Method and system of constructing an underground tunnel

Abstract

Long tunnels of many kilometres are likely to pass through a range of geologies which may cause problems. The present invention seeks to overcome the disadvantages of the prior art by: drilling a first bore 10 along a first predetermined path, the first bore having a length of at least 25 m; drilling a plurality of second bores 20 along respective second predetermined paths, each substantially parallel to the first predetermined path in order to define a substantially prism-shape region therebetween; and excavating material within the substantially prism-shape region to form a tunnel. In this way, data from drilling the first bore 10 and the plurality of second bores 20 can be recorded and used to inform operators as to the types of material through which they will be excavating. Thus, a more complete view of the underlying geology can be achieved before beginning excavations.

Claims

1. A method of constructing an underground tunnel, the method comprising the steps of: drilling a first bore along a first predetermined path through underlying geology, the first bore having a length of at least 25 m; drilling a plurality of second bores along respective second predetermined paths through the underlying geology, each of the respective second predetermined paths being substantially parallel to the first predetermined path in order for the plurality of second bores alone, or a combination of the plurality of second bores and the first bore together, to define a substantially prism-shape region having a cross-section of a geometric shape along an entire length of the first and second bores, the geometric shape and a size of that shape being constant along the entire length; lining any one of the first bore and the plurality of second bores with a liner, the liner having holes therein; treating the underlying geology through the holes in specific pre-defined directions, in advance of excavating the material in order to increase efficiency of excavating the material; and excavating material within the substantially prism-shape region to form a tunnel.

2. The method of claim 1, wherein excavating material within the substantially prism-shape region to form a tunnel is carried out from a tunnelling shield, the tunnelling shield comprising a plurality of probes on a leading edge thereof, each probe of the plurality of probes aligned with a respective bore of the first bore and plurality of second bores, each probe equipped with optionally interchangeable tools that allows each probe to excavate from within the first and/or second bores.

3. The method of claim 2, wherein treating comprises hydraulic fracturing of the material within the substantially prism-shape region.

4. The method of claim 1, wherein treating comprises hydraulic fracturing of the material within the substantially prism-shape region.

5. The method of claim 1, wherein treating comprises stabilising the underlying geology outside the substantially prism-shape region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

(2) FIG. 1 is a view of a tunnel profile defined by circular bores.

(3) FIG. 2 is a side view of bores drilled into a hillside.

(4) FIG. 3 is a view of a portion of the tunnel profile of FIG. 1 showing direction of explosions from a perforation gun.

(5) FIG. 4 is a similar view to FIG. 3, showing fractures formed by hydraulic fracturing.

(6) FIG. 5 is a similar view to FIGS. 3 & 4, showing various stabilisation techniques.

(7) FIG. 6 is view of a completed tunnel profile, similar to FIG. 1.

(8) FIG. 7 is a side view of a dragline shield.

(9) FIG. 8 is a view of a pre-perforated sacrificial liner for use within the bores.

(10) FIG. 9 is a view of a down hole telescopic chemical delivery carriage.

(11) FIG. 10 is a view of a down hole cable return carriage.

DETAILED DESCRIPTION

(12) The present invention will be described with respect to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily be considered to be an embodiment of the invention. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

(13) Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein. Likewise, method steps described or claimed in a particular sequence may be understood to operate in a different sequence.

(14) Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

(15) It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

(16) Similarly, it is to be noticed that the term “connected”, used in the description, should not be interpreted as being restricted to direct connections only. Thus, the scope of the expression “a device A connected to a device B” should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. “Connected” may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other. For instance, wireless connectivity is contemplated.

(17) Reference throughout this specification to “an embodiment” or “an aspect” means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases “in one embodiment”, “in an embodiment”, or “in an aspect” in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any one embodiment or aspect of the invention may be combined in any suitable manner with any other particular feature, structure or characteristic of another embodiment or aspect of the invention, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

(18) Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

(19) Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

(20) In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

(21) In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

(22) The use of the term “at least one” may mean only one in certain circumstances. The use of the term “any” may mean “all” and/or “each” in certain circumstances.

(23) The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features. It is clear that other arrangements can be configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching, the invention being limited only by the terms of the appended claims.

(24) FIG. 1 is a view of a tunnel profile defined by circular bores. Three central lead bores 10 are drilled along the path of the tunnel. Around these, a plurality of shape-defining bores 20 are drilled to form an arch-shape tunnel profile having a flat lower floor. The angle of slope of the tunnel is optimised to the specific requirements of the tunnel in question, and could for example be vertical.

(25) FIG. 2 is a side view of the lead bores 10 and shape-defining bores 20 during drilling into a hillside 30, the length of each of the bores 10, 20 being shorter than their final lengths. As can be appreciated, some of the bores may be drilled at the same time as others, some may be completed before others are started, and/or some may be partially drilled and interrupted while others are continued.

(26) FIG. 3 is a view of a portion of the tunnel profile of FIG. 1, specifically the top left quadrant including a single lead bore 10 and six of the shape-defining bores 20. The bores 10, 20 are lined with a sacrificial lining (not shown), into which are inserted respective perforation guns (also not shown). Perforation guns allow shaped charges to perforate the sacrificial linings in predetermined directions, leading to directed explosions 40. The explosions 40 shown here are directed inside the region to be excavated, and only from three of the bores; however, additional perforations may be formed concurrently, or subsequently. In alternative embodiments, the perforation guns may operate pneumatically to punch perforations in the sacrificial liner.

(27) FIG. 4 is a similar view to FIG. 3, showing fractures 50 formed by hydraulic fracturing through perforations similar to those shown in FIG. 3.

(28) FIG. 5 is a similar view to FIGS. 3 & 4, showing stabilisation outside the region to be excavated via freezing 60 and via chemical injection 70. These techniques require the use of perforations directed outward, away from the region to be excavated.

(29) FIG. 6 is a view of a completed tunnel 100 profile, similar to FIG. 1, in the hillside 30 of FIG. 2. Outside the profile 80 defined by the shape-defining bores 20 and excavated out, the underlying geology has been reinforced/stabilised to form a reinforced region 90 surrounding the tunnel. An example of the lining options that may be applied is depicted with an outer concrete lining 120 being separated from an inner concrete lining 110 by a waterproof membrane 115 if required.

(30) Many other methods of tunnel lining and finishing are available. For example, temporary reusable metal formers may be placed within the tunnel and concrete 120 is applied behind the formers to form a smooth internal wall of the tunnel. Once the concrete 120 has fully hardened, the temporary formers may be removed and reused in another section of the tunnel, leaving the smooth concrete 120 as the internal wall.

(31) Optionally, during excavation, two of the shape-defining bores 20 on the floor of the tunnel may be left to act as gullies/troughs 130 to help guide machinery (in particular the dragline shield) along the tunnel. These gullies/troughs 130 can be filled in at a later date, once the tunnel excavation is complete.

(32) FIG. 7 is a side view of a dragline shield. Arrow 200 indicates the direction of motion of the dragline shield during excavation. The profile of the dragline shield matches the predefined outer tunnel shape. The angle of slope of the leading edge 202 of the shield is optimised to the specific requirements of the tunnel in question, and could for example be vertical.

(33) Propulsion of the shield through the tunnel may be via hydraulic rams 206 that push the dragline shield and/or via cables 208 attached to the ends of the probes that run through the lined bores to winches that pull the dragline shield forward. The latter will be the preferred method as it facilitates continuous movement.

(34) Lower shape-defining bores along the floor of the tunnel may be swept clean behind the point where the spoil enters the shield so that the wheels 210 (or alternatively undercarriage) of the dragline shield can then run in the rough half-pipes that are left in place from the sacrificial liner. No rails need be installed or extended as the dragline shield advances.

(35) Probes 204 on the lead face of the shield align with and extend into the shape-defining bores. The probes 204 are spaced and sized such that they engage with the shape-defining bores and the dragline shield moves forward through the now predefined tunnel shape. While the accuracy of the bores is extremely precise, the probes 204 will be able to tolerate some variation should the path of the bore have deviated from the targeted course. Short stretches where deviation outside the tolerance has occurred could see the probe being retracted until such time as it can be reengaged following a period of excavation by other means such as boom-mounted cutting heads 212 as found on roadheader units.

(36) The probes 204 are equipped with interchangeable tools that allow them to be as brutal or as sensitive as the situation dictates. These include but are not limited to disc cutters, rotating cutter cylinders or cones, chainsaw type arms with teeth suitable to the material being worked on, high pressure water, plough blades 214, and hydraulic splitters 216 that can apply enormous pressure directed as required both around the circumference/perimeter of the tunnel profile and/or inwards (toward the interior of the tunnel) to further loosen and break up the material to be removed (in addition to removing the sacrificial liner of the shape-defining bores).

(37) Collapsing/slumping techniques can be used on soft and/or loose material to be excavated, in particular if the region outside the perimeter of the tunnel has been stabilised to form a self-supporting shell. For this type of work the probes are fitted with plough blades 214 as the dragline shield advances.

(38) A laser array (not shown) will constantly scan 218 the newly exposed outer surface of the excavation to ensure that no material has been left protruding inwards such that it would foul or impede the progress of the dragline shield. Ground penetrating radar may also be used where spoil covers areas of the newly exposed tunnel. Should any such area be discovered it will be tackled immediately, without hindering progress, by one or more robotic arms 212 mounted with a pneumatic drill or interchangeable cutting head or other suitable tool.

(39) Working under the protection of the dragline shield, the spoil is excavated continuously (assisted where required by a mechanical excavator 220) onto a loading mechanism 222 inside the shield. Loading onto the loading mechanism 222 may be primarily by the action of the dragline shield moving forward through the spoil much like a bulldozer. Spoil removal is by conventional methods; it having been moved rearwardly on a conveyor 224 back to where the newly laid tunnel floor is able to take heavy machinery.

(40) FIG. 8 shows axial cross-sectional and oblique views of a pre-perforated sacrificial liner for use within the bores, the liner having a substantially cylindrical shape with an array of perforated holes 230 from an exterior to an interior thereof.

(41) FIG. 9 is a view of a down hole telescopic chemical delivery carriage 236 configured to travel down an individual bore 238 to the area requiring chemical treatment. The carriage comprises 5 telescopic delivery probes 240 arranged around a carriage body 242, although other numbers are envisaged. Once moved into position the chemical being used is pumped into the carriage under pressure by conventional means. The pressure causes the telescopic probes to extend, pushing out into the material outside the bore through the corresponding pre-perforated holes (or holes made when the liner is in place) in the sacrificial liner. The quantity of chemical being delivered and the region to which it is delivered will be chosen for each instance based on the knowledge of the geology gained during the boring process and on the ultimate design strength of the tunnel required.

(42) FIG. 10 is a view of a down hole cable return carriage, shown with the carriage housing 250 as transparent. A clamping system 252 that engages with the walls of the lined bore into which it has been deployed is disposed on the housing 250. The clamping system 252 can be engaged or disengaged by an operator, to permit the carriage to be moved within the bore, and secured in place ready for winching. A first end of a cable 254 is connected to the shield. A second end of the cable 256 is attached to a winch. As the winch winds in the second end of the cable 256, a series of pulleys 258 within the carriage reverse direction of the cable so that the shield is pulled by the first end of the cable 254.