastening
elements. This type of installation is simple, uncomplicated and
not prone to errors.
The object of the invention is further solved by the use of a
polystyrene compression element for absorbing rock deformations
in tunnel construction, in particular a polystyrene compression
element with layers of different densities.
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The use of a polystyrene compression element for absorbing rock
deformations in tunnel construction is a simple, inexpensive and
uncomplicated method for absorbing the deformations which occur
in tunnel construction, for example in a shotcrete shell or in
segments.
The object of the invention is further solved by a process for
manufacturing a device as described above, wherein the device is
assembled from a plurality of polystyrene bodies. The polysty-
rene bodies can be cuboidal. In addition, the polystyrene bodies
can be joined together by gluing.
The process of manufacturing a device from several polystyrene
bodies is extremely uncomplicated and flexible. The device can
be assembled from two or more polystyrene bodies. A polystyrene
body then corresponds to a layer of a device for absorbing rock
deformations. It is conceivable that polystyrene bodies of dif-
ferent densities are joined together. The polystyrene bodies can
be joined together by gluing. It is also conceivable to fasten
the polystyrene bodies together using other fastening means, for
example screws, nails, pins, cable ties, straps or chains.
The invention is explained in more detail in the following fig-
ures.
As shown in:
Fig. 1: A device for accommodating rock deformations in under-
ground mining, in particular a compression element,
Fig. 2: A device for absorbing rock deformations in underground
mining, in particular a compression element, installed in a
shotcrete shell,
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Fig. 3: An exemplary stress-strain diagram of poly-styrene with
a linear-elastic zone, a flow zone and a compaction zone,
Fig. 4: A schematic representation of different, exemplary ar-
rangements of several element layers of a device for recording
rock deformations with the same or different densities,
Fig. 5: A schematic cross-section of a tunnel with four exempla-
ry arrangements of devices for recording rock deformations,
Fig. 6: A device for accommodating rock deformations in under-
ground mining, in particular a compression element, with a re-
taining grid, two hooks, a horizontal fastening element and two
fastening arches,
Fig. 7: A view of a plurality of devices for accommodating rock
deformations in underground construction, installed in the shot-
crete formwork of a tunnel lining,
Fig. 8: A cross-section of a segment of a shotcrete tunnel lin-
ing with a built-in device for absorbing rock deformations in
underground construction,
Fig. 9: A view of a segment of a tunnel lining in the construc-
tion stage with a built-in device for absorbing rock defor-
mations in underground construction, a horizontal fastening ele-
ment, two fastening arches and a retaining grid.
Figure 1 shows a device for absorbing rock deformations in un-
derground mining, in particular a compression element 1, with an
exemplary arrangement of several element layers 2, whereby the
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compression element 1 in this example is cuboidal and the longi-
tudinal extension is greater than the height extension and/or
the depth extension of the compression element. The compression
element 1 is composed of six element layers 2. In this example,
the compression element 1 also has a longitudinal extension of
80 cm, a height extension of 30 cm and a depth extension of 25
cm.
Figure 2 shows a device for absorbing rock deformations in un-
derground mining, in particular a compression element 1, in-
stalled in a shotcrete shell 3, whereby the compression element
1 is essentially cuboid in shape and the height extension of the
device is arranged tangentially to the cavity and the base sur-
face is arranged radially to the cavity. The base surface of the
compression element 1 fits snugly against the shotcrete shell 3,
which ensures advantageous force transmission between the com-
pression element 1 and the shotcrete shell 3. The dimensions of
the compression element 1 and the arrangement of the compression
element 1 in the recess of the shotcrete shell 3 ensure that the
compression element 1 has a low probability of tilting when a
force is applied by the shotcrete shell 3 and a high probability
of being compressed and can therefore absorb forces from the
shotcrete shell 3 and deformation of the shotcrete shell 3.
Figure 3 shows an exemplary stress-strain diagram of polystyrene
with an essentially linear-elastic zone 4, a flow zone 5 and a
compaction zone 6. The stress-strain diagram of the respective
compression element (not shown) can be advantageously adapted by
a different density of the element layers 2, so that the proper-
ties of the compression element (not shown) can be advantageous-
ly adapted to the given conditions and the technical require-
ments in the specific application.
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Figure 4 shows a schematic representation of different, exempla-
ry arrangements of several element layers 2 of a device for ab-
sorbing rock deformations with the same or different densities,
whereby the element layers 2 of a compression element 1, if they
have different densities, can be arranged in such a way that the
element layers 2 with the higher density are on the outside in
the vertical expansion. The element layers 2 can also be ar-
ranged in such a way that the element layers 2 with the lower
density are on the outside of the height expansion. An asymmet-
rical arrangement of the element layers 2 in relation to the
density along the height extension of the compression element 1
is also conceivable. It is possible that the two outer element
layers 2 in relation to the height extension have the highest
and the lowest density of the element layers 2 of the compres-
sion element 1, while the element layers 2 enclosed by the outer
element layers 2 have a density that lies between the highest
and the lowest density of the element layers 2 of the compres-
sion element 1.
Figure 5 shows a schematic cross-section of a tunnel with four
exemplarily arranged devices for accommodating rock deformations
(compression elements), whereby the height extensions of the
compression elements 1 are arranged tangentially to the cavity
and the base surfaces of the compression elements 1 are arranged
radially to the cavity. In Figure 5, the compression elements 1
are arranged in the ridge and in the elm of the tunnel cross-
section as an example. It is possible for the compression ele-
ments 1 to be arranged in every area of the shotcrete shell 3.
It is also possible for several compression elements 1 to be ar-
ranged in direct contact in such a way that their base surfaces
touch each other. A single compression element 1 or a plurality
of compression elements 1 can be installed in the cross-section.
The compression elements 1 can be arranged axially symmetrically
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or point-symmetrically. An asymmetrical arrangement of the accu-
mulation elements 1 is also possible.
Figure 6 shows a device for absorbing rock deformations in un-
derground mining, in particular a compression element 1 with a
retaining grid 7, two hooks 8, a horizontal fastening element 9
as well as two fastening arches 10 and a wire 11. The advanta-
geous attachment of hooks 8 to the compression element 1 means
that the compression element 1 can be processed and installed in
an advantageous manner. The hooks 8 can be made of steel, plas-
tic, a composite material or another suitable material. In this
example, the hooks 8 are made of steel. At a first end of the
hooks 8, the hooks are connected to the compression element 1 by
inserting the first end of the hooks 8 into the compression ele-
ment 1. At a second end of the hooks 8, the hooks 8 are hook-
shaped. With the hook-shaped second end, the hooks 8 are at-
tached to an essentially horizontal fastening element 9. In this
example, the second end of the hooks 8 is semi-circular in
shape. The upsetting element 1 is attached to a horizontal fas-
tening element 9 with the hooks 8. In this example, the horizon-
tal fastening element is an essentially cylindrical steel rod.
The horizontal fastening element 9 is suspended in the two fas-
tening arches 10. In this example, the upsetting element 1 is
fastened by a wire 11. This allows the retaining element 1 to be
brought into a desired position, the shotcrete shell 3 can be
installed and it is extremely unlikely that the retaining ele-
ment 1 will move significantly during the installation of the
shotcrete shell. This ensures that the compression element 1 re-
mains in the intended position during further construction work.
It is also conceivable that the retaining element 1 is fixed to
the retaining grid with cable ties, straps, belts, hoses or oth-
er fasteners.
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Figure 7 shows a view of a number of devices for absorbing rock
deformations in underground construction (retaining elements),
installed in the shotcrete formwork 3 of a tunnel lining. In
this installation state, the retaining grid is covered by the
shotcrete shell 3 or by the compression elements 1 and is no
longer or only partially visible. The height extension of the
compression elements 1 is aligned tangentially to the cavity in
the shotcrete shell 3 and the base surface of the compression
elements 1 is arranged radially to the cavity. This advantageous
alignment of the compression elements 1 in the shotcrete shell 3
makes it extremely unlikely that the compression elements 1 will
tilt, bend or buckle. It is therefore very likely that the com-
pression elements 1 will be compressed as intended. In combina-
tion with the shotcrete shell, the function of the system is
therefore very reliable. In addition, the compression elements
are visible when installed. This means that the compression ele-
ments 1 can be visually checked for correct seating and function
by a user or by appropriate measuring equipment.
Figure 8 shows a cross-section of a segment of a shotcrete tun-
nel lining with a built-in device for absorbing rock defor-
mations in underground construction (compression element). Here,
the compression element 1 is placed on a horizontal fastening
element 9. It is possible for the compression element 1 to be
fixed by a wire 11 or several wires. This allows the compression
element 1 to be brought into a desired position, the shotcrete
shell 3 can be installed and it is extremely unlikely that the
compression element 1 will move significantly during the instal-
lation of the shotcrete shell 3. This ensures that the compres-
sion element 1 remains in the intended position during further
construction work. The height extension of the compression ele-
ments 1 is aligned tangentially to the cavity of the tunnel and
the base surface of the compression elements 1 is arranged radi-
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ally to the cavity. The height extension of the element layers 2
is also aligned tangentially to the cavity of the tunnel. The
surface on which the individual element layers 2 lie on top of
each other is thus aligned radially to the cavity of the tunnel.
Figure 9 shows a view of a segment of a tunnel lining made of
shotcrete with a built-in device for absorbing rock deformations
in underground construction (compression element). A retaining
grid 7 is fitted between the compression element 1 and the moun-
tam n on the mountain side. The compression element 1 is fixed to
the retaining grid 7 with a wire 11 or several wires. In addi-
tion, the compression element 1 rests on a horizontal fastening
element 9. The horizontal fastening element 9 is suspended in
two fastening brackets 10.
20
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