EP4041961B1 - Prefabricated compressible building block with voids, that can be integrated into gallery linings by traditional methods or by tunnel boring machine method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of the construction of underground works, and in particular the construction of tunnels, galleries or shafts.

The invention relates more particularly to a prefabricated compressible building block, as well as to a method for producing an underground structure of the tunnel, gallery, well or similar type using such blocks.

The building block according to the invention is intended in particular, but not exclusively, for integration between the rock and a prefabricated segment (tunnel boring) but also for lining a support just before pouring a gallery lining or well (digging by traditional method).

STATE OF THE ART

Conventionally, underground structures of the tunnel, gallery, shaft or similar type are lined as they are dug. Two types of digging methods are currently used: the so-called traditional digging method and the tunnel boring method. Regarding the traditional method of excavation, a support is first put in place as the excavation progresses. It is then proceeded to the establishment of the poured coating. Concerning the mechanized method of excavation with a tunnel boring machine, a lining is put in place by segment ring as it advances via the skirt of the tunnel boring machine. For each of these excavation methods, the lining is designed to absorb the forces resulting from the convergence of the rock on its extrados.

In order to limit the impact linked to the convergence of the ground on the tunnels, damping devices are planned within the underground structures. Among the devices of the prior art, we know the one proposed in the patent application FR3034451 for the construction of an underground structure using the tunnel boring method. The damping device in question comes in the form of a compressible one-piece segment obtained by making the first layer of "conventional" reinforced concrete then adding during manufacture and before the concrete sets, a second compressible layer integral with the first layer so to form a one-piece prefabricated building element.

Such a segment, however, has several drawbacks which can influence the progress, the construction, transport and storage constraints.

A first drawback lies in the manufacture of the segment and its compressible layer. This compressible layer is produced following the pouring of the reinforced concrete part, itself followed by the production of a protective layer for the compressible layer. The manufacturing time of such a segment is considerably lengthened. In fact, the pouring of the compressible layer following the reinforced concrete part means that the complete segment cannot be manipulated until the compression layer has acquired acceptable mechanical resistance characteristics at a young age, which allow on the one hand the installation of a layer of protection and on the other hand the break of the voussoir at its extrados. This waiting period influences the construction schedule for the segments.

A second drawback is the storage of one-piece segments. The compressible layer being fragile, it happens that during transport, storage and possible reversals of the segment, the compressible concrete layer of the latter suffers deterioration and spalling, even after adding a protective layer. The damage to the compressible layer may jeopardize the integrity of the segment and therefore requires a complete replacement of the latter. The storage of one-piece segments can also prove to be problematic due to the limitation of the stacking of the segments induced by the influence of the weight of the segments on the compressible layers. This constraint implies reduced stacking and consequently an increased storage surface.

The invention aims to reduce the problems of the one-piece prefabricated segment of the aforementioned application by proposing a prefabricated building block in parallel and independently of the segment. This building block will be placed on the segment on the excavation site and during excavation with the tunnel boring machine.

US 4585371A describes an oblong building block made of plastic materials with channels.

The object of the invention is also to propose a building block making it possible to carry out a segment damping the convergence of the ground, simply, quickly and at low cost.

OBJECT OF THE INVENTION

To this end, and according to a first aspect, the invention proposes a prefabricated compressible building block exhibiting elasto-plastic behavior having an elastic threshold of between 1 and 2 MPa and a plastic plate of the order of 40 to 75% of deformation at non-zero and maximum load of 4 MPa, said block comprising channels having a first open end, the channels defining voids occupying 40 to 75% of the total volume of the building block.

The type of material (and choice of its resistance), the arrangement of the "vacuum" channels (disposition, size, shape) are defined to give the compression block satisfactory mechanical behavior and more particularly a minimum elastic threshold of the order of 1 MPa, a plastic plate/bearing of the order of 40 to 75% deformation; this plastic bearing must operate at non-zero loading in such a way as to always keep a confinement applied to the rock.

Advantageously, the building block is made of a mineral material.

Advantageously, the building block is made of a material chosen from the group of materials comprising concrete, terracotta or concrete mortar.

Advantageously, the compressible building block does not include any metallic component and, if it does, in a quantity of metallic component not exceeding 4% of the total mass of the building block.

Advantageously, the channels are distributed within said block to define staggered channel beds. The arrangement of the channels is however not limited to this staggered arrangement of the channels. In particular, any arrangement can be provided, it being understood however that it will define an ordered geometric pattern which, depending on the nature and behavior of the material, will make it possible to target the desired characteristics. As a result, several configurations and natures of these blocks will make it possible to target the same behavior. Each block will be made symmetrically with respect to the radius of the gallery intercepting its center, the idea being to achieve a homogeneous distribution of these elements, whether behind the segments or the poured linings.

According to a particular configuration, the channels have a second blind end. It can also be provided according to another configuration that the channels extend right through the compression block.

Advantageously, the channels may have a section of circular or oval shape for the concrete or mortar solution (for manufacturing reasons).

Advantageously, the building block may comprise a plurality of channels of the same cross-section or of different cross-sections, the latter possibly being arranged to form staggered rows of channels, or any other ordered arrangement.

For each block, a thickness of 1 to 2 cm of concrete, concrete mortar or continuous terracotta should be made on the extrados and the intrados, the need being to stiffen the block as well as to have a good contact between elements. For blocks based on concrete, concrete mortar or terracotta, the inter-channel distance is at least 6 millimeters. Concrete blocks, concrete mortar or terracotta can be blind on one side. This has the advantage in the case of concretes of guaranteeing the existence of voids in the channels following the injection of the sealing grout (tunnel boring machine) or pouring of the concrete (traditional method).

Concerning the manufacture by terracotta, the usual method of manufacture (such as extrusion) will allow a wide range of choices of voids to be targeted.

Advantageously, the compressible building block can be joined together with similar building blocks, at the level of the longitudinal but also transverse edges. According to a particular embodiment, the building block is arranged to fit into a similar building block. Glue, filling mortar or bolts can consolidate the junctions between blocks and between blocks and other elements.

The invention also relates to a segment having an upper surface covered with a building block or a plurality of building blocks as described above.

The invention also relates to a lining of a block layer between the support and the final lining of a gallery dug by the traditional method. More particularly, it relates to a method for producing an underground structure of the tunnel, gallery, well or similar type comprising support operations and the installation of a lining, characterized in that, prior to the installation of the coating, a compressible layer formed from one or more building block(s) as described above is fixed to the lining so as to form the support/lining interface.

The invention also relates to a method for producing an underground structure of the tunnel, gallery, well or similar type using segments arranged within the underground space, characterized in that, prior to the installation of the segments within the underground space, compressible building blocks as described previously are fixed to the extrados of the segments.

The installation of these multi-blocks in the two cases of excavation figures can be carried out via robotic workshops in the galleries or behind the tunnel boring machine.

BRIEF DESCRIPTION OF FIGURES

• [Fig. 1] La figure 1 représente une vue en perspective d'un bloc de construction en selon un premier exemple de réalisation de l'invention, ledit bloc de construction étant en béton ;
• [Fig. 2] La figure 2 représente respectivement des vues schématiques en coupe d'exemples d'arrangement de canaux d'un bloc de construction en béton selon l'invention ;
• [Fig. 3] La figure 3 représente une vue en perspective d'un bloc de construction selon un autre exemple de réalisation de l'invention, ledit bloc de construction étant en terre cuite.

Other characteristics and advantages of the invention will emerge from the detailed description of the invention which will follow with reference to the appended figures and in which:

• [ Fig. 1 ] There figure 1 shows a perspective view of a building block according to a first embodiment of the invention, said building block being made of concrete;
• [ Fig. 2 ] There figure 2 respectively represents schematic cross-sectional views of examples of the arrangement of channels of a concrete building block according to the invention;
• [ Fig. 3 ] There picture 3 shows a perspective view of a building block according to another embodiment of the invention, said building block being made of terracotta.

For greater clarity, identical or similar elements of the various embodiments are marked by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF THE INVENTION

In relation to the figures 1 and 2 , there is described a compressible building block 1 which is, in the example shown, made of concrete. The building block 1 has an elastic threshold of the order of 1 to 2 MPa, followed by a plastic plateau for a non-zero applied stress not exceeding 4 MPa before the start of the stiffening phase. The building block 1 comprises straight longitudinal channels 2, extending over the entire length of the building block and open on the transverse faces, the blocks can be blind on one side which will facilitate the sealing of the final layer. Channels 2 run parallel to each other. Channels 2 are configured in number and size to define voids occupying 40-75% of the volume of the building block.

The building block 1 is advantageously devoid of metallic component or at least, if it includes any, it will be a quantity not exceeding 4% of the total mass of the building block.

In the example shown in the figure 1 , the building block 1 comprises channels 2 of circular section and of the same diameter. The channels are arranged parallel to each other. They are also distributed within the building block 1 over four rows a1 to a4, the rows being arranged to present a staggered arrangement of the channels. The channels of the same row are arranged equidistant from each other. The building block can of course have channels 2 with different shapes and/or arrangements. There picture 2 gives as such other examples of channel arrangements in concrete building blocks.

There can thus be provided a building block having channels 2 of different diameters. Depending on the diameter of these, the building block will include more or fewer rows of channels, and 2 channels per row. There figure 2a shows for example a building block 1A of the same dimension as that of the figure 1 , comprising channels 2 of diameters smaller than that of channels 2 of the figure 1 . In order to maintain the presence of 40 to 75% vacuum of the volume of the building block, the compression block 1A comprises more rows of channels (in the example illustrated five rows) and 2 channels per row. Conversely, building block 1B of the figure 2b , also of the same size as that of the figure 1 , comprises channels 2 of diameter greater than those of the figure 1 . In fact, building block 1B has fewer rows and fewer channels per row. The channels 2 can also have a section with a substantially oval diameter, as illustrated in the figure 2c .

In the examples previously described, each building block 1, 1A, 1B, 1C comprises within them channels having substantially similar diameters. It can of course be provided concrete building blocks comprising channels 2 of different sections. THE 2d and 2e figures show building blocks 1D, 1E with channels 2 of different diameters. In these examples, the building blocks 1D, 1E comprise two series of channels 2 of different diameter. The two series of channels 2 are distributed in such a way that the building blocks have a central symmetry. It is of course obvious that the building block may comprise more than two types of channels 2 and an arrangement other than that shown in the 2d and 2e figures , with or without central symmetry.

There picture 3 represents a compressible building block 10 whose mineral material is a terracotta. The building block 10 incorporates all the characteristics of the concrete compression blocks previously described. Thus the building block comprises rectilinear transverse channels 2, extending right through the building block 10 and extending parallel to each other. The voids thus created within the building blocks represent 40 to 75% of the volume of the building block.

The building block 10, however, differs from the previously described concrete compression blocks in the shape and arrangement of the channels 2.

In particular, in the example illustrated in the picture 3 , the building block 10 comprises three rows of channels 2 of rectangular section and of different dimensions. Advantageously, the walls of the building block 10 and the ribs delimiting the channels 2 have thicknesses of the same order.

In the example illustrated, the building block 10 comprises three rows b1, b2, b3. Similarly, unlike the concrete compression blocks, the channels 2 of each row do not have a staggered arrangement of the channels 2 but on the contrary arranged aligned with each other to form columns of channels c1 to c6. Each row has two sets of superimposed 2 channels.

Advantageously, the compression blocks are arranged so that they can be butted together.

The building blocks just described can, according to a particular application, be intended to be placed on the extrados of a segment. In this case, the compression blocks have a curvature corresponding to the curvature of the extrados of the segment on which they will be placed. The channels provided within the building block will present an axis longitudinal having a radius of curvature corresponding to that of the bend. Advantageously, the manufacture of the compression blocks is separated from that of the segments on which they are intended to be affixed. As a result, these blocks may have curved sections.

The building blocks form a one-piece piece advantageously manufactured using a vibrating press when they are made of concrete or mortar or by extrusion when they are made of terracotta. The building blocks can also consist of an assembly of “sub-blocks”. We then speak of multi-blocks.

• Méthode de creusement au tunnelier comme suit : après cure (béton/mortier) ou séchage et cuisson (terre cuite), les blocs de construction sont mis en place à l'extrados du voussoir (possibilité via atelier robotisé), avant que ces derniers ne soient placés dans la jupe du tunnelier. La fixation des blocs de compression sur les voussoirs peut être effectuée par collage desdits blocs sur les voussoirs concernés.
• Méthode de creusement traditionnelle : après cure (béton/mortier) ou séchage et cuisson (terre cuite), les blocs de construction tapisseront le soutènement d'une galerie déjà en place. Ils seront spittés via des boulons et/ou avec une interface injectée ou collée. A la suite, le revêtement coulé sera mis en place.

Tunnels, galleries, shafts or the like are made with the building blocks as follows:

• Method of digging with a tunnel boring machine as follows : after curing (concrete/mortar) or drying and firing (terracotta), the building blocks are placed on the extrados of the segment (possibility via a robotic workshop), before the latter are placed in the skirt of the tunnel boring machine. The fixing of the compression blocks on the segments can be carried out by gluing said blocks on the segments concerned.
• Traditional excavation method : after curing (concrete/mortar) or drying and firing (terracotta), the building blocks will line the support of a gallery already in place. They will be spitted via bolts and/or with an injected or glued interface. Subsequently, the poured lining will be put in place.

The invention is described in the foregoing by way of example. It is understood that a person skilled in the art is able to produce various variant embodiments of the invention without thereby departing from the scope of the inventior as described by the appended claims.

Claims (12)

1. Prefabricated building block (1, 1A to 1E, 10) comprising longitudinal channels (2) having a first open end, the channels (2) defining voids occupying 40 to 75% of the total volume of the building block, characterized in that said block is compressible, exhibiting an elasto-plastic behavior having an elastic threshold of between 1 and 2 MPa and a plastic plateau of approximately 40 to 75% deformation at non-zero load and at most 4 MPa.
2. Compressible building block (1, 1A to 1E, 10) according to claim 1, characterized in that it is made of a mineral material.
3. Compressible building block (1, 1A to 1E, 10) according to claim 1, characterized in that it is made of a material selected from the group of materials comprising a concrete, a terracotta or a concrete mortar.
4. Compressible building block (1, 1A to 1E, 10) according to claim 1 or claim 2, characterized in that it does not comprise a metal component or, if it does comprise a metal component, it comprises said metal component in an amount no greater than 4% of the total mass of the building block (1, 1A to 1E, 10).
5. Compressible building block (1, 1A to 1E, 10) according to any of the preceding claims, characterized in that the channels (2) are distributed within said block (1, 1A to 1E, 10) to define staggered beds of channels (2).
6. Compressible building block (1, 1A to 1E, 10) according to any of the preceding claims, characterized in that the channels (2) have a second blind end.
7. Compressible building block (1, 1A to 1E, 10) according to any of claims 1 to 5, characterized in that the channels (2) extend from one side of the compression block (1, 1A to 1E, 10) to the other.
8. Compressible building block (1, 1A to 1E, 10) according to any of the preceding claims, characterized in that the building block (1, 1A to 1E, 10) has a continuous thickness between the extrados surface of said block (I, 1A to 1E, 10) and the channels (2) located closest to the extrados surface on one side and between the intrados surface of said block (1, 1A to 1E, 10) and the channels (2) located closest to the intrados surface on the other side of between 1 to 2 cm, the distance between the channels being at least 6 millimeters.
9. Compressible building block (1, 1A to 1E, 10) according to any of the preceding claims, characterized in that it can be joined with similar building blocks.
10. Voussoir having an extrados covered with a building block (1, 1A to 1E, 10) or a plurality of building blocks (1, 1A to 1E, 10) according to any of the preceding claims.
11. Method for producing an underground structure, such as a tunnel, gallery, well or similar, comprising operations of supporting and placing a covering, characterized in that, prior to the placement of the covering, a compressible layer formed from one or more building blocks (1, 1A to 1E, 10) according to any of claims 1 to 9 is attached to the covering so as to produce the supporting/covering interface.
12. Method for producing an underground structure, such as a tunnel, gallery, well or similar, using voussoirs which are arranged within the underground space, characterized in that, prior to the placement of the voussoirs within the underground structure, compressible building blocks (1, 1A to 1E, 10) according to any of claims 1 to 9 are attached to the extrados of the voussoirs.

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