FR3081493A1 - Method and device for excavating cavities underground - Google Patents

Abstract

The invention relates to a method of excavating cavities (1, 2) underground, more particularly cavities (1, 2) with cavities sections of at least 5 square meters. , with the production of at least one deformable layer in a planned manner (16 - 19, 21 - 24) in the excavation state when the pressure of the rock appears on an inner side (11) of an underground cavity (1, 2), the deformable layer being made by means of a 3D printing. Figure for the abstract: Fig.3

Description

Description

Title of the invention: Method and device for excavating underground cavities

Field of the Invention The present invention relates to a method and a device for enlarging underground cavities, more particularly cavities with excavation sections of at least 5 square meters (hereinafter: m ² ) .

STATE OF THE ART In the mining field, there are different methods for erecting structures in a rock exerting pressures and liable to swell.

A structure can be erected according to the principle of resistance when the pressures of the mountain must be mastered with the rigid excavation systems known today. A rigid excavation system withstands rock pressure without significant deformation.

However, the thickness of the excavation and therefore the use of the resistance principle are subject, especially for the largest diameters of structures, in combination with large coverage, to limits. The size increases greatly for high digging resistance, so that large digging diameters become necessary. In a rock exerting a pressure and likely to swell with high mountain pressures and large diameters, the works according to the principle of resistance can be difficult to realize and only with great efforts or not at all and are therefore generally not profitable.

If the pressures of the rock and the deformations associated with a rigid excavation are no longer controllable or profitable, different variants of a deformable excavation are used. During a deformable excavation, deformation of the rock is authorized and the resulting stresses on the excavation are therefore reduced.

For a conventional sequential advance, there are different excavation systems in combination with injected concrete. Compression elements, installed parallel to the tunnel axis on the wall of the tunnel and filled with injected concrete, absorb the deformation. The absorption of loads and the deformation in the compression elements takes place tangentially with respect to the profile of the tunnel.

For continuous mechanical advance, the systems mentioned above are not suitable, because they are not compatible with casing elements. In addition, the systems described above, with the possibility of tangential deformation, do not include a deformable layer between the rock and the internal shell with the possibility of radial deformation. Systems with the possibility of radial deformation are also called flat systems. Different flat systems are known and used:

- annular gap mortar, for example Compex: the annular gap between the rock and the casing is compressed with a compressible mortar.

- flat sandwich casing elements, for example Solexperts hiDCon-F, Andra Bure: on the casing segment, a deformable layer made up of small terracotta tubes is added.

- compressible injected concrete: a deformable mortar or concrete is injected pneumatically on the surface of the excavation.

These flat systems are certainly suitable for mechanical advance of tunnel tubes. However, at the level of crossing structures or in the case of transverse galleries, these systems are only suitable under certain conditions. Crossing structures require more complex excavation geometries than constant tunnel sections.

For the compression of a compressible mortar, an annular gap is necessary. It is therefore only suitable for the TBM feed, in which an annular gap exists between the rock and the casing. In bifurcation or crossing works, complex shell constructions are necessary for the compression of compressible mortar.

Due to the complex geometry, the manufacture of casing segments with an additional deformable layer for crossing and bifurcation works is extremely difficult.

The state of the art is to make the inner shell in one direction and create the crossing or the transverse gallery in a conventional manner at a later time. The internal shell is then often made with special formwork carriages.

For the operation of a deformable flat system, the thickness of the layers and their deformation properties are important parameters. When using injected concrete, these two parameters are, in practice, subject to relatively large uncertainties. The deformation properties and the thickness of the applied layer are very difficult to guarantee within a tolerance range and are highly dependent on the conductor of the machine and the method of application.

Patent EP 0 557 269 A1 describes a system for the excavation of tunnels by casing, which makes it possible to obtain a planned flexibility with respect to the pressure of the rock thanks to the use of springs.

A 3D printing method is described in patent EP 3 147 269 A1, in which a BCT cement is used.

Description of the invention The aim of the present invention is to create devices and methods for excavating underground cavities, more particularly cavities with excavation sections of at least 5 m ² , improved over the state of the art.

This objective is achieved with a method of excavating cavities underground, more particularly cavities with excavation sections of at least 5 square meters, with - the production of at least one deformable layer in a planned manner in the state of excavation when the pressure of the rock appears, on an internal side of an underground cavity, the deformable layer being produced by means of 3D printing.

This objective is also achieved with a method for the excavation of underground cavities, more particularly cavities with sections of cavities of at least 5 square meters with:

- The production of at least one deformable layer in a planned manner in the excavation state when the pressure of the rock appears, [0022] - the deformable layer being produced by means of printing 3D and the deformable layer being produced with a geometric shape as a function of an internal side of an underground cavity or of an internal side of a deformable layer already applied before.

This objective is, again, achieved with a device for excavating cavities underground, this device is designed to execute at least one of the methods mentioned above and is constituted by a 3D printing unit which includes a robot on the arm of which is a printhead with which a printing product is applied to an excavation surface which constitutes an internal side of an underground cavity.

A first aspect of the present invention relates to a method of excavating underground cavities, more particularly cavities with excavation sections of at least 5 square meters, with the manufacture of at least one deformable layer or flexible in a planned manner in the excavation state when the pressure of the rock appears, on an internal side of an underground cavity, the deformable layer being produced by 3D printing. One or each of the at least one deformable layer typically having several pressure layers, that is to say that several pressure layers are compressed for a deformable layer.

The smallest diameter of the cavity is typically 2 m, in some embodiments at least 3 m or at least 4 m. The smallest diameter is the smallest distance between two opposite excavation surfaces in a section. Typical minimum cavity sizes have a cross section of more than 5 m ² or typically more than 10 m ² or typically less than 300 m ² . Typical embodiments include a planatically deformable layer. Such deformable or flexible layers in a planned manner are known in the state of the art, in order to absorb the deformations of the surrounding rock and thus reduce the stresses.

The deformation capacity can typically be defined as a minimum plastic deformation, typically a plastic deformation of at least 10% or at least 20% or at least 30% in the excavated state. Typically, the deformation capacity of T of at least one deformable layer is at least 40%, or 80% maximum or 90% maximum. The deformation capacity typically indicates the reduction in volume which can be achieved with a plastic deformation before the resistance of the layer has reached twice the compression limit, therefore has increased until the transition between an elastic deformation and the plastic deformation. .

The at least one deformable layer can also be defined by the fact that T at least one deformable layer has a relatively low modulus of elasticity for concrete. The at least one deformable layer typically has a resistance of 20 MPa maximum or 10 MPa maximum or 5 MPa maximum. The at least one deformable layer typically has a resistance of at least 0.1 MPa or at least 0.2 MPa.

In typical embodiments of the methods of the invention, a rigid layer is also produced radially inside the at least one deformable layer. Typically, the rigid layer is also produced by 3D printing. A device can thus be used for the two types of layers, rigid and deformable. In other embodiments, precast elements or in-situ concrete with formwork elements are used for the rigid layer.

Typically, the deformable layer is produced with micro-pores. Typical micropores have a size of 16 mm maximum or 8 mm maximum or 4 mm maximum. Typically, the micro-pores are produced in the deformable layer by the addition of a porous aggregate, a foaming agent or a foam in a printing product used in 3D printing for the manufacture of the deformable layer. The addition to the printing product typically takes place before the printing process and thus allows efficient work with the method according to the present invention.

In typical methods, the deformable layer is produced with macro-pores. A control device can then be used to produce the macro pores according to guidelines. Macro-pores can also be formed by allowing deformations more particularly in the circumferential direction of the deformable layer, in order to facilitate the bending of the layer.

Typically, the macro-pores are produced in the deformable layer by providing, during 3D printing, recesses in selected compression layers. This allows simple and efficient creation of macro-pores.

Typically, the printing product used for 3D printing comprises cement or a plastic material. Depending on the requirements for the layer, the resistance of the print product can be selected between 0.2 and 5 MPa or up to 20 MPa for the deformable layer or up to 55 MPa or up to 35 MPa for the non-deformable layer. deformable. The print product itself can be deformable or rigid, even the deformable layers can be made from a rigid print product using micro-pores or macro-pores. The term "rigid" refers to a condition after the print product has hardened. The basic material of the print product can be cement or plastic. Properties such as the deformation capacity and the resistance of the printing product can be modified by additives. Possible additives are: limestones, granules with open and closed cells, for example glass foam, polystyrene, expanded clay, metallic or plastic foams, gas pores resulting either from the action foaming agents or the addition of foam, sand as well as plastic fibers, steel, carbon and glass. Typically, the print product comprises a binder, the typical binders being based on cement or plastics.

Typically, in methods according to the present invention, before or during the application of an additional deformable layer, the internal side of the cavity or the internal side of an already applied deformable layer is measured by means of a laser scanner. The layer to be applied can thus be precisely adapted to the existing conditions.

In typical methods, the thickness of the additional deformable layer is adapted according to the measured internal side of the deformable layer applied previously or to the internal side of the cavity. In typical methods, during the application or printing of a layer, the already printed layer thickness of this layer during printing is measured. The thickness of the layer can thus be produced as precisely as possible. Typically, during methods according to the present invention, a printing model for producing cavities, the width of a printing jet or the mixture of the printing product are adapted according to the measurement.

In typical methods, the application of the at least one deformable layer or the at least one rigid layer takes place as a function of reference points. It is thus possible to obtain, in a reliable manner, a determined internal profile of the deformable layer. The reference points can for example be arranged on a section already made or can be points which are continuously monitored in order to determine offsets with respect to a fixed point, which can be outside the cavity or the section of the tunnel.

Typically, the at least one deformable layer has a thickness of at least 5 mm, at least 10 mm or at least 20 mm or a maximum of 550 mm or a maximum of 800 mm. In typical methods, the micro-pores or the macro-pores are provided according to a predetermined deformation capacity. Thus, the adjustment of the micro-pores or of the macro-pores makes it possible to adjust a behavior of macroscopic deformation desired.

One aspect of the present invention relates to a method for the excavation of underground cavities, more particularly cavities with excavation sections of at least 5 m ² , with the production of at least one deformable layer of planned manner in the state of excavation when the pressure of the rock appears, the deformable layer being produced by 3D printing and the deformable layer being produced in a geometric form as a function of an internal side of a cavity underground or on an internal side of a deformable layer already applied previously.

Typically, before the production of a layer, more particularly of a deformable layer or of a plurality of deformable layers printed on each other, the internal side of the cavity or the internal side of the deformable layer already previously applied is measured by a laser scanner and the result of this measurement is used when making the next deformable layer. This allows the thickness to be optimally adapted to existing conditions.

The surface of the excavation can be sealed before printing the first deformable layer or be left unsealed. A seal, also called a first seal, can help ensure job safety. The increased cohesion obtained by sealing allows, in embodiments, to stabilize the surface and reduce the risk of collapse. In typical embodiments, a mesh is injected, which can have advantages as head protection.

In typical embodiments, rigid and compressible layers are combined, for example alternately. Typically, several deformable layers are first placed or printed on the surface of the excavation and then a rigid layer is applied on the internal side.

For printing, a 3D printing unit is used, which includes a pumping system for pumping the print product and a robot on which there is a print head which makes it possible to apply the product. printing.

For any excavation geometry, it is possible, with methods typical of the invention, to apply both deformable layers with a predetermined extension and defined deformation properties as relatively rigid layers or combinations deformable and rigid layers on the surface of the excavation, which can be sealed or unsealed. The first layer, typically a deformable layer, can be applied as well as sealed excavation surfaces, for example a layer of injected concrete, as directly on unsealed rock. Layers can consist of one or more layers or print layers. A stratum typically denotes a print layer. Typical embodiments can be used in conventional, sequential feed or in continuous mechanical feed, for example with tunnel boring machines.

Typical methods of the invention can be carried out with mobile or stationary printing units. The printing unit consists, in typical embodiments, inter alia, of a pumping system and a robot or an industrial robot, the robots typically used comprising at least 4, at least 5 or at least 6 axes. The robot comprises an arm with a plurality of degrees of freedom, for example at least 5 or 6, a printhead being arranged at this first element, with which the print product is applied to the surface of the excavation . The printing unit is typically mounted on a platform. In typical mobile printing units, embodiments, the platform is moved using a crawler mount, undercarriages or on rails.

In typical processes, the mechanical properties such as the resistance and the plastic deformation capacity of a printed layer do not depend solely on the properties of the print product. Mechanical properties are also determined, in typical methods, by selection of the pattern of print layers of a layer.

The porosity of a printing layer with models typically consists, on the one hand, of micro-pores in the printing product itself, as well as macropores of the model of the printing layer. The variation of this double porosity makes it possible to produce layers in a very large range of deformation capacity (for example from 0% to 85%) and of resistance (for example from 0.6 to 60 MPa).

With typical methods, the width as well as the thickness of different printing layers can vary within a wide range. This allows the realization of smooth or regular surfaces for the internal formwork regardless of whether it is made with concrete poured on site or made up of casing segments. This is particularly advantageous for bifurcation or crossing structures with typically complex surface geometries, but it can also have considerable advantages in the case of straight sections.

With typical methods, preformed flat or linear deformable elements, with the properties described here for the deformable layers, can be produced. These prefabricated elements can be applied directly to the surface of the excavation or used in combination with casing segments or steel arches. Prefabrication can also take place outside the underground cavity, for example a tunnel.

Brief description of the figures In the following, embodiments of the present invention are explained with the aid of the attached figures, which show:

[Fig-1] schematically, a device with which typical methods of the invention can be performed;

[Fig.2] schematically, a detail of the device of the Eig. 1, more precisely during the execution of a typical process;

[Fig.3] schematically, a detail of the device of the Eig. 1, more specifically when performing another typical process;

[Fig.4] to [Eig.8] schematically models which can be produced with methods typical of the invention;

[Fig.9] in a schematic flow diagram, the flow, represented in a simplified manner, of a typical process; and [fig.10] schematically, different situations of intersection of tunnel sections.

Description of preferred exemplary embodiments [0057] In the following, typical exemplary embodiments are described, the same references being generally used for identical or similar parts, also partly for several different embodiments. In principle, the request is not limited to the various embodiments, its scope being rather determined by the claims. The individual parts are explained in part only in connection with a figure, if these parts are represented in other figures, they are not necessarily described again.

[0058] FIG. 1 schematically shows a device with which methods typical of the invention can be carried out. For printing a 3D printing unit 12, as shown schematically in FIG. 1, is used.

The printing unit 12 comprises a pumping system 9 for pumping the printing product and a robot 5 on the arm of which is a printing head 7, with which the printing product is applied . The print product is conveyed, via a pipe not shown, from a mixer or tank to the pumping system.

In addition, the printing unit 12 includes a scanner 8 which is designed as a real-time scanner system with a laser scanner. In addition, the printing unit comprises a basic platform 6 built on a running gear 4, which supports the robot 5 and a control computer 10 with a graphical user interface and a wireless interface for the transmission of data.

With the print head 7, the print product is applied to an excavation surface 11 of a main tunnel 1, which constitutes an internal side of an underground cavity. The print product can, in embodiments, be applied directly to the surface of the excavation 1, on a surface of a rock 3.

In FIG. 1, there is also shown a transverse gallery 2 of the main tunnel 1, an embodiment of an internal formwork with the printing unit 12 at the crossing of the main tunnel 1 with the transverse gallery 2 having particular advantages because an adaptation flexible to different geometries is then possible.

[0063] FIG. 2 shows how printing layers 16, 17 and 18 of variable thickness are produced with the printing unit 12 of the exemplary embodiment of FIG. 1. The surface of the excavation 11 has an irregular contour.

For example, to achieve a regular internal shell for a regular tunnel section, the irregularities of the excavation surface can be automatically equalized with methods according to the invention or typical 3D printing units. Typical embodiments of the invention, for example typical 3D printing units, include a print head with thickness control. The thickness control includes, for example, a valve or a diaphragm on the print head of the 3D printing unit. The thickness control is designed to influence a thickness of the printed layer. Typical embodiments of 3D printing units include flow control or speed control. Flow control, thickness control or speed control are used individually or together in typical methods of the invention to adapt the amount of printing material applied or the thickness of a layer printing.

The printing layers 16, 17 and 18 of FIG. 2 are strata of a deformable layer with a resistance in this example of 1.5 MPa and a deformation capacity of 50%. Adjusting the thickness of the print layers 16, 17 and 18 allows the resulting layer to almost completely compensate for irregularities in the surface of the excavation. The application of another layer with varying thicknesses of the different printing layers of this other layer makes it possible to obtain additional uniformity.

In FIG. 3, another embodiment of the internal structure of a multi-layer tunnel is shown, which can be carried out with methods and devices typical of the invention. On an excavation surface 11 have been applied, in this example, unlike the example in FIG. 2, first several non-deformable layers 16 to 19, provided for equalization. The layers 16 to 19 have a resistance of 30 MPa and have, at least overall, no deformation capacity and serve to compensate for irregularities in the surface of the excavation 11.

Layers 16 to 19 of the exemplary embodiment of FIG. 3 have at least the same overall thickness, however, as shown schematically in FIG. 3, not all the layers are applied everywhere, in order to obtain a height equalization. This allows, but not necessarily, works with a print head that does not include any mechanical thickness control on the print head.

On the last layer 19, four highly deformable layers 21 to 24 have already been applied, which have a resistance of only 1.5 MPa and a deformation capacity of 70%. The large deformation capacity is obtained by means of macro-pores and micro-pores in the highly deformable layers 21 to 24.

Typical exemplary embodiments include combinations of deformable layers with different properties. For example, external equalization layers may have a lower or higher deformation capacity than layers located further inside.

As a top layer, a rigid layer 25 is applied to the innermost highly deformable layer 24. The rigid layer 25 has a resistance of 30 MPa and a deformation capacity of less than 5% or is generally non-deformable.

In FIG. 4 is shown what the printing pattern of a portion of a printing layer applied in typical processes may look like. The printing layer of FIG. 4 is produced with a relatively simple parallel printing pattern of several printing strips 32. The printing strips 32 are printed in parallel in a single pass with a typical printing unit, a turn 33 being made at the end of a straight line. Little or no macro-pores appear in the layer, comprises several printing layers according to FIG. 4, more particularly the macro-pores can be avoided by shifting the different superposed strips by half a strip width. The model in FIG. 4 is more particularly suitable for rigid layers but also for deformable layers with a low deformation capacity.

In FIG. 5 shows another printing model, which can be produced with typical methods. The printing model of Fig. 5 comprises different printing bands 32 which extend slightly in a zigzag, so as to produce small intermediate spaces 36, which form, in the finished layer, with several printing layers according to the printing model of FIG. 5, macro-pores.

In FIG. 6, a printing model is shown with printing bands 32 extending strongly in a zigzag fashion, so as to obtain large intermediate spaces 37. In addition, the superimposed printing layers are printed with a non-offset model and identical (simple stacking), the printing strip 38 of the next printing layer is therefore located exactly above the printing strip 32 of the first printing layer. These two printing layers are shown only in schematic section as in all of the Figs. 4 to 8.

In FIG. 7 shows a printing model which uses printing strips 32 and 38 similar or identical to the printing model of FIG. 6, however the printing layers 32 and 38 are arranged in an offset manner (offset stacking). Very large intermediate spaces are obtained, which make it possible to obtain a significant deformation capacity.

In FIG. 8, there is shown a printing model which uses printing strips 32 and 38 similar or identical to the printing models of FIGS. 6 and 7, but the printing layers 32 and 38, are arranged in a 90 ° rotation (offset and crossed stacking). This makes it possible to obtain large intermediate spaces which guarantee a large capacity for deformation, a relatively high resistance being however also obtained.

A typical method of the invention is shown schematically in FIG. 9. This method can be used in order to produce a plurality of layers, more particularly several deformable layers, and possibly at least one rigid layer. In the process, other typical features described here can be used.

In addition to the printing models of Figs 4 to 8, achievable in 3D printing, many other printing models can be used. More particularly, the printing models can be produced with a printing product comprising micro-pores. For example, the print model in Fig. 8 can be combined with micro-pores to further increase the deformation capacity while maintaining acceptable strength.

First, in a block 110, a positioning of the printing unit is carried out by means of a conventional measurement or by position detection using reference points installed previously. In a block 120, a real-time scanner system measures the geometry of the surface of the excavation or of the deformable or rigid layers already applied before by printing. This real-time scanner system can be realized with a central laser scanner or with a system made up of different scanning modules.

In a block 130, a measurement of the real state and a planning of the next excavation take place, typically of the next deformable or rigid layer to be applied, a virtual three-dimensional model of the geometry of the excavation being created. with the scanner data. In this model, the desired excavation of the tunnel is integrated, i.e. the deformable layer and the following rigid layers. The layout, dimensions and properties of the different print layers for the next layer to be created are also defined.

After a verification of the excavation planned by a user in block 140, the printing program is created according to the directives coming from block 130 and the printing product is prepared. In a block 150, the different layers are applied to the surface of the excavation. The printhead applies either a cement-based or plastic-based mortar in strata on the surface. It is also possible to apply a quick-setting mortar at the top.

The three-dimensional model is updated in block 160 with the scanner data recorded and compared with the reference model of the excavation in block 170.

If it is found, in a block 170, which has already finished the layer, the process goes to block 180, in which it is checked whether a layer has yet to be printed. If this is the case, the process proceeds to block 130 in which the next layer, a deformable layer or a rigid layer, is planned.

On the other hand, if it is found, in block 170, that the layer currently produced is not yet finished, the process returns to block 150 so as to continue printing with the updated model. In typical embodiments, a printing layer being printed in the block 150 is immediately noted in step 160, shown in the model and therefore influences the printing of the next printing layer of the deformable or rigid layer during printing.

If it is found, in block 180, that all the layers are printed, the process is completed in block 190.

In FIG. 10 are shown, for purposes of explanation, situations of crossing of a main tunnel 1 with a transverse gallery 2 in schematic sectional view from above. The illustration on the left represents a bifurcation structure, with which the transverse gallery 2 branches off from the main gallery 1. In the illustration on the right in Fig. 10, a niche with a tip 50 is shown for future extensions. More particularly, in non-circular tunnel sections, we obtain, in these crossing zones, complex geometries, which must be taken into account when excavating tunnels. The methods and devices according to the present invention make it possible to flexibly produce segments suitable for such geometries.

The present invention is not limited to the exemplary embodiments described here.

The scope of the present invention is defined by the claims.

Claims (1)

claims [Claim 1] Method for excavating cavities (1,2) underground, more particularly cavities (1,2) with excavation sections of at least 5 square meters, with - the production of at least one deformable layer in a planned manner (16 - 16, 21 - 24) in the excavation state when the pressure of the rock appears, on an internal side (11) of an underground cavity (1, 2), - the deformable layer being produced by means of 3D printing. [Claim 2] Method according to claim 1, a rigid layer (25) being further produced radially inside the at least one deformable layer (16-19,21-24). [Claim 3] Method according to one of the preceding claims, the deformable layer (16 - 19, 21 - 24) being produced with micro-pores. [Claim 4] Method according to claim 3, the micro-pores being produced in the deformable layer (16 - 19, 21 - 24) by the addition of a porous granule, a foaming agent and / or a foam in a product printing which is used during 3D printing for the production of the deformable layer (16 - 19, 21 - 24). [Claim 5] Method according to one of the preceding claims, the deformable layer (16 - 19, 21 - 24) being produced with macro-pores. [Claim 6] Method according to claim 5, the macro-pores being produced in the deformable layer, by providing, during 3D printing, recesses (36) in selected printing layers. [Claim 7] Method according to one of the preceding claims, the printing product used for 3D printing comprising cement and / or a plastic material. [Claim 8] Method according to one of the preceding claims, the internal side of a deformable layer (16 - 19, 21 - 23) already applied before being measured by means of a laser scanner (8) before and / or during the application of '' another deformable layer (17 - 19, 21 - 24). [Claim 9] Method according to claim 8, the thickness of the other deformable layer (17-19, 21-24) being adapted as a function of the measured internal side of the deformable layer (16-19, 21-23) already applied before, this by adapting a printing model for the production of cavities, the width of a printing jet or the mixing of the printing product. [Claim 10] Method according to one of the preceding claims, at least one deformable layer (16 - 19, 21 - 24) having a thickness of at least 5 mm and / or 800 mm maximum. [Claim 11] Method according to one of the preceding claims, the at least one deformable layer having a resistance of at least 0.1 MPa and / or a maximum of 60 MPa. [Claim 12] Method according to one of the preceding claims, at least one deformable layer (16 - 19, 21 - 24) having a deformation capacity of at least 20% and / or 80% maximum. [Claim 13] Method according to one of the preceding claims, at least one deformable layer (16 - 19, 21 - 24) and / or l> at least one rigid layer (25) being produced as a function of reference points. [Claim 14] Method for the excavation of cavities (1,2) underground, more particularly cavities (1,2) with sections of cavities of at least 5 square meters with - producing at least one deformable layer in a planned manner (16 - 19, 21 - 24) in the excavated state when the pressure of the rock appears, - the deformable layer (16 - 19, 21 - 24) being produced by means of 3D printing and - the deformable layer (16 - 19, 21 - 24) being produced with a geometric shape as a function of an internal side (11) of an underground cavity (1, 2) or of an internal side of a deformable layer (16 - 19, 21 - 23) already applied before. [Claim 15] Method according to claim 14, the internal side (11) of the cavity (1,2) or the internal side of the deformable layer (16 - 19, 21 - 23) already applied before being measured by means of a front laser scanner the production of the deformable layer (16 - 19, 21 - 24) and the result of this measurement being used for the production of the deformable layer (17 - 19,21-24). [Claim 16] Device for excavating cavities (1,2) underground, this device is designed to execute at least one of the methods of claims 1 to 15 and is constituted by a 3D printing unit (12) which comprises a robot (5) on the arm of which there is a print head (7) with which a print product is applied to an excavation surface (11) which constitutes an internal side of an underground cavity 1/6