FR2794797A1 - Tunnelling machine operating procedure uses concrete curtain with series of seals at tunnel entrance - Google Patents

Abstract

The procedure, for use when using a tunnelling machine with a front shield (2) and cutting ring (3), consists of first setting up a concrete curtain (14') at the entrance to the tunnel to position the machine for starting. The curtain is fitted with a system of seals in the form of a ring (17) fastened to the inner edge of the curtain and lips (241, 242, 243) which project radially and engage with the tunnelling machine's skirt (3) to the rear of its shield. During operation grease is injected into the cavities between the seal lips to prevent friction, followed by a sealing material once the machine has passed the seal zone.

Description

 The present invention relates to a method of implementing a tunnel boring machine comprising a cylindrical skirt in front of which is disposed a shield itself preceded by a cutting wheel, a method according to which the cutting edge is progressively progressed by means of a set of jacks exerting a thrust between said shield and the edge of the last of a series of segments set up at each of these stages to support the tunnel as it is digging.

It is known that in order to dig a tunnel in the presence of water and / or in unstable terrain, it is necessary to create a start-up "airlock" between the tunnel being excavated and the outside, in order to make the tunnel boring machine undergo external pressure. p = 0 at the pressure p more or less high prevailing in the field. Currently there are essentially two solutions.

In Figure 1 of the attached drawing is shown schematically in axial section a tunnel digging machine, or tunneling machine, of the type used in the above-defined method, according to a first solution. In this drawing, the tunnel boring machine comprises a cutting wheel 1, a shield 2 delimiting a felling chamber, and a cylindrical skirt 3, and has been installed in an "attack chamber" constituted by a concrete borehole 4. The progression of the face of size 5 is ensured by the thrust of jacks schematically in 6 and supported, in the starting step, on a starter ring 7 and then on the edge of a first voussoir 8. The seal between the inside of the attack chamber and the outside is provided on the one hand by a peripheral lip seal 9 installed between the cylindrical skirt 3 and the outer surface of the last voussoir set up (in the drawing, it s' is the first voussoir 8), and secondly by a system 10 of seal and retainer of the starter ring 7, installed at the outlet of the pilot hole 4.

The other known solution has been shown in FIG. 2, also in schematic axial section. The process implemented here does not require digging a concrete drilled hole. To do this, it installs outside the area to be digged a thrust frame 11 on which support a starter ring 12 and a series of voussoirs 13 to support the tunnel during digging. The cutting wheel, the shield, the cylindrical skirt and the thrust cylinders have been designated by the same references as in FIG. 1. Finally, between the cylindrical skirt 3 and a start-up sponge 14, on the one hand, the last voussoir 13d second, a double sealing system - peripheral lips 15, 16, sealing between the inside of the tunnel being digged and the outside.

The disadvantage of these known digging start methods lies in the fact that they function properly only under certain conditions, in particular with a relatively low pressure p, and require preparatory field treatment.

They may also not work properly and cause more or less serious disorders (cracks, settlement, water supply in gallery, or even breakage) which anyway result in a slowdown at startup, expenses that are not always taken into account by the control of work and especially increased risks for the personnel. The object of the present invention is to avoid these drawbacks, in particular in a highly fractured horizon over long lengths, with significant water masses in the vicinity, as well as pressures of up to 3 bars in static and 4 bars in dynamic.

For this purpose, a tunnel digging method according to the invention, of the general type defined at the beginning, is characterized in that for the operation of starting said digging, a start-up eardrum is established at the entrance of the tunnel. concrete, there is fixed in this eardrum a sealing system comprising on the one hand a ferrule in tight connection with the tympanum and on the other hand at least two peripheral lips spaced apart from each other, projecting radially in the tunnel , said cutting wheel and the tunneling tunnel shield are engaged in this sealing system, with which the tunneling machine skirt then cooperates, said wheel is used to advance the cutting edge until it is possible to establishment of a voussoir at the right of the exit of said tympanum, and there is established at this location a containment ring closing the space between said shell of the eardrum and said voussoir, then what is advancing the advancement digging the tunnel in the known way.

In this way, and as this will be better seen later along with other advantages, it achieves a seal at the level of the tunnel boring machine wheel and it avoids that water and materials do not come to occupy the the space between this wheel and the sealing systems provided at the outlet of the tunnel being excavated, which, with the known methods, favored the furrows, settlements and other disorders mentioned above. In addition, this allows a visual check of possible leaks. According to another embodiment of the invention, the method may further be characterized in that after the tunnel boring machine has left the zone of said sealing system, a sealing material is injected behind its cylindrical skirt into each of the annular chambers separating two successive spaced peripheral lips of said sealing system as well as in the space which is provided between said shell of the eardrum and the corresponding voussoir and which at the rear is limited by said ring of confinement.

Thus, definitive and secure stiffening and sealing is ensured at the tunnel entrance, while the sealing at this level during the introduction of the tunnel boring machine can be ensured externally by removable means with peripheral lip seals. of any known type.

For this purpose and according to a complementary characteristic of the invention, the method can be further characterized in that during the introduction phase of the tunnel boring machine in the tunnel being excavated, the seal is externally sealed by means of two crowns, the first of which is bolted to said eardrum and internally carries a first lip seal in sealing contact with the cylindrical skirt of the tunnel boring machine, and the second of which is bolted to the first and internally bears a second gasket. lips in sealing contact with the voussoirs.

 Also conventionally, provision can be made for sealing the annular space formed between the cylindrical skirt of the tunnel boring machine and the outer surface of the segments by means of annular greased metal ring joints known in themselves. An embodiment of the invention will now be described by way of non-limiting example with reference to the other figures of the attached drawing, which are partial views in axial section - Figure 3 shows the operation of implementation. place of the tunnel borer inside the shell of the tympanum; - Figure 4 shows the implementation of external sealing means at the rear of the tunnel boring machine; - Figure 5 shows an intermediate position after establishment of said containment ring; and FIG. 6 shows the final position reached at the level of the tympanum, after complete sealing.

In FIGS. 3 to 6, the tunnel boring machine has been further schematically represented, and its various parts are designated 1 to 3 with the same meaning as in FIGS. 1 and 2.

The eardrum formed at the entrance of the tunnel has been referenced 14 'and is internally equipped with a metal ferrule 17 maintained in sealed connection with the eardrum with hydrogenation joints and snap connectors 18. The reference 19 designates a discharge tube allowing the flow of materials to the outside under the effect of the pressure of the ground, and provided at its outer end with a valve 20. Inside the shell 17 are fixed for example three rails circular shaped members 21 held in place by shims 22, with intercalation stiffeners 23. In each of these three rails is attached a greased conventional lip seal 241, 242, 243. In Figure 3 it has been shown the seal 241 deformed by the advance of the cutting wheel 1. The other parts of Figure 3 will be described below. During this phase of installation of the tunnel boring machine, the seal at its rear part can be ensured 1) by a first ring 251 bolted to anchoring means 26 to the tympanum 14 'and internally bearing a first lip seal 271 in contact sealing with the cylindrical skirt 3 of the tunnel boring machine; 2) by a second ring <B> 252 </ B> internally bearing a second lip seal 272 in sealing contact with the outer surface of the concrete segments 28.

These two rings 251 and <B> 252 </ B> are connected to each other by bolting on an intermediate ring 29.

The digging phase which follows that illustrated in FIG. 3 is illustrated in FIG. 5 and shows the three lip seals 241, 24e and 243 in sealing support on the skirt 3 of the tunnel boring machine. These seals define between them two containment chambers C which can be filled with fat by injection by injection tubes 37 passing through the tympanum 14 'and the ferrule 17, and opening through the stiffeners 23 mentioned above.

We see that any entry of material behind the tunnel boring machine and around the segments under the effect of pressure is thus prohibited. Furthermore, there is shown at 30 (see also FIGS. 4 and 6) hand-greased conventional metal beam annular seals, sealing between the cylindrical skirt 3 and the outer surface of the voussoirs 28 during the advancement of the TBM.

According to an important additional provision of the invention, it is possible at this stage to establish a concreted confinement ring 31 at the entrance to the tympanum 14 ', to completely and completely seal the annular space formed between the shell 17 and the corresponding voussoir. The pouring of the concrete of the ring 31 can take place inside a steel box consisting of two flat plates 32 constituting a lost formwork, welded between curved brackets 33 themselves welded to the shell 17 of a part, and brackets 34 anchored on the voussoir 28 on the other hand.

Finally, FIG. 6 shows the possibility of injecting, behind a conical plate 35 of the tunneler skirt 3, a sealing material 36 similar to that of the containment ring 31 into each of the two annular chambers C which separate two successive peripheral lips 243 and 242, 242 and 241, as well as in the space between the plate 35 and the lip 243, and in that which extends between the lip 241 and the box of the ring 31, so as to perfect the rigidity and static tightness between the shell 17 and the voussoirs 28.

This sealing material 36 is injected into these annular spaces C through the injection tubes 37 mentioned above.

It should be noted, in addition to the advantages already indicated, that this process can be adapted to any type of containment, liquid, solid or gaseous, while avoiding the usual risks as well as the long work that must be subcontracted and which are expensive.

Claims (5)

1. A method of implementing a tunnel boring machine comprising a cylindrical skirt (3) in front of which is disposed a shield (2) itself preceded by a cutting wheel (1), the method according to which is ensured advancing the cutting face (5) in stages by means of a set of jacks (6) exerting a thrust between said shield (2) and the edge of the last of a series of voussoirs (8) set up at each of these steps for supporting the tunnel as it is excavated, characterized in that for the operation of starting said digging, a concrete eardrum (14 ') is fixed at the tunnel entrance, tympanum a sealing system comprising on the one hand a ferrule (17) sealingly connected to the eardrum (14 ') and, on the other hand, at least two peripheral lips spaced from one another (241, 242,. ..) projecting radially in the tunnel, said cutting wheel (1) and the shield (2) of the tunnel boring machine are engaged in this sealing system, which then cooperates with the skirt (3) of the tunneling machine, is used said wheel (1) to advance the cutting edge (5) until it is possible to establish a voussoir (28) at the exit of said tympanum (14 '), and there is established at this location a containment ring (31) closing the space between said shell (7) of the eardrum and the voussoir (28) mentioned above, then what is progressing the digging of the tunnel in the known manner. 2. Method according to claim 1, characterized in that the grease is injected into each of the annular confinement chambers (c) separating two successive peripheral lips (241, 242, ...) of said sealing system. 3 Process according to claim 1 or 2, characterized in that after the tunneling machine has left the zone of said sealing system, a sealing material (30) is injected into each of the annular confinement chambers behind its cylindrical skirt (3). (C) separating two successive peripheral lips (241, 242, ...) of said sealing system and in the space between said ferrule (17) of the eardrum (14 ') and the corresponding voussoir (28) and which at the rear is bounded by said containment ring (31). 4. Method according to any one of claims 1 to 3, characterized in that during the introduction phase of the tunnel boring machine in the digging tunnel, the outside is sealed with two rings (251, 252) of which the first (25, _) is bolted to said tympanum (14 ') and internally carries a first lip seal (271) in sealing contact with the cylindrical skirt (3) of the tunnel boring machine, and the second ( 252) is bolted to the first and internally carries a second lip seal (272) in sealing contact with the segments (28). 5. Method according to any one of the preceding claims, characterized in that it ensures the tightness of the annular space formed between the cylindrical skirt (3) of the tunnel boring machine and the outer surface of the voussoirs (28) thanks to greased metal ring rings (30) known per se.