FR2694045A1 - Method, equipment and device for generating and injecting foam for tunneling. - Google Patents

Abstract

The partition (8) of the confinement chamber (9), the front and the rear of the excavator disc (7), the screw (10) for the removal of debris, as well as the peripheral skirt (6) of the boring tool (1), are provided with orifices (21) for injection of foam, in proximity to each of which at least one pressurised foam generator device (24) is situated, which device has its own operational control.

Description

i The present invention relates to a method of digging a

  containment pressure tunnel by means of a tunnel boring machine, of the type in which pressure foam is injected into a cut-off chamber located behind the disc

  excavator, through a plurality of injection orifices

  tion crossing the rear wall of this room.

  It is known in the tunneling by means of a tunneling machine, in particular in the sandy-clay type terrains, to balance the pressure of the terrain by means of a foam sent under pressure in the confinement chamber located behind the disc excavator and receiving the cuttings Foam is generally sent at the same time forwards and backwards through the excavator disc, around the tunnel boring machine through the skirt or peripheral shield of this one, and in the screw of removal of cuttings The foam used must be sufficiently load-bearing, under the selected confining pressure, so that it is a suspension of cuttings in the foam that is transported by the discharge screw. In the known technique, a foam generator, located in the tunnel at a certain distance behind the tunnel boring machine, generates the necessary foam, and this is conveyed by a pipe into the

  tunneling machine, where it is distributed by a series of diversions

  up to each injection site.

  In practice, it can be seen that it is not possible to obtain in this way, at the injection points, a foam of homogeneous quality, having a defined and controllable pressure. In addition, the injection of foam is not modular according to real conditions encountered

  at every moment of the progress of the site.

  The invention aims to allow a much more efficient and reliable use of the foam. To this end, the subject of the invention is a method of the aforementioned type, characterized in that foaming solution and compressed air are carried into the tunnel boring machine, where the foam is generated under pressure at locations immediately adjacent to the injection ports. According to other characteristics:

  in addition, at least one location is generated

  cement immediately adjacent to the cuttings evacuation screw, of the foam that is injected into this screw, and / or it is also generated, in at least one location

  immediately adjacent to the peripheral skirt of the tunnel

  tie, foam which is injected outwards through this skirt, and / or further generates, in at least one location immediately adjacent to said partition, foam which is injected into a hollow shaft connected to foam injection nozzles mounted on the excavator disc; the generation of the foam is independently controlled at each of said locations or in each of a plurality of groups of these locations; said command is carried out as a function of at least one of the following parameters: confining pressure, torque of the excavator disc, torque of the cuttings removal screw, advancement of the tunnel boring machine; at each location where we generate

  foam, a constant flow of soft solution is ensured

  and the compressed air pressure is controlled.

  The subject of the invention is also a tunneling equipment intended for implementing the above method. This equipment, of the type comprising a containment tunneling machine whose rear partition of the cuttings receiving chamber is provided with orifices. for injecting pressurized foam, and means for generating pressurized foam connected to these orifices, is characterized in that the means for generating foam include a plurality of foam generators each connected to a line of foaming solution and to a compressed air line, each foam generator being located in the immediate vicinity of an injection orifice, or of a group

  injection ports associated therewith.

  In one embodiment of this team-

  ment, the following train of the TBM carries a balance tank partially filled with foaming solution, and a supply manifold for foaming solution and a compressed air supply manifold for said generators starting respectively from the bottom and from the top of this tank, and it also carries, preferably on the same trailer as the balance tank, a foam product reservoir, pumps for transferring foam product and water to the lower part of the balance tank, and a compressor d air connected to the part

upper part of this tank.

  The invention also relates to a device for generating and injecting foam which is particularly suitable for implementing the method defined above. This device comprises: a body for supplying foaming solution and compressed air; an expansion chamber filled with packing; and

  an outlet nozzle of converging shape.

  According to other characteristics of this device: the supply body comprises two supply ducts, namely a foaming solution supply duct equipped with a flow regulator and

  preferably a flow detector, and a supply duct

  compressed air line preferably fitted with a pressure detector, these two conduits opening into a single conduit which itself opens into the expansion chamber; the expansion chamber has at its inlet and at its outlet a calibrated grid; the packing is a loose packing, in particular made up of roughly shaped elements

toric.

  An exemplary embodiment of the invention will now be described with reference to the accompanying drawings, in which: FIG. 1 is a partial schematic view of tunnel digging equipment according to the invention; Figure 2 schematically illustrates

  powering generation and information devices

foam jection;

  Figure 3 is a sectional view along

  dinal of a foam generation and injection device; and Figure 4 shows in section, on a larger scale, an element of the lining of the device

of Figure 3.

  FIG. 1 shows the general arrangement of equipment for digging a tunnel, the diameter of which can be of the order of 7 m, which is the

  case of certain underground railway galleries.

  This equipment essentially comprises a tunnel boring machine 1 to which a follower train 2 consisting of a series of trailers 3 is coupled, and an apparatus 4 for generating and injecting foam in the front region of

size 5.

  The tunnel boring machine comprises a cylindrical skirt or shield 6, of substantially horizontal axis XX, open towards the rear and provided at its front end with an excavating disc 7 At a small distance from this disc, a transverse watertight partition 8 is fixed in the skirt and defines with the disc a chamber 9 for confining and receiving the cuttings A screw 10 for discharging the cuttings leaves obliquely from the bottom of the chamber 9, and its

  casing crosses the partition 8 in a sealed manner.

  The trailers 3 of the following train are coupled to each other and carry all the equipment necessary for the progress of the site.

  the needs of this description, no one will describe

  that one of these trailers, referenced 3 A and shown schematically in Figure 1, which carries part of

the above-mentioned apparatus 4.

  More specifically, the trailer 3 A carries a tank 11 of foaming product, a balancing tank 12 and a control cabinet 13 A pipe 14 of foaming product, equipped with a pump 15, opens into the delivery pipe 16 of a pump 17 powered

  by a water pipe 18 from the network The soft solution

  resulting health reaches the lower part of the tank 12 An air compressor 19 also attached to the trailer 3 A sends compressed air to a tank

  pad 20 connected to the upper part of the tank 12.

  The apparatus 4 comprises another part mounted in the tunnel boring machine 1, namely: in the disc 7, a series of foam injection nozzles 21 arranged at different distances

  of the X-X axis and oriented some forward, that is

  that is to say towards the face, and the others towards

  the rear, that is to say, opening into chamber 9.

  Each nozzle is connected by a conduit 22 inside the disc to a central hollow shaft 23 closed at its two ends and passing through the partition 8 with a watertight seal; behind partition 8, a series of

  foam generation and injection devices 24.

  One of these devices opens into the shaft 23.

  Several others open directly into the chamber 9 through the orifices of the partition 8; others open into the housing of the screw 10; and still others open radially outside the skirt 6.

  Each device 24 is supplied independently

  in particular by two supply lines, namely a line 25 of foaming solution and a line 26 of compressed air All the lines 25 and 26 start from a distribution box 27 to which a manifold 28 supplying a foaming solution ends which

  from the bottom of the tank 12, and a manifold 29 for supplying

  compressed air from the top of this tank.

  As seen in Figure 2, the box 27 includes a solution distribution box 30

  foaming and a compressed air distribution box 31.

  The box 30 includes an inlet pipe 33 connected to the manifold 28 and provided with a main solenoid valve 34 and a flow controller 35 Downstream of the latter there are as many branches 36 as there are devices 24, each bypass being fitted with a manual shut-off valve 37 and a solenoid valve 38 and

  being connected to the pipe 25 of the associated device 24.

  The box 31 includes an inlet pipe 39 equipped with a main solenoid valve 40 and connected to the manifold 29 Downstream of the solenoid valve 40 there are as many branches 41 as there are devices 24, each branch being equipped with a manual shut-off valve 42 and a solenoid valve 43 and being connected to

  the pipe 26 of the associated device 24.

  FIG. 3 shows the structure of a device 24 for generating and injecting foam. This device comprises a supply body.

  44, an expansion chamber 45 and an outlet nozzle 46.

  The device can have a length of the order of 0.6 m and a diameter of the order of 0.10 m for a foam production of the order of 200 l / min. The body 44 comprises two conduits 47 of

  foaming solution and 48 of compressed air connected res-

  pectively to the corresponding pipes 25 and 26 The pipe 47 comprises a flow detector 49 followed by a flow regulator 50 and a nozzle 51 The pipe 48 comprises an air pressure detector 52 followed by a nozzle 53 Downstream sprinklers, the two conduits 47 and 48 meet in a single outlet conduit 54

which leads into room 45.

  The chamber 45 is cylindrical, coaxial with the duct 54 and fixed at one end to the body 44 It has at each end a calibrated grid 55 and is filled with a loose packing 56 As shown in Figure 4, satisfactory packing elements are are revealed to be constituted by elements 57 of generally toric shape, of the "pearl necklace" type, made of glass or ceramic, which are inert materials with respect to

foaming solution.

  The outlet nozzle 46 forms a cap fitted on the downstream end of the expansion chamber. It has a convergent shape between an inlet diameter close to the diameter of the chamber 45 and a significantly smaller outlet diameter. The nozzle can be directly connected to the corresponding foam injection orifice, in the partition 8, the housing of the screw 10, the skirt 6 or

  the hollow shaft 23 As a variant, if the need for implantation

  tation requires it, a short section of tube can connect the outlet of the nozzle to the injection orifice For example, the device 24 can be fixed by collars along the partition 8 and the nozzle can be connected by an elbow at

the injection port.

  In operation, the site advances in successive steps corresponding to the length of a ring 58 of the tunnel lining (Figure 1) Each ring consists of several segments prefabricated in the sector

  of circle assembled to each other.

  During each step in advance, the disc 7, driven in rotation, digs the cutting face while a ring of jacks 59 parallel to the axis XX, one of which is shown diagrammatically in Figure 1, resting on the last ring 58 in place, cause displacement

  forward of the TBM and the following train.

  During this advance, foam generated under pressure by a device 24 is injected into the hollow shaft 23 and, from there, onto the cutting face and into the chamber 9 through the nozzles 21; foam, generated by the other devices 24, is injected directly into the chamber 9 and into the housing of the screw 10, and

  also directly around the shield 6 Backwards-

  re, the foam is retained by a filling based on cement previously injected around the rings 58 of

coating already in place.

  The cuttings pass through the disc lights 7, remain more or less suspended in the foam, and the screw 10 discharges a mixture of cuttings towards the rear.

  and foam, which is not recycled.

  The control cabinet 14 (Figure 1) controls on the one hand the dosage of the foaming solution and the

  filling of the tank 13, and on the other hand the electro-

  valves 38 and 43 (Figure 2) It can thus

  service or out of service each device 24.

  The cabinet 14 can also adjust the foam outlet pressure at will, by action on the compressor 19. This pressure, of the order of a few absolute bars, is for example greater by a predetermined value, which can be l order of 1 bar, at the desired confining pressure On the other hand, in this example, the flow rate of foaming solution from each device 24 is constant and regulated by the regulator 50 (FIG. 3) The monitoring provided by the detectors 49 and 52 triggers alarms in the event of an incident, their output signals being sent via a line 60 (Figure 3) The proper functioning of each injector is thus

constantly checked.

  The choice of foam injection pressure can for example be made according to the

  following parameters: containment pressure, i.e.

  say back pressure to be established in chamber 9, torques exerted on the disc 7 and on the screw 10, advancement of the tunnel boring machine This pressure can actually be obtained at each injection point since the foam is

  produced in its immediate vicinity and is not transported

  ted over long distances with the creation of random pressure drops In addition, the choice of

  injectors to be commissioned depends on the terrain encountered

  very different parameters of the site and can be

  modulated at will The entire device management-

  lage 4 can be provided in a largely automated manner,

in particular by an expert system.

  Optionally, the same device 24 can be connected to a small number of immediately adjacent injection ports and, in some cases, several

  24 devices can be controlled in a group.

Claims (9)

  1 Method of digging a containment pressure tunnel by means of a tunnel boring machine (1), of the type in which foam is injected under pressure into a chamber (9) for receiving cuttings located   behind the excavator disc (7), through a plura-   lity of injection orifices passing through the rear partition (8) of this chamber, characterized in that foaming solution and compressed air are carried into the tunnel boring machine (1), where the foam is generated under pressure at locations (24) immediately adjacent to injection ports.   2 Method according to claim 1, ca-   characterized in that, in addition, at least one location (24) immediately adjacent to the screw (10) for removing the cuttings, from the foam which is injected into this screw, and / or is generated in in addition, in at least one location immediately adjacent to the peripheral skirt (6) of the tunnel boring machine (1), foam which is injected outwardly through this skirt, and / or is also generated, at least a location immediately adjacent to said partition (8), to the foam which is injected into a hollow shaft (23) connected to injection nozzles (21)   foam mounted on the excavator disc (7).   3 Method according to claim 1 or 2, characterized in that the generation of the foam is independently controlled in each of said locations (24) or in each of a plurality of groups of these locations. 4 Method according to claim 3, characterized in that said control is carried out as a function of at least one of the following parameters: confinement pressure, torque of the excavator disc (7),   torque of the cuttings discharge screw (10), forward cementing of the tunnel boring machine (1).   he Method according to any one of   Claims 1 to 4, characterized in that each time   location (24) where foam is generated, a constant flow of foaming solution is ensured, and the pressure of compressed air is controlled. 6 Tunneling equipment, of the type comprising a containment boring machine (1), the rear partition (8) of the cut-off chamber (9) of which is provided with pressure foam injection ports, and means for generating pressure foam connected to these orifices, characterized in that the foam generation means comprise a plurality   foam generators (24) each connected to a pipe   te (25) of foaming solution and a compressed air line (26), each foam generator being located in the immediate vicinity of an injection orifice, or of a   group of injection ports associated with it.   7 Equipment according to claim 6, characterized in that it comprises for each generator   foam (24) an independent function control   is lying. 8 Equipment according to claim 6, characterized in that the generators (24) are grouped into a plurality of sets of generators, each set being equipped with an independent operating control. 9 Equipment according to any one of   Claims 6 to 8, characterized in that the train   follower (2) of the tunnel boring machine (1) carries a balancing tank (12) partially filled with foaming solution, and a manifold (28) for supplying foaming solution and a manifold (29) for supplying compressed air to said generators (24) starting from the bottom and from the top of this tank.   10 Equipment according to claim 9, characterized in that the follower train (2) carries,   preferably on the same trailer (3 A) as the equilibrium tank   free (12), a tank (11) of foaming product, pumps (15, 17) for transferring foaming product and water to the lower part of the balancing tank, and an air compressor (19) connected to the top of this tank.   11 Device (24) for generating and injecting foam, in particular for implementing   of a method according to any one of the claims   1 to 5, characterized in that it comprises: a body (44) for supplying foaming solution and compressed air; an expansion chamber (45) filled with a lining (56); and   an outlet nozzle (46) of convergent shape   kind. 12 Device according to claim 11, characterized in that the supply body (44) comprises two supply ducts, namely a duct (47) for supplying foaming solution equipped with a flow regulator (50) and preferably a flow detector (49), and a conduit (48) for supplying compressed air preferably equipped with a pressure detector (52), these two conduits opening into a single conduit (54) which   itself opens into the expansion chamber (45).   13 Device according to claim Il or 12, characterized in that the expansion chamber (35) has at its inlet and at its outlet a calibrated grid (55).   14 Device according to any one of   Claims 11 to 13, characterized in that the lining   sage (56) is a loose filling, in particular consisting   elements (57) of roughly toroidal shape.