GB2291099A - Tunnel lining - Google Patents

Abstract

A tunnel lining system comprises a tubular shutter centred by slipper shoes 16 carrying a moveable stop end 14 and towing a train of tubular elastomeric shutter extensions. Concrete is pumped into the annular space between the shutter 12 and the tunnel wall by a pipe 24 and allowed to set whilst the shutter moves in the direction of the arrow A through the section of tunnel to be lined. The shutter may be self propelled by pumped concrete pressure reacting against the fixed end stop 26 and the moveable end stop 14, and/or towed by winch 42 and tow line 44. <IMAGE>

Description

TUNNEL LINING This invention relates to tunnel lining for the creation or renovation of water mains, sewers and the like.

A successful prior art technique is disclosed in patent GB 2167796, wherein sheet metal shuttering is made in segments which are assembled together edge to edge to form a ring inside a tunnel, the ring is centred by screw jacks, and concrete is pumped into the annular space between the shuttering ring and the tunnel bore.

From time to time the shuttering is dismantled at the first formed end and re-erected at the last formed end so that a continuous lining may be formed. This system is particularly convenient with tunnels of say 2 metres in diameter (the tunnels are not necessarily circular but usually the major dimension is the vertical one, for example tunnels may be pear shaped) but when a tunnel is down to say I metre or even less, conditions for workers erecting and dismantling the shuttering become claustrophobic and, with reducing diameter, eventually become impossible.

The object of the present invention is to provide a system for use primarily, although not necessarily exclusively, with such smaller diameter tunnels, for forming linings or re-lining in the same.

According to the invention a tunnel lining system comprises the use of a tubular shutter and means for pumping concrete or like into the space between the shutter and the tunnel bore, and is characterised in that the shutter is moved along the tunnel simultaneously with or alternately with the pumping of concrete into said space.

When the system is brought into use, concrete is pumped into the space surrounding the stationary shutter.

When the space is filled to a desired pressure, shutter movement may benin.

Preferably a filling sensor or pressure sensor is employed to give an indication of filling or pressure, and this is connected to the pump and/or to means for movement of the shutter so that shutter movement begins when a certain pressure is achieved, and stops when the sensor indicates a full in pressure. This may enable an automatic operation to be carried out.

In a non-automatic operation, the sensor will give an indication that the desired pressure is attained, and an operator will stop the pump, move the shutter, and restart the pump until the pressure is again attained, and so on.

In all situations, the shutter is not dissembled, moved and re-assembled, but is simply displaced along the tunnel length when the concrete formed about it has become self-supporting, but before it has set to a point where the shutter might become immovably engaged in the concrete.

According to one possibility the concrete or like is mixed with a setting/curing accelerator which shortens the time needful before the concrete lining becomes selfsupporting and no longer needs shuttering to retain it in position. This time value is to be related to the speed of movement of the shuttering along the tunnel and to the length of shuttering. Thus for example if the shuttering travels at 8 metres per hour and the setting time is say 15 minutes, the required shuttering length is 2 metres.

The movement is preferably continuous but could be intermittent.

According to another possibility, means are provided for injecting and possibly mixing a setting decelerator into the concrete or like material adjacent to the point of entry into the space which is to be filled to form the lining, which injection means may be actuated manually or possibly automatically in the event of any delay in shuttering travel so as to avoid the possibility of the shuttering becoming immovably fixed in position as a result of such delay. However, the generally reverse arrangement may also be employed, that is to say the decelerator may be injected adjacent the concrete supply means so as to ensure that the concrete remains fluid in the pipe, and an accelerator injected at times when the shutter is moving and at a point close to the point of delivery into the space between the shuttering and tunnel bore.Chemical products for fluidising the wet concrete and delaying curing/setting, and also for the reverse procedure are well known and readily available.

The shuttering may comprise a number of sections which are flexibly coupled, e.g. articulated together so as to enable the shuttering to traverse curves and other non-straight portions of the tunnel length. In one typical embodiment of the invention the shuttering may comprise a first portion or tractor carrying means for centering the shuttering in the tunnel, and towing a train of shuttering through the tunnel. The actual shuttering may comprise a tubular steel shell, and one or more following tubular sections comprising inner and outer cylindrical walls at least the outer being elastomeric, which are inflated apart to maintain a required form. These inflated sections may be made of a suitable plastics or rubber-lie material.Typically the mentioned carts of the train namely the sheet metal tube and the possibly two rubber like tubes may have a combined length of say 2 or 3 metres but as explained hereinbefore this will depend upon the setting time of the mixture in use and the required speed of travel of the train along the tunnel. Often it will be convenient to line a length between two adjacent access points in one working shift, which will dictate speed.

According to a feature of the invention the train of shuttering is partly or wholly self-propelled by pumped concrete pressure. In use a fixed stop-end of annular shape will be provided at the start point of a tunnel, and the leading end of the train will be provided with a moveable (with the train) stop end, also of annular shape, which substantially fills the space between the shuttering and the tunnel wall. Concrete is pumped into the annular space between the two stop ends and as it fills the space the pumping pressure reacts against the fixed stop end and displaces the moveable stop end and hence the train on which it is mounted so as to displace the same along the tunnel. So the moveable stop-end may tow the train.

It is however preferred to provide winch or tractor means to tow the shuttering along the tunnel, arranged to operate at the required speed as hereinbefore explained: this may be additional to or as replacement for the use of the concrete pumping pressure for propulsion.

The shuttering may be of constant diameter or transverse dimension, i.e. parallel sided. Or it may taper along its length in either direction. If the larger end leads, this may help propulsion by the concrete pressure. Reverse taper shuttering creates vector forces acting contrariwise, as explained hereinafter, and a winch or like is then essential.

In general, a sewer being renovated is likely to have manholes for access at for example 50 metre intervals and the fixed stop end will be mounted at one of them, and the concrete supply pipe and the towing winch if used will extend through the next one.

The purpose of renovation is to perfect the interior surface of the sewer. Many sewers requiring renovation are brick built and there may be sections of brick missing or even complete bricks missing. It is therefore desirable to provide means to maintain the shuttering centred in the true tunnel bore but making allowance for such variations as are due to missing bricks and the like. For these purposes the leading end of the train, i.e. the tractor unit ahead of the first shuttering section provided with the moveable stop end, may have slipper like shoes to contact the tunnel wall over an arc greater than the dimension of a single brick in both directions that is, along the tunnel and around the tunnel so as to minimise the possibility of the apparatus being damaged through misalignment resulting from a missing brick.

Surface finish of the set lining may be improved by making one or more of the sections of the train of shuttering so that they are non-parallel along their length (as mentioned earlier) for example so that they taper slightly along their length, with the larger end trailing. This feature also increases the desirability of means for automatically introducing a curing deceleration agent into the concrete in the event that travel of the shuttering stops albeit temporarily, to avoid the shuttering frame becoming fixed in position.

As an alternative, a lining may be laid inside the concrete, extending rearwardly from the moving shutter, and being extended in length as the shutter moves. In this case this laid lining may be a relatively thin elastomeric tube inflated by air or liquid, and it could be left in the formed tunnel as a permanent lining.

However it is presently preferred to make this a reusable lining.

The stationary lining to be laid may be wound on a reel in a folded state so that it can be fed into the tunnel. In one possibility the lining tube is fed in through the start end, that is to say the part of the tunnel ere the concrete lining is first formed, and everted adjacent the shuttering, so that the everted part is the inflated stationary tube with the folded and noninflated part lying within that tube and extending along the length of the already formed and lined tunnel and possibly out of the tunnel through an access shaft to the reel, and in this case there will be a pressure door at the end of the tunnel adjacent the shaft, with a relatively small gap in it through which the folded length of the tube is fed, as well as connections allowing inflation fluid to be pumped into the tube interior between the folded and the everted lining.

There may be feed rolls synchronized with the speed of travel of the shuttering so as to ensure that the leading end of the tube closely follows the shutter as the shutter progresses along the tunnel and further portions of lining are formed. If the tube is removed from the concrete when cured, this may be done by deflation, removing the pressure door, withdrawing the tube through the shaft and refolding and coiling it ready for use on another section.

Alternatively, the complete pressure door may be provided at the start end of the shaft, one end of the tube may be anchored to that, and the length of the tube may extend through the shuttering and for example to a reel mounted on a tractor hauling the shuttering and the reel along the tunnel, so that the folded and flattened tube on the reel erects and expands to fill the tunnel behind the shuttering as the tractor proceeds, with inflation again being carried out for example through the pressure door at the shaft end. Again, in such a possibility the lining tube may be left behind as a permanent lining or removed for recoiling and re-use.

Sewers and tunnels of the kind in question are provided with numerous junctions, branches, inlets and the like and in general it is necessary to block these temporarily as the lining progresses past each of them.

According to a feature of the invention, this is done as a pre-lining step 1s~ng inflated balloons inserted into each branch duct, which balloons can later be ruptured so as to r-open te duct. n one ossijilit for fitting stoppers to ducts, a tractor is remote controlled, and the tractor is provided e.g. with a camera or other device to sense the presence of a duct and then insert a balloon, for example one end of a coil of tube carried on the tractor, into the duct, inflate the same, and then seal the inflated end and sever that from the length of tube thus leaving a fresh sealed end for insertion into the next duct, and so on.

Another tractor operation is subsequently (after concrete lining) to run through the cured concrete lined tunnel to rupture the balloons and allow them to be flushed through by ordinary usage of the sewer.

Preferably the stopper balloons are located so that their ends adjacent the tunnel are generally in line with the surface of the shuttering so that there is no lining of concrete on the area of the stopper, or only a thin lining which is easily ruptured as compared to that applied elsewhere in the tunnel Various embodiments of the invention are somewhat diagrammatically described with reference to the accompanying drawings wherein: : Figure 1 is a section through a sewer showing one embodiment in place; Figure 2 is an enlarged scale section of the apparatus (alone) taken on the line 2-2 of Figure 1; Figure 3 is a similar scale section of the apparatus on the line 3-3 of Figure 1; Figure 4 is a fragmentary view similar to part of Figure 1, on an enlarged scale Figure 5 is a view similar to Figure 4 but showing a second embodiment; Figure 6 is a view similar to Figure 5 showing a third embodiment; and Figure 7 shows another embodiment.

Turning first to Figs. 1-4, the apparatus comprises tubular steel shutter sections 10,12 carrying a movable annular stop end 14 and a centring device 16 est seen in Fig. 3 as comprising a plurality of radially extending shafts 18 carrying slippers to contact the tunnel wall.

The shafts may be adjusted outwardly to centre the apparatus in tunnels where a particular lined diameter is required but which vary in original (unlined) diameter to a small extent. In general, a different shutter would be used if there was substantial variation in diameter.

Concrete is pumped in to form the lining through the delivery pipe 24 extending through one or more radial ports in the shutter section 12; Figs. 1 and 4 show only a single delivery port.

The apparatus includes a fixed stop end 26, conveniently mounted at one of the access shaft 28. The steel shutter tows, in this case, a pair of inflated elastomeric tubular lining parts 30,32, the significance of the plurality being that the joints 34 allow a limited lateral flexing so as to accommodate bends in the tunnel being lined.

When the space 40 fills with concrete, the pressure in the same (due to the concrete being pumped) reacts on the removable stop end 14 to displace the apparatus in the direction of the arrow A. Additionally, the apparatus is towed from winch 42 via a tow-line 44.

Appropriate pulleys guide the tow-line and also the concrete supply pipe 24. Alternatively a remote controlled tractor in the tunnel may haul the shuttering.

the concrete adjacent the rear end of the apparatus i.e. the trailing end of the shutter section 32 requires to be set sufficiently to be self supporting by the time the shutter has moved on. After the trailing end 32 has passed the stop end 26, the pressure in the unset concrete is contained between the movable stop end 1 and that ring of set concrete which surrounds the trailing end.

n te modification shown in ai, 5, the towed or pressure displaced apparatus comprises the single length of preferably tubular steel shutter SO carrying the moveable stop end 14, and with pressure at least initially contained by the fixed stop end 52 which in this case substantially closes the tunnel apart from an admission port for pressurising fluid, probably air, supplied by a pipe 54 connected to that port and extending out of the access shaft 28.The concrete lining is supported in the unset state by a plastic or preferably elastomeric tube liner 56 fixed to the stop end 52 inflated via a line 54, and extending from a reel of folded tube 60 carried by the steel shutter section 50 and extending between possibly driven rolls 62 which are mounted on a pressure containment wall 64 in the shutter 50. As the steel shutter moves to the left in Fig. 5 the tube is paid out or driven out from the reel 60, and inflated The arrangement in Fig. 6 differs from that in Fig.

5 in that instead of providing a reel 60 in the shutter, the reel 70 is located above ground and the tube is fed in through pinch rolls 72 on the fixed stop end 52, and is everted at the steel shutter 50 so as to form the lining 56. The extreme end of this lining is fixed to the stop end 52, as in Fig.5. Again it will be appreciated that as the shutter moves to the left, the lining is extended.

Fig. 7 shows the branch tunnel stopper apparatus.

In this case, tractor 72 running on endless tracks 74 may be battery powered and remote controlled. This therefore is provided with means to sense the position of branch connections, such as probes or the t.v. camera 76.

Tractor 72 tows a trailer 78 carrying a reel of tube 79 to form stopper balloons 82 in the branches 80 by the means explained hereinbefore: in general.

An end portion of the tube carried by the reel is to be extended by a system of link arms (not shown) and positioned in an associated branch tunnel such as the one 80 shown in the drawing, inflated, and then sealed and severed so as to block tat adjacent end of the branch tunnel. The tube 79 may contain an innertube supplying the inflating pressure, extending spirally through the coil to a pressure source at the hub of the wheel and there may be a pinch roller for clamping the outer tube which is to form the balloon and the inner tubes supplying that pressure, which pinch roller can be relaxed as part of the sealing process to allow the inflation and then re-clamped, whilst the sealing and severance take place. Alternatively, air may be pumped through the length of tube on the reel and allowed to exhaust into the tunnel, until such time as a balloon is required when the free end of the tube may be sealed for example by an electric resistance heater mounted at the end of an arm, and then a further similar seal carried out in a second place after the balloon has become lodged in the branch passage, and then the tube cut adjacent that seal to allow the apparatus to move on along the tunnel leaving the detached balloon in the illustrated position.

Claims (10)

1. A tunnel lining system comprising the use of a tubular shutter and means for pumping concrete or like into the space between the shutter and the tunnel bore, characterised in that the shutter is moved along the tunnel simultaneously with or alternately with the pumping of concrete into said space.

2. A system as claimed in Claim 1 wherein a winch is used to move the shutter along the tunnel.

3. A system as claimed in Claim 1 in which fixed and movable stop ends are used and the shutter is arranged to be displaced by concrete pressure therebetween.

4. A system as claimed in any preceding claim wherein the shutter comprises an inflated tube.

5. A system as claimed in Claim 4 wherein the said tube is towed by the shutter.

6. A system as claimed in Claim 4 wherein the said tube is stationary and is extended along the tunnel as the shutter progresses.

7. A system as claimed in Claim 6 wherein the said tube is fed in from the first lined end and everted at the shutter.

8. A system as claimed in Claim 6 wherein the tube is carried by the shutter.

9. A system as claimed in Claim 1 wherein the tunnel includes branches and means are provided for sealing the branches.

10. A system as claimed in Claim 9 wherein the shutter is provided with a supply of tube and means for inflating the tube to seal a branch, and also means for severing the inflated portion.