EA046986B1 - METHOD AND SYSTEM FOR CONSTRUCTION OF UNDERGROUND TUNNEL - Google Patents

Description

Description

The present invention relates generally to a method and system for constructing an underground tunnel and has specific, although not exclusive, practical value in the construction of tunnels over many kilometers in length.

In addition to cost and speed, the main challenges in tunnel construction are the geological conditions that may be encountered. In relatively short tunnels, geological conditions can be fairly constant and easy to plan. However, long tunnels spanning many kilometers are likely to pass through different geological conditions, causing significant and even potentially catastrophic problems. Ideally, the tunnel will be constructed under favorable and/or constant geological conditions along its entire length. However, conventional methods involve simply taking geological samples along the proposed tunnel length from above (where possible) and extrapolating from these samples.

Tunnel boring machines (TBMs) are known to contain a large metal cylindrical shield fronted by a rotating cutting disc and containing a chamber into which the excavated soil is placed (and optionally mixed with the slurry to be separated, depending on the type of geological/soil conditions). At the rear of this chamber is a set of hydraulic jacks that are used to push the TVM forward against the concrete tunnel wall at the rear. The tunnel wall is installed in segments as the TVM moves forward. Once the TBM has excavated the length of the segment, it stops and a new tunnel ring is constructed using the erector using precast concrete segments. At the rear of the shield within the completed portion of the tunnel there may be additional operating mechanisms that are generally considered part of the TBM system: for dirt removal, slurry lines if applicable, control rooms, rails for transporting prefabricated segments, etc. However, TBMs have various disadvantages, including the start-stop nature of their tunneling and the fact that one TBM cannot easily transition from one rock/soil type to another (especially in the case of highly fractured and chipped rock layers).

In addition, various directional drilling technologies are used in the mining, oil and gas and construction industries. For example, for laying pipes, etc. Horizontal directional drilling (HDD) is used. HDD allows you to drill fairly accurate wells up to approximately 800 m in length with a diameter of only 100-1200 mm. Alternatively, the oil and gas industry uses directional drilling to allow much longer wells to be drilled.

The object of the present invention is to overcome the disadvantages of the prior art by providing the system and method described below. The present invention can be used in the construction of new tunnels, as well as in the process of expanding and/or replacing supports and/or repairing existing tunnels.

According to a first aspect of the present invention, there is provided a method for constructing an underground tunnel, the method comprising the steps of: drilling a first borehole along a first predetermined path through the underlying geology, the first borehole having a length of at least 25 m; drilling a plurality of second wells along respective second predefined paths through the underlying geology, each of the respective second predefined paths being substantially parallel to the first predefined path, to form a substantially prism-shaped region therebetween; and excavating material in a substantially prism-shaped region to form a tunnel from the tunnel boring shield, wherein the tunnel boring shield comprises at its leading edge a plurality of probes, each probe of the plurality of probes being aligned with a corresponding borehole of the first borehole and the plurality of second boreholes, the probes being equipped with tools configured to carry out excavation from the first and/or second wells.

In this way, the efficiency of tunnel excavation can be increased, allowing continuous and dynamic excavation of large tunnels. In particular, the tunnel advance can be carried out continuously as the tunnel boring shield advances, and the probes can be adapted according to the geological conditions that may be encountered.

Drilling may include directional drilling, such as HDD, or types of directional drilling used in the oil and gas industry.

Drilling operations may be carried out from a pre-built tunnel entrance and/or exit, an intermediate shaft and/or from the surface.

Each well of the first well and/or the plurality of second wells may include a well and/or shaft that is substantially circular in cross section and has a length that is an order of magnitude greater than its diameter. For example, each well may have a diameter of 1001200 mm; each well may be at least 25 m, at least 50 m, at least 100 m, at least 200 m or more in length.

The method may include determining a first predefined path (and optionally

- 1,046,986 second predefined paths); however, this should be done using generally accepted methods.

The substantially prism-shaped region may be formed independently by a plurality of second wells or may be formed jointly by a combination of a plurality of second wells and a first well. For example, a first well in combination with two second wells may form a triangular prism-shaped area. As another example, the three second wells may independently define a triangular prism-shaped region, the first well being located within the triangular prism-shaped region; alternatively, the second three wells, together with the first well, may form a cube-shaped (square prism-shaped) region when suitably positioned relative to each other.

The prism-shaped area may become curved; that is, the area may have a cross-section of a geometric shape (e.g., triangular, square, etc.), regular or otherwise, along its entire length (and that geometric shape and the size of that shape may be constant along its entire length), however the path The , on which the area is based may not be a straight line, but may be a curved line.

The first well may be a single first well or a plurality of first wells (eg, two or three first wells). The first well may be a pilot well. The pilot well may be spaced from the perimeter of the prism-shaped region by being located in the interior of the prism-shaped region.

Data obtained from the first hole can be collected to determine the material being drilled through.

A plurality of second boreholes may form a tunnel profile; that is, multiple second paths could run along the walls of the proposed tunnel.

The cross-section of the tunnel can be circular; however, other cross-sections are possible, such as rectangular, semi-circular, arc-shaped, flat-bottomed, etc. Circular or curved walls can improve the stability of the tunnel structure formed in this way, however, if this is considered unnecessary (for example, based on data obtained from the first borehole/second boreholes), to ensure easy movement of people, excavation equipment and carts for transporting excavated material soil, a flat floor can be selected.

The first well and/or second wells may be reinforced, for example, with a sacrificial pipe or support. In this way, the integrity of each well can be protected. The first well may be strengthened before/after drilling of a plurality of second wells is started and/or completed. Likewise, at least one of the second wells may be reinforced before/after drilling of the first well begins and/or is completed. The support may be the support of the entire well or only part of the well. The support of any well may be removed or partially removed before excavation.

All or some of the first well and the second wells may be drilled simultaneously, or each well may be drilled separately. This can be especially important when drilling through sand/soil, where the integrity of each hole is at risk.

Excavation of material in a substantially prism-shaped region to form a tunnel may be performed from a tunnel boring shield, wherein the tunnel boring shield comprises at its leading edge a plurality of probes, each probe of the plurality of probes being aligned with a corresponding borehole of the first borehole and the plurality of second boreholes.

The shape of the shield corresponds to the profile of the tunnel; that is, the cross section of the area to be excavated. The probes may be sized to fit the first well and/or second wells; in particular, the probes may be sized to allow some deviation in the location of each probe from its predetermined path, for example up to 50 cm, in particular up to 30 cm.

In areas where deviations outside of tolerance have occurred, the associated probe may be temporarily retracted/retracted (until it can be reused) and excavated by alternative means (eg boom-mounted cutting heads used in roadheaders).

The probes may be equipped with (optionally removable) tools allowing them to excavate from the first borehole and/or second boreholes. In particular, different tools can be used for different materials, such as disc cutters, cylindrical or conical rotary cutters, chain saws with teeth suitable for the material being cut, high-pressure water, plow blades and hydraulic punches, which can apply enormous pressure , properly directed both around the circumference of the tunnel and inward, to further loosen and crush the material to be removed.

The probes may be designed to be retractable so that they can be removed or tools can be changed without the need to move the shield.

For soft and/or loose material to be excavated, caving/falling techniques can be used. For this type of work, as the shield advances, the probes are equipped with plow knives.

As the shield advances to continually scan the newly formed outer surface

- 2046986 Excavation excavators may use a matrix laser to ensure that no material that would impede or impede the progress of the shield is left protruding into the tunnel from the peripheral wall. In areas where excavated soil covers areas of the newly formed tunnel outcrop, ground penetrating radar may also be used.

The method may further include removing such areas when they are detected, for example, using a robotic arm(s) on which a pneumatic drill or removable cutting head or other suitable tool is mounted.

Directional drilling technology can be combined with shield-based technology such that drilling is carried out in front of each probe on the shield, thereby allowing the shield to advance until drilling is completed.

The shield may have an inclined leading edge, the angle of which can be selected by generally accepted methods, based on the nature of the material to be excavated. In particular, the inclined leading edge is inclined upward and towards the tunnel to be excavated.

The shield can be pushed by hydraulic cylinders.

The shield may be a rope scraper shield, and the method may further include pulling the rope scraper shield through the material. The rope scraper shield can be a combination of tunnel boring shield and rope scraper excavator technology. The rope scraper shovel may include a rope scraper bucket suspended from a boom so that it can be positioned by the boom. Ropes/cables/chains (usually operated by winches) are used to drag the bucket and thereby scoop the material to be excavated into the bucket. The rope scraper shield is similarly dragged by ropes controlled by winches (which will pass through the first hole and/or second holes), but no positioning boom is required since the rope scraper shield is located in the tunnel and positioning is not necessary.

The wireline scraper shield may be pulled through the material by a plurality of ropes, each rope of the plurality of ropes passing through a corresponding borehole of a first borehole and a plurality of second boreholes.

Thanks to this, the advance of the shield can be reliable and continuous. Each rope can be attached to a corresponding probe. The winch or winches may act on a corresponding rope of a plurality of ropes or on several ropes of a plurality of ropes to pull the shield forward. Winches may be provided at the opposite end (eg, the open end) of the wells.

Each rope of the plurality of ropes may extend down through its respective borehole from the first borehole and the plurality of second boreholes to a rope return carriage secured within the borehole, and extends back up through the corresponding borehole to the rope-scraper shield.

In this way, winches can be provided behind or inside the shield and can keep the shield running until each well is completed.

The rope return carriage may include a clamping system that engages the walls of the boreholes in which it is placed. The clamping system may be remotely controlled to engage and disengage on command so that it can be moved to a new location if necessary.

The excavated soil may be continuously removed, for example by a mechanical excavator, onto a loading and unloading mechanism. However, in preferred embodiments, the shield is shaped such that moving the shield forward through the excavated tunnel lifts the excavated soil from the excavation site onto the loading and unloading mechanism. In particular, the action of lifting the excavated soil is similar to that of a bulldozer or a rope scraper bucket.

The extracted soil is removed from the shield using generally accepted methods; it is transferred back to where the bottom of the tunnel is capable of receiving heavy equipment. Heavy equipment may include self-contained electric or hydrogen-fueled transportation vehicles that do not emit exhaust gases. These vehicles can deliver materials, such as prefabricated support segments, if used, to the work site, as well as remove excavated soil. The vehicles may be configured to automatically return to a refueling point if necessary before resuming operation.

The lowest boreholes (e.g. along the bottom of a tunnel) can be cleared beyond the point where the excavated soil enters the shield so that the running gear of the shield (e.g. wheels/slides) can move in the rough half-pipes left from the sacrificial support. Thanks to this, there is no need to lay or extend the rails as the shield advances.

Any well or each well can be reinforced with support. The support may be a sacrificial support. The support can be a solid wall. Alternatively, the support may be pre-perforated; This means that in situations where the underlying geology is well understood, time and expense spent on site can be avoided. The pre-perforated support may include an outer casing covering the perforations; thanks to

- 3 046986 this can prevent material or water from entering the well in an uncontrolled manner.

The equipment can be passed through the support in the usual way to carry out work in the desired location. The equipment may include a return carriage, a drill head, and/or a hammer drill. In particular, a hammer drill (commonly used in the field of hydraulic fracturing) can be passed through the support to perforate the support in the desired location. The hammer drill may contain a plurality of shaped explosive charges. The hammer drill may be configured to weaken the material on the outside of the support; those. explosives can act to destroy the material. Perforations may be formed at desired locations on the support, for example, facing inward toward the prism-shaped region, facing outward away from the prism-shaped region, and/or laterally along the profile of the prism-shaped region.

The method may further include the step of processing the underlying geology before removing the material to improve the efficiency of removing the material.

The treatment may involve acoustically and/or hydraulically fracturing the material in a substantially prism-shaped region.

In cases where the material in the area is relatively hard, high pressure water may be introduced, for example through perforations, and thereby cause the material to fracture. Unlike hydraulic fracturing operations to extract natural gas or oil, small grains of hydraulic fracturing proppant (sand or alumina) are not required to keep fractures open.

The use of acoustic and/or hydraulic fracturing technologies through perforations ensures that fracturing can only occur in specific predefined directions, for example into an area.

Ahead of the shield, reaming tools can be passed through the borehole(s) to break up the sacrificial support, allowing the material to be excavated to collapse/collapse, thereby aiding the removal process.

The treatment may include stabilizing the underlying geology outside the substantially prism-shaped area.

In this way, in cases where the material outside the prism-shaped region is relatively weak, contains voids, is unstable or is saturated with water, the material can be stabilized. To stabilize the underlying geology, equipment may be placed in the borehole.

Stabilization can be accomplished through soil freezing techniques, such as a coolant pumped through the support and potentially exiting the support through perforations. Freezing technologies may be temporary.

Alternatively, permanent stabilization can be achieved by pumping a chemical stabilizer, for example through chemical injection nozzles (eg in telescopic arms). The amount and type of stabilizer used will be determined by the geology to be stabilized and can be controlled as needed, and the stabilizer may include cement or any other suitable material such as microcements, mineral solutions (known as colloidal silica), hydrophilic polyurethanes (fast-reacting foaming resin to prevent water penetration), fast-reacting and non-hydrophilic polyurethane and silicate systems (polyurethane foam for filling voids), acrylic resins, jet grouting, that is, curing the soil on site to the required specification; often known as soil concrete (RTM), etc.

Stabilizing the underlying geology outside the essentially prism-shaped area can greatly reduce, if not completely prevent, further water intrusion. Any groundwater remaining within the tunnel to be excavated can be drained through the lowest of the boreholes.

The stabilization or weakening described above can be synchronized with the shield so that ground preparation does not need to be completely completed before the shield begins to advance.

Stabilization of the underlying geology outside the essentially prism-shaped region can be used to form the initial outer structure (shell) of the tunnel prior to excavation.

Alternative and/or additional tunnel support options include precast concrete segments (with or without waterproof lining), in-situ concrete (including modular formwork using rebar, for example), and/or shotcrete such as shotcrete (with with or without sprayed waterproof membranes and optionally containing roof bolts, wire mesh or steel ribs/reinforcement).

It is conceivable that the present invention can also be used with tunnel supports made of wood, brick, blocks, stone, pipe-in-tunnel method and/or cast steel/iron segments.

For example, the formation of tunnel support may involve the spraying of a waterproof membrane (for example, BASF's sprayed waterproof membranes (RTM) form a continuous waterproof system and are designed to work in combination with shotcrete and in-situ concrete to facilitate the construction of composite structures) and internal

- 4 046986 finishing spraying of fiber-reinforced concrete. Alternatively, when the geology requires greater structural integrity, on-site installation may be the preferred technology.

The method may further include a continuous concrete forming process. In particular, as the shield moves forward, the last in a series of successive reusable metal forms, after the older concrete has set, can be moved forward and placed in front, where placement will continue in an almost non-stop process. Water and cement may be supplied to the work site and mixing of the concrete mixture may be carried out at the site of the excavation operation, using excavated aggregate where possible. Formworks are expected to be approximately 10m long with 3 or 4 pieces per sectional set and with 10 or more segmental sets in use. This will mean that for a section of tunnel approximately 90m behind the shield there will be formwork in place with newly placed concrete at the front and set concrete at the rear, where sets of formwork segments are removed and carried forward in a continuous cycle. The forms can be missed and the units where the concrete is the oldest and has set can be moved forward to be reinstalled at the start of the process. The seam between the formwork and the surface where the concrete is to be laid can be made with pneumatic spacers. After the most recent formwork has been installed and the spacer has been inflated, the air from the previous spacer will be released to keep the installation continuous. This process may simply be repeated.

The excavated soil after directional drilling and excavation can be used to prepare a concrete mixture, which can be pumped into the space between the tunnel lining (when using prefabricated support) and the shell to fill the void between them and further stabilize the structure. Alternatively or additionally, such excavated soil (eg, rock fragments) may be used as part of the aggregate required to prepare the concrete mixture in situ for forming the tunnel support using reusable movable forms or other fastening methods such as sprayed concrete.

The flat bottom may be poured in a continuous process as the backboard is moved forward with a metal plate or structure protecting the concrete mixture while it sets. For the shield, some of the directionally drilled holes in the tunnel floor can be used as tracks or rails (their required number is determined by the design of the shield). Once the tunneling is completed and the shield is removed, they can be filled or adapted for another purpose.

In accordance with a second aspect of the present invention, there is provided a method for constructing an underground tunnel, the method comprising the following steps: drilling a first borehole along a first predetermined path through the underlying geology; drilling a plurality of second wells along respective second predefined paths through the underlying geology, each of the respective second predefined paths being substantially parallel to the first predefined path, to form a substantially prism-shaped region therebetween; strengthening the first well and/or at least one of the plurality of second wells with a pipe and/or support; and excavating material in the substantially prism-shaped region to form a tunnel. In this way, the integrity of each well can be protected.

The first well and/or a plurality of second wells may be reinforced with (eg, sacrificial) pipe or support. The pipe and/or support may contain a polymeric material, as is well known in the art.

The first well may have a length of at least 25 m or less than 25 m. For example, the first well may have a length of at least 5 m, 10 m, 15 m and/or 20 m. However, other features of the second aspect may be common to those of the first aspect.

According to a third aspect of the present invention, there is provided a system for constructing an underground tunnel according to a method in accordance with the first aspect or the second aspect, the system comprising: directional drilling equipment configured to drill a first well and a plurality of second wells; and excavation equipment configured to excavate material from a substantially prism-shaped region defined by the first borehole and the plurality of second boreholes to form a tunnel.

The above and other characteristics, features and advantages of the present invention will become apparent upon reading the following detailed description, taken in conjunction with the accompanying drawings, which illustrate by way of example the principles of the present invention. This description is given solely by way of example and without limiting the scope of the present invention. The reference numbers mentioned below refer to the accompanying graphics.

In fig. Figure 1 shows a view of the profile of a tunnel formed by wells of circular cross-section.

In fig. Figure 2 shows a side view of wells drilled into the mountainside.

In fig. 3 is a view of part of the tunnel profile shown in FIG. 1, which shows the direction of explosions from a perforator.

In fig. 4 is a view similar to that shown in FIG. 3, which shows times

- 5 046986 ruptures formed as a result of hydraulic fracturing.

In fig. 5 is a view similar to those shown in FIG. 3 and 4, which shows various stabilization technologies.

In fig. 6 is a view of a completed tunnel profile similar to the profile in FIG. 1.

In fig. Figure 7 shows a side view of the rope-scraper shield.

In fig. 8 shows a view of pre-perforated sacrificial support for use in wells.

In fig. Figure 9 shows a view of a downhole carriage for telescopic delivery of chemicals.

In fig. 10 shows a view of a downhole rope return carriage.

The present invention will be described in connection with certain drawings, but the present invention is not limited by them, but only by the claims. The graphics described are schematic only and are non-limiting. Each of the drawings may not contain all features of the invention and therefore should not necessarily be considered an embodiment of the invention. In graphic materials, the size of some elements may be exaggerated and not to scale for reasons of clarity. The dimensions and relative dimensions do not correspond to the actual reduction for the implementation of the invention in practice.

In addition, the terms first, second, third and the like in the specification and claims are used to distinguish between like elements and not necessarily to describe a sequence, whether temporal, spatial, ordering or any other. It should be understood that, under appropriate circumstances, the terms so used are interchangeable and that operation is possible in sequences other than those described or illustrated herein. Likewise, method steps described or stated in a particular sequence may be understood to be carried out in a different sequence.

Moreover, the terms above, below, over, under, and the like in the specification and claims are used for descriptive purposes and not necessarily to describe relative positions. It should be understood that, under appropriate circumstances, the terms so used are interchangeable and that operation is possible in orientations other than those described or illustrated herein.

It should be noted that the term containing, as used in the claims, should not be interpreted as limited to the means listed after it; it does not exclude other elements or steps. Thus, it should be interpreted as a term defining the presence of specified features, systems, steps or components as specified, but not excluding the presence or addition of one or more other features, systems, steps or components or groups thereof. Thus, the scope of the expression "device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that, for the purposes of the present invention, the only relevant components of a given device are A and B.

Likewise, it should be noted that the expression connected as used in the description should not be interpreted as limited only to direct connections. Thus, the scope of the expression device A connected to device B should not be limited to devices or systems in which the output of device A is connected directly to the input of device B. It means that between the output of device A and the input of device B there is a path that can represent is a path that includes other devices or means. The term connected can 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 still act together or interact with each other. For example, wireless communication is assumed.

Reference throughout this specification to an embodiment or aspect means that the particular feature, structure, or characteristic described in connection with that embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, all occurrences of the phrases in one embodiment, embodiment, or aspect at various places throughout this specification do not necessarily refer to the same embodiment or aspect, but may refer to different embodiments or aspects. Moreover, specific features, structures, or characteristics of any one embodiment or aspect of the present invention may be combined in any suitable manner with any other specific features, structures, or characteristics of another embodiment or aspect of the present invention, as will be apparent to one skilled in the art from the present descriptions, in one or more embodiments or aspects.

Likewise, it should be understood that in the present description, various features of the present invention are sometimes grouped together in a single embodiment, in the figure or thereof.

- 6 046986 description for the purpose of simplifying the disclosure and facilitating understanding of one or more different aspects of the invention.

However, this manner of disclosure should not be interpreted as reflecting the idea that the claimed invention requires more features than are expressly listed in each claim. Moreover, the description of any particular graphic material or aspect should not necessarily be regarded as an embodiment of the invention. Rather, as can be seen from the following claims, aspects of the invention are contained in less than all of the features of a single previously disclosed embodiment. Thus, the claims appearing after the detailed description are expressly incorporated into the detailed description, with each claim itself being considered a separate embodiment of the invention.

In addition, although some embodiments described herein include some features included in other embodiments, combinations of features from different embodiments are intended to fall within the scope of the invention and constitute additional embodiments as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments may be used in any combination.

Numerous specific details are set forth in the description herein. However, it is understood that embodiments of the present invention may be practiced without these specific details. In other cases, well-known methods, designs and techniques are not shown in detail so as not to complicate the understanding of this description.

In discussing the invention, unless otherwise stated, disclosure of alternative values for the upper or lower limit of the permissible range of a parameter, coupled with a statement that one of the stated values is much more preferable than the other, should be understood as an implied statement that each intermediate value of the specified of a parameter lying between the more preferred and the less preferred of said alternatives is itself preferable to said less preferred value, as well as to each value lying between said less preferred value and said intermediate value.

Use of the term at least one may, under certain circumstances, mean only one. The use of the term any under certain circumstances can mean all and/or every.

The principles of the present invention will now be described by describing in detail at least one drawing regarding exemplary features. It is understood that other designs may be developed in accordance with the knowledge of those skilled in the art without departing from the fundamental concept or technical idea, and the present invention is limited only by the appended claims.

In fig. Figure 1 shows a view of the profile of a tunnel formed by wells of circular cross-section. Three central guide holes 10 are drilled along the tunnel path. A plurality of shape-defining boreholes 20 are drilled around them to form an arch-shaped tunnel profile having a flat bottom bottom. The angle of inclination of the tunnel is optimized for the specific requirements of the tunnel in question and can be, for example, vertical.

In fig. 2 is a side view of guide boreholes 10 and shape-determining boreholes 20 when drilling into a mountain slope 30, with the length of each of the boreholes 10, 20 being less than their final length. It should be understood that some of the wells may be drilled at the same time as others, some may be completed before others begin, and/or some may be partially drilled and interrupted while others continue to be drilled.

In fig. 3 is a view of part of the tunnel profile shown in FIG. 1, in particular the upper left quadrant containing one guide well 10 and six shape-defining wells 20. The wells 10, 20 are reinforced with sacrificial support (not shown) into which corresponding perforators (also not shown) are inserted. Hammers allow shaped charges to punch a hole in the sacrificial support in predetermined directions, resulting in directed explosions 40. The explosions 40 shown here are directed into the area to be excavated, and from only three holes; however, additional perforations may form simultaneously or subsequently. In alternative embodiments, the hammer drills may be pneumatically operated to punch perforations into the sacrificial support.

In fig. 4 is a view similar to that shown in FIG. 3, which shows fractures 50 caused by hydraulic fracturing through perforations similar to those shown in FIG. 3.

In fig. 5 is a view similar to those shown in FIG. 3 and 4, which shows stabilization of the outside of the area to be excavated by freezing 60 and by pumping 70 chemicals. These technologies require the use of perforations directed outward from the area to be excavated.

- 7 046986

In fig. 6 is a view of a completed tunnel 100 profile similar to the profile in FIG. 1, in the mountain slope 30 shown in FIG. 2. Outside the profile 80, which is formed by the shape-defining boreholes 20 and from which the excavation is made, the underlying geology is strengthened/stabilized to form a reinforced area 90 surrounding the tunnel. An example of support options that may be used is depicted as an outer concrete support 120 separated from an inner concrete support 110, if necessary, by a waterproof membrane 115.

Many other methods of strengthening and finishing a tunnel are known. For example, temporary reusable metal forms may be placed in the tunnel, and a concrete mixture 120 is placed behind the forms to form a smooth inner wall of the tunnel. Once the concrete mixture 120 has completely cured, the temporary forms can be removed and reused in another section of the tunnel, with the smooth concrete mixture 120 remaining as the inner wall.

Optionally, during excavation, two shape-defining boreholes 20 on the tunnel floor may be left to act as grooved rails/channels 130 to help guide equipment (particularly a rope scraper) through the tunnel. These grooved rails/channels 130 can later be filled after the tunnel excavation is completed.

In fig. Figure 7 shows a side view of the rope-scraper shield. Arrow 200 shows the direction of movement of the rope-scraper shield during excavation. The profile of the rope-scraper shield corresponds to the predetermined outer shape of the tunnel. The angle of inclination of the leading edge 202 of the shield is optimized for the specific requirements of the tunnel in question and can be, for example, vertical.

Advancement of the shield through the tunnel can be carried out by hydraulic cylinders 206 pushing the rope-scraper shield, and/or by means of ropes 208 attached to the ends of the probes moving along reinforced boreholes to winches pulling the rope-scraper shield forward. The latter method will be preferred since it ensures continuous movement.

Lower shape-defining boreholes running along the bottom of the tunnel can clear beyond the point where the excavated soil enters the shield so that the wheels 210 (or alternatively the undercarriage) of the rope scraper shield can then move in the rough half-pipes left from the sacrificial support. There is no need to lay or extend the rails as the rope-scraper shield advances.

Probes 204 on the front surface of the shield are aligned with and extend into the shape-defining boreholes. The probes 204 are spaced and sized such that they engage the shape-defining boreholes and the scraper wire is moved forward through the now predetermined tunnel shape. Although the accuracy of the wells is extremely high, the probes 204 can tolerate some deviation if the well path deviates from the target course. In short sections where out of tolerance has occurred, the probe can be retracted until it can be reused after a period of excavation by other means, such as the boom-mounted cutting heads 212 used in roadheaders.

The 204 probes are equipped with removable instrumentation, allowing them to be coarse or sensitive depending on what the situation requires. These tools include, but are not limited to, circular cutters, cylindrical or conical rotary cutters, chain saws with teeth suited to the material being cut, high pressure water, plow knives 214 and hydraulic punches 216 which can apply enormous pressure, properly directed in both directions. circumference/perimeter of the tunnel profile, and/or inward (towards the inside of the tunnel) to further loosen and crush the material to be removed (in addition to removing the sacrificial support that determines the shape of the boreholes).

For soft and/or loose material to be excavated, collapse-based techniques can be used, particularly if the area outside the tunnel perimeter is stabilized to form a self-sustaining shell. For this type of work, the probes are equipped with 214 plow knives as the rope-scraper shield advances.

A matrix laser (not shown) will continuously scan 218 the newly formed outer surface of the excavation exposure to ensure that no material that would impede or impede the progress of the scraper shield is left protruding inward. In areas where excavated soil covers areas of the newly formed tunnel outcrop, ground penetrating radar may also be used. If any such area is detected, it will be immediately brought to order without delay in progress by one or more robotic arms 212 mounted with a pneumatic drill hammer or removable cutting head or other suitable tool.

When working under the protection of a rope-scraper shield, the excavated soil is continuously loaded (with the help of a mechanical excavator 220, if required) onto a loading and unloading mechanism 222 inside the shield. Loading onto the loading and unloading mechanism 222 may occur primarily under the action of a scraper board moving forward through the excavated soil much like a bulldozer. Removal of the excavated soil is carried out using generally accepted methods; it is moved back on conveyor 224 back to where the newly laid tunnel bottom is capable of receiving

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Claims (5)

heavy equipment. In fig. 8 shows an axial cross-sectional view and an oblique view of a pre-perforated sacrificial support for use in wells, the support having a substantially cylindrical shape with a series of perforated holes 230 from the outside to the inside of it. In fig. 9 is a view of a telescopic chemical delivery well carriage 236 configured to move down a separate well 238 to an area requiring chemical treatment. The carriage includes 5 telescopic delivery probes 240 located around the carriage body 242, although other numbers are provided. Once the carriage has moved into position, the chemical used is pumped under pressure into the carriage by conventional means. This pressure causes the telescopic probes to extend and project forward into the material outside the borehole through corresponding pre-perforated holes (or holes made while the support is in place) in the sacrificial support. The amount of chemical delivered and the area to which it is delivered are selected on a case-by-case basis based on the geological knowledge gained from the drilling process and the required ultimate strength of the tunnel structure. In fig. 10 is a view of a downhole wireline return carriage shown with the carriage body 250 as transparent. A clamping system 252 is located on the housing 250 and engages the walls of the reinforced well in which it is located. The clamping system 252 can be engaged or disengaged by the operator so that the carriage can be moved in the well, and can be secured in place, ready to be winched. The first end 254 of the rope is connected to the shield. The second end 256 of the rope is attached to the winch. When the second end 256 of the rope is winched, a series of pulleys 258 in the carriage reverse the direction of the rope so that the shield is pulled by the first end 254 of the rope. CLAIM 1. A method for constructing an underground tunnel, the method including the following steps: drilling a first borehole along a first predetermined path through the underlying geology, the first borehole having a length of at least 25 m; drilling a plurality of second wells along respective second predefined paths through the underlying geology, each of the respective second predefined paths being substantially parallel to the first predefined path, to form a substantially prism-shaped region therebetween; and excavating material in a substantially prism-shaped region to form a tunnel from the tunnel boring shield, wherein the tunnel boring shield comprises at its leading edge a plurality of probes, each probe of the plurality of probes being aligned with a corresponding borehole of the first borehole and the plurality of second boreholes, the probes being equipped with tools configured with the possibility of excavation from the first and/or second wells. 2. The method according to claim 1, characterized in that the shield is a rope-scraper shield, and the method additionally includes pulling the rope-scraper shield through the material. 3. The method according to claim 2, characterized in that the rope-scraper shield is pulled through the material by a plurality of ropes, each rope of the plurality of ropes passing through a corresponding hole from the first hole and the plurality of second holes. 4. The method according to claim 3, characterized in that each rope of the plurality of ropes passes down through its respective hole from the first hole and the plurality of second holes to a return carriage fixed inside the hole, and passes back up through the corresponding hole to the rope-scraper shield . 5. A system for constructing an underground tunnel according to the method according to any of the previous paragraphs, the system comprising: directional drilling equipment configured to drill a first borehole along a first predefined path through the underlying geology, the first borehole having a length of at least 25 m, and further configured to drill a plurality of second boreholes along corresponding second predefined paths through the underlying geology, wherein each of the respective second predefined paths is substantially parallel to the first predefined path to form a substantially prism-shaped region between them; excavation equipment configured to excavate material in the substantially prism-shaped region to form a tunnel; and a tunnel boring shield comprising at its leading edge a plurality of probes, each probe of the plurality of probes being alignable with a corresponding borehole from the first borehole and the plurality of second boreholes, the probes being equipped with tools configured to excavate from the first and/or second boreholes. -