EP3540178B1

EP3540178B1 - Supporting device for stabilising underground cavities, particularly tunnels, as well as mining openings

Info

Publication number: EP3540178B1
Application number: EP18161850.5A
Authority: EP
Inventors: Prof. Dr. Kalman Kovári; Patrick Steiner
Original assignee: Solexperts AG
Current assignee: Solexperts AG
Priority date: 2018-03-14
Filing date: 2018-03-14
Publication date: 2021-08-25
Anticipated expiration: 2038-03-14
Also published as: EP3540178A1; JP6938555B2; JP2019196694A

Description

The object of the invention relates to a device serving for stabilising underground cavities. The device is preferably used in poor rock exhibiting low strength, and possibly situated under elevated overburden. In such cases squeezing phenomena may occur resulting in great deformation and/or in high rock pressure on the support elements.
A known procedure used in underground structures (tunnels, galleries, caverns and the like) is stabilising the excavated cavity using a lining, i.e. using supporting means such as steel arches, sprayed concrete, anchors, and prefabricated concrete elements. The profile of the excavated cavity in squeezing rock has a tendency to narrow. Hindering this with linings and other known supporting means may result in large pressure acting on them. However, by allowing the rock to deform in a controlled way, the pressure will diminish.
Various solutions allowing the deformation of supports and so of the surrounding rock are known in underground engineering. For I beams, also known as H beams, consisting of two flanges and a web, Hoek, E. and Guevara, R. proposed a solution in "Overcoming squeezing in the Yacambú-Quibor Tunnel, Rock Mechanics and Rock Engineering, Vol. 42, .
An individual "steel arch" contains at least two segments serving as supporting parts, between which there is a contraction gap. The two segments are connected to each other with straps ensuring a friction connection. Although this supporting structure during the deformation of the rock surrounding a tunnel has the ability to deform, it is only capable of exerting a small rock-supporting effect.
EP 2 918 772 A2 discloses a supporting device with arched supporting beams, two of the arched supporting beams are connected with a sliding connector, however they do not exhibit any compression body between them. At least two of the supporting beams representing an expansion unit. The supporting devices further comprise a vault in the sense of shell segments made of shotcrete and compression bodies, which are arranged between said concrete segments. Said compression bodies support temporary hardening of the shotcrete concrete segments by the deformability of the compression elements and thus prevents overload and thus fractures in the shotcrete concrete segments.
CH 451 233 A comprises a supporting device for stabilizing tunnels, having at least a first supporting beam and a second supporting beam and at least one compression body. Said first and second supporting beams are formed by arched beam elements, and said compression body is arranged such that the supporting beam is able to move under load. Said compression body is arranged between said arched beam elements.
The task to be solved by the invention is the provision of a supporting device consisting in arched supporting beams used in underground cavities, especially tunnels and mining openings suitable for guaranteeing secure support by overcoming at least one or more of the disadvantages of the prior art, in particular the disadvantages of the supporting device detailed above even in the case of significant rock deformation or rock pressure.
The invention is based on the recognition that if a high-strength compression body with a substantial deformation ability is placed between the two beam elements of an arched supporting beam, in addition to the occurrence of the desired deformation, significant resistance of support against movements can be ensured, which can be adjusted in accordance with the prevailing requirements.
On the basis of this recognition the set objective has been solved in accordance with the invention with the device defined in claim 1, as well as in claim 11.
The object of the invention relates to a supporting device for stabilising underground cavities, especially as well as mine adits and similar structures.
The preferable embodiments of the supporting device are defined in the subclaims.
Further details of the invention will be explained on the basis of the attached figures, which contain the preferable embodiments of the device.
The invention is directed to a supporting device for stabilizing underground cavities, especially tunnels. The supporting device has at least a first supporting beam and at least one compression body. The compression body is arranged such that the supporting beam is able to move under load. The compression body is made of a material with high strength and great permanent deformation ability.
High strength means a yield strength of at least 235 N/mm^2, preferably at least 355 N/mm^2.
Great permanent deformation ability means a yield-to-tensile ratio of at least 1.05, preferably a yield-to-tensile ratio of at least 1.08. The yield-to tensile ratio is the ratio between the yield strength and the ultimate tensile strength. Such a compression body enables to have the supporting beam in an unloaded state positioned in a specific position and enables a movement of the supporting beam in direction of the compression body such that a hypothetic cross section of the cavity is reduced. The supporting device comprises at least a second supporting beam.
The supporting beams are formed by arched beam elements. The arched beam elements are able to move under load towards each other. The compression body is arranged between said arched beam elements.
Such a configuration enables to keep the distance between the arched beam elements without load and may be deformed under load. The deformation enables the arched beam elements to alter its position and to move relatively to each other such that a hypothetic cross section of the tunnel is reduced.
In an alternative embodiment, the supporting device for stabilising underground cavities, especially mine adits has at least a second supporting beam. The first and the second supporting beams are fitted into or on the side walls of the underground cavity, preferably arranged essentially parallel to each other. The at least one compression body is arranged between a ground of the underground cavity and the first supporting beam or between the first supporting beam and a roof or a roof element of the supporting device. The supporting device comprises a second compression body arranged between the ground of the underground cavity and the second supporting beam or between the supporting beam and a roof or a roof element of the supporting device. It is also possible to have more than one compression bodies arranged at the first supporting beam, e.g. one below the supporting beam and the ground and one between the supporting beam and the roof.
This enables to lower a roof, which may be arrange on top of the first and second supporting beam to be lowered in case of rock pressure.
The compression body contains a pipe.
The space inside of the pipe provides a huge amount of space for deformation of the pipe and thus for movement of the supporting beams.
The pipe may have a circular cross-section.
The circular cross section enables easy manufacturing of the supporting device. Furthermore, pipes with circular cross section are available premanufactured in several different dimensions.
The pipe may have a right-angled rectangular cross-section preferably with curved corners.
Such a pipe enables to provide a specific progression of force during the deformation process.
In the case a rectangular pipe is used, the sides of the pipe parallel to a longitudinal direction of the supporting beam are bent inwards in their middle range.
During the deformation process, a specific progression of the force is provided.
The wall thickness of the pipe is selected in the range of 0.05 to 0.15 times the diameter of the circular cross-section pipe for circular pipes, and 0.05 to 0.15 times the beam-direction side length of the pipe with a right-angled rectangular cross-section for rectangular cross-section pipes.
This leads to a supporting device which is stable in its nondeformed condition and which enables a huge deformation and thus a huge movement of the supporting beams.
The pipe can be fixed between load plates that are lateral, preferably perpendicular to the longitudinal direction of the supporting beam.
This has the advantage that the forces are introduced in a specific way into the pipe.
The ends of the supporting beams may be provided with face plates for closing off the ends of the supporting beams. The load plates can be fixed to said face plates.
Hence, a interface between the supporting beams and the compression body is provided.
In an alternative embodiment, the pipe can be fixed directly to the face plate closing off the end of the supporting beam.
This has the advantage, that the supporting device may be provided as a single element.
In case a circular cross section-section-pipe is used, the circular cross-section pipe can fit to the load plates along a flat surface.
A specific first position of the circular-cross-section pipe can be provided. The input of the force into the circular-cross-section pipe can be specified.
In an alternative embodiment in case a circular-cross-section-pipe is used, the circular cross-section pipe can fit to the load plates along a curved surface of the load plates.
A specific first position of the circular-cross-section pipe can be provided. The circular-cross-secion pipe can be held in this specific position.
Additionally, or alternatively, the load plates loading the circular cross-section pipe can have protruding parts that come into contact with the external surface of the pipe at a distance on two sides from the longitudinal geometric centre plane of the pipe.
A specific first position of the circular-cross-section pipe can be provided. The circular-cross-section pipe can be held in this specific position. The input of the force into the circular-cross-section pipe can be specified.
The protruding parts can be wedge-shaped.
The input of the force into the circular-cross-section pipe can be specified.
The protruding parts may be hemispherical.
The input of the force into the circular-cross-section pipe can be specified.
The specific form of the protruding parts has in each case an influence onto the deformation of the compression body. Thus, for a desired deformation, the protruding parts can be adjusted specifically.
The material of the compression body may be steel, preferably E355 quality steel.
Steel is cheap and available in different qualities. E355 steel is a preferred steel which is typically used for manufacturing tubes. Hence, the tubes are available as premanufactured parts.
The supporting beams may be steel I-profile beams, also known as H beams, or steel pipes preferably with circular cross-section.
Such elements are available as premanufactured parts and are easy bendable into the arched form. Furthermore, they provide enough stability.
As to the figures:

Fig. 1: shows the side view of the connection of the arched segments of a tunnel support device according to the state of the art as a cross-section taken on the line marked X-X in figure 2,
Fig. 2: shows the cross-section between the holes f of figure 1, viewed in direction g of figure 1,
Fig. 3: shows a schematic cross-section of a tunnel, where the arched beams contain the compression bodies according to the invention,
Fig. 4: shows the detail B marked in figure 3 in larger scale,
Fig. 5: shows the view marked with the arrow A in figure 4,
Fig. 6: shows a perspective view of the device in the case of I-beams according to figures 4 and 5,
Figs. 7 and 8: respectively show the compression body of figures 4 to 6 in unloaded and loaded states,
Fig. 9: is a diagram showing the possible deformational behaviour of the compression body of figures 7 and 8,
Fig. 10: shows the front view of a preferable embodiment of the compression body according to the invention,
Fig. 11: shows the cross-section taken on the line S1-S1 marked in figure 10,
Fig. 12: shows the cross-section taken on the line S2-S2 marked in figure 11,
Fig. 13: shows a schematic front view of the basic structural elements of the compression body according to a special embodiment,
Fig. 14: illustrates the transfer of force in the case of the compression body established according to figure 13,
Fig. 15 and 16: show an embodiment of the compression body where the pipe and the load plate are modified in the interest of being able to vary the transfer of force,
Figs. 17 to 19: show an embodiment of the compression body in which the load plate is again modified as compared to the basic solution in figure 14 in the interest of being able to vary the transfer of force,
Fig. 20: shows a force-deformation diagram that correlates to differing structure embodiments of the compression body,
Fig. 21: shows a diagram similar to that in figure 20, where the one curve belongs to the basic compression body solution, and the other to an embodiment that has a wedge load plate,
Fig. 22: shows the front view of another embodiment of the compression body,
Fig. 23: shows the view of the compression body taken from the direction marked with he arrow C in figure 22,
Fig. 24: illustrates the possible course of the deformation occurring as a result of the force effect according to the arrow P marked in figure 22 with indication of the associated force-deformation diagram,
Fig. 25: illustrates the possible course of the deformation of the compression body according to figures 22 and 23, also with indication of the associated force-deformation diagram,
Fig. 26: shows a perspective view of the embodiment of the compression body according to the invention according to figure 15,
Fig. 27: shows the cross-section of a mining adit, in the case of which the compression body according to the invention forms a part of the supporting structure.

According to the state of the art a junction point of a tunnel support made from the arched steel I-profiles mentioned in the introduction is shown in figures 1 and 2, where the two I-profiles a and b are connected to each other. There is a contraction gap c of width S between the I-profiles a and b. To connect these segments to each other in a force-resisting way the I-profiles a and b are pressed between two encompassing steel straps d and e by bolts f. As a result of the pressure when the I-profiles a and b move towards one another as shown by the arrows g in figure. 2, friction forces are created between the surfaces of the straps and the I-profiles, which are exerted against the contraction of the gap c. In this way the tunnel support permits the rock mass surrounding the tunnel to deform while simultaneously exerting a supporting effect against it, the magnitude of which depends on the friction resistance. This friction resistance is a function of the friction factor between the straps and the I-profiles, i.e. between steel and steel, as well as of the tension force created in the bolts.
However, there are certain practical disadvantages of this type of connection of the arched steel I-profiles. The limits of the friction resistance between the straps and the steel I-profile support beams are obviously presented by the limited number and diameter of the bolts and the low steel-steel friction factor. Especially due to the low friction factor the supporting effect on the rock surrounding the tunnel during its deformation, i.e. when the rock moves to close the contraction gap c, is very low. A further disadvantage is that as a consequence of a possible bending moment in the beams the bolts may be subjected to an extra load that can lead to their breakage.
In the following the method and device according to the invention are presented in detail with reference to figures 3 to 6.
The compression body 7 located between the tunnel beam elements 2 of the tunnel supporting device 1 according to the invention, which is subjected to a load caused by the deforming rock 5 must constantly shorten when a specified amount of pressure is reached exceeded as the width of the gap 6 is reduced. This shortening occurs as a consequence of the change of shape of the compression body 7 having a great deformation capacity. After the elastic limit of the material of the compression body 7 is exceeded, it must also have a great yielding capability. In addition the shape of the compression body 7 must be selected so that it is able to slightly rotate when there is simultaneous moment resistance between the beam elements 2. The device according to the invention is able to satisfy these requirements, as will be seen, by the appropriate selection of the material, size and geometric shape of the compression body 7.
The following discussion uses figures 7 to 9 to explain the functional principle of the supporting device 1 including the compression body 7 between two beam elements 2 as shown in figures 4 to 6.
Figures 7 and 8 show a region of the supporting device with the compression body 7 in the unloaded and loaded states, where the compressive force acting in the beam elements 2 and therefore on the compression body 7 is designated as N, and the height of the compression body 7 in unloaded state is designated as d and as d' in the loaded state. Figure 9 shows a diagram in which the deformation ε=(d-d')/d) for the compression body 7 is indicated on the horizontal axis and the normal force N acting on the compression body 7 is indicated on the vertical axis.
Deformations in the rock 5 cause a reduction in the profile of the tunnel cavity 4, with the result that the supporting device 1 elements, namely the beam elements 2 are subject to compressive forces and begin to shift relative to each other. At the same time the compressive bodies are subjected to loads causing their shortening. When the compression bodies 7 first experience the load, their deformation ε proceeds essentially linearly with increasing load (N in figure 7 to 9). Upon reaching a given force permanent (plastic) deformations begin to take place in the compression bodies 7. The tunnel beam elements 2 gradually give way under the growing load from the rock and shift towards each other while reducing the hight d. The compression elements 7 are compressed at an increasingly greater rate. As figure 9 shows, the compressive stress in region II remains at a relatively high level. Subsequently there is a phase III of increasing resistance.
An embodiment of the compression body 7 has been shown in figures 10 to 12, which is formed here by a circular cross-section, thick-walled steel pipe 8, or pipe member, and two, also steel, parallel load plates 9 placed opposite one another fixed to the pipe 8 by, for example, welding. The beam elements 2 shown in figures 1 to 3 of the arched beams positioned longitudinally along the tunnel separated by spaces forming a part of the entire supporting device 1, are here shown in larger scale and in the case of this embodiment are arched steel I-profile beams, the ends of which are closed off with face plates 3, and are positioned at a distance from each other equal to the length h of the compression body 7, and so the gap 6 in figure 6 between the beam elements 2 is able to accommodate the entire compression body 7, which with the load plates 9, fits to the face plates 3 of the beam elements 2.
It should be noted here that in the use in the present invention the concept "beam element" is to be interpreted as broadly as possible, its cross-section shape may differ from the I shape, and compression bodies may be positioned between beam elements with a complex profile, such as between beam elements consisting of two or more I-profile beams.
The ratio of the diameter of the circular profile pipe 8 and its wall thickness, in other words the V/D ratio indicated in figure 10 is selected to be in the range of 0.05 to 0.15, which in the case of the present example, where the diameter D of the pipe 8 is 300 mm, means a wall thickness of V=30 mm. The quality of the steel used is preferably E355, and the load plates 9 are also made of this material. In this way its tensile strength is 400 to 500 N/mm² and its plastic deformation may be 15 to 20%.
A number of possible cases of guiding the forces P exerted on the pipe 8 - pipe member - of the compression body 7 via the load plates 9 are illustrated through figures 13 to 20. In the interest of better illustration, with the exception of figure 16, the load plate 9 and the pipe 8 have been illustrated separated from each other, in other words in an as yet unassembled state.
The case according to figures 13 and 14, the general case for a cylindrical pipe, is the simplest, here the load plates 9 and the pipe 8 are present still in their original condition, they have not been modified, as in the cases of the solutions in the other figures. In this case the force transfer takes place from the load plate 9 to pipe 8 with centre axis K initially along a line V in the centre plane Z indicated with a dashed line in figure 15. It should be noted that only the one load plate 9 and a part of the pipe 8 have been shown in figures 14 and 15 and in figures 17 to 19, however, it is obvious that in these cases, just as in figure 13, the forces P are exerted in two opposite directions onto the pipe 8.
In the case of the solution according to figure 15, at those places where the pipe 8 and the load plates 9 come into contact a part of the wall of the pipe 8 has been removed along the entire length of the pipe 8 in this way establishing a flat resting surface 10 for the load plate 9. As a result of this the force transfer takes place when the load starts to be exerted along the flat surface 10. In this case, therefore, the pipe 8 has been modified.
However, according to figure 16 depressions 11 with a curved surface matching the surface of the pipe 8 have been formed in the two load plates 9 at those locations where they fit up to the pipe 8. Therefore in this case the transfer of the force takes place along the curved surfaces fitting up to each other.
However, the load plates 9 can not only be modified with the depressions 11 according to figure 16, instead they can be modified to have protruding parts 12 from the load plate 9 directed towards the pipe 8. This theoretical possibility is illustrated in figure 17, where the dimensions of the symbolic protruding parts 12, primarily the height m, and their distance n from the longitudinal centre plane Z passing through the geometric centre point K of the pipe 8, as well as their shape influence the force input.
This means that by suitably selecting the shape of the protruding parts 12 and the dimensions m and n it is possible to comply with the force transfer requirements originating from the prevailing rock loads in accordance with the force-deformation diagrams according to figure 20. The protruding parts 12 are positioned symmetrically to the centre plane Z, may be fixed to the latter by welding, for example.
In the case according to figure 18 the protruding parts 12 are wedge-shaped, with their inclined surfaces fitting up to the curved surface of the pipe 8. In the case according to figure 19 though the protruding parts 12 are hemispherical in shape.
It is obvious that the use of protruding parts 12 of any shape and size must be viewed as being within the scope of protection of the invention.
It should be noted that in addition to that described above the protruding parts 12 also have a role in preventing the pipe 8 from slipping apart, if a load creating such a force-component is exerted onto the beam.
Of the two force-deformation diagrams shown in figure 20, the curve shown with a solid line running in a flatter way conforms to the simplest solution, in other words to the structural solution according to figure 14, where the force introduction takes place along the line V, while the curve with a dotted line running in a steeper way conforms to the force introduction case provided with the structural solution according to figure 18. In figure 20 has also been illustrated as a function of the increase of the forces P exerted on it and of the progression of the increase, this process is also illustrated with a schematic but concrete indication of the two kinds of structural solution in figure 21.
Figures 22 and 23 show a compression body according to the invention designed with reference number 13. In this case the steel pipe 14 is rectangular preferably with rounded right-angled corners, and in this case its sides parallel to the longitudinal direction of the beam elements 2 created from steel I-profiles are bent inwards to a relatively small extent. Here the ends of the beam elements 2 are closed off with flanged face plates 3, into which the load plates 9 fitted to the pipe 14 by welding, for example, are inserted.
In the case of this embodiment also the load plates 9, and the rectangular pipe 14 preferably with right-angled corners, which may have a square or a rectangular cross-section, are made of E355 quality steel, and the wall thickness v is, as stated previously, selected as a function of the height H on the basis of the relationship v/H=0.05-0.15, 30 mm.
As a result of the forces P illustrated in figure 22 the deformation of the pipe 14 may have two outcomes according to the selected shape of the tube. Figure 24 illustrates the case when with the increase of the force P the centre, inward bending part of the pipe 14 is pressed outwards, and the two other side walls become dented inwards. The two figures drawn on the graph illustrate this process well, at the end the pipe 14 is practically completely flattened between the beam elements 2, accordingly the two beam elements 2 can move towards one another, and behind them the desired movement of the rock mass becomes possible, as does the stabilising of the entire tunnel supporting device.
With the increase of the forces P the inward bending part of the pipe 14 bends inwards even more, and during the process the deformation depicted in the upper part of figure 25 takes place, in other words in this case an increasing degree of compression of the pipe 14 between the load plates 9.
The compression body 15 illustrated in figure 26 differs from the compression body 7 shown in figures 10 to 12 in that here there are no load plates 9, instead their function is carried out directly by the face plates 3 closing off the ends of the beam elements 2 or I-profiles.
The advantage of the outward bulging of the pipe 14 according to figure 25 is that the pipe 14 is practically completely deformed, in other words the degree of approach of the beam elements 2 to each other and the shortening of the entire beam is at the maximum, as only two plates are resting on each other, however, the parts bulging out on the two sides may be not always be preferable with respect to the possible placement of other types of rock support (for example shotcrete) between two neighbouring beams.
Finally figure 27 presents that the invention does not have to be only used for tunnels, it can be used as a supporting device for rock surrounding other underground spaces. Figure 27 shows a mine adit 16, which has been driven into the rock 5. The mine adit 16 has side walls and a roof 18 supported by them. Columns 17 are fitted into or on the side walls. The forces exerted on the mine adit 16 are illustrated with the arrows P and p. In this case the supporting device is formed by the columns 17 and compression bodies 7 being placed under the columns 17. The compression bodies 7 used here can be those as shown in figures 10-13, the compression of which makes it possible for the roof 18 to move downwards, and for the mass of rock 5 above it to move, and so reduces the rock pressure on the mine edit 16.
The advantage of the invention is that it makes arched supporting beams or columns suitable for the desired deformation of the rock to take place, contrary to the friction-connected arched supporting beams presented in the introduction, it ensures a higher load-bearing capacity required to support the rock.
Naturally, the invention is not limited to the embodiments presented in detail above, it may be implemented in various ways within the scope of protection defined by the claims.
The reference list is part of the disclosure.

Reference list

1: supporting device
2: beam elements
3: face plates
4: underground cavities / tunnel cavities
5: rock
6: gap
7: compression body
8: pipe
9: load plates
10: resting surface
11: depression
12: protruding parts
13: compression body
14: pipe
15: compression body
16: mine adit
17: Columns
18: roof

Claims

Supporting device (1) for stabilizing underground cavities (4), especially tunnels, having at least a first supporting beam and at least one compression body (7, 13, 15), the supporting device comprising at least a second supporting beam, said first and second supporting beams are formed by arched beam elements (2) being able to move under load towards each other, the supporting beams are steel I-profile beams or steel pipes, and said compression body (7, 13, 15) is arranged such that the supporting beams are able to move under load, wherein the compression body (7, 13, 15) is made of a material with a high yield strength of at least 235 N/mm^2 and great permanent deformation ability with a yield-to tension ratio of at least 1.05, the compression body (7, 13, 15) is arranged between said arched beam elements (2), characterized in that said compression body (7, 13, 15) contains a pipe (8, 14), wherein
said pipe (8) has a circular cross-section and the wall thickness (v) of the pipe (8) is selected in the range of 0.05 to 0.15 times the diameter (D) of the circular cross-section pipe (8), or
said pipe (14) has a right-angled rectangular cross-section and the wall thickness (v) of the pipe (14) is selected in the range of 0.05 to 0.15 times the beam-direction side length of the pipe (14) with a right-angled rectangular cross-section.
Supporting device according to claim 1, characterised by that said pipe (14) with a right-angled rectangular cross-section has curved corners wherein preferably the sides of the pipe (14) parallel to the longitudinal direction of the supporting beam are bent inwards in their middle range.
Supporting device according to claim 1 or 2, characterised by that the pipe (8, 14) is fixed between load plates (9) that are lateral, preferably perpendicular to the longitudinal direction of the supporting beam.
Supporting device according to one of claims 1 to 2, characterised by that the pipe (8, 14) is fixed directly to a face plate (3) closing off the end of the supporting beam.
Supporting device according to claim 3, characterised by that the load plates (9) are fixed to face plates (3) for closing off the ends of the supporting beam.
Supporting device according to any of claims 3 or 5, when claim 3 is not dependent on claim 2, characterised by that
the circular cross-section pipe (8) fits to the load plates (9) along a flat surface (10), or the circular cross-section pipe (8) fits to the load plates (9) along a curved surface (11).
Supporting device according to any of claims 3, 5 or 6, when claim 3 is not dependent on claim 2, characterised by that
the load plates (9) loading the circular cross-section pipe (8) have protruding parts (12) that come into contact with the external surface of the pipe (8) at a distance on two sides from the longitudinal geometric centre plane (z) of the pipe (8).
Supporting device according to claim 7, characterised by that the protruding parts (12) are wedge-shaped or hemispherical.
Supporting device according to any of claims 1 to 8, characterised by that the material of the compression body (7, 13, 15) is steel, preferably E355 quality steel.
Supporting device according to any of claims 1 to 9, characterised by that the supporting beams are steel pipes with circular cross-section.
Supporting device for stabilising underground cavities (4), especially mine adits (16),
having at least a first supporting beam and at least one compression body (7, 13, 15), having at least a second supporting beam, said first and second supporting beam fitted into or on the side walls of the underground cavity, preferably arranged essentially parallel to each other, said first and second supporting beams are formed as columns (17) and are steel I-profile beams or steel pipes, wherein the compression body (7, 13, 15) is made of a material with a high yield strength of at least 235 N/mm^2 and
great permanent deformation ability with a yield-to tension ratio of at least 1.05, the at least one compression body (7, 13, 15) is arranged between a ground of the underground cavity (4) and the first supporting beam or between the first supporting beam and a roof or a roof element of the supporting device, the supporting device comprises a second compression body (7, 13, 15) arranged between the ground of the underground cavity (4) and the second supporting beam or between the second supporting beam and a roof or a roof element of the supporting device, wherein the compression bodies are arranged such that the supporting beams are able to move under load, characterized by that each of said compression bodies (7, 13, 15) contains a pipe (8, 14), wherein
said pipe (8) has a circular cross-section and the wall thickness (v) of the pipe (8) is selected in the range of 0.05 to 0.15 times the diameter (D) of the circular cross-section pipe (8), or
said pipe (14) has a right-angled rectangular cross-section and the wall thickness (v) of the pipe (14) is selected in the range of 0.05 to 0.15 times the beam-direction side length of the pipe (14) with a right-angled rectangular cross-section.
Supporting device according to claim 11, characterised by that said pipe (14) with a right-angled rectangular cross-section has curved corners wherein preferably the sides of the pipe (14) parallel to the longitudinal direction of the supporting beam are bent inwards in their middle range.
Supporting device according to claim 11 or 12, characterised by that the pipe (8, 14) is fixed between load plates (9) that are lateral, preferably perpendicular to the longitudinal direction of the supporting beam.
Supporting device according to claim 13, characterised by that the load plates (9) are fixed to face plates (3) for closing off the ends of the supporting beam.
Supporting device according to claim 14, characterised by that the circular cross-section pipe (8) fits to the load plates (9) along a flat surface (10), or the circular cross-section pipe (8) fits to the load plates (9) along a curved surface (11) and preferably the load plates (9) loading the circular cross-section pipe (8) have protruding parts (12) that come into contact with the external surface of the pipe (8) at a distance on two sides from the longitudinal geometric centre plane (z) of the pipe (8) and further preferably the protruding parts (12) are wedge-shaped or hemispherical, and/or the material of the compression bodies (7, 13, 15) is steel, preferably E355 quality steel.