FR3081909A1 - TUNNELIER, AS WELL AS METHOD FOR DIGGING A SECOND TUNNEL FROM A FIRST TUNNEL USING SUCH A TUNNELIER - Google Patents

Abstract

The tunnel boring machine (1) comprises a cutting head (10) and a shield (20). The cutting head comprises a plate (11), which is rotatable about an axis (XX) and which includes a main body and a deployable part (16) movably mounted between a retracted position, in which the plate has a first diameter, and a deployed position in which the deployable part extends in radial projection from the main body by giving the plate a second diameter (D11) which is greater than the first diameter. The cutting head also comprises first axial felling tools which are carried by the main body and which are adapted to cut the ground along the axis so as to excavate a region of the ground situated in axial view of the main body when the plate is rotated. So that this tunnel boring machine can dig a second tunnel (T2) from a first tunnel (T1) safely, quickly and economically, the cutting head also includes radial felling tools (18), which are carried by the deployable part and which are adapted to cut the ground radially to the axis so as to excavate a region of the ground situated all around the deployable part when, concomitantly, the plate is driven in rotation and the deployable part is driven in displacement from the retracted position in the deployed position.

Description

Tunneler, as well as method for digging a second tunnel from a first tunnel using such a tunneling machine

The present invention relates to a tunnel boring machine, otherwise known as a tunneling machine. The invention also relates to a method for digging a second tunnel from a first tunnel, using such a tunneling machine.

The invention relates to tunnel boring machines which, in the front part, have a cutting head and which, behind this cutting head, have a shield. When the TBM is in normal operating phase, the cutting head cuts down the ground in which the TBM is advancing to dig a tunnel: to do this, this cutting head is rotatable on itself around its central axis and carries axial felling tools, such as knobs, teeth, etc., which excavate the ground at the cutting face against which the cutting head is applied along the axis while it is being rotated. The shield ensures the stability of the walls of the excavation: this shield generally consists of a ferrule either monolithic, or made in several sections which, if necessary, can be articulated between them. In practice, various embodiments are known for the cutting head. In all cases, the cutting head includes a rotating plate in which openings are made to allow the passage of the materials felled by the axial felling tools carried by the plate to the rear. These felling tools are distributed over the entire tray, from its central region to its outer peripheral region, so that the outer periphery of the tray corresponds substantially to the diameter of the front that the cutting head cuts, this diameter being commonly qualified as cutting diameter.

Recently, FR 3 050 758 proposed a tunnel boring machine having the specific features that its head and its shield can contract / deploy radially. In particular, the cutter head plate includes, in addition to a central main body, arms which carry axial felling tools and which are mounted in a radially displaceable manner on the main body so as to be able to pass between a retracted position and a deployed position in which the arrangement of the arms projecting radially from the main body gives the plate a cutting diameter which is greater than that which it has when the arms are in the retracted position. This tunnel boring machine can thus adjust its cutting diameter efficiently, quickly and substantially. As explained in FR 3 050 758, this advantage is used to cope with the problem of highly convergent terrain or also to facilitate the evacuation of the cutting head once the digging of the tunnel is finished, in particular by retreating the tunnel borer inside this tunnel.

This being recalled, the present invention is concerned with another problem in the field, namely digging, from a first tunnel, a second tunnel, and in particular perpendicular to the first tunnel. This problem is encountered, for example, when a connecting tunnel must be dug between two parallel tunnels, to connect the latter to each other and thus create emergency access. This problem also occurs when we want to create an underground storage network. To dig such a second tunnel from and, if necessary, perpendicular to a first tunnel, one generally uses traditional excavation methods, that is to say without a tunnel boring machine, which poses problems of safety, delay, cost, geological hazards and destabilization of the land. The use of a shielded tunnel boring machine encounters a lack of space in the first tunnel: if the second tunnel must have a diameter much smaller than the diameter of the first tunnel, which is often the case for the aforementioned connecting tunnels, one can use a microtunnelier; on the other hand, if the second tunnel has a larger diameter, in particular equal to or greater than the diameter of the first tunnel, the installation of a shielded tunnel boring machine will be particularly tedious because it will first require creating a pre-tunnel with traditional excavation methods mentioned above, with all the aforementioned drawbacks, then she will ask that the TBM be assembled in this pre-tunnel, again with safety, time and cost problems.

The aim of the present invention is to improve the existing tunnel boring machines, to allow a second tunnel to be dug from a first tunnel in a safe, rapid and economical manner.

To this end, the subject of the invention is a tunneling machine, comprising a cutting head and a shield which follow one another along an axis along which the tunneling machine is intended to advance to dig a tunnel, the cutting head being arranged at the front of the shield, which cutting head includes:

- a plate, which is rotatable around the axis relative to the shield and which includes both a main body, through which the axis passes, and a deployable part which is mounted on the main body so as to be movable between a position retracted, in which the plate has a first plate diameter, and a deployed position, in which the deployable part extends in radial projection from the main body, giving the plate a second plate diameter which is greater than the first plate diameter, and

- first axial felling tools, which are carried by the main body and which are adapted to cut down the ground along the axis so as to excavate a region of the ground situated axially opposite the main body when the plate is driven in rotation around the axis, characterized in that the cutting head also comprises radial felling tools, which are carried by the deployable part and which are adapted to cut the ground radially to the axis so as to excavate a region of the terrain located all around the deployable part when, concomitantly, the plate is driven in rotation about the axis and the deployable part is driven in displacement from the retracted position to the deployed position.

The subject of the invention is also a method for digging a second tunnel from a first tunnel, which method successively comprises:

- an installation phase, during which a tunnel boring machine, which is as defined above and whose deployable part of the cutting head is in the retracted position, is installed in the first tunnel;

- a start-up phase, which successively includes:

a step of radial digging, during which the plate of the cutting head of the tunnel boring machine resulting from the installation phase is driven in rotation about the axis and, while the plate is thus driven in rotation, the part deployable of the plate has passed from the retracted position to the deployed position so that the radial felling tools dig a primer from the second tunnel into the wall of the first tunnel,

- a first axial digging step, during which the plate is driven in rotation and the TBM is advanced along the axis, so that the first axial felling tools, as well as second axial felling tools carried by the deployable part digs a first longitudinal part of the second tunnel from the start, and

a step for fitting the shield, during which, in the first longitudinal part of the second tunnel, the shield of the tunneling machine is put in place, being dimensioned to surround the upper surface of the consolidation rings of the second tunnel, and to present a diameter substantially equal to the second plate diameter; and

- a normal operating phase, during which the TBM resulting from the start-up phase is operated to dig the rest of the second tunnel.

Thus, the invention provides that the cutting head of the tunnel boring machine takes advantage of the fact that its plate includes a deployable part making it possible to adjust the cutting diameter of this plate, so that this cutting head can achieve radial digging all around it thanks to radial felling tools carried by this deployable part of the plate: when the cutting head is driven in rotation, while the TBM is fixed along the axis, the deployment of the deployable part relative the main body of the plate allows these radial felling tools to dig the ground radially to the axis, by excavating the region of the ground located all around the deployable part. The digging of a second tunnel from and perpendicular to a first tunnel is improved: the installation of the TBM in the first tunnel is facilitated by the fact that its cutting head can then have its deployable part in the retracted position, then the second tunnel can be started by the aforementioned radial digging, operated by the cutting head of the tunnel boring machine whose radial felling tools are provided, during the deployment of the deployable part of this cutting head, to pass through the upper and lower portions of the wall of the first tunnel, typically the upper and lower portions of rings of this first tunnel. This deployment of the cutting head can, if necessary, bring the cutting diameter of its plate to a value substantially equal to the diameter of the first tunnel, thus making it possible to start a second tunnel which will then have the same diameter as the first tunnel . Once the radial digging has been carried out and the start of the second tunnel has been completed, the second tunnel can continue to be dug by the tunnel boring machine, whose tools for axially cutting the cutting head are then used to excavate the ground according to the axis of the TBM. As soon as a sufficient length of the second tunnel is dug from the aforementioned primer, the shield of the tunnel boring machine can be put into service behind the cutting head by dimensioning it to the cutting diameter of the plate of the latter, the shield thus being put in place either by in situ assembly, or by deployment by means of dedicated arrangements of the shield, detailed below. In any case, the TBM according to the invention can quickly reach a normal operating configuration, allowing it to effectively dig all the rest of the second tunnel. Thus, even if the diameters of the first and second tunnels are substantially identical, the invention makes it possible to set up and start a shielded tunneling machine in a simple, rapid, safe and economical manner, in particular without requiring the creation of a pre- tunnel.

According to additional advantageous characteristics of the tunnel boring machine and of the method in accordance with the invention, taken individually or in any technically possible combination:

- The deployable part of the tray has an end edge, which is turned away from the axis and which includes both a running part, extending along the axis so as to separate one of the other of the front and rear faces of the plate, and of the front and rear edges which connect the current part to, respectively, the front face and the rear face of the plate, the radial felling tools being arranged on the current part and the edges front and rear of the end edge of the deployable part.

- The deployable part of the tray includes at least one arm, which extends in length and is movable relative to the main body radially to the axis and which has a longitudinal end, opposite the axis and carrying the tools d radial felling.

- The cutting head further comprises second axial felling tools, which are carried by the deployable part of the plate at least when the deployable part is in the deployed position and which are adapted to cut the ground along the axis so to excavate a region of the ground located in axial view of the deployable part in the deployed position when the plate is rotated about the axis.

- The shield defines an envelope inside which the shield embeds both a laying device for laying segments so that the latter form a tunnel consolidation ring, arranged in the axial extension towards the front of a previously installed ring, and an advancement device for advancing the TBM by pressing on a front edge of the recently installed ring; in addition, the shield comprises a central frame, as well as a peripheral part which extends all around the frame and which defines the envelope of the shield by being mounted on the frame in a movable manner in order to pass the shield between a retracted configuration, in which the shield envelope is dimensioned to have a first envelope diameter, and an extended configuration, in which the shield envelope is dimensioned to surround the upper surface of the rings, presenting a second envelope diameter, which is greater than the first envelope diameter and which is substantially equal to the second plate diameter.

- The shield further comprises a skirt portion which is adapted for successively:

- be held in place, by the fitting device, vis-à-vis the rest of the shield axially juxtaposed at the rear of an upper portion of the peripheral part of the shield, without being integral with the latter, and

- Be attached to the upper part of the peripheral part of the shield when the shield is in the extended configuration, so as to extend axially towards the rear this upper portion of the peripheral part at the level of the envelope.

- The first tunnel and the second tunnel have substantially the same diameter.

- During the installation phase, the TBM is installed in the first tunnel so that the axis of the TBM extends substantially perpendicular to the longitudinal direction of the first tunnel.

- during the installation phase, during the radial digging step and during the first axial digging step, the tunnel bumper is in the retracted configuration; moreover, during the shield commissioning stage, the shield changes from the retracted configuration to the extended configuration.

- During the first axial digging step, said skirt skirt portion is held by the fitting device in a position axially juxtaposed behind a high portion of the peripheral part of the shield; in addition, the start-up phase also includes:

- A second axial digging step, which is implemented after the shield placement step and during which, at the same time, said shield skirt portion is held by the laying device in an axially position juxtaposed behind a high portion of the peripheral part of the shield and the plate is driven in rotation while the tunnel boring machine is advanced along the axis so that the first and second axial felling tools dig a second longitudinal part the second tunnel, extending axially forward the first longitudinal part of the second tunnel, and

a step for extending the shield towards the rear, during which said skirt portion and other skirt portions are both secured to one another and attached integrally to the peripheral part of the shield so that said skirt portion and these other skirt portions jointly form a skirt extending axially towards the rear the peripheral part of the shield at the level of the envelope of the shield.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which:

- Figure 1 is a schematic longitudinal section of a tunnel boring machine according to the invention, shown in a service configuration and used in a normal operating phase to dig a second tunnel from and perpendicular to a first tunnel;

- Figure 2 is an elevational view of the tunnel boring machine of Figure 1, according to arrow II of Figure 1;

- Figure 3 is an enlarged view of the detail in box III in Figure 1;

- Figure 4 is a section along the line IV-IV of Figure 1;

- Figure 5 is a view similar to Figure 1, illustrating a phase of installation of the tunneling machine of Figure 1 in the first tunnel to dig the second tunnel;

- Figure 6 is a section along line VI-VI of Figure 5;

- Figures 7 and 8 are views respectively similar to Figures 5 and 6, illustrating the start of a radial digging step, implemented by the TBM;

- Figures 9 and 10 are views respectively similar to Figures 5 and 6, illustrating the end of the radial digging step;

- Figure 11 is a view similar to Figure 5, illustrating the start of a first axial digging step, implemented by the TBM;

- Figure 12 is a view similar to Figure 5, illustrating the continuation of the first axial digging step;

- Figure 13 is a section along the line XIII-XIII of Figure 12;

- Figure 14 is a view similar to Figure 5, illustrating a step of setting up a shield of the TBM;

- Figure 15 is a section along line XV-XV of Figure 14;

- Figure 16 is a view similar to Figure 5, illustrating a second axial digging step, implemented by the TBM;

- Figure 17 is a section along line XVII-XVII of Figure 16;

FIG. 18 is a view similar to FIG. 5, illustrating a step for extending the shield towards the rear;

- Figure 19 is a section along the line XIX-XIX of Figure 18; and

- Figures 20 and 21 are views similar to Figure 5, respectively illustrating two other steps implemented by the TBM at the end of its start-up phase.

In Figures 1 to 21 is shown a tunnel boring machine 1 which makes it possible to dig a tunnel T2 from and perpendicular to a tunnel T1, this tunnel T1 having been produced before the tunnel T2 without this aspect being limiting of the invention. In the embodiment considered here, the tunnel T1 is consolidated by a tube made up of 2 juxtaposed rings. In practice, the tunnel T1 may have been produced by an appropriate tunnel boring machine.

In FIGS. 1 to 4, the tunnel boring machine 1 is in a service configuration, which will be detailed below and which makes it possible to implement a normal operating phase in which the boring machine 1 is operated to make the tunnel T2 through a geological formation or, more generally, a terrain in which the tunnel boring machine is intended to advance.

In FIGS. 5 and 6, the tunnel boring machine 1 is in a compact configuration, which will be detailed below and which makes it possible to implement an installation phase in which the boring machine 1 is installed in the tunnel T1 in order to carry out the T2 tunnel.

In FIGS. 7 to 21, the TBM is in different successive intermediate configurations from the compact configuration to the normal operating configuration, these different intermediate configurations being detailed below. The implementation of these intermediate configurations corresponds to a start-up phase in which the TBM is operated, from the installation phase to the normal operating phase, to initiate the digging of the T2 tunnel from the T1 tunnel.

Before setting out the specifics and the sequence of installation, start-up and normal operation phases, tunnel boring machine 1 is described below with reference to the figures

I to 6.

As clearly visible in FIG. 1, the tunnel boring machine 1 extends along an axis XX and comprises, successively along this axis XX, a cutting head 10, located in the front part of the boring machine, and a shield 20 located behind the cutting head 10. By means of arrangements detailed below, the cutting head 10 allows, when the TBM is in the service configuration, to cut down the ground in which the TBM 1 advances to dig the T2 tunnel, coming into contact with a size F front at the front end of the tunnel boring machine 1, while the shield 20 ensures the stability of the walls of the T2 tunnel as the size F front is excavated .

As clearly visible in FIGS. 1 and 2, the cutting head 10 comprises a plate

II which is centered on the axis XX: this plate 11 is rotatable on itself around the axis XX relative to the shield 20. The plate 11 carries, on its front face, axial felling tools 12, such like knobs, teeth, spikes, etc. These axial felling tools 12 are known in the art and their embodiment is not limiting as long as these axial felling tools 12 allow the front face of the plate 11 to cut down, along the axis XX, the terrain against which this front face is axially brought into contact and thus advancing the size F front in the terrain to be crossed, when the plate 11 is rotated about the axis XX.

As shown in Figures 1, 2, 5 and 6, the plate 11 of the cutting head 10 comprises a main body 13, which occupies the central region of the plate 11 being crossed by the axis X-X. Among the axial felling tools 12, axial felling tools 12.1 are carried by this main body 13 and make it possible to excavate a region of the ground located axially facing the main body 13 when the plate 11 is rotated around axis XX. In the embodiment considered here, the main body 13 generally has the shape of a star with radial branches: thus, the main body 13 includes a central hub 14, centered on the axis XX, and eight branches 15, which s 'each extend from the central hub 14 in a direction radial to the axis XX, the respective ends of these branches 15, opposite the axis XX, jointly defining an outer periphery of the main body 13. The branches 15 are distributed around the axis XX and delimit between them free spaces, forming through openings within the main body 13 to allow the passage of the materials felled from the size F front by the axial felling tools 12, in particular by the axial slaughter

12.1 carried by these branches.

This star shape of the main body 13 is suitable for digging coherent terrains, but, in practice, the main body 13 of the plate 11 can have other embodiments, such as, for example, a plate or an assembly of plates. , openings being made in this plate or this assembly of plates to allow the passage, through the main body 13, of materials separated from the cutting face by the axial felling tools 12, in particular by the axial felling tools 12.1 .

In addition, as clearly visible in Figures 1 to 3, the plate 11 of the cutting head 10 also includes arms 16, which are mounted on the main body 13 and which each extend in length radially to the axis XX . The longitudinal end of each arm 16, opposite the axis X-X, is referenced 16A. In the embodiment considered here, the arms 16 are provided in eight copies, being distributed in a substantially regular manner around the axis X-X. In addition, each of these eight arms 16 is mounted on one of the branches 15 of the main body 13, extending in the rectilinear extension of this branch.

Whatever the embodiment of the main body 13, each arm 16 is mounted on this main body 13 so that it can move radially to the axis XX so as to be able to extend, at least for the part of the arm opposite to the axis XX, projecting radially from the main body 13, in other words projecting, radially to the axis XX, from the outer periphery of this main body 13. It should be understood that the capacity of movement of the arms 16 vis-à-vis -screw of the main body 13 of the plate 11 is not free, but is controlled so as to pass each arm 16 between two different positions, namely a deployed position, shown in FIGS. 1 to 3, and a retracted position, shown on Figures 5 and 6. To do this, each of the arms 16 is controlled to move, that is to say driven and then reversibly locked relative to the main body 13, and this by an ad hoc motor member 17, integrated on stage 11, as q a cylinder which is interposed between the main body 13 and the arm 16 and the actuator of which is lockable in position.

In the deployed position, each of the arms 16 extends more radially projecting from the main body 13 than in the retracted position, it being noted that, in the example considered in the figures, the projecting extent of the arms 16 relative to the body 13 is substantially zero when the arms are in the retracted position, only the longitudinal end 16A of each arm 16 in the retracted position being found flush with the outer periphery of the main body 13 as clearly visible in FIG. 6. In all cases , it is understood that the arms 16 in the deployed position give the plate 11 a maximum transverse dimension, in other words a diameter, denoted D11 in FIG. 2, which is greater than the diameter, denoted d11 in FIGS. 5 and 6, which the arms give 16 to the plate 11 when these arms are in the retracted position.

In addition, as clearly visible in FIGS. 2 and 3, each of the arms 16 carries felling tools which, as detailed below, are distributed between, on the one hand, axial felling tools 12.2, which correspond to the axial felling tools 12 other than the tools 12.1 carried by the main body 13, and, on the other hand, radial felling tools 18.

The axial felling tools 12.2 are carried on the front face of the arms 16, being arranged in the terminal longitudinal part of these arms, opposite the axis XX, so that, when the arms 16 are in the deployed position, these axial felling tools 12.2 are found located beyond the periphery of the main body 13, that is to say are found more distant from the axis XX than the outer periphery of the main body 13. Thus, when the arms 16 are in the deployed position as in FIGS. 1 to 3 and the plate 11 is rotated about the axis XX, the axial felling tools

12.2 allow the ground to be felled along the axis XX so as to excavate a region of the ground located axially opposite the arms 16. With the axial felling tools 12.2, the cutting diameter of the cutting head 10, with which the size F face is advanced by the tunnel boring machine 1, then corresponds to the diameter D11 of the plate 11.

The radial felling tools 18 are also carried by the arms 16, without however being located on the front face of the latter, but being carried by the longitudinal end 16A of these arms 16, as clearly visible in the figure 3. These radial felling tools 18 are, for example, teeth, spikes, etc., the embodiment of these radial felling tools 18 not being limiting as long as these radial felling tools allow to cut the ground radially to the axis XX so as to excavate a region of the ground situated all around the arms 16 when, at the same time, the plate 11 is rotated around the axis XX and the arms 16 are driven in displacement from the retracted position to the deployed position.

According to a practical and effective embodiment, which is implemented in the embodiment here and which is clearly visible in Figure 3, the radial felling tools 18 are arranged over the entire axial extent of a song end 16.1 of the arms 16, opposite the axis XX: more precisely, as clearly visible in FIG. 3, at the longitudinal end 16A of each arm 16, the edge song 16.1 of the arm includes both a main part 16.1.1, extending along the axis XX so as to separate the front and rear faces of the plate 11 from one another, as well as a front edge 16.1.2 and a rear edge 16.1.3 which connect the main part 16.1.1 to, respectively, the front face and the rear face of the plate 11, the radial felling tools 18 being arranged on both the main part 16.1.1 and the front edges 16.1. 2 and rear 16.1.3 of the end edge 16.1 of the arms 16. When the plate 11 has entered elder in rotation around the axis XX and that the arms 16 are driven in displacement from the retracted position to the deployed position, the radial excavation, carried out all around the arms 16 by the radial felling tools 18, is generated effectively over the entire axial extent of the end edges 16.1 of the arms 16, in other words over the entire thickness, along the axis XX, of the arms 16. Of course, at the front edge 16.1.2 of the end edge 16.1 of the arms 16, the presence of a portion of the radial felling tools 18 does not prevent the provision of a portion of the axial felling tools 12.2 there, as clearly visible in FIGS. 2 and 3 in the example considered here. In contrast, unlike radial felling tools 18, axial felling tools

12.2 are not located on the current portion 16.1.1 of the end edges 16.1 of the arms 16, such an arrangement for felling tools allowing the ground to be felled only radially to the axis XX, and not of cut the ground along this axis XX.

Furthermore, the positioning, around the axis XX, of the radial felling tools 18 on the arms 16 is not limiting of the invention: in the embodiment considered here, the radial felling tools 18 are located on one of the lateral flanks of the arms 16, in this case the flank turned in the direction of rotation of the plate 11 around the axis XX, it being understood that, by way of variants not shown, the tools radial felling 18 could be distributed over the two lateral flanks of the arms 16, in particular in the case where the plate 11 is rotatable in both directions, or else could be located between the two lateral flanks of the arms 16.

In practice, all or part of the axial felling tools 12.2 and / or all or part of the radial felling tools 18 can be removably carried on the arms 16. In particular, such removability can be provided to facilitate retraction of the arms 16 relative to the main body 13, avoiding that at least some of the axial felling tools 12.2 and / or at least some of the radial felling tools 18 do not interfere with the main body 13 when the arms 16 are in the retracted position, which could hinder the movement of these arms in movement from their deployed position to the retracted position. In the embodiment considered in the figures, in which the longitudinal end 16A of the arms 16 remains flush with the periphery of the main body 13 when the arms 16 are in the retracted position, the radial felling tools 18, as well as the part of the axial felling tools 12.2 arranged on the front edge

16.1.2 end edges 16.1 of the arms 16 can be permanently mounted on the arms 16, while the rest of the axial felling tools 12.2 is advantageously removably mounted on the arms 16.

It will be noted that the embodiment of the arms 16 which has just been detailed is not limitative of the invention, in the sense that, more generally, it is understood that all of these arms 16 constitute a deployable part of the tray 11, which is designed to carry the axial felling tools 12.2 on its front face and the radial felling tools 18 on its end edge turned away from the axis XX, and which is mounted on the body main 13 movably between a retracted position and a deployed position in which this deployable part extends radially projecting from the main body 13 by giving the plate 11 a diameter which is greater than that which is given to the plate by this deployable part in retracted position. Likewise, the arms 16 or, more generally, the above-mentioned deployable part of the plate 11 may have optional arrangements, not detailed here since they are known per se and such as blades making it possible to collect the cuttings from the ground cut down, closing plates allowing to vary the rate of passage of slaughtered material through the cutting head, etc.

As clearly visible in FIGS. 1, 4 and 5, the shield 20 comprises, for its part, a frame 21, which, with respect to the rest of the shield 20, is located in a central region of this shield and which is substantially centered on the axis XX. In the embodiment considered in the figures, the frame 21 has a generally tubular shape, centered on the axis X-X.

The front part of this frame 21 supports the cutting head 10, internally receiving the rear of the central region of the main body 13 of the plate 11, with the interposition of bearings or the like, allowing the relative rotation of the plate 11 by relative to the chassis 21 around the axis XX. The chassis 21 internally carries a motorization 30 making it possible to drive the cutting head 10 in rotation around the axis X-X. This motorization 30 is known per se and will not be detailed here further.

The rear part of the chassis 21 supports a fitting device 40 allowing, inside the shield 20, to install segments 3 whose embodiment is not limiting. As shown in FIG. 1, the segments 3 are, whatever their embodiment, designed to be joined together so as to jointly form a ring 4, which is intended to consolidate the internal wall of the tunnel T2 dug by the TBM 1 and which, by juxtaposition at the front of a similar ring, previously installed, extends forward a tube 5 consisting of the succession of rings 4 along the tunnel T2. The segments 3 are routed to the inside of the shield 20 from the surface of the ground and via the tunnel T1 then the tunnel T2, for example using a transporter or a service train. The segments 3 thus transported into the shield are manipulated using the laying device 40, gradually assembling them to each other, until the ring 4 is produced in the forward extension of a ring 3 previously installed, as shown in cross section in Figure 1. By way of non-limiting example, the delivery device 40 is an erector, such a device being well known per se in the art.

As shown in Figures 1, 4 and 5, the shield 20 also includes petals 22, which are distributed in a substantially regular manner all around the axis XX, on the outer periphery of the frame 21, and which, in the example of realization considered here, are twelve in number. The petals 22 delimit, opposite the axis XX, respective outer peripheral surfaces 22A which, jointly, define an envelope E20 of the shield 20: this envelope corresponds to the outer lateral surface of the geometric volume occupied by the shield 20, geometrically extended forwards and backwards along the XX axis. In practice, this envelope E20 is here cylindrical, with a circular base and centered on the axis X-X, the petals 22 corresponding, in a way, to respective portions of a tubular crown, centered on the axis X-X.

Whatever the embodiment of the petals 22, these petals are mounted on the frame 21 in a movable manner, each petal thus being movable relative to the frame radially to the axis X-X. It should be understood that the displacement capacity of the petals 22 is not free, but is controlled in order to pass the shield 20 between two different configurations, namely an extended configuration, shown in FIGS. 1 and 4, and a retracted configuration, shown in FIG. 5. For this purpose, each of the petals 22 is controlled to move, that is to say driven and then reversibly locked relative to the chassis 21 in one of the two above-mentioned configurations, and this by an ad hoc motor system: advantageously, the displacement and locking in position of the petals 22 relative to the chassis 21 are controlled by drive jacks 23, each of these drive jacks 23 being interposed between the chassis 21 and one of the petals 22, it being understood that each of the petals 22 is associated with one or more drive jacks 23.

When the shield 20 is in the extended configuration of FIGS. 1 and 4, the petals 22 occupy a separated position, in which the peripheral surfaces 22A of the petals 22 are sufficiently radially distant from the axis XX so that, on the one hand, the envelope E20 of shield 20 has a maximum transverse dimension, in other words a diameter, which is substantially equal to the diameter D11 that presents the plate 11 in the deployed position of the arms 16 and, on the other hand, so that this envelope E20 of the shield 20 surrounds the upper surface 4A of the rings 4 of the tube 5. In practice, the diameter of the envelope E20 is then expected to be substantially equal to the diameter D11 in the sense that this diameter of the envelope can be strictly equal to the diameter D11 or be slightly less than the diameter D11 to avoid jamming of the shield in the ground, as well known in the art. Thus, in the extended configuration of the shield 20, the petals 22 of the latter are kept sufficiently spaced from the axis XX so that the envelope E20 of the shield 20 is dimensioned to allow, on the one hand, outside of this envelope, consolidating the tunnel T2 dug with a cutting diameter corresponding to the diameter D11, that is to say while the arms 16 of the cutting head 10 are in the deployed position, and, on the other hand, inside of this envelope, to install a new ring 4 using the installation device 40. It will be noted that the petals 22 in extended configuration of the shield 20 are spaced apart from each other around the axis ZZ, leaving free spaces respective e22 between two petals 22 succeeding each other around the chassis 21.

When the shield 20 is in the retracted configuration, as in FIG. 5, the petals 22 occupy a close position, in which the peripheral surfaces 22A of the petals 22 are closer to the axis XX in a direction radial to this axis than when these petals are in the position separated from the extended configuration of the shield: the envelope E20 of the shield 20, defined jointly by the peripheral surfaces 22A of the petals 22, is then reduced as regards its radial dimension, compared with when the petals 22 are in the deployed position. The envelope E20 defined by the petals 22 in the close position thus has a maximum transverse dimension, in other words a diameter, which is smaller than the diameter of the envelope E20 in the extended configuration of the shield 20. Furthermore, in the example considered here, the diameter of the envelope E20 in the retracted configuration of the shield is substantially equal to or less than the diameter d11 presented by the plate 11 in the retracted position of the arms 16, as clearly visible in FIG. 5: in the retracted configuration of the shield 20, the petals 22 are thus kept close enough to the axis XX so that the envelope E20 of the shield 20 has a transverse dimensioning which is not larger than that of the cutting head 10 in the retracted position of the arms 16. From more, the petals 22 in the close position are advantageously provided contiguous with each other all around the axis XX, surrounding the chassis 21, with the disappearance of the aforementioned free spaces e22. Thus, it is understood that the free spaces e22 formed between two successive petals 22 when the petals are in the separated position make it possible to accommodate the radial movement of the petals towards the axis X-X to pass the petals in the close position.

Furthermore, as clearly visible in FIG. 1, the petals 22 have an advancement device 50 intended to advance the tunnel boring machine by pressing on the edge of the rings 4. This advancement device 50 is known as such and, in the embodiment considered here, this device consists of a plurality of jacks 51:

the fixed part of each cylinder 51 is secured to one of the petals 22 while its movable part is designed to come to bear, substantially parallel to the axis XX, against the front edge of the segments 3 of the ring 4 recently assembled inside the shield 20, so as to exert on the shield 20 and, thereby, on the cutting head 10, a forward thrust necessary for the axial felling of the ground to be crossed.

Note that the delivery device 40 and the advancement device 50 remain inside the envelope E20 of the shield 20 whether the latter is in the retracted configuration or in the extended configuration.

The petals 22 may have other specificities than those described so far, as long as these petals 22 jointly constitute a peripheral part of the shield 20, which extends all around the frame 21, which defines the envelope E20 of the shield 20 and which is mounted on the chassis 21 in a movable manner, in particular radially to the axis XX, in order to modify the dimensioning of this envelope E20, by passing this dimensioning between that associated with the extended configuration of the shield, in which the envelope E20 has a diameter substantially equal to the diameter D11 of the plate 11 when the arms 16 of the latter are in the deployed position and in which the envelope E20 surrounds the upper surface 4A of the rings 4, and the dimensioning associated with the retracted configuration of the shield, in which the envelope E20 has a diameter substantially equal to or less than the diameter d11 of the plate 11 when the arms 16 of this the latter are in the retracted position.

According to an optional arrangement, which is implemented in the embodiment considered here, the shield 20 comprises, in its extended configuration, a ferrule 24, which is centered on the axis XX and which is secured to the petals 22 in the separated position so as to extend axially rearward these petals 22 at the level of the envelope E20, in other words so as to constitute a section of this envelope E20 juxtaposed at the rear of the petals 22 in the separated position. This ferrule 24, which is clearly visible in FIG. 1, increases the axial extent of the protection conferred by the shield 20. For reasons which will appear later, this ferrule 24 consists of a skirt or several skirt, juxtaposed along the axis XX and secured to each other, this skirt or each of these skirts being itself made up of several portions of skirts, which are distributed around the axis XX and which include, among other things, a high skirt portion secured to the petal (s) 22 located vertically at the top when the shield is in the extended configuration. In the embodiment considered here, the ferrule 24 comprises, as clearly visible in FIG. 1, two juxtaposed skirts 24.1 and 24.2, the upper skirt portion of the skirt 24.1 being referenced 24.1.1.

Other characteristics of the tunneling machine 1 will emerge from the description which follows, relating to a method for digging the tunnel T2 from the tunnel T1, by means of the passage of the tunneling machine 1 from its compact configuration of FIGS. 5 and 6 to its service configuration of the Figures 1 to 4, via intermediate configurations shown in the other figures.

A first phase of the method for digging the tunnel T2 consists of the installation phase indicated above, implemented while the tunnel boring machine 1 is in compact configuration: as shown in FIGS. 5 and 6, in this compact configuration, the arms 16 are in the retracted position and the shield 20 is in the retracted configuration, while being devoid of the ferrule 24. During the installation phase, the TBM 1 maintained in compact configuration is installed in the tunnel T1 so that the axis XX of the tunnel boring machine extends substantially perpendicular to the longitudinal direction of the tunnel T1, that is to say 90 °, to within a few degrees both horizontally and vertically, of an axis along which extends in length of tunnel T1.

According to a particularly advantageous practical arrangement, the tunnel boring machine 1 in compact configuration is placed in the tunnel T1 by being supported there by a structure 100, which makes it possible to transport the boring machine along the tunnel T1 to the level where the tunnel T2 must be dug and which also, for reasons explained below, achieve, on the one hand, a support for the tunnel T1 and, on the other hand, a thrust support for the tunnel boring machine 1.

A second phase of the method for digging the tunnel T2 consists of the start-up phase mentioned above, implemented while the tunnel boring machine 1 changes from the compact configuration to its service configuration. This start-up phase includes several successive stages, detailed below.

The start-up phase begins with a radial digging step, illustrated in FIGS. 7 to 10. During this radial digging step, the plate 11 of the cutting head 10 is rotated around the axis XX, as indicated by the arrow R1 in FIG. 8, and, at the same time, the arms 16 of the cutting head have passed from their retracted position to their deployed position, as indicated by the arrows Z1 in FIGS. 7 and 8. On note that Figures 7 and 8 illustrate the arms 16 in an intermediate position between their retracted position, shown in Figures 5 and 6, and their deployed position, which is shown in Figures 9 and 10, these Figures 9 and 10 thus illustrating the end of the radial digging step. The drive of the radial felling tools 18 both in rotation about the axis XX, due to the rotation of the plate 11, and in translation radially to the axis due to the drive in deployment of the arms 16 by the drive members 17, allows these tools to cut down the ground radially to the axis XX and thus to excavate the region of the ground situated all around the arms 16, thus digging into the wall of the tunnel T1 a primer T2. 1 of the tunnel T2, as clearly visible in FIGS. 7 and 9. The diameter of the tunnel T2 can thus be provided as large as that of the tunnel T1, as in the figures. Of course, in a variant not shown, the diameter of the tunnel T2 can be smaller or much larger than the diameter of the tunnel T1.

In the exemplary embodiment considered in the figures, the radial felling tools 18 dig the opening T2.1 of the tunnel T2 by crossing the rings 2 of the tunnel T1. The rings 2 thus crossed by the arms 16 of the cutting head 10 may be weakened, but are advantageously held by the structure 100.

Furthermore, during this radial digging step, lateral protection panels 101 are advantageously attached to the structure 100, being provided on either side, in the longitudinal direction of the tunnel T1, of the cutting head 10, as shown in Figures 7 to 10. At the end of the radial digging step, these side protection panels 101 can be removed.

The start-up phase continues, if necessary, with a step of installing additional axial cutting tools, illustrated in FIGS. 9 and 10. During this step, at least some of the axial cutting tools 12.2, which could not be present on the arms 16 in the retracted position, are reported on the arms 16 in the deployed position. At the end of this step, the arms 16 are found equipped with all of their axial cutting tools 12.2, as illustrated in FIGS. 9 and 10.

The start-up phase continues with a first axial digging step, illustrated in FIG. 11. During this step, the arms 16 are kept in the deployed position while the shield 20 is kept in the retracted configuration: by driving the plate 11 in rotation around the axis XX, while the tunnel boring machine 1 is advanced along the axis XX as indicated by the arrow X1, the axial felling tools 12.1 and 12.2 cut the ground along the axis XX and thus excavate the front of size F, by digging into the latter a first longitudinal part T2.2 of the tunnel T2 from the start T2.1. In practice, to advance the tunnel boring machine 1 axially forwards, the advancement device 50 is supported on the structure 100.

As illustrated by FIGS. 12 and 13, this first axial digging step continues until the longitudinal part T2.2 of the tunnel T2 thus dug has an axial dimension substantially equal to or slightly greater than that of the petals 22. For this depending on the nature of the advancement device 50, one or more temporary spacers can be attached axially between the structure 100 and the advancement device 50: thus, in the example considered in the figures, a temporary spacer, in the form of a ring 102 visible in FIG. 12, can be added between the structure 100 and the jacks 51 of the advancement device 50 to form a thrust support for the latter.

According to a particularly advantageous optional arrangement of the method for digging the tunnel T2, the upper skirt portion 24.1.1 of the skirt 24.1 is used during this first axial digging step, in order to provide protection for the operators and the tunnel boring machine 1 To do this, as illustrated in FIGS. 12 and 13, this skirt portion 24.1.1, which is not yet secured to the rest of the shield 20, is held by the positioning device 40 in a position axially juxtaposed with the 'rear of the highest petals 22 or more of the shield 22, while the tunnel boring machine 1 digs the longitudinal part T2.2 of the tunnel T2. In a variant not shown, the skirt portion 24.1.1 can be put in place by another handling system, embedded in the shield 20.

The start-up phase continues with a step of setting up the shield 20, illustrated by FIGS. 14 and 15. During this step, the petals 22 of the shield 20 are driven in displacement so as to pass the shield of the configuration. retracted to the extended configuration. In FIGS. 14 and 15, the translational drive, radially to the axis X-X, of the petals 22 is indicated by the arrows Z2. In addition, in these Figures 14 and 15, the six lowest petals 22 have been shown in the open position while the six highest petals 22 have been shown in the close position: this representation is only intended to illustrate the drive petals 22, it being understood that, in practice, the order or the sequencing with which the petals 22 are moved are not limiting of the invention. In all cases, at the end of this step of fitting the shield, all the petals 22 are in their separated position and the shield 20 reaches the extended configuration described above, in particular with regard to FIG. 4: the shield 20 then has a diameter substantially equal to the diameter D11 of the plate 11 in the deployed position of the arms 16 of the latter.

According to an advantageous optional arrangement of the shield 20, the latter comprises junction pieces 25 making it possible to mechanically connect the petals 22 in the separated position to one another: more precisely, as shown in FIGS. 4 and 15, two petals 22 in the separated position , succeeding each other around the frame 21, are connected to one another by one of the joining pieces 25 which is mechanically secured to these two successive petals so as to cover the free space e22 formed between these two petals 22 Thus, in the extended configuration of the shield 20, the junction pieces 25, which follow one another along the periphery of the shield, close the free spaces e22 formed between the petals 22 in the separated position. The junction pieces 25 therefore provide overall resistance to the shield 20 in an extended configuration, while preventing the introduction, inside this shield, of materials originating from the walls of the tunnel T2. In practice, in the embodiment considered in the figures, each junction piece 25 is pivotally carried by the petals 22, so that it can be tilted from a folded position between the petals 22 when the latter are in their close position, as illustrated by the upper half of FIG. 15, at a position of connection between the petals 22 when the latter are in their separated position, as shown in FIG. 4, as well as for some of the connecting pieces 25 on the Figure 15. This tilting of the junction pieces 25 can be controlled by ad hoc drive members, such as jacks.

The start-up phase continues with a second axial digging step, illustrated in FIGS. 16 and 17. During this step, the plate 11 is rotated around the axis XX while the tunnel boring machine 1 is advanced along the axis XX as indicated by the arrow X2, so that the axial felling tools 12.1 and 12.2 dig a second longitudinal part T2.3 of the tunnel T2, which extends axially forwards the first part T2.2 of this tunnel T2 . Similarly to the first axial digging step, this second axial digging step is advantageously carried out by protecting the operators and the tunnel boring machine 1 by the skirt portion 24.1.1, by providing that the latter is maintained, advantageously by the fitting 40 or else by another handling system embedded in the shield, in an axially juxtaposed position at the rear of the petal (s) 22 located highest, as clearly visible in FIGS. 16 and 17. Where appropriate, also as shown in FIG. 16, the advancement device 50 can rest on the resected portion of the tube of the rings 2 of the tunnel T1, from which extend the primer T2.1 and the parts T2.2 and T2.3 of the T2 tunnel.

The second axial digging step continues until the rear of the petals 22 is sufficiently spaced, along the axis XX, from the start T2.1 of the tunnel T2, to be able to attach the skirt portion 24.1. 1 to the petal (s) 22 located highest so as to extend axially towards the rear the peripheral surface 22A of this or these petal (s) 22, as illustrated by FIGS. 18 and 19. The start-up phase can then continue with a step extension of the shield 20 towards the rear, during which this skirt portion 24.1.1 and the other skirt portions of the skirt 24.1 are both secured to one another and attached integrally to the petals 22 so that these different portions skirt together form the skirt 24.1 extending the petals 22 axially towards the rear at the level of the envelope E20 of the shield 20. At the end of this step of extending the shield towards the rear, the j upe 24 is as shown in figure 20.

The start-up phase continues as illustrated in FIGS. 20 and 21, namely that:

- special segments 6, designed to provide the junction between the resected portion of the rings 2 of the tunnel T1 and the first ring to come from the tunnel T2, are put in place by the laying device 40, as illustrated by the lower half of the figure 20,

the advancement device 50 bears against the special segments 6 so that the tunnel boring machine 1 continues to dig the tunnel T2, by advancing its cutting front F, as illustrated by the lower half of FIG. 21, and

the skirt portions constituting the skirt 24.2 are attached integrally to the rear of the skirt 24.1 so as to form the skirt 24.2 extending axially towards the rear the petals 22 of the shield 20 at the level of the envelope E20 of the latter, as shown in the upper half of Figure 21.

At the end of the start-up phase detailed so far, the method for digging the tunnel T2 passes into a third phase, which consists of the normal operating phase, mentioned above, implemented while the tunnel boring machine 1 is in service configuration. During this normal operating phase, the tunnel boring machine 1, the arms 16 of the cutting head of which are kept in the deployed position and the shield 20 is kept in the separated configuration, is operated to dig the rest of the tunnel T2, as illustrated by figure 1.

Various modifications and variants to TBM 1 described so far, as well as the method for digging the T2 tunnel detailed above, are also conceivable. As examples:

- rather than the arms 16 or, more generally, the deployable part of the plate 11 is movable, vis-à-vis the main body 13 of this plate 11, in a rigorously radial manner to the axis XX, this movement can be oriented differently as long as the movable mounting between the main body and the arms 16 or, more generally, the deployable part allow that in the deployed position, these arms or this deployable part extend in radial projection from the main body 13 by giving the plate 11 a diameter which is greater than the diameter of the plate in the retracted position of these arms or of this deployable part;

- Similarly, the petals 22 or, more generally, the peripheral part of the shield 20 can be moved other than rigorously radially to the axis ZZ, as long as the movable mounting between the frame 21 and the petals 22 or, more generally, the peripheral part makes it possible to modify the size of the envelope E20 of the shield 20 to pass the latter between the retracted and extended configurations;

- In the retracted configuration of the shield 20, the envelope E20 of the latter can advantageously be sized to be surrounded by the lower surface 4B of the rings 4: in this way, once the tunnel T2 is dug and consolidated by the rings 4, the tunnel boring machine 1 can be moved back inside the tube 5 formed of the rings 4 after the shield 20 has been passed from the extended configuration to the retracted configuration and the arms 16 or, more generally, the deployable part of the plate 11 of the cutting head 10 has been moved from the deployed position to the retracted position; details relating to the technical methods to allow such a retreat of the tunnel boring machine 1 are given in EP 3 241 985 to which the reader may refer;

- Furthermore, also in the retracted configuration of the shield 20, the diameter of the envelope E20 may not be substantially equal to or less than the diameter d11 of the plate 11, but may be greater than this diameter d11, taking advantage of the space available under vault in the central region of tunnel T1 according to the orientation of TBM 1 in tunnel T1 during the installation phase;

- rather than the shield 20 of the tunnel boring machine 1 integrating a movable peripheral part, such as the petals 22 detailed above, it can be provided that the elements constituting the peripheral region of the shield are separated from the rest of the boring machine in the compact configuration of the latter and are only reported to the rest of the tunnel boring machine during the shield installation stage, by means of assembly operations which are carried out by operators in the T2.2 part of the T2 tunnel and which result in the shield thus assembled has a diameter substantially equal to the diameter D11 of the plate 11; and or

- rather than the tunnel T2 being dug perpendicular to the tunnel T1, the tunnel T2 can be dug transversely to the tunnel T1, with an angle between the respective longitudinal directions of the two tunnels which is different from 90 °; the T2 tunnel can also be dug substantially in the axis of the T1 tunnel, but with a diameter larger than that of the T1 tunnel.

Claims (11)

22 CLAIMS 1Tunnelier (1), comprising a cutting head (10) and a shield (20) which follow one another along an axis (XX) along which the tunnel boring machine (1) is intended to advance to dig a tunnel (T2), the cutting head being arranged at the front of the shield, which cutting head comprises: - A plate (11), which is rotatable about the axis (XX) relative to the shield (20) and which includes both a main body (13), through which the axis (XX) passes, and a deployable part (16) which is movably mounted on the main body between a retracted position, in which the plate has a first plate diameter (d11), and a deployed position, in which the deployable part extends in radial projection the main body by giving the plate a second plate diameter (D11) which is greater than the first plate diameter, and - First axial felling tools (12.1), which are carried by the main body (13) and which are adapted to knock down the ground along the axis (XX) so as to excavate a region of the ground situated axially opposite the main body when the plate (11) is rotated about the axis, characterized in that the cutting head (10) also includes radial felling tools (18), which are carried by the deployable part (16 ) and which are adapted to cut the ground radially to the axis (XX) so as to excavate a region of the ground situated all around the deployable part when, concomitantly, the plate (11) is rotated about the axis and the deployable part is driven in displacement from the retracted position to the deployed position. 2, - Tunneling machine according to claim 1, characterized in that the deployable part (16) of the plate (11) has an end edge (16.1), which is turned away from the axis (XX) and which includes both a running part (16.1.1), extending along the axis so as to separate from one another the front and rear faces of the tray, and the front (16.1.2) and rear edges (16.1.3) which connect the current part to, respectively, the front face and the rear face of the plate, and in that the radial felling tools (18) are arranged on the current part (16.1.1) and the front (16.1.2) and rear (16.1.3) edges of the end edge (16.1) of the deployable part (16). 3. -Tunnelier according to one of claims 1 or 2, characterized in that the deployable part of the plate (11) includes at least one arm (16), which extends in length and is movable relative to the main body ( 13) radially to the axis (XX) and which has a longitudinal end (16A), opposite the axis and carrying the radial felling tools (18). 4. -Tunnelier according to any one of the preceding claims, characterized in that the cutting head (10) further comprises second axial felling tools (12.2), which are carried by the deployable part (16) of the plate (11) at least when the deployable part is in the deployed position and which are adapted to knock down the ground along the axis (XX) so as to excavate a region of the ground situated axially opposite the deployable part in the deployed position when the platform is rotated around the axis. 5. -Tunnelier according to any one of the preceding claims, characterized in that the shield (20) defines an envelope (E20) inside which the shield embeds both: a laying device (40) for laying segments (3) so that the latter form a ring (4) for consolidating the tunnel (T2), arranged in the axial extension towards the front of a ring previously laid, and - an advancement device (50) for advancing the tunnel boring machine (1) by pressing on a front edge of the recently installed ring, and in that the shield (20) comprises a central chassis (21), as well as a peripheral part (22) which extends all around the frame and which defines the envelope (E20) of the shield while being mounted on the frame in a movable way to pass the shield between: - a retracted configuration, in which the shield envelope is dimensioned to have a first envelope diameter, and - an extended configuration, in which the shield envelope is dimensioned to surround the upper surface (4A) of the rings (4), having a second envelope diameter, which is greater than the first envelope diameter and which is substantially equal to the second plate diameter (D11). 6. -Tunnelier according to claim 5, characterized in that the shield (20) further comprises a skirt portion (24.1.1) which is adapted for successively: - be held in place, by the fitting device (40), vis-à-vis the rest of the shield axially juxtaposed at the rear of a high portion of the peripheral part (22) of the shield, without being secured to the latter, and - Be attached to the upper part of the peripheral part (22) of the shield (20) when the shield is in the extended configuration, so as to extend axially towards the rear this upper portion of the peripheral part at the level of the envelope (E20). 7, - Method for digging a second tunnel (T2) from a first tunnel (T1), which method successively comprises: - An installation phase, during which a tunnel boring machine (1), which is in accordance with any one of the preceding claims and whose deployable part (16) of the cutting head (10) is in the retracted position, is installed in the first tunnel (T1); - a start-up phase, which successively includes: a radial digging step, during which the plate (11) of the cutting head (10) of the tunnel boring machine (1) resulting from the installation phase is rotated around the axis (XX) and, while the plate is thus driven in rotation, the deployable part (16) of the plate has passed from the retracted position to the deployed position so that the radial felling tools (18) dig a primer (T2.1) of the second tunnel (T2) in the wall of the first tunnel (T1), - A first axial digging step, during which the plate (11) is rotated and the tunnel boring machine (1) is advanced along the axis (XX), so that the first axial felling tools (12.1) , as well as second axial felling tools (12.2) carried by the deployable part (16) dig a first longitudinal part (T2.2) of the second tunnel (T2) from the primer (T2.1), and - a step of fitting the shield, during which, in the first longitudinal part (T2.2) of the second tunnel (T2), the shield (20) of the tunneling machine (1) is put in place, being dimensioned to surround the upper surface (4A) of rings (4) for consolidating the second tunnel (T2) and to present a diameter substantially equal to the second diameter of the plate (D11); and -a normal operating phase, during which the tunneling machine (1) resulting from the start-up phase is operated to dig the rest of the second tunnel (T2). 8. - Method according to claim 7, wherein the first tunnel (T1) and the second tunnel (T2) have substantially the same diameter. 9. - Method according to one of claims 7 or 8, in which, during the installation phase, the tunneling machine (1) is installed in the first tunnel (T1) so that the axis (XX) of the tunneling machine extends substantially perpendicular to the longitudinal direction of the first tunnel. 10. - Method according to any one of claims 7 to 9, in which the tunneling machine (1) is in accordance with any one of claims 5 or 6, in which, during the installation phase, during the radial digging step and during the first axial digging step, the shield (20) of the tunnel boring machine (1) is in the retracted configuration, and in which, during the step of putting the shield into service, the shield (20 ) changes from the retracted configuration to the extended configuration. 11. - Method according to claim 10, in which the tunnel boring machine (1) is in accordance with claim 6, in which, during the first axial digging step, said skirt portion (24.1.1) of the shield (20) is maintained by the positioning device (40) in an axially juxtaposed position behind a high portion of the peripheral part (22) of the shield, and in which the start-up phase further comprises: - A second axial digging step, which is implemented after the step of placing the shield and during which, at the same time, said skirt portion (24.1.1) of the shield (20) is maintained by the laying device (40) in an axially juxtaposed position behind a high portion of the peripheral part (22) of the shield and the plate (11) is rotated while the TBM is advanced along the axis (XX) so that the first and second axial felling tools (12.1, 12.2) dig a second longitudinal part (T2.3) of the second tunnel (T2), extending the first longitudinal part axially forward (T2. 2) the second tunnel, and a step of extension of the shield towards the rear, during which said skirt portion (24.1.1) and other skirt portions are both secured to one another and attached integrally to the peripheral part (22) of the shield (20) so that said skirt portion and these other skirt portions jointly form a skirt (24.1) extending axially towards the rear the peripheral part of the shield at the level of the envelope (E20) of the shield.