GB2590377A

GB2590377A - A subterranean excavation machine

Info

Publication number: GB2590377A
Application number: GB1918284.9A
Authority: GB
Inventors: Arnautov Max
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2021-06-30
Also published as: GB201918284D0

Abstract

A subterranean excavation machine comprising a cutting head, the cutting head comprising inlets for receiving abrasive and cutting fluid, and one or more nozzles 60. The or each nozzle comprises a mixing chamber 88 for mixing together the abrasive and the cutting fluid from the inlets, and a fluid focussing passageway 63b for focussing the mixed abrasive and cutting fluid into a cutting jet that exits the nozzle for cutting into subterranean substrate. The fluid focussing passageway is defined by a plurality of nozzle members 63, 64 that are movable towards and away from one another within a cavity 65 to respectively decrease and increase a width of the fluid focussing passageway.

Description

A SUBTERRANEAN EXCAVATION MACHINE

FIELD OF THE INVENTION

The present invention relates to a subterranean excavation machine, and in particular to a subterranean excavation machine comprising a cutting head at an end of a cable.

BACKGROUND OF THE INVENTION

Subterranean excavation machines have several application purposes, for example mining, drilling, or tunnel boring. Many such machines utilise mechanical blades or wipers to cut into the subterranean substrate so the substrate can be removed. However, such machines are typically high-maintenance and the mechanical cutting parts need replacement at regular intervals.

The Applicant's UK Patent No. GB 2564327 discloses a subterranean excavation machine comprising a cable and a cutting head at an end of the cable. The cutting head comprises a plurality of nozzles which receive cutting fluid from one or more cutting fluid conduits passing along a length of the cable. The nozzles eject the cutting fluid under pressure to cut into subterranean substrate. The cutting fluid is preferably mixed with an abrasive to increase the cutting power of the cutting fluid, and the patent describes a mixing chamber in each nozzle that may be used to mix the cutting fluid with the abrasive just before it exits the nozzle.

In practice, most commercially available abrasives have a wide range of different particle sizes, and there is a risk that if a much larger than expected abrasive particle is sent to the nozzle, the nozzle may block. The cutting head may be operating deep underground, and so retrieving it back to the surface to unblock the nozzle is very inconvenient and wasteful of time.

The cutting fluid may be under very high pressure, for example 50,000 PSI. If the nozzle becomes blocked with abrasive, then the cutting fluid may back-up within the nozzle, and force its way back up the cable along the passageways that normally deliver the abrasive to the cutting head, and/or along passageways that normally deliver the abrasive to other nozzles. These passageways and the surface equipment feeding the abrasive could easily be damaged by the reverse flow of high pressure cutting fluid mixed with abrasive.

It is therefore an aim of the invention to provide a subterranean excavation machine comprising a cutting head, in which the cutting head is more resilient to variable sized abrasive particles.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a subterranean excavation machine comprising a cutting head, the cutting head comprising inlets for receiving abrasive and cutting fluid, and one or more nozzles. The or each nozzle comprises a mixing chamber for mixing together the abrasive and the cutting fluid from the inlets, and a fluid focussing passageway for focussing the mixed abrasive and cutting fluid into a cutting jet that exits the nozzle for cutting into subterranean substrate. The fluid focussing passageway is defined by a plurality of nozzle members that are movable towards and away from one another within a cavity to respectively decrease and increase a width of the fluid focussing passageway.

Since the plurality of nozzle members are movable towards and away from one another within a cavity to respectively decrease and increase the width of the fluid focussing passageway, the width of the passageway can be temporarily increased to allow any larger than expected abrasive particles that block the passageway to pass through the passageway. Once the blockage has been cleared, the nozzle members can be moved back closer to one another for normal cutting operation. Each nozzle may have only two nozzle members for simplicity, but three, four, or even more nozzle members could be provided if desired.

The positions of the nozzle members could be varied using actuators that are remotely controlled, however for greater autonomy the nozzle members may be spring biased away from one another towards an open position in which the width of the fluid focussing passageway is maximised. Then, when the nozzle is not being used for cutting, the nozzle members move towards the open position under the spring bias to clear any blockages in the fluid focussing passageway and/or reduce the chances of any new blockages occurring.

The cavity may have a width that is tapered along a length of the cavity, the taper defined by walls of the cavity, and wherein the taper forces the nozzle members to move towards one another when they are moved along the length of the cavity. Then, the width of the fluid focussing passageway can be controlled by moving the nozzle members along the passageway.

The nozzle members may be closed together to meet one another in a closed position in which the width of the fluid focussing passageway is minimised, for normal cutting operation. Preferably, the nozzle members are moved to this position under pressure exerted by the cutting fluid, so that no specific actuators are needed. The nozzle members may comprise peripheral surfaces that define an entrance into the fluid focussing passageway, and pressure exerted on the peripheral surfaces by the mixed abrasive and cutting fluid adjacent the entrance may force the nozzle members forwardly to decrease the width of the fluid focussing passageway due to the taper. If the nozzle becomes blocked, then pumping of the cutting fluid and abrasive to the nozzle can be suspended, and the nozzle members move apart from one another under the spring bias to help clear the blockage.

The mixing chamber may formed by a portion of the cavity that is upstream of the nozzle members in the direction of flow of the cutting fluid, the cutting head may comprise a pipe that receives the cutting fluid from the inlets, and the pipe may comprise a narrowed portion defining an orifice through which the cutting fluid is forced. The orifice may be axially aligned with the fluid focussing passageway, so that a jet of cutting fluid from the orifice will pass directly into the fluid focussing passageway via the mixing chamber, mixing with abrasive particles as it goes through the mixing chamber. Optionally, the orifice may be sized to generate the velocity of the cutting jet exiting the nozzle, and the fluid focussing passageway in the closed position sized larger than the orifice and primarily intended to help focus the cutting jet when mixed with the abrasive into a laminar flow pattern. Accordingly, the width/diameter of the orifice may be smaller than the width/ diameter of the fluid focussing passageway in the closed position.

The mixing chamber may be formed inside of the pipe, downstream of the orifice in the direction of flow of the cutting fluid. The pipe may comprise holes in its sidewalls, wherein the holes admit abrasive from the inlets into the mixing chamber, allowing the abrasive to become entrained within the jet passing from the orifice to the fluid focussing passageway.

The pipe may be slidable within the cavity, and arranged so that pressure exerted on the narrowed portion of the pipe by the cutting fluid causes the pipe to slide and push against the nozzle members, thereby moving the nozzle members along the length of the cavity in the direction of flow of the mixed abrasive and cutting fluid. This causes the nozzle members to automatically close together due to the tapered cavity when cutting fluid is pumped into the cutting head at high pressure. A lower pressure which is insufficient to overcome the spring bias keeping the nozzle members apart may be used to help clear any blockages in the fluid focussing passageway.

The subterranean excavation machine may further comprise one or more cables for delivering the abrasive and cutting fluid to the inlets.

According to a second aspect of the invention, there is provided a subterranean excavation machine comprising a cutting head, the cutting head comprising inlets for receiving abrasive and cutting fluid, and one or more nozzles for ejecting the cutting fluid and abrasive to cut into subterranean substrate. The or each nozzle comprises a pressure-actuated non-return valve and a mixing chamber for mixing together the abrasive and the cutting fluid from the inlets, wherein the pressure-actuated non-return valve is connected between the inlet for receiving abrasive and the mixing chamber to prevent back-flow of fluid from the mixing chamber.

Therefore, should the nozzle become blocked and prevent cutting fluid from exiting the nozzle, the non-return valve will close and protect the passageways that deliver the abrasive from the high-pressure cutting fluid. The other nozzles will also be able to continue operating, without cutting fluid from the blocked nozzle disrupting the flow of abrasive to the nozzles that are still operating correctly. The subterranean excavation machine of the second aspect may be the same machine as the subterranean excavation machine of the first aspect.

The cutting head may comprise a housing and one or more support members which are rotatable within the housing, wherein the or each support member comprises the one or more nozzles. The nozzles preferably direct fluid at a non-parallel angle to the axis of rotation of the support members, causing the jets from the nozzles to impact different areas of subterranean substrate as the support members rotate. The axis of rotation of one of the support members may be non-parallel to the axis of rotation of another one of the support members, to further increase the diversity of directions in which the high pressure cutting fluid is directed by the cutting head.

Each support member may have at least two of the nozzles formed in the support member, and the at least two nozzles may be configured to rotate about the central axis of the support member. The at least two nozzles may be are arranged about the central axis of the support member at regular angular intervals to one another. Providing more than one nozzle per support member spaced at regular angular intervals increases the cutting capacity of the cutting head, and balances the thrust from each of the nozzles about the central axis of the support member, so that the support member can easily rotate about its central axis without excessive vibration. Each support member may be substantially spherical in shape.

The or each support member may comprise gear teeth that mesh with a toothed ring, the toothed ring configured to drive the rotation of the support member and the nozzle(s) formed in the support member. Alternatively, the or each support member may be configured to rotate under the thrust produced by the cutting fluid exiting the nozzle(s) formed in the support member.

According to a third aspect of the invention, there is provided a subterranean excavation machine comprising a cutting head, the cutting head comprising: inlets for receiving abrasive and cutting fluid; one or more nozzles for ejecting the cutting fluid and abrasive to cut into subterranean substrate, the or each nozzle comprising a mixing chamber for mixing together the abrasive and the cutting fluid from the inlets; a housing and one or more support members which are rotatable within the housing, the or each support member comprising the one or more nozzles; and one or more swivel joints that rotatably mount the or each support member to the housing. The or each swivel joint comprises an inner passageway via which the cutting fluid is supplied to the mixing chamber, and an outer annular chamber via which the abrasive is supplied to the mixing chamber.

The mounting of each support member to the housing using a respective swivel joint allows the support member to rotate relative to the housing, and the inner passageway and outer annular chamber allow the cutting fluid and the abrasive to cross the interface between the housing and the rotating support member, so they can be mixed in the mixing chamber of each nozzle.

The or each support member may comprise an annular chamber which communicates with the outer annular chamber of the corresponding swivel joint, allowing abrasive to flow from the outer annular chamber to the annular chamber. The or each support member may comprise one or more pipes that lead from the annular chamber to the one or more mixing chambers of the one or more nozzles of the support member. Preferably, the annular chamber and outer annular chamber are two annular trenches which fit together to form a larger annular chamber, the larger annular chamber allowing the abrasive to cross from the swivel joint into the support member even as the annular chamber and outer annular chamber rotate relative to one another.

The outer annular chamber may be defined by inner and outer cylindrical walls of a collar of the swivel joint, and ends of the inner and outer cylindrical walls may fit inside the annular chamber of the support member to securely connect the outer annular chamber to the annular chamber of the support member in a manner that allows the support member to rotate relative to the collar. The collar may comprise an annular flange and a securing ring that secures the annular flange to the support member to retain the ends of the inner and outer cylindrical walls inside the annular chamber of the support member. Preferably, the securing ring screws into the support member. The securing ring may have an annular seal for sealing against the annular flange to help prevent the escape of abrasive. A race of ball bearings may be provided between the collar and the support member to ease the relative rotation of the collar and support member.

The subterranean excavation machine of the third aspect may be the same machine as the subterranean excavation machine of the first and/or second aspect. The subterranean excavation machine may further comprise one or more cables for delivering the abrasive and cutting fluid to the inlets, and optionally a surface station for pumping the cutting fluid and abrasive along the one or more cables to the cutting head. Each cable may be composed of one or more pipes for supplying the cutting fluid or abrasive, and the cable(s) may be routed from the surface station to the cutting head within a tubular casing. The tubular casing could also be considered to be a cable composed of various pipes or individual cables within it.

The tubular casing may be a rigid cable, for example if the subterranean excavation machine is intended for drilling a fixed diameter hole such as a tunnel, or the tubular casing may be a bendable cable, for example if the subterranean excavation machine is intended for mining applications. The bendable cable may comprise a plurality of rigid length portions and a plurality of actuable bend portions, for example as described in GB 2564327.

The cutting head may further comprise a return port for carrying the cutting fluid and the cut subterranean substrate back along the cable, and optionally a bulk fluid supply port for supplying additional fluid to collect and sweep the excavated subterranean material into the return port, similar to the return port and bulk fluid supply port described in GB 2564327

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According to a fourth aspect of the invention, there is provided a subterranean excavation machine comprising a tubular casing and a cutting head, the cutting head comprising: one or more inlets for receiving cutting fluid from one or more cables passing along the tubular casing; a housing and one or more support members mounted to the housing and configured to rotate relative to the housing, the or each support member comprising one or more nozzles for ejecting the cutting fluid to cut into subterranean substrate; and a return port connected to a return pipe passing along a length of the tubular casing, the return port for receiving the cutting fluid and the cut subterranean substrate and the return pipe for carrying the cutting fluid and the cut subterranean substrate along the tubular casing. The return pipe is configured to rotate within the tubular casing, and the cutting head further comprises a transmission that transmits the rotation of the return pipe to the support members to drive the support members to rotate relative to the housing.

Since the cutting head may be operating in potentially explosive environments during mining, the use of electric motors to drive the rotation of the support members is undesirable. Hydraulic motors may be used instead of electric motors, but these still require periodic maintenance, which is undesirable. Using the return pipe to transmit rotational force down to the cutting head rather than using a motor in the cutting head itself, in accordance with the fourth aspect of the invention, is much more reliable and avoids the need to service or repair underground motors. A motor may be provided at the surface station to rotate the return pipe, which is much easier to access than a motor positioned underground. The return pipe serves the dual purpose of both transporting the cut subterranean substrate up to the surface and providing rotational force to drive the rotation of the nozzles, which is a very efficient use of equipment.

The transmission could for example comprise one or more gears that mesh with one or more gears of the support members, or an arrangement of belts or pulleys could also be used. The gears of the support members may be the same as the gears of the support members described in GB 2564327, but driven by rotation of the return pipe instead of by a motor.

The subterranean excavation machine of the fourth aspect may be the same machine as the subterranean excavation machine of the first, second, and/or third aspect.

According to a fifth aspect of the invention, there is provided a subterranean excavation machine comprising a tubular casing and a cutting head. The cutting head comprises one or more inlets for receiving cutting fluid from one or more cables passing along the tubular casing, and one or more nozzles for ejecting the cutting fluid to cut into subterranean substrate. The cutting head is mounted to the tubular casing by one or more hydraulic pistons that control an advancement of the cutting head perpendicularly away from a length of the tubular casing, and the tubular casing comprises a main portion of tubular casing and a terminal end portion of tubular casing for anchoring into the subterranean substrate. The one or more hydraulic pistons are mounted at an interface of the main portion of tubular casing and the terminal end portion of tubular casing.

The thrust generated by the cutting fluid exiting the nozzles may be very high, and risks destabilising the cutting head. Therefore, according to the fifth aspect of the invention, the tubular casing has a terminal end portion of tubular casing that helps to anchor the tubular casing in the substrate and to stabilise the cutting head against the high thrust forces produced at the nozzles. The hydraulic pistons enable the cutting head to be moved forwardly against the thrust produced at the nozzles, advancing it towards the subterranean substrate to be cut.

The main portion of tubular casing may be rotated by a surface station, thereby rotating the cutting head about an axis of the tubular casing. This allows the subterranean excavation machine to cut out a disk-shaped underground cavern, for example during mining.

The subterranean excavation machine of the fifth aspect may be the same machine as the subterranean excavation machine of the first, second, third, and/or fourth aspect.

According to sixth aspect of the invention, there is provided a subterranean excavation machine comprising a cutting head, the cutting head comprising inlets for receiving abrasive and cutting fluid, and one or more nozzles. The or each nozzle comprises an orifice through which the cutting fluid is forced, a mixing chamber for mixing together the abrasive and the cutting fluid from the orifice, and a fluid focussing passageway for focussing the mixed abrasive and cutting fluid into a cutting jet that exits the fluid focussing passageway for cutting into subterranean substrate, wherein a width of the orifice is narrower than a width of the fluid focussing passageway.

The mixing chamber is therefore positioned between the orifice and the fluid focussing passageway. The orifice and fluid focussing passageway may both have a circular cross section perpendicular to the direction of fluid flow through the orifice and the fluid focussing passageway, the widths being the diameters of the circular cross sections, but alternatively shaped cross sections could be implemented in alternate embodiments. The orifice is preferably aligned with the fluid focussing passages, so that the high-speed fluid that is forced out of the orifice is aimed by the orifice directly into the fluid focussing passageway.

The subterranean excavation machine of the sixth aspect may be the same machine as the subterranean excavation machine of the first, second, third, fourth, and/or fifth aspect.

DETAILED DESCRIPTION

Embodiments of the invention will now be described by way of non-limiting example only and with reference to the accompanying drawings, in which: Fig. 1 shows a schematic diagram of a subterranean excavation machine according to an embodiment of the invention being used to mine subterraneously; Fig. 2 shows an enlarged schematic diagram of the cutting head of Fig. 1, intended for cutting through earth or soil substrates; Fig. 3 shows a schematic diagram of a cutting head according to another embodiment of the invention, in which the internal details of how support members including nozzles are rotated can be seen; Fig. 4 shows a schematic cross-sectional diagram taken along line A-A' marked on Fig. 3; Fig. 5 shows an enlarged schematic diagram of internal details of one of the support members in which the nozzles are formed; Figs. 6a and 6b show enlarged schematic diagrams of a nozzle within one of the support members, the nozzle in a closed position for normal cutting operation; Figs. 7a and 7b show enlarged schematic diagrams of the nozzle of Figs. 6a and 6b, but in an open position for cleaning; Fig. 8 shows a schematic cross-sectional diagram similar to Fig. 4 but for an alternate embodiment in which the support members comprise non-return valves; Fig. 9 shows a schematic cross-sectional diagram taken along line B-B' marked on Fig. 8; Fig. 10 shows a schematic diagram of one of the non-return valves of Fig. Fig. 11 shows a schematic cross-sectional diagram of an interface between the support member and a swivel joint; Fig. 12 shows a schematic diagram of the interface between the support member and the swivel joint; and Fig. 13 shows a schematic diagram of a subterranean excavation machine according to another embodiment of the invention.

The figures are not to scale, and same or similar reference signs denote same or similar features.

The schematic diagram of Fig. 1 shows a subterranean excavation machine according to an embodiment of the invention. The machine comprises a cutting head 10 at the an end of a tubular casing 21 including a bendable cable 15 and a rigid cable 20, the rigid cable 20 being at an opposite end of the bendable cable 15 from the cutting head 10. The end of the rigid cable 20 opposite from the end where the bendable cable 15 is connected, is held in place by a support structure 25. The support structure 25 is positioned in place by a vehicle 30, which together

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form a surface station.

The cutting head 10 comprises nozzles and at least one return port. The nozzles eject cutting fluid into a hole 5 in the alluvial soil layer 2, cutting through the soil and creating a turbulent slurry of soil and cutting fluid, that is sucked up through the return port. The bendable and rigid cables 15 and 20 define a cutting fluid conduit that delivers cutting fluid from the support structure 25 to the nozzles, and a return pipe that carries the slurry of soil and cutting fluid from the return port up to the support structure 25. A collar 22 seals around the casing pipe at ground level.

The surface station pumps the cutting fluid down to the nozzles at high pressure, via the support structure 25. In this embodiment, the cutting fluid is water, however other cutting liquids could be used in alternate embodiments. The cutting fluid may be mixed with abrasive to increase the cutting power of the jet exiting the nozzles, for example for cutting through rock rather than alluvial soil substrates.

The return pipe is connected to the surface station via the support structure 25, where precious minerals may be extracted from the slurry of soil and cutting fluid that is sucked up/pumped through the return pipe.

As shown, the bendable cable 15 comprises a plurality of rigid length portions 16 that alternate with actuable bend portions 17. Each actuable bend portion 17 is connected between two adjacent rigid length portions 16, and controls a bend angle between the two adjacent rigid length portions 16. The actuable bend portions are controlled by a controller at the support structure 25, to move the cutting head 10 within the hole 5 to target different areas of the alluvial layer 2. The rigid cable 20 is joined to the bendable cable 15 at a joint 19.

Mining commences using the cutting head 10, and the hole 5 begins to form around the cutting head. The hole 5 is expanded to excavate more and more areas of the alluvial layer 2 by controlling the position of the cutting head 10 using the actuable bend portions 17. An air inlet pipe 23 connects to the cavity between 13' the cable and the outer casing 21, and pumping air into the cavity via the air inlet pipe raises the pressure inside the hole 5, and aids extraction of the alluvial layer up the bendable cable via the return pipe. The seal created by the collar 22 prevents the air that is pumped into the cavity from escaping at ground level.

The schematic diagram of Fig. 2 shows the cutting head 10 in more detail. The cutting head 10 comprises a rotatable collar 76 surrounding a fixed front ring 70, and a return port 62 that is positioned centrally of the fixed front ring 70. The cutting head 10 has nozzles 60 within the fixed front ring 70, for delivering the high-pressure cutting fluid to the alluvial soil deposit. Subterranean material that is dislodged by the cutting fluid from the nozzles 60 can be easily sucked up into the return port 62, and along the return conduit to the return fluid pumping station 8. In addition to the return port 62, further return ports connected to the return conduit may be positioned at the sides of the cutting head 10, to suck up further subterranean material and cutting fluid.

The fixed front ring 70 has a plurality of holes at its exterior, in which nozzle support members 72 are located. The nozzles 60 are formed in the support members 72. In this embodiment, each support member 72 is a spherical ball, which is rotatable within the corresponding hole in the fixed front ring 70. There are two nozzles 60 formed in each spherical ball, the nozzles pointing away from the spherical ball in directions that are different from one another and different from the axis of rotation of the spherical ball.

The cutting head 10 is substantially cylindrical, and the spherical balls 72 with the nozzles 60 are arranged in a ring shape around the fixed front ring 70, at a front end of the cutting head 10. There are two rings of spherical balls 72 arranged in the fixed front ring 70; the outermost ring has spherical balls that each rotate about an axis parallel to the rigid length portion 16, and the innermost ring has spherical balls that each rotate about an axis that is not parallel to the axis of the rigid length portion 16. The return port 62 is positioned inside of the rings formed by the spherical balls 72.

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In this embodiment, the fixed front ring 70 also has a series of bulk fluid supply ports 74 that are interspaced between the nozzles 60. The bulk fluid supply ports 74 are connected to a bulk fluid supply conduit passing along the lengths of the bendable and rigid cables. In use, the bulk fluid supply ports 74 supply a much larger volume of bulk fluid than the volume of the cutting fluid supplied by the nozzles 60, and the bulk fluid helps to sweep the subterranean material into the return port 62. The bulk fluid may for example be water, but other liquids could alternatively be used. The bulk fluid is pumped to the bulk fluid supply ports 74 from the surface station.

The rotatable collar 76 surrounds the fixed front ring 70, and is configured to rotate relative to the fixed front ring 70 and the end-most rigid length portion that the cutting head 10 is connected to. The rotatable collar 76 also has holes in its exterior which form nozzles 60a, the nozzles 60a for ejecting cutting fluid at high pressure to aid cutting of the soil. During operation, the cutting fluid is squirted out of the nozzles 60 and 60a at very high pressure, and dislodges subterranean substrate material, so that it is swept up by the bulk fluid from ports 74 into the return port 62. Since the spherical balls 72 all rotate about different axes to one another, and since the nozzles 60 of each spherical ball eject fluid in directions different from the axis of rotation, the cutting fluid from each spherical ball spreads out in a cone shape. Those cone shapes of adjacent spherical balls overlap with one another, so that the full area of the subterranean substrate in front of the cutting head can be struck with cutting fluid by moving the cutting head closer and further away from the subterranean substrate.

In alternate embodiments, the cutting head 10 may be provided with many more of the spherical balls 72, to assist in cutting through harder subterranean substrates such as rock. Multiple return ports may be provided around the nozzles 60, instead of just one central return port 62. Then, the front centre of the cutting head can be used for additional ones of the spherical balls 72. For example, Fig. 3 shows an example of a cutting head according to an embodiment of the invention which is the same as that of Figs. 1 and 2, but in which many spherical balls 72 are arranged in concentric circles at the front of the cutting head.

Each spherical ball 72 has gear teeth around its periphery, just behind the fixed front ring 70. These gear teeth are driven by a toothed ring to make all the balls of the fixed front ring rotate. Alternatively, the balls 72 may be configured to rotate under thrust generated by the nozzles 60 as they eject the cutting fluid. Fig. 3 shows how the spherical balls 72 of the cutting head can be rotated by a plurality of toothed rings 80, 81, and 82 that are arranged concentrically with one another. The toothed rings each have teeth 83 running around their internal and external circumferences, which mesh with teeth 75 of the balls 72. The outermost toothed ring 80 is driven to rotate by a gear 78, and the rotation of the toothed ring 80 drives the rotation of the spherical balls and the other toothed rings. Some of the balls 72, such as 72a, may only have one nozzle 60 if desired. The gear 78 is preferably driven to rotate by the return pipe, the return pipe being rotated at the surface station to carry rotational force down to the cutting head. Alternatively, a hydraulic or electric motor could be used to drive the rotation of the gear 78 instead of using a rotating return pipe.

A cross-sectional diagram of two of the spherical balls is shown in Fig. 4, taken along line A-A' marked on Fig. 3. As shown, each ball 72 is mounted on a swivel joint 85, allowing the ball 72 to rotate about the central axis 72c of the ball. Each ball 72 has the two nozzles 60 directed at approximately 90 degrees to one another, both nozzles 60 directed at approximately 45 degrees to the axis of rotation 72c of the spherical ball 72. To improve the efficiency of cutting, an abrasive material may be supplied to the nozzle of each ball, and mixed with the cutting fluid in a mixing chamber 88 of each nozzle 60. The abrasive material in this embodiment is a suspension of fine metal particles, however other types of abrasive material could alternatively be used, for example stone or ceramic.

The high-pressure cutting fluid is supplied to each ball 72 via a cutting fluid inlet pipe 85a that passes through the swivel joint 85, and abrasive material is supplied via inlet pipe 88a and support member pipe 88b. The pipes 88a are fixed in position external to the balls 72, and the pipes 88b are internal to the balls 72, and so the pipes 88b rotate relative to the pipes 88a. The pipes 88a communicate with the pipes 88b via slots 88c. This is more easily appreciated from the schematic diagram of Fig. 5, which shows the internal details of the spherical ball 72a when looking towards the ball in the direction 89 marked on Fig. 4. The inlet pipes 85a constitute inlets of the cutting head for receiving the cutting fluid, and the inlet pipes 88a constitute inlets of the cutting head for receiving the abrasive.

The slots 88c are formed as a series of arcs around the axis of rotation of the ball 72, and each slot 88c is connected to a corresponding pipe 88b that leads to the mixing chamber 88. As the ball 72 rotates, different ones of the slots 88c come into alignment with the pipes 88a, and the abrasive material is carried to the mixing chamber 88, where it becomes mixed with the high pressure cutting fluid, and ejected from the nozzle 60.

The schematic diagram of Fig. 6a shows a more detailed diagram of one of the nozzles 60, where the internal details of the nozzle can be more easily seen. As shown, the nozzle 60 is screwed into the surface of the spherical ball 72, and comprises two nozzle members 63 and 64 that together define a fluid focussing passageway 63b between them. The nozzle members 63 and 64 together form a conical shape, with the fluid focussing passageway 63b running along the axis of the conical shape. For example, Fig. 6b shows a view of the nozzle members 63 and 64 looking in from direction 20 marked on Fig. 6a. The nozzle 60 comprises a cavity 65 that is defined by various cavity walls including walls 65a and 65b. The walls 65a and 65b are slanted to match the conical shape of the nozzle members 63 and 64, and so the width of the cavity 65 tapers along its length, from its base where the nozzle members 63 and 64 are widest to its top where the nozzle members 63 and 64 are narrowest.

The cavity wall 65b is formed by an insert 68 that screws into a main body of the nozzle 60, the main body defining the cavity walls 65a. Each nozzle member 63 and 64 has a skirt 63a protruding outwardly in a direction away from the fluid focussing passageway 63b. A coiled spring 69 is trapped between the insert 68 and the skirts 63a, thereby urging the nozzle member 63 and 64 to move downwardly as viewed in Fig. 6a, in the direction of arrow 20.

Each nozzle member 63 and 64 also has a protrusion 66 that protrudes outwardly from the nozzle member, and which fits into a slot 67 in the cavity wall F' 65a. The slot 67 acts as a rail along which the protrusion 66 can slide as the corresponding nozzle member 63 or 64 slides up and down in the cavity.

The tube 85b (also marked on Fig. 4) carries cutting fluid under high pressure to the mixing chamber 88 of the nozzle 60. The end of the tube 85b is fitted with a slidable pipe 90 that goes inside the tube 85b, and a buffer collar 86b inside the tube 85b limits how far the slidable pipe 90 can move into the tube 85b. The slidable pipe 90 comprises a narrowed portion formed by an orifice plate 92 with an orifice 93. Cutting fluid under high pressure is forced through the orifice 93 towards the fluid focussing passageway 63b, via the mixing chamber 88. The slidable pipe 90 also comprises holes 95 in its sidewalls adjacent the mixing chamber 88, and the holes 95 admit abrasive from the pipes 88b into the mixing chamber 88, where the abrasive mixes with the cutting fluid from the orifice 93, before passing through the fluid focussing passageway 63b and exiting the nozzle 60 as a cutting jet.

The nozzle members 63 and 64 are shown in a closed position in Figs. 6a and 6b, as they are fully closed together. This is because the high-pressure cutting fluid from the tube 85a pushes the orifice plate 92 upwardly as drawn in Fig. 6a, pushing the slidable pipe 90 upwardly, and causing the end of the slidable pipe 90 to push against the end 63c of the conical nozzle members 63 and 64. The force from the slidable pipe 90 overcomes the bias force exerted by the coiled spring 90, and the nozzle member 63 and 64 move upwardly, being forced together by the taper in the cavity 65 defined by walls 65a and 65b. Each nozzle member 63 and 64 comprises a rubber seal 63c around its periphery to prevent the abrasive from entering in between the nozzle member and the walls of the cavity 65.

Should the fluid focussing passageway 63b become blocked, then the pumping of high pressure cutting fluid along the tube 85b is reduced/halted by the surface station, and so cutting fluid no longer pushes on the orifice plate 92 hard enough to overcome the bias of the coiled spring 69. Therefore, the slidable pipe 90 and nozzle members 63 and 64 move downwardly in direction 20, to the positions shown in Figs. 7a and 7b. The coiled spring 69 pushes the nozzle members 63 and 64 downward until the skirt 63a meets the stepped portion 65c of the cavity walls, and the slidable pipe 90 abuts against the buffer collar 86b to prevent it moving too far into the pipe 85b. The protrusions 66 slide along the slot rail 67, drawing the nozzle members apart from one another, and widening the fluid focussing passageway 63b so that cutting fluid passing through the orifice 93 at low pressure can clear the blockage out of the nozzle. Pumping of abrasive along the pipes 88b is preferably suspended during this time to fully clear the fluid focussing passageway 63b of any abrasive, and to allow the nozzle members 63 and 64 to move back to their positions in Figs. 6a and 6b once pumping of cutting fluid at high pressure is started again.

The tapered width of the cavity 65 and the conical shape of the nozzle members 63 and 64 in combination with the bias of the coiled spring is an effective way of controlling the width of the fluid focussing passageway based on the pressure of the cutting fluid, but alternate ways of controlling the nozzle members 63 and 64 to move towards or apart from one another are also possible, for example by using hydraulic actuators instead of relying on the pressure of the cutting fluid. Whilst the nozzle 60 has been described in the context of the rotating support members 72, it will be appreciated that the nozzle 60 could easily be incorporated into almost any type of support member.

An alternate embodiment of the cutting head will now be described with reference to Fig. 8, which is the same as Fig. 4, but uses an improved method of routing the abrasive into the support members, and has protective non-return valves 40 to prevent high-pressure cutting fluid back-flowing along the abrasive delivery passageways in the event of blockages in the fluid focussing passageway 60. Fig. 8 shows two support members 721 and 721a, one with two nozzles and one with one nozzle, similar to the support members 72 and 72a of Fig. 4.

The swivel joint 85 in this embodiment comprises a collar 85c which is positioned against the base of each support member 721 and 721a. The collar 85c helps route the abrasive material from the inlet pipe 88a to the support member pipes 88b. Each swivel joint 85 comprises an inner passageway 85a, via which the cutting fluid is supplied to the mixing chamber, and an outer annular chamber 54 formed by the collar 85c, via which the abrasive is supplied to the mixing chamber.

A schematic cross-sectional diagram of the collar 85c is shown in Fig. 9. The swivel joint 85 comprises a spigot 52 for connecting the inlet pipe 88a, so that the abrasive enters the outer annular chamber 54. The outer annular chamber 54 is defined as the space between an outer cylindrical wall 85c1 and an inner cylindrical wall 85c2, the inner cylinder 85c2 being inside of and having a smaller diameter than the outer cylinder 85c1.

Each support member 721 and 721a comprises an annular chamber 56 at the bottom of the support member where the swivel joint is connected. The annular chamber 56 communicates with the outer annular chamber 54 of the swivel joint, allowing abrasive to flow from the outer annular chamber 54 to the annular chamber 56. The pipe(s) 88b for abrasive lead from the annular chamber 56 to the mixing chamber(s) of the nozzle(s) of the support member. The annular chamber 56 and outer annular chamber are two annular trenches which fit together to form a larger annular chamber that fully encircles around the joint between pipes 85a and 85b. Thus, the annular trench 56 is provided in this embodiment instead of the slots 88c shown in Fig. 5, allowing abrasive to be more continuously supplied to the support member.

The non-return valves 40 are positioned in the pipes 88b for the abrasive, to allow flow of the abrasive towards the mixing chamber, and block backflow of fluid from the mixing chamber back towards the swivel joint. The non-return valves 40 could equally be implemented in the support members 72 and 72a of Fig. 4, or in any other support member with a pipe for feeding abrasive to a mixing chamber. Non-return valves are well known and the non-return valve is not limited to any particular construction, however the details of the non-return valve 40 are shown in Fig. 10.

The non-return valve 40 comprises a main body 41 and a movable valve member 42 that controls the flow of abrasive through the valve. The main body 41 defines a cavity in which the movable valve member 42 is retained, and the cavity has two annular flanges 46a and 46b spaced apart from one another that protrude into the cavity. The annular flange 46b comprises an annular sealing portion 47.

The movable valve member 42 comprises a cylindrical pipe 48 having an annular flange 44a at one end and an annular flange 44b at an opposite end of the pipe 48. There are a series of holes 49 through the cylindrical pipe 48 adjacent the annular flange 44b, and the annular flange 44b comprises an annular sealing portion 43.

The annular flange 44a of the cylindrical pipe 48 is retained between the annular flanges 46a and 46b that protrude into the cavity of the main body 41, and a coiled spring 45 is between the annular flanges 44a and 46b, biasing the movable valve member 42 towards the position shown in Fig. 10. In this position, the annular sealing portion 43 is urged towards the annular sealing portion 47, blocking the flow of abrasive between those portions.

During normal cutting operation, abrasive enters the non-return valve 40 in direction 58, which exerts a downward pressure on the movable valve member 42 as viewed in Fig. 10, causing the movable valve member 42 to move downwardly against the spring bias, and separating the annular sealing portions 43 and 47 to allow abrasive to flow between them. Accordingly, the abrasive moving in direction 58 flows along the cylindrical pipe 48, through the holes 49, between the annular sealing portions 43 and 47, and out of the non-return valve in direction 59.

If the fluid focussing passageway 63b was to become blocked, then high pressure cutting fluid may cause the abrasive to move in the opposite direction to direction 59, causing the movable valve member 42 to move upwardly and firmly closing the annular sealing portions 43 and 47 together to prevent back-flow through the non-return valve. Accordingly, the non-return valve is pressure-actuated by the direction of flow of the abrasive.

Another manner of connecting the swivel joint to the support member will now be described in detail with reference to Figs. 11 and 12. Fig. 11 shows a cross-sectional diagram through the support member 721 and collar 85c, in an embodiment where the ends of the inner and outer cylindrical walls 85c2 and 85c1 forming the outer annular chamber 54 (see Fig. 9) are sized to fit inside the annular chamber 56 of the support member 721. As shown in Fig. 11, the annular chamber 56 of the support member is defined by an inner annular wall 85d2 and an outer annular wall 85d1, which receive the ends of the inner and outer cylindrical walls 85c2 and 85c1 between them.

The end of the outer cylindrical wall 85c1 has an annular flange extending outwardly from the outer cylindrical wall 85c1, and this annular flange is used to secure the collar 85c to the support member by keeping the ends of the inner and outer cylindrical walls 85c2 and 85c1 inside of the annular chamber 56 of the support member. Specifically, an annular fastening ring 87a having an 0-ring seal 87b is screwed into the annular chamber 56 after the ends of the inner and outer cylindrical walls 85c2 and 85c1 have been fitted into the annular chamber 56, the annular fastening ring 87a thereby retaining the annular flange inside the annular chamber 56. The annular fastening ring 87a has screw threads that are screwed into corresponding screw threads of the outer annular wall 85d1.

The ends of the inner and outer cylindrical walls 85c2 and 85c1 are a loose fit inside of the annular chamber 56, so that the support member 721 can rotate relative to the collar 85c. In a further embodiment, a race of ball bearings could be provided between the collar and the support member to ease the relative rotation of the collar and support member.

The abrasive pipes 88b are connected from the annular chamber 56 of the support member to the nozzles 60, and incorporate the non-return valves 40 along their lengths, as best shown in Fig. 12.

A further embodiment of the invention will now be described with reference to Fig. 13. Fig. 13 shows a subterranean excavation machine comprising a tubular casing 120 which has been inserted into a hole 104 in a subterranean substrate 100. The tubular casing 120 supports various cables which are routed along the tubular casing from a surface station (not shown) to a cutting head 110, including pipes 180 for carrying cutting fluid and abrasive to the cutting head, and a return pipe 165 for carrying the subterranean substrate that is cut by the cutting head 110 up to the surface station above the subterranean substrate 100. The return pipe 165 comprises a return port 162 at the cutting head 110 to allow the cut subterranean substrate to enter. Bulk fluid supply pipe(s) connected to bulk fluid supply port(s) at the cutting head 110 may also be implemented to supply bulk fluid such as water to help sweep the cut subterranean substrate to the return port 162, although these are not shown in Fig. 13 for the sake of clarity.

The pipes 180 are connected to various inlets of the cutting head 110, and pass to support members 172 that have nozzles 160. The support members 172 are the same as the support members 721 of Fig. 8, but have a more elongated shape. The nozzles 160 are the same as the nozzles 60 of Figs. 6a to 7b, and eject high-pressure cutting jets 163 that cut into the subterranean substrate 100.

The support members 172 are rotatably mounted to a housing 111 of the cutting head by swivel joints, and comprise gear teeth 174 that mesh with each other and mesh with gear teeth 175 encircling around the return port 165. Then, the return pipe 165 can be rotated by the surface station, as shown by the arrows in Fig. 13, and the rotational force transmitted by the gear teeth used to rotate the support members 172 and therefore the nozzles 160, so that the cutting jets 163 traverse along the exposed face of the subterranean substrate 100. The gear teeth 174 and 175 therefore constitute a transmission that transmits the rotation of the return pipe to the support members to drive the support members to rotate relative to the housing.

The tubular casing 120 comprises a main portion 120a and a terminal end portion 120b, with a cut-away 125 in the tubular casing positioned at an interface between the main portion 120a and the terminal end portion 120b. The tubular casing 120 has an internal frame 130 arranged inside the tubular casing 120 opposite the cut-away 125. The frame 130 supports two hydraulic pistons 195 which are extendable through the cut away 125 and hold the cutting head 110. The hydraulic pistons 195 are controlled from the surface station, using cables 190 which pass along the casing pipe up to the surface station.

The terminal end portion 120b of the tubular casing extends into a base 106 of the hole 104. The jets of cutting fluid 163 are at very high pressure and so create a large amount of thrust, which is borne by the hydraulic pistons 195 and tubular casing 120. The terminal end portion 120b of the tubular casing helps to stabilise the tubular casing in the subterranean substrate and resist the thrust exerted by the cutting head 110.

In use, the whole of the tubular casing 120 is also rotated by the surface station, so that the cutting head 110 follows a circular path extending around the tubular casing, and cuts a disk-shaped cavern 105 within the subterranean substrate. The hydraulic pistons 195 are gradually extended during cutting of the subterranean substrate, to extend the diameter of the disk-shaped cavern 105. In an alternate embodiment, the hydraulic pistons may indirectly act on the cutting head rather than being directly connected to it, for example a scissor type arrangement could be used where the piston(s) control the scissoring action and therefore how far the scissors move the cutting head away from the tubular casing.

Many other variations of the described embodiments falling within the scope of the invention will be apparent to those skilled in the art.

Claims

CLAIMS1. A subterranean excavation machine comprising a cutting head, the cutting head comprising inlets for receiving abrasive and cutting fluid, and one or more nozzles, wherein the or each nozzle comprises a mixing chamber for mixing together the abrasive and the cutting fluid from the inlets, and a fluid focussing passageway for focussing the mixed abrasive and cutting fluid into a cutting jet that exits the nozzle for cutting into subterranean substrate, wherein the fluid focussing passageway is defined by a plurality of nozzle members that are movable towards and away from one another within a cavity to respectively decrease and increase a width of the fluid focussing passageway.
2. The subterranean excavation machine of claim 1, wherein the nozzle members are spring biased away from one another towards an open position in which the width of the fluid focussing passageway is maximised.
3. The subterranean excavation machine of claim 1 or 2, wherein the cavity has a width that is tapered along a length of the cavity, the taper defined by walls of the cavity, and wherein the taper forces the nozzle members to move towards one another when they are moved along the length of the cavity.4. The subterranean excavation machine of claim 3, wherein the nozzle members comprise peripheral surfaces that define an entrance into the fluid focussing passageway, and wherein the nozzle members move along the length of the cavity in the direction of flow of the mixed abrasive and cutting fluid in response to pressure exerted on the peripheral surfaces by the mixed abrasive and cutting fluid adjacent the entrance, the movement along the length of the cavity causing the nozzle members to move towards one another and decrease the width of the fluid focussing passageway due to the taper.
4. The subterranean excavation machine of any one of claims 3 or 4 when claim 3 is appended to claim 2, wherein the spring bias urges the nozzle members to move in a direction along the length of the cavity that is opposite the direction of direction of flow of the mixed abrasive and cutting fluid, the movement along the length of the cavity allowing the nozzle members to move away one another and increase the width of the fluid focussing passageway due to the taper.
5. The subterranean excavation machine of claim 4, wherein the cavity comprises a region bounded by a front ring, the cavity walls, the nozzle members, and a seating of each nozzle member that extends outwardly from the nozzle member towards the cavity walls, and wherein the region contains a coiled spring that is compressed between the front ring and the seatings to provide the spring biasing.
6. The subterranean excavation machine of claim 4 or 5, wherein each nozzle member comprises a protrusion that is movable along a slot defined in the cavity walls, and wherein the slot extends in a direction along the length of the cavity.
7. The subterranean excavation machine of any preceding claim, wherein the nozzle members together form a conical shape with the fluid focussing passageway aligned with an axis of the conical shape.
8. The subterranean excavation machine of any preceding claim, wherein the mixing chamber is formed by a portion of the cavity that is upstream of the nozzle members in the direction of flow of the cutting fluid, wherein the cutting head comprises a pipe that receives the cutting fluid from the inlets, and the pipe comprises a narrowed portion defining an orifice through which the cutting fluid is forced, wherein the orifice is axially aligned with the fluid focussing passageway.
9. The subterranean excavation machine of claim 8, wherein the mixing chamber is formed inside of the pipe, downstream of the orifice in the direction of flow of the cutting fluid, wherein the pipe comprises holes in sidewalls of the pipe, and wherein the holes admit abrasive from the inlets into the mixing chamber.
10. The subterranean excavation machine of claim 8 or 9, wherein the pipe is slidable within the cavity, and arranged so that pressure exerted on the narrowed portion of the pipe by the cutting fluid causes the pipe to slide and push against the nozzle members, thereby moving the nozzle members along the length of the cavity in the direction of flow of the mixed abrasive and cutting fluid.
11. A subterranean excavation machine comprising a cutting head, the cutting head comprising inlets for receiving abrasive and cutting fluid, and one or more nozzles for ejecting the cutting fluid and abrasive to cut into subterranean substrate, wherein the or each nozzle comprises a pressure-actuated non-return valve and a mixing chamber for mixing together the abrasive and the cutting fluid from the inlets, and wherein the pressure-actuated non-return valve is connected between the inlet for receiving abrasive and the mixing chamber to prevent back-flow of fluid from the mixing chamber.
12. The subterranean excavation machine of claim 11, wherein the subterranean excavation machine is also in accordance with any one of claims 1 to 10.
13. The subterranean excavation machine of any preceding claim, wherein the cutting head comprises a housing and one or more support members which are rotatable within the housing, wherein the or each support member comprises the one or more nozzles.
14. A subterranean excavation machine comprising a cutting head, the cutting head comprising: inlets for receiving abrasive and cutting fluid; one or more nozzles for ejecting the cutting fluid and abrasive to cut into subterranean substrate, the or each nozzle comprising a mixing chamber for mixing together the abrasive and the cutting fluid from the inlets; a housing and one or more support members which are rotatable relative to the housing, the or each support member comprising the one or more nozzles; and one or more swivel joints that rotatably mount the or each support member to the housing, wherein the or each swivel joint comprises an inner passageway via which the cutting fluid is supplied to the mixing chamber, and an outer annular chamber via which the abrasive is supplied to the mixing chamber.
15. The subterranean excavation machine of claim 14, wherein the or each support member comprises an annular chamber which communicates with the outer annular chamber of the corresponding swivel joint, allowing abrasive to flow from the outer annular chamber to the annular chamber, and wherein the or each support member comprises one or more pipes that lead from the annular chamber to the one or more mixing chambers of the one or more nozzles of the support member.
16. The subterranean excavation machine of claim 15, wherein the annular chamber and outer annular chamber are two annular trenches which fit together to form a larger annular chamber.
17. The subterranean excavation machine of claim 15 or 16, wherein the outer annular chamber is defined by inner and outer cylindrical walls of a collar of the swivel joint, and wherein ends of the inner and outer cylindrical walls fit inside the annular chamber of the support member.
18. The subterranean excavation machine of claim 17, wherein the outer cylindrical wall of the collar comprises an annular flange, and wherein the collar further comprises a securing ring that secures the annular flange to the support member to retain the ends of the inner and outer cylindrical walls inside the annular chamber of the support member.
19. The subterranean excavation machine of claim 18, wherein the annular flange is located at the end of the outer cylindrical wall and inside of the annular chamber of the support member, and wherein the securing ring comprises an annular seal that fits against the annular flange.
20. The subterranean excavation machine of any one of claims 14 to 19, wherein the subterranean excavation machine is also in accordance with any one of claims 1 to 13.
21. A subterranean excavation machine comprising a tubular casing and a cutting head, the cutting head comprising: one or more inlets for receiving cutting fluid from one or more cables passing along the tubular casing; a housing and one or more support members mounted to the housing and configured to rotate relative to the housing, the or each support member comprising one or more nozzles for ejecting the cutting fluid to cut into subterranean substrate; and a return port connected to a return pipe passing along a length of the tubular casing, the return port for receiving the cutting fluid and the cut subterranean substrate and the return pipe for carrying the cutting fluid and the cut subterranean substrate along the tubular casing, wherein the return pipe is configured to rotate within the tubular casing, and wherein the cutting head further comprises a transmission that transmits the rotation of the return pipe to the support members to drive the support members to rotate relative to the housing.
22. The subterranean excavation machine of claim 21, wherein the subterranean excavation machine is also in accordance with any one of claims 1 to 20.
23. A subterranean excavation machine comprising a tubular casing and a cutting head, the cutting head comprising one or more inlets for receiving cutting fluid from one or more cables passing along the tubular casing, and one or more nozzles for ejecting the cutting fluid to cut into subterranean substrate, wherein the cutting head is mounted to the tubular casing by one or more hydraulic pistons that control an advancement of the cutting head perpendicularly away from a length of the tubular casing, and wherein the tubular casing comprises a main portion of tubular casing and a terminal end portion of tubular casing for anchoring into the subterranean substrate, wherein the one or more hydraulic pistons are mounted at an interface of the main portion of tubular casing and the terminal end portion of tubular casing.
24. The subterranean excavation machine of claim 23, further comprising a surface station that is configured to rotate the main portion of tubular casing, thereby rotating the cutting head about an axis of the tubular casing.
25. The subterranean excavation machine of claim 23 or 24, wherein the subterranean excavation machine is also in accordance with any one of claims 1 to 22.
26. A subterranean excavation machine comprising a cutting head, the cutting head comprising inlets for receiving abrasive and cutting fluid, and one or more nozzles. The or each nozzle comprises an orifice through which the cutting fluid is forced, a mixing chamber for mixing together the abrasive and the cutting fluid from the orifice, and a fluid focussing passageway for focussing the mixed abrasive and cutting fluid into a cutting jet that exits the fluid focussing passageway nozzle for cutting into subterranean substrate, wherein a width of the orifice is narrower than a width of the fluid focussing passageway.
27. The subterranean excavation machine of claim 26, wherein the subterranean excavation machine is also in accordance with any one of claims 1 to 25.