RELATED APPLICATION

This application is an application under 35 U.S.C. 371 of International Application No. PCT/IB2018/055713 filed on Jul. 31, 2018, the entire contents of which are incorporated herein by reference.

FIELD OF INVENTION

THIS INVENTION relates to a mobile underground tunnel borer arrangement.

BACKGROUND OF INVENTION

A tunnel boring machine (TBM) is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock. Tunnel diameters can range from 1 meter (done with micro-TBMs) up to around 19 meters. Tunnels of less than 1 meter or so in diameter are typically done using horizontal directional drilling rather than TBMs.

Tunnel boring machines are used as an alternative to drilling and blasting methods in rock, and conventional “hand mining” in soil. TBMs have the advantages of limiting the disturbance to the surrounding ground and producing a smooth tunnel wall. This significantly reduces the cost of lining the tunnel and makes them suitable to use in heavily urbanized areas. The major disadvantage is cost, since TBMs are expensive to construct and can be difficult to transport. The longer the tunnel, the less the relative cost of tunnel boring machines versus drill and blast methods. This is because tunneling with TBMs is more efficient and results in shortened completion times (and is thus relatively safer).

Modern TBMs typically consist of the rotating cutting wheel, called a cutter head, followed by a main bearing, a thrust system and a trailing support arrangement. The type of machine used depends on the particular geology of the project, the amount of ground water present and other factors. In hard rock, which is typically where TBMs are most commonly used, either shielded or open-type TBMs can be used. In addition, TBMs can be used in either a ‘wet-cutting’ application, in which mist is sprayed onto the cutter head, or in a ‘dry-cutting’ application, in which no mist is spayed. In all cases, however, TBMs excavate hard rock using disc cutters mounted on the cutter head. The disc cutters create compressive stress fractures in the rock, causing it to chip away from the rock in front of the machine, called the tunnel face. The excavated rock, known as muck, is transferred through openings in the cutter head to a belt conveyor, where it runs through the machine to a system of conveyors or muck cars for removal from the tunnel.

Open-type TBMs have no shield, and are thus unsupported, which is not ideal from a safety point of view. To advance, the machine uses a gripper system that pushes against the side walls of the tunnel. The machine will then push forward off the grippers gaining thrust. At the end of a stroke, the rear legs of the machine are lowered, the grippers and thrust cylinders are retracted. The retraction of the thrust cylinders repositions the gripper assembly for the next boring cycle. The grippers are extended, the rear legs lifted, and boring begins again. The open-type TBM typically uses ground support methods, such as ring beams, rock bolts, shotcrete, steel straps, ring steel and wire mesh.

It is thus an aim of the present invention to provide a mobile underground tunnel borer arrangement that addresses most of the inherent problems or disadvantages associated with conventional TBMs, whilst still retaining and utilising the proven advantages associated with current TBMs.

SUMMARY OF THE INVENTION

1stVersion

According to the invention, there is provided a mobile underground tunnel borer arrangement comprising:a mobile tunnel boring unit comprising first drive means to drive the mobile tunnel boring unit, a gripper arrangement to facilitate boring by providing grip and thrust, and a rotatable cutter head fitted with cutters to bore the tunnel face; andat least one backup unit trailing behind the mobile tunnel boring unit, each backup unit comprising second drive means to drive the backup unit and a support frame on top of the second drive means.

In a first version of the borer arrangement, the gripper arrangement includes a front gripper assembly and a rear gripper assembly, each gripper assembly including a support body and four movable gripper elements that can be extended and retracted, using first actuators, relative to the support body. In the extended position, the gripper elements grip against the tunnel wall and in the retracted position, the first drive means can be operated to move the mobile tunnel boring unit.

In an embodiment, the gripper elements take the form of gripper pads that are fitted on spherical joints. In an embodiment, the four movable gripper elements extend at 45 degree angles around the support body, so as to define an ‘X’. In an embodiment, the front and rear gripper assemblies are fitted to either end of a torque shaft housing with second actuators being arranged to extend and retract the support body of the front gripper assembly and the cutter head relative to the torque shaft housing.

In an embodiment, the cutter head includes a central engaging face with a plurality of cutter segments extending at an angle away from the central engaging face, so as to define a tapered, self-centring arrangement. In one version, the cutter segments can be removed from the cutter head; in another version, the cutter segments can be movably collapsible relative to the cutter head. In an embodiment, a dust shield is provided between the front gripper assembly and the cutter head, with a conveyor arrangement extending from the dust shield to enable the muck and cuttings to be transported to a tunnelling truck for subsequent disposal. The conveyor arrangement comprises a first conveyer on top of the mobile tunnel boring unit, to receive the cuttings via a chute provided on the dust shield, and a second conveyor on top of a first backup unit to continue conveying the cuttings towards the truck. In an embodiment, the borer arrangement includes a support drill and related platform, which is disconnected from the mobile tunnel boring unit.

2ndVersion

In a second, preferred version of the borer arrangement, the mobile tunnel boring unit is fitted with a telescopic shield arrangement comprising a front shield proximate the front of the mobile tunnel boring unit, from which the cutter head protrudes, and a rear shield that surrounds at least an upper portion of the mobile tunnel boring unit.

1. Main Drive

The front shield accommodates cutter head drive means (mounted onto the cutter head) to rotatingly drive the cutter head, the cutter head drive means typically comprising hydraulic drive motors that drive a ring gear which is stabilised by a thrust bearing. A special sealing arrangement is provided to keep dust outside so as to not penetrate the cutter head drive means. The cutter head drive means was shaped specifically to aid fast assembly of the front shield in the correct sequence. A special quick attachment method is used to aid fast assembly/connection between the cutter head drive means to the cutter head when the cutter head has been assembled in the cutting face. The cutter head drive was designed with an open hollow centre to allow the main conveyor to collect dust inside the cutter head. The same opening allows access to the cutter head for maintenance

2. Thrust Arrangement

In an embodiment, an actuating arrangement, comprising a plurality of hydraulic thrust cylinders, extends between the cutter head drive means and a support arrangement on a rear end of the mobile tunnel boring unit, the actuating arrangement being arranged to telescopingly move the front shield relative to the support arrangement on a rear end of the mobile tunnel boring unit, and thus relative to the rear shield which is fixed to the rear end of the mobile tunnel boring unit.

The thrust cylinder arrangement provides a flexible link between the cutter head drive and the support arrangement, that allows for correction of the support arrangement after rotational slippage. The thrust cylinders, typically four pairs of thrust cylinders, extend slightly inwardly from the support arrangement on the rear end of the mobile tunnel boring unit towards the cutter head drive means. This enables the mobile tunnel boring unit arrangement to be steered in all directions i.e. up, down, left and right, thus enabling cut-aways, cross-cuts, declines, inclines and even spiral shafts to be bored. Connection of the thrust cylinders are via spherical ball joints on either end to accommodate free movement. The thrust cylinders are equipped with position sensors, enabling the system to establish the position of the cutter head relative to the support arrangement

3. Grippers

In an embodiment, the gripper arrangement includes a front gripper stabilizer assembly, fitted to, so as to extend from, the front shield, and a rear gripper assembly, fitted to, so as to extend from, the support arrangement on a rear end of the mobile tunnel boring unit. Each gripper assembly includes a support body and two movable, curved gripper elements that can be extended and retracted, using first actuators, relative to their respective support body. A stabilizer gripper assembly extends at 45° and the rear gripper assembly extends at 180°. In the extended position, the curved gripper elements grip against the tunnel wall, and in the retracted position, the mobile tunnel boring unit can be pulled forwards. In an embodiment, the gripper elements take the form of curved gripper pads that are fitted on pin type spherical joints to accommodate free movement.

4. Cutter Head

In an embodiment, the cutter head takes the form of a full face cutter head fitted with disc cutters, the cutter head defining scoops and channels to allow cuttings and muck to pass automatically through the cutter head for discharge into a muck hopper and collection onto a first conveyor arrangement located immediately behind the cutter head. The first conveyor arrangement extends through the mobile tunnel boring unit for subsequent offloading onto a first backup unit.

In an embodiment, the cutter head is detachably secured to the mobile tunnel boring unit using a quick attachment method, which improves the efficiency of the boring cycle. The centre segment has a tapered profile to accommodate accurate segment attachment. All cutters are of the back-loading type, to accommodate efficient maintenance. In addition, the cutter head comprises a plurality of segments that can be pre-installed with the front shield. The cutter head may also have varying sizes, as required in use; the envisaged diameter range is between 4.5 metres and 5.5 metres. This is achieved by having a common centre segment onto which the various segments for the 4.5 and 5.5 configurations are bolted.

5. Conveyor

The first conveyor arrangement extends through the mobile tunnel boring unit for subsequent offloading onto a first backup unit. The first conveyor is retractable away from the cutter head drive to allow access for cutter change and maintenance. All conveyors are designed with variable geometry, to enable the conveyors to be compacted to assist manoeuvrability during transportation. All conveyors have a modular design to enable common parts inventory to ease spares and maintenance requirements. In an embodiment, the first, second and third conveyor arrangements are all collapsible, so as to improve and facilitate manoeuvrability.

6. Support Drill and Probe Drill

In an embodiment, a support drill rotation ring and associated ring drive means to rotate the ring are fitted proximate the rear end of the mobile tunnel boring unit, typically behind the support arrangement. The support drill rotation ring carries two spaced apart drills, to facilitate the fitting of rock bolt supports to the surrounding wall. The drills are able to rotate on their own axes to allow a V-configuration for varying support bolt drilling arrangements. The drills are equipped with sliders so they can be stabilised against the tunnel wall. The shields house the probe drill near the cutter head. The probe drill position and orientation can be manually adjusted to allow cover drilling in three directions through the cutter head. In turn, the cutter head is equipped with three openings through which the probe drill rods can advance

7. Shields

In an embodiment, the rear shield includes a plurality of fingers that define gaps through which the drills can extend and drill. These fingers are hydraulically actuated to provide adjustment during transport and also support to the tunnel wall during support drilling, to protect the support drill operators. Shields are designed to be modular, to ease transport by limiting size and weight. Shield assembly is efficient with a shield interface, resulting in quick alignment and easy access for fasteners.

The bottom/belly shield segment stabilises the mobile tunnel borer, in cooperation with the gripper pads, by skidding on the tunnel invert at all times. The belly shield is equipped with replaceable wear plates to extend its operating lifespan. Shields operate telescopically relative to each other, assisting in machine mobility and agility whilst boring direction changes and curves.

8. Crawler Tracks

In an embodiment, the first drive means for driving the mobile tunnel boring unit includes a pair of spaced apart tracks in contact with the tunnel floor, and related track driving means to move the tracks, and thus the mobile tunnel boring unit. In an embodiment, the tracks are mounted to the bottom of the mobile tunnel boring unit and can hydraulically be pivoted/adjusted, to better accommodate the round shape of the bored tunnel. In addition, the tracks can be moved with six degrees of freedom relative to the boring unit, to accommodate varying diameters of the boring unit and perfect alignment when assembling the mobile tunnel borer to the cutter head. The crawler tracks are also equipped with stabilising cylinders that are actuated to lift the mobile tunnel borer from its tracks when a pivot adjustment is made. The crawler tracks are powered by a diesel powered hydraulic motivator, which is latched to the back of the mobile tunnel boring unit. The crawler track is operated by a handheld remote control, by one operator in close proximity to the mobile tunnel borer.

9. 1stBack-Up Unit

In an embodiment, the first backup unit is fitted with a second conveyor arrangement to receive the cuttings and muck from the first conveyor arrangement on the mobile tunnel boring unit towards a second backup unit. In an embodiment, the first backup unit is fitted with the main hydraulic power pack and also the electric panel that is equipped with the PLC system. The first back-up unit is also fitted with the scrubber unit to assist with dust suppression.

10. 2ndBack-Up Unit

In an embodiment, the third backup unit is fitted with a third conveyor arrangement to receive the cuttings and muck from the second conveyor arrangement on the first backup unit towards a truck. In an embodiment, the second backup unit is fitted with the cooling water circulation pumping system. The second back-up unit is also fitted with the main incoming transformer substation and also the dust extraction fan unit. Cable and hose reels are fitted as well to allow continuous operation for 300 meters.

