FIELD OF THE INVENTION

[0001] The present invention relates to a grout free expandable standpipe and a method for grouting ground formation. The present invention also relates to a method of anchoring and sealing a standpipe into a ground formation with an expandable standpipe having a swage seal set by an inflatable packer.

[0002] More specifically, the present invention relates to a standpipe having a swage seal for anchoring and sealing into the ground formation to obviate the need for grouting the standpipe into the ground formation. Using swage set expandable standpipes instead of grout standpipes has the advantage that the standpipes can be anchored and sealed in less than an hour (more typically less than 30 minutes), whereas prior art grouted standpipes require up to 24 hours for the grout to set to effect sealing and anchoring of the standpipe. Conventional standpipes are not expandable.

[0003] More particularly, the grout free expandable standpipe of the present invention can be used to form grout curtains to protect advancing tunnel excavations from inundation from high- pressure ground water from the ground formation around the tunnel. The expandable standpipe can also be used in underground mining processes. Stopping in-rush of ground water is particularly important during subterranean excavations. It is known to use curtains of grouted drill holes around subterranean excavations to resist the flow of ground water. However, the time needed for the grout to cure and set dramatically slow the progress of the excavation.

TERMINOLOGY

[0004] The following specific terminology is used in the context of the present invention:

• “curtain” in the context of the present invention means a curtain of grout set into a ground formation ahead of and around a tunnel for use in stabilising the ground and inhibiting the flow of ground water into the tunnel;

• “grout” in the context of the present invention means a settable, flowable agent, typically made from a mixture of cement, water, and sand, as is known for use in pressure grouting. Typically, grout is made with Portland cement and, when set, provides a waterproof barrier. In prior art standpipes grout is used to seal the standpipe into a pilot hole in the ground. Such prior art standpipes are herein referred to as grout sealed standpipes. Grout in the context of the present invention is not used to seal the standpipe into the ground, and is only used to stabilise ground formation around a grout hole drilled through the standpipe;

• “grout free” in the context of the present invention means that the operation of setting and sealing the standpipe into the ground formation does not require the use of grout, nevertheless grout is still required for producing a grout curtain ahead of and around a tunnel;

• “grout hole” in the context of the present invention refers to a hole drilled through the end of the pilot hole, once the standpipe has been sealed into the pilot hole. Grout holes are typically from 15 to 50 metres long and substantially coaxial with the pilot holes;

• “grouting” in the context of the present invention means the process of injecting grout into ground formation through a standpipe in advance and around a subterranean tunnel;

• “inflatable packers” in the context of the present invention refer to plug equipment that can block, temporarily or permanently, a hole in the ground or inside a pipe, such as a standpipe. Inflatable packers of the type preferred in the context of the present invention incorporate elastomers, reinforcement layers and external anchoring surface finishes and covers within a single, vulcanised composite element. Suitable inflatable packers are made by Inflatable Packers International. Other forms of inflatable packers are made in three or more separate components laid over each other and are not well suited for use in the standpipe of the present invention;

• “mechanical packers” in the context of the present invention refers to a resilient tubular member with a mandrel through its longitudinal axis, expansion of the mechanical packer is achieved by compressing the ends of the tubular member towards each other. Mechanical packers usually do not achieve high expansion ratios and do not operate at pressures as high as inflatable packers. In the context of the present invention mechanical packers are not capable of swaging the standpipe to seal against the pilot hole;

• “pilot hole” in the context of the present invention refers to hole drilled in the ground formation for receiving the standpipe. The pilot hole is typically 2 to 4 metres long;

• “pressure” in the context of the present invention is a reference to differential pressure, between the pressure inside the standpipe or its setting tool and the pressure outside the standpipe or setting tool;

• “high-pressure” in the context of the present invention typically refers to water pressure of more than about 10 MPa and up to around 100 MPa, and “low-pressure” refers to water pressure below about 500 kPa. In relation to swaging with inflatable packers used in the present invention high-pressure is around 70 MPa;

• “shallow” in the context of the pilot hole of the present invention, refers to a distance of less than about 5 metres; • “standpipe” in the context of the present invention refers to a pipe that is disposed substantially horizontally in a ground formation during tunnelling and underground mining. The standpipe is used to deliver grout into the ground formation, such as, for example, to stabilise ground ahead of and around a tunnel as it is being excavated;

• “standpipe” disambiguation: it is to be noted that the term standpipe is also used in relation to plumbing and delivery of water services in the operation of a building or in delivering water into a tunnel. The use of the term standpipe for delivery of water is entirely different to and it not analogous to the use of the term standpipe in the present invention. The main reason for the difference is that in the context of the present invention the standpipe is sealed and anchored into a pilot hole bored in the ground, and filled with set grout to prevent the flow of water through it and so is incapable of allowing the passage of water. That is, the standpipes of the present invention are opposite to the standpipes known for use in plumbing;

• “substantially horizontal” in the context of the present invention means in a generally horizontal direction, and can be 10 to 20 degrees from the horizontal. Generally, the pilot and grout holes referred to in the present invention diverge from the path of a tunnel, they are used in connection with, by 10 to 20 degrees. In the event that the tunnel is not horizontal, then “substantially horizontal” refers to radiating outwardly from the tunnel at an angle of 10 to 20 degrees to the longitudinal direction of the tunnel;

• “swage” in the context of the present invention means the use of outward expanding force to enlarge the diameter of a tubular component such as a standpipe. Swage in the context of the present invention does not relate to swage connections or swaging to make tubular components smaller in diameter;

• “swaging” in the context of the present invention means the act of increasing the diameter of a tubular such as a standpipe by the use of an expanding inflatable packer or by explosive force. More particularly, swaging, in the context of the present invention, relates to sealing between a standpipe and a pilot hole in the ground, by the act of swaging; and

• “unitary construction” in the context of inflatable packer elements of the present invention means that the inner bladder, reinforcing and outer cover of the element are fused together into a single unit, such that they expand and contract as a single unit, which tend to make it very well suited to multiple inflation and deflation cycles.

[0005] It is important to note that the expandable standpipes of the type of the present invention typically have a wall thickness of around 10 mm and are made of ductile metal materials that are amenable to swaging to increase the diameter of the standpipes. Conventional standpipes used in pressure grouting, and the like, are made from non-ductile metal materials, due to their desire for lower cost, and are not able to be swaged to increase their diameter. [0006] It is also important to note that the standpipes of the type of the present invention include an outer cover made of resilient material for assisting the standpipe in confirming to, sealing to and anchoring to the interior of the pilot hole once swaging is complete.

BACKGROUND OF THE INVENTION

PRESSURE GROUTING

[0007] In the art of excavations, such as tunnelling and underground mining and the like, it is common to set “grout curtains” around and ahead of the tunnel when encountering unstable ground formations. The curtains are used to stabilise the ground formation and to reduce the flow of ground water into the tunnel, during its construction. This art is often referred to as strata consolidation. For a detailed understanding of this technology refer to Knut F. Garshol Pre- Excavation Grouting in Rock Tunneling, copyright 2003 by MBT International Underground Construction Group, Division of MBT (Switzerland) Ltd (available from https://www.academja.edu/8ie72ee/Pre Excavation Grouting In Rock Tunneling Fre Excav afion Grouting in Rock Tunneling). This art is often referred to as pressure grouting.

[0008] Stabilisation is achieved by pumping grout into the ground formation. In simple, lower- pressure situations pilot holes are drilled into the ground formation and mechanical packers inserted and expanded (typically with a turnbuckle) to seal against the ground formation and allow grout to be pumped into the ground formation. In more difficult, high-pressure situations, with ground water of 6 MPa (60 bar) or more, expanding mechanical packers into the holes drilled in the ground formation are not effective, because either the packers slip out or the high-pressure water passes around the packer. Such mechanical packers have a typical length of 0.5 to 1 .0 metres. At these high-pressures delivery of grout into the ground formation requires the use of standpipes.

[0009] Prior art standpipes are cylindrical and typical have a length of about 2 to 4 metres, an outer diameter of about 66 mm and an inner diameter of about 55 mm. The standpipe is inserted into a substantially horizontal pilot hole having a diameter of about 76 mm drilled into the ground formation. Patterns of such holes are typically drilled ahead of the tunnel, in an outwardly radiating manner at an angle or around 10 degrees for a horizontally disposed tunnel. Since the ground formation is unstable the pilot hole tends to wander, hence the hole is typically 10 mm, or more, larger in diameter than the standpipe.

[0010] In the prior art the annulus between the standpipe and the pilot hole is filled with grout which is allowed to set to prevent the flow of water out of the ground formation and into the tunnel being bored, via the annulus. The grout is typically a high-quality shrinkage compensated cement grout. So-called grouting of the standpipe is typically done by locating a mechanical packer both proximate the downhole end of and inside the standpipe. Typically, the mechanical packer is located a few metres from the out of hole end of the standpipe. Then grout is pumped through the standpipe to the end of the pilot hole. The grout then flows into the annular space between standpipe and pilot hole, back along the standpipe until the grout begins to pump out of the annular space between the standpipe and the pilot hole into the tunnel.

[0011] Once set in place and primed with grout, prior art standpipes must then be left for the grout to cure. The cement grout (typically in the form of Portland cement) typically requires about 24 hours to set/cure to a hardness of 10 to 20 MPa, in order to provide an adequate seal between the standpipe and the pilot hole. If adequate hardness is not attained, then further drilling for pumping a curtain of cement grout into the ground formation is dangerous and cannot proceed.

[0012] For this purpose pressure testing of the grouted standpipe is often done after 24 hours curing time. If the standpipe fails the pressure test, then that standpipe is abandoned and a new pilot hole, standpipe and grouting process is undertaken and retested after another 24 hours curing time. Water pressure testing is typically carried out at 1 MPa, however, if there is high pressure water in the ground formation then testing at much higher pressures are required - up to 10 MPa in some cases.

[0013] The purpose of the pressure testing is to ensure that the standpipe will not be pushed out of the pilot hole by either the weight of the grout that is supports or by the pressure of water that may exist in the ground formation around the grout curtain. The pressure testing is also to ensure that the standpipe will not leak water out of the ground formation into the tunnel.

[0014] Once the standpipe passes the pressure test a grouting hole can be drilled through the standpipe and into the ground formation. The grouting hole is typically around 25 metres long; much longer than the pilot hole that contains the standpipe. Then a pump is attached to the standpipe and grout can be injected into the ground formation via the standpipe and the grout hole to form a curtain of grout in the ground formation ahead of and around the direction of excavation of a tunnel. A typical curtain may include several tonnes of grout, such as, for example, about 4 tonnes.

[0015] The grout around the standpipe is also needed to anchor the prior art standpipes into the ground formation to prevent them being forced out of the shallow pilot hole when grout is pumped into the grout hole and the ground formation. The anchoring also prevents high ground water pressure forcing the standpipe out of the pilot hole. [0016] Once the curtain has set the tunnel can be excavated a further distance into the ground formation within the safety and stabilising effect of the grout curtain. Typically, the distance of advancement of the tunnel is less than the distance of the grout curtain, so as to ensure that further operations remain under the safety of the grout curtain that has already been injected, set and tested. This avoids flooding or collapse of the tunnel where the ground formation has not yet been stabilised or rendered impermeable to high pressure water.

[0017] In the prior art of forming tunnels, typically between 4 and 16 standpipes are grouted around and ahead of the path of the tunnel in a ring type structure. The number of standpipes is typically increased in proportion to the pressure of the water encountered while drilling probe holes in the direction of construction of the tunnel and the porosity of the ground formation. Typically, standpipes are grouted into 4 primary perimeter holes around the tunnel, and if excessive water ingress is encountered 4 secondary standpipes are set and grouted, and if still further water is encountered a set of 4 tertiary standpipes are also set and grouted. Once the water encountered is below a trigger rate of flow no further standpipes are installed and the tunnel can be advanced by further excavations.

[0018] The main disadvantage of prior art standpipes and grouting techniques for tunnelling is the time needed for the grout to set around the standpipe before the grout holes can be drilled and additional grout pumped in to stabilise the ground formation. This is particularly troublesome in ground formations that are prone to high pressure water. Also, in the event the standpipe fails its pressure test, another standpipe has to be installed, requiring further time for curing of grout to seal and anchor the standpipe into the ground formation.

[0019] The present invention seeks to overcome the disadvantages of the prior art standpipes, by using a swage seal to anchor and seal the standpipe into the ground formation. Hence, grout is not needed to seal and anchor the standpipe of the present invention into the ground formation. This has the advantage of being much faster to set the expandable standpipe (typically less than 1 hour, more typically less than 30 minutes) and so grouting of the ground formation can occur much sooner than in prior art standpipe techniques and advancement of excavations is much faster (by up to 24 hours per ring of standpipes), thus reducing the overall cost of excavation operations.

SWAGEABLE SEALS

[0020] It is known to swage expand pipes in downhole applications, such as drilling for oil or water, by using mandrels pulled or driven from a distal end towards a proximal end of the pipe, to gradually expand the pipe as the mandrel moves through the pipe. Examples of these include US6457532 and US9702229. However, these types of swaging are not suitable for short pipes such as expandable standpipes.

[0021] In particular, the expandable standpipe of the present invention is used in a very shallow substantially horizontal hole (typically less than 5 metres in length), whereas the swage expanding pipes of the prior art are used in a deep at least partly vertical hole (typically more than 100 metres deep). The consequence of the much greater depth of the prior art holes is that the weight of metal tubing upstream of the portion of the pipe that is to be swaged resists the tendency of the pipe string to come out of the hole as the mandrel is pulled through the pipe.

UNITARY CONSTRUCTION INFLATABLE PACKER ELEMENTS

[0022] Most conventional prior art inflatable packer elements are made in three components, being a separate inner bladder, a separate reinforcing layer and a separate outer cover layer, whereby the three layers expand and contract according to their own characteristics, which tends to lead to failure of the element with multiple inflation and deflation cycles. The characteristics of the separate layers of such prior art inflatable packers tends to inhibit their ability to deflate to their original diameter, thus risking the inflatable packer becoming stuck in a pipe in which it is operated. Also, these multiple layer inflatable packers do not tend to perform well at the high pressures (around 70 MPa) required to expand ductile standpipes (having a wall thickness of around 10 mm).

[0023] By way of contrast the inflatable packers used in the setting tool of the present invention are of unitary construction, having been vulcanised to fuse the inner bladder, reinforcing and outer cover together into a single unit. The consequence of this fusion is that the fused components expand and contract as a single unit, which tend to make the unitary construction inflatable packer very well suited to multiple inflation and deflation cycles, especially at high differential pressure.

SUMMARY OF THE INVENTION

[0024] Therefore, it is an object of the present invention to provide apparatus and methods of sealing and anchoring expandable standpipes and of grouting ground formations by using expandable standpipes having swage seals, thus obviating the need for grout setting of the expandable standpipes prior to injecting grout into the ground formation. [0025] In accordance with one aspect of the present invention, there is provided a method of anchoring and sealing an expandable standpipe into a ground formation, including the steps of: forming a shallow pilot hole into the ground formation; inserting the expandable standpipe most of the way into the pilot hole; and expanding the standpipe radially outwardly to anchor and seal into the pilot hole; whereby expanding the standpipe causes it to anchor and seal into the ground formation without the need for grout.

[0026] Typically, the expandable standpipe has a swage seal that is expandable radially outwardly under internally applied pressure.

[0027] Typically, the swage seal is located proximate the blind end of the pilot hole.

[0028] Typically, an inflatable packer is used to expand the swage seal to anchor and seal into the pilot hole.

[0029] Typically, the pilot hole has a diameter of between 75 mm and 150 mm, for example, about 90 mm.

[0030] Typically, the grout hole has a diameter of between 30 mm and 60 mm, for example, about 45 mm.

[0031] Typically, the grout hole has a diameter about half of the diameter of the pilot hole.

[0032] Typically, the inflatable packer is of unitary construction and capable of multiple cycles of inflation and deflation, whilst returning substantially to its original diameter and without failure.

[0033] It is advisable to ensure there is no debris in the pilot hole before inserting the standpipe, otherwise the debris can beckon stuck in the standpipe and inhibit expansion of the swage seal.

[0034] In accordance with another aspect of the present invention, there is provided a method of grouting ground formation with an expandable standpipe, the method of grouting ground formation including the steps of: forming a shallow pilot hole into the ground formation; inserting the expandable standpipe most of the way into the pilot hole; expanding the standpipe radially outwardly to anchor and seal into the pilot hole; forming a grout hole through a bore of the expandable standpipe into the ground formation ahead of the pilot hole; and injecting grout through the standpipe and through the grouting hole into the ground formation; whereby expanding the standpipe causes it to anchor and seal into the ground formation, without the need for grout.

[0035] Typically, the pilot hole is formed by drilling.

[0036] Typically, the pilot hole has a length about the same length as the standpipe.

[0037] Typically, the standpipe is inserted into the pilot to a depth that leaves a space of between 150 mm to 500 mm, for example, about 300 mm, between an inserted end of the standpipe and the blind end of the pilot hole.

[0038] Typically, the expandable standpipe has a swage seal that is expandable under internally applied pressure.

[0039] Typically, the swage seal is positioned proximate the blind end of the pilot hole.

[0040] Typically, an inflatable packer is used to expand the swage seal radially outwardly to anchor and seal into the pilot hole.

[0041] Typically, the inflatable packer is of unitary construction and capable of multiple cycles of inflation and deflation, whilst returning substantially to its original diameter and without failure.

[0042] In accordance with another aspect of the present invention, there is provided a grout free expandable standpipe for anchoring and sealing into a pilot hole in a ground formation without grout, the expandable standpipe being useful for pumping grout into a grout hole in the ground formation, the expandable standpipe comprising: an elongate tube comprising a delivery tube connected endwise to a swage tube, the elongate tube being dimensioned for insertion into the pilot hole, the elongate tube also comprising a bore which passes through the delivery tube and the swage tube, the bore being capable of receiving a setting tool for expanding the swage tube and for receiving a drill rod for drilling a grout hole, about half the diameter of the pilot hole, through a blind end of the pilot hole; the delivery tube being configured for inserting the elongate tube into the pilot hole, and the delivery tube being able to project, when in use, out of the pilot hole; and, the swage tube being disposable in the pilot hole to a position proximate the blind end of the pilot hole, the swage tube being expandable radially with an inflatable packer element to contact the pilot hole; and a swage seal located on the external curved surface of the end of the elongate tube proximate the blind end of the pilot hole, the swage seal being expandable radially outwardly to anchor and seal the standpipe into the pilot hole; wherein anchoring and sealing of the expandable standpipe into the ground formation does not require grout; and wherein grout can be pumped through the expandable standpipe and into the grout hole for stabilising the ground formation around the grout hole.

[0043] Typically, the swage seal is ductile for expanding radially outwardly without fracturing or splitting.

[0044] Typically, the swage seal is made of ductile metals materials, such as ductile stainless steel.

[0045] Typically, the swage seal has an elastomer layer on its outer curved surface.

[0046] Typically, an expansion tool is removably inserted into the standpipe and expanded radially outwardly to expand the swage seal.

[0047] Typically, the expansion tool is a swage packer. More particularly, the expansion tool includes an inflatable packer configured as a swage packer.

[0048] Typically, the inflatable packer is of unitary construction and capable of multiple cycles of inflation and deflation, whilst returning substantially to its original diameter and without failure.

[0049] In accordance with another aspect of the present invention, there is provided a grout free expandable standpipe system for pumping grout into a grout hole in formed in a ground formation, the expandable standpipe system comprising: an elongate tube comprising a delivery tube connected endwise to a swage tube, the elongate tube being dimensioned for insertion into the pilot hole, the elongate tube also comprising a bore which passes through the delivery tube and the swage tube, the bore being capable of receiving a setting tool for expanding the swage tube and for receiving a drill rod for drilling a grout hole, about half the diameter of the pilot hole, through a blind end of the pilot hole; the delivery tube being configured for inserting the elongate tube into the pilot hole, and the delivery tube being able to project, when in use, out of the pilot hole; and, the swage tube being disposable in the pilot hole to a position proximate the blind end of the pilot hole, the swage tube being expandable radially with an inflatable packer element to contact the pilot hole; and a swage seal located on the external curved surface of the end of the elongate tube proximate the blind end of the pilot hole, the swage seal being expandable radially outwardly to anchor and seal the standpipe into the pilot hole; a setting tool comprising an inflatable packer element locatable within the standpipe for expanding the swage seal into contact with the pilot hole, the setting tool being removable from the standpipe once the swage seal is expanded; and a high-pressure pump connected to the setting tool for inflating and deflating the inflatable packer; wherein anchoring and sealing of the expandable standpipe into the ground formation does not require grout; and wherein grout can be pumped through the expandable standpipe and into the grout hole for stabilising the ground formation around the grout hole.

[0050] In one example, the expansion tool (also referred to as a setting tool) includes an inflatable swage packer.

[0051] In another example, the expansion tool includes a high energy rate device (HERD) capable of rapidly expanding the swage seal into contact with the interior wall of the pilot hole. The HERD could be high pressure liquid, such as water, explosively injected into the swage seal. Alternatively, the HERD could be an explosive charge located in the bore of the swage seal and detonated to cause the swage seal to expand.

[0052] Throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Likewise, the word “preferably” or variations such as “preferred”, will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention. [0053] Unless the context requires otherwise reference to a standpipe or the standpipe is equivalent to a grout free expandable standpipe or the grout free expandable standpipe.

DETAILED DESCRIPTION OF THE DRAWING(S)

[0054] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawing, in which:-

[0055] Figure 1 is a part cross-sectional side cut-away view of a grout free expandable standpipe, in accordance with the present invention, shown located in a pilot hole in a ground formation, the standpipe being in an insertion state of operation;

[0056] Figure 2 is a part cross-sectional side cut-away view of the standpipe of Figure 1 , shown with a setting tool in the form of an inflatable swage packer expanded within the standpipe for swaging a swage seal of the standpipe;

[0057] Figure 3 is a cross-sectional side view of a swage seal of the standpipe of Figure 1 , shown to a smaller scale and including an anchor coupling;

[0058] Figure 4 is a cross-sectional side view, taken on section lines A-A of Figure 5, of the inflatable swage packer of Figure 2 (setting tool), shown in a deflated mode of operation;

[0059] Figure 5 is a side view of the inflatable swage packer of Figure 4, shown to a smaller scale;

[0060] Figure 6 is a part cut-away view of the standpipe of Figure 1 , shown installed into a pilot hole in a ground formation and with a grout hole formed through the blind end of the pilot hole; and

[0061] Figures 7 to 9 are schematic cut-away side views of the standpipe of Figure 1 , showing respectively, insertion of the standpipe, inflation of the swage packer to expand the swage seal of the standpipe, and removal of the swage packer to reveal the swaged standpipe anchored in the ground formation;

[0062] Figures 10 to 16 show the steps of use of the grout free expandable standpipe of the present invention;

[0063] Figure 10 is a part cut-away side view of the standpipe of Figure 1 , shown inserted into a pilot hole in a ground formation;

[0064] Figure 11 is a part cut-away side view of the standpipe of Figure 1 , shown with a setting tool temporarily inserted into the standpipe;

[0065] Figure 12 is a part cut-away side view of the standpipe of Figure 1 , shown with the standpipe expanded with the setting tool to seal into the pilot hole, without the use of grout; [0066] Figure 13 is a part cut-away side view of the standpipe of Figure 1 , shown with the setting tool removed and being pressure tested, with non-settable liquid, for testing the integrity of the seal of the standpipe against the pilot hole;

[0067] Figure 14 is a part cut-away side view of the standpipe of Figure 1 , shown with a drill inserted through the standpipe for drilling a grout hole in the ground formation in advance of the standpipe;

[0068] Figure 15 is a part cut-away side view of the standpipe of Figure 1 , shown with grout pumped through the standpipe and through the grout hole and into the ground formation around the grout hole;

[0069] Figure 16 is a part cut-away side view of the standpipe of Figure 1 , shown with a standpipe extension of the standpipe removed from the standpipe;

[0070] Figure 17 is a perspective view, seen from above, of a grout free expandable standpipe system of the present invention, including the expandable standpipe of Figure 1 , the setting tool of Figures 4 and 5, and a high-pressure pump, both the standpipe and the setting tool are shown with their in-hole end front most;

[0071 ] Figure 18 is a perspective view of the standpipe of Figure 1 , shown with its out-of hole end front most;

[0072] Figure 19 is a perspective view of the setting tool of Figures 4 and 5, shown with its out-of hole end front most;

[0073] Figure 20 is a perspective view of the out-of hole end of the setting tool of Figure 18, shown to a larger scale; and

[0074] Figure 21 is a cross sectional perspective view of the setting tool of Figure 19.

[0075] In the drawings like reference numerals are used to identify like parts.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT(S)

[0076] Further features of the present invention are more fully described in the following detailed description of several non-limiting embodiments. This detailed description is included solely for the purposes of exemplifying the present invention to the skilled addressee. This detailed description is not to be understood as a restriction on the broad summary, disclosure or description of the invention as set out above.

[0077] Shown in the drawings is one exemplary embodiment of a grout free expandable standpipe 10 in accordance with the present invention. [0078] Particularly as shown in Figure 1 , the standpipe 10 comprises a delivery tube 12 and a swage tube 14. The standpipe 10 is shown inserted in a pilot hole 16 in a rock wall 18.

[0079] The pilot hole 16 is formed, typically by drilling or boring, into a ground formation 22, such as, for example, a tunnel face of a tunnel that is under construction. Typically, the pilot hole 16 has an internal diameter of about 89 mm and is shallow, having a blind end 20 located less than 5 m into the ground formation 22 as measured from the rock wall 18. Typically, the pilot hole is 2 to 4 metres long. The pilot hole 16 is disposed substantially horizontally and diverged from the longitudinal axis of the tunnel, such that a pattern of pilot holes 16 distributed evenly around an advancing tunnel form a substantially frustoconical ring that has its widest extent foremost from the tunnel face.

[0080] The delivery tube 12 is elongate and has two externally threaded pin ends 30 and 32. Typically, the delivery tube 12 is in the form of well casing pipe. Typically, the threads of the pin ends 30 and 32 are API threats. Typically, the delivery tube 12 is made from schedule 40 or SCH 80 grade carbon steel, with an external diameter of about 73 mm and a length of about 2 m to 4 m, although other lengths could be used. The delivery tube 12 typically has a wall thickness of about 10 mm. The delivery tube 12 is not prone to deforming or expanding radially outwardly at the pressure of operation of the expandable standpipe 10. That is the delivery tube 12 does not need to be ductile.

[0081] The swage tube 14 comprises a tube 40 about which is formed an elastomeric cover, conveniently in the form of a vulcanised rubber cover 42. The rubber cover 42 and the portion of the tube 40 covered by the rubber cover 42 together constitute a swage seal 43 of the present invention. The swage tube 14 also has a bore 44, an in-ground end 46 and a centraliser 48, located opposite the in-ground end 46. The centraliser 48 is in the form of a box and is internally threaded to receive the pin end 32 of the delivery tube 12. The centraliser 48 typically has an external diameter of about 86 mm.

[0082] Typically, the tube 40 is made of ductile metal materials such as, for example, stainless steel, conveniently schedule 10 stainless steel of grade 304 or 316 can be used to make the tube 40. The ductility of the tube 40 is essential to allow the swage seal 43 to expand radially outwardly into contact with the internal surface of the pilot hole 16, as described hereinafter.

[0083] Typically, the tube 40 has an external diameter of about 62 mm. Typically, the tube 40 is a pipe of circular cross-section and constant internal dimension along its length. However, when the tube 40 is expanded the expanded portion of the tube 40 has a large cross-section area than the remainder of the tube 40.

[0084] Typically, the rubber cover 42 is vulcanised and has a castellated longitudinal cross- section. The castellations include recurring pairs of peaks and troughs, each of substantially square or rectangular cross-section, as shown in Figure 3. The castellations allow the rubber cover 42 to better conform to the shape of the inside of the pilot hole 16, and thereby achieve a better seal with the ground formation 22 around the swage tube 14. The castellations also achieve better anchoring of the swage seal 43 into the pilot hole 16, since they provide higher friction engagement of the swage seal 43 with the pilot hole 16. If the castellations and/or the rubber cover 42 were omitted the standpipe would be prone to sliding out of the pilot hole 16, even after radial expansion of the swage seal 43. Typically, the rubber cover 42 has a length of about 1200 mm and a thickness of about 10 to 15 mm. The rubber cover 42 extends around the external surface of the tube 40 adjacent it’s in-ground end 46. The external diameter of the rubber cover 42 is about 86 mm.

[0085] Typically, the swage tube 14 has a length of approximately 2 m.

[0086] Typically, the overall length of the expandable standpipe 10 is approximately 4 m to 6 m, although other lengths could be used.

[0087] Particularly as shown in Figure 3, the standpipe 10 conveniently also comprises an anchor coupling 50 threadedly attached to the free end of the delivery tube 12. The anchor coupling 50 is conveniently made from metal materials, such as, for example, carbon steel or stainless steel. The coupling 50 has two flanges 52, disposed in opposite directions and each with a hole 54 dimensioned for attachment of a delivery machine or drilling jumbo (not shown), for manipulation of the standpipe 10 into and/or out of the ground formation 22.

[0088] The swage tube 14 is intended for use with an expansion setting tool conveniently in the form of a swage packer tool 60, as shown in Figures 2 and 8. Typically, the swage packer tool 60 is an inflatable swage packer capable of being inflated by a high-pressure fluid, typically, in the form of water or oil delivered by a high-pressure pump 61. The swage packer tool 60 is capable of operation at inflation pressures up to about 70 MPa. More particularly, the swage packer tool 60 is operated at fluid pressures of above about 50 MPa for swaging the swage tube 14

[0089] The swage packer setting tool 60 comprises a top connector 62, a push rod 64 and an inflatable packer 66. As shown in Figures 2, 4 and 5 the top connector 62 typically has an external diameter that is larger than the internal diameter of the delivery tube 12. The push rod 64 is of sufficient length to be able to dispose the inflatable packer 66 within the bore 44 of the rubber cover 42 of the swage tube 14. Typically, the push rod 64 is about 2.5 m to 4.5 m long.

[0090] Particularly as shown in Figures 3 and 4 the top connector 62 has a central flow path 70 for the flow of high-pressure inflation fluid for inflating the packer 66. The top connector 62 also has two lift rings 72 for manipulation of the standpipe 10 via a lifting machine. Typically, the top connector 62 is threaded to one end of the push rod 64. [0091] The push rod 64 is cylindrical and elongate and has a bore 76 for communication of fluid from the top connector 62 to the inflatable packer 66. Typically, the push rod 64 has an external diameter of about 43 mm and a wall thickness of about 9 mm.

[0092] The inflatable packer 66 comprises a packer mandrel 80 conveniently in the form of a solid rod having a ferrule 82 at its upstream end and a ferrule 84 at its downstream end. The inflatable packer 66 also comprises a packer element 86 secured between the ferrules 82 and 84, and a top sub 87 for connecting the inflatable packer 66 to one end of the push rod 64 opposite the top connector 62. The inflatable packer 66 also has an annular cavity 88 located between an inside curved surface of the packer element 86 and an external curve surface of the packer mandrel 80. The cavity 88 is in fluidic communication with the push rod 64 via inflation galleries 90 in the top sub 87. The inflatable packer 66 also has a sliding end sub 92 to which the ferrule 84 is threadedly engaged. The sliding end sub 92 is capable of sliding along the packer mandrel 80 to accommodate expansion of the packer element 86. The inflatable packer 66 also has various CD- ring seals indicated in figure 2 as small square black elements. The O-ring seals are required to permit the inflatable packer 66 to operate at inflation pressures of up to approximately 70 MPa, without leaking.

[0093] The packer element 86 is conveniently made of wire reinforced rubber material and is capable of expanding under inflation pressure and contracting once the inflation pressure is removed. The packer element 86 typically has an external diameter of about 55 mm and a thickness of about 20 mm. The packer element 86 is capable of supplying sufficient outward radial force to plastically deform the swage tube 14 to cause the swage tube 14 to expand radially outwardly to engage with the interior of the pilot hole 16 proximate the blind end 20.

[0094] Typically, the packer element 86 has an effective length of about 1 m, a non-inflated diameter of about 55 mm and an inflated diameter of about 75 to 80 mm. That is, the packer element 86 is capable of expansion to more than about 130% of its original diameter, and more particularly up to about 150% of its original diameter. Also, the packer element 86 must be reusable multiple times and must be able to contract from its expanded diameter to approximately 100% of its original diameter. To achieve these specifications the packer element 86 needs to be of unitary construction. Primarily unitary construction requires that the packer element 86 be vulcanised to fuse its inner bladder, reinforcing and outer cover together into a single unit. The consequence of this fusion is that the fused components expand and contract as a single unit, which tend to make the unitary construction packer element very well suited to multiple inflation and deflation cycles, especially at high differential pressure.

[0095] It is to be noted that the swage tube 14 is hollow and its bore 44 is in fluidic communication with the pilot hole 16. Consequently, a grout hole 96 can be formed, such as by drilling, through the bore 44 of the swage tube 14 and into the ground formation 22 at the blind end 20 of the pilot hole 16, for delivery of grout into the ground formation 22. The grout hole 96 has a blind end 98 distant from the standpipe 10. Typically, the length of the grout hole 96 is from 15 m to 50 m, more particularly from 20 m to 30 m, such as, for example, approximately 25 m, although other lengths could be used. The grout hole 96 is typically coaxial with the pilot hole 16.

[0096] The high-pressure pump 61 is conveniently of conventional type as used for inflating high pressure inflatable packer elements with liquid to pressures of between about 40 and 70 MPa.

USE

[0097] In use, the standpipe 10 of the present invention is used when building underground tunnels or other subterranean excavations, including underground mining and the like.

[0098] More generally, the grout free standpipe 10 of the present invention can be used in various applications, including, but not limited to:

• groundwater control in tunnelling and mining;

• pre-excavation grouting;

• high pressure curtain grouting;

• underground exploration drilling; and

• tunnel construction using tunnel boring machines.

[0099] The method of operation of the standpipe 10 of the present invention is conveniently shown in Figures 7 to 9 and more particularly in Figures 10 to 16.

[0100] The steps of operation of the grout free standpipe 10 of the present invention comprise:

• drilling the pilot hole 16 into the ground formation 22 (Figure 10);

• inserting the standpipe 10 into the pilot hole 16 to a depth wherein the standpipe 10 is proximate the blind end 20 of the pilot hole (Figure 10);

• inserting the setting tool 60 into the standpipe 10 (Figure 11);

• connecting the high-pressure pump 61 to the setting tool 60 (Figure 17);

• inflating the packer element 86 to expand the swage seal 43 to anchor and seal against the inside of the pilot hole 16, without the need for grout (Figure 12);

• removing the setting tool 60 from the standpipe 10 and connecting the pump 61 to the standpipe 10 and pressure testing the standpipe 10 to ensure that injected liquid does not leak out between the standpipe 10 and the pilot hole 16 into the tunnel (Figure 13);

• inserting a drill 100 through the standpipe 10 and drilling the grouting hole 96 into the ground formation 22 (Figure 14);

• removing the drill 100 from the standpipe 10, connecting the standpipe to a grouting pump (not shown) and pumping grout through the standpipe 10, into the grout hole 96 and into the ground formation 22 around the grout hole 96. [0101] Following is further detail of the above steps of operation of the standpipe 10.

[0102] The pilot hole 16 is drilled into the rock wall 18 in the advancing face of the tunnel or about the periphery of the tunnel, where it is desired to inject grout into the ground formation 22 in the vicinity of the tunnel so as to consolidate and stabilise the ground formation 22. Typically, the pilot hole 16 is drilled to a depth of about 4 m where the standpipe 10 has a length of about 4 m.

[0103] It is advisable to ensure there is no debris in the pilot hole 16 before inserting the standpipe 10, otherwise the debris can become stuck in the standpipe 10 and inhibit both insertion of the standpipe 10 and expansion of the swage seal 43.

[0104] Next the standpipe 10 is inserted into the pilot hole 16, leaving a gap of between 150 mm and 500 mm to the blind end 20 of the pilot hole 16. In this arrangement the standpipe 10 is orientated with its swage tube 14 and swage seal 43 approximate the blind end 20.

[0105] The inflatable swage packer setting tool 60 is then inserted into the standpipe 10 with its inflatable packer element 86 disposed within the bore 44 of the rubber cover 42 of the swage seal 43.

[0106] The end of the inflatable swage packer tool 60 that is protruding from the standpipe 10 is then connected to the high-pressure pump 61 via a shut off valve (not shown). The pump 61 is then turned on and the inflatable packer 66 injected with water or oil, or other non-settable inflation liquid, at high-pressure so as to inflate the packer element 86. The inflation causes the packer element 86 to expand and meet the internal curved surface of the swage seal 43. The water (or oil) pressure is continued to increase to between about 40 and 70 MPa, which causes the swage seal 43 to be plastically deformed and to expand radially outwardly to contact the internal curved surface of the pilot hole 16. This inflation causes the rubber cover 42 of the swage seal 43 to anchor and seal into the pilot hole 16, which inhibits removal of the standpipe 10 from the pilot hole 16 and inhibits flow of liquids, such as groundwater, out of the pilot hole 16 via the annular space between the delivery tube 12 and the pilot hole 16.

[0107] The pressure in the pump 61 is then reduced in order to deflate the packer element 86. Then the inflatable swage packer tool 60 can be withdrawn from the standpipe 10. The swage seal 43 has been fully swaged into engagement with the pilot hole 16 and is available and ready for grouting operations into the ground formation 22.

[0108] Next the pump 61 is connected to the standpipe 10 and water or oil pumped in to test whether any liquid leaks passed the swage seal 43 and out of the pilot hole 16 via the annular space that remains between the delivery tube 12 and the pilot hole 16. The swage seal 43 leak test is usually performed with the pump delivering liquid at up to 10 MPa. If there is no or little leakage then the standpipe is considered adequately anchored and sealed into the pilot hole 16. If there is an unacceptable amount of water leaking out of the pilot hole 16 then another pilot hole 16 has to be drilled, another standpipe 10 inserted into the new pilot hole 16, swaged into sealing connection with the new pilot hole 16 and then pressure tested.

[0109] The process of inserting, inflating, and removing the swage tool 60 from the standpipe 10, and pressure testing the integrity of the seal of the swage seal with the pilot hole 16, typically takes less than 30 minutes.

[0110] When the standpipe 10 passes the pressure test, the grout hole 96 can then be drilled by passing the drill 100 through the bore 44 of the swage tube 14 into drilling into the ground formation 22 to a distance of typically around 25 m.

[0111] It is to be noted that there is no delay between the swaging of the swage tube 14 and the drilling of the grout hole 96. This is in stark distinction to prior art standpipes which require grouting to seal the standpipe into the pilot hole.

[0112] Next a grout pump is threadedly connected to the connector 50 and provided with a source of grout for delivery into the ground formation 22 through the standpipe 10 and the grouting hole 96. Typically, a quantity of grout equal to about 4 tonnes is injected into the ground formation 22 in a single grouting operation for each standpipe 10, for 25 meter grout holes 96.

[0113] Once the grout operation has ended the shut off valve is turned to the off position, which prevents flow of the grout out of the ground formation 22 through the bore of the standpipe 10. The pump can then be disconnected from the standpipe 10 and moved to another standpipe 10 for further grouting operations.

[0114] Such delivery of grout has the effect of producing part of a curtain of grout into the ground formation 22 in the vicinity of the advancing tunnel.

[0115] Typically, a number of such standpipe installations are performed during each stage of a tunnelling operation. The number of standpipe installations used typically varies between 4 and 16 depending on the condition of the ground formation 22 and the amount and pressure of water contained within the ground formation 22.

[0116] Once the grout in the curtain has cured and hardened tunnelling operations can recommence. Such curing typically takes a period of up to about 24 hours. It is to be noted that the grout curtain extends approximately 25 m in front of the current tunnel excavations. Once the grout is cured tunnelling can be recommenced a distance of around 20 m. The tunnelling distance is less than the grout curtain so as to provide some safe working area for another series of standpipes to be installed around the tunnel for producing another set of standpipes and grout holes 96 to form another grout curtain. By terminating the tunnelling within the confines of the grout curtain further tunnelling operations can safely be conducted and the ingress of water into the tunnel kept to a minimum. [0117] It is to be noted that standpipes 10 can be installed ahead of the tunnel advancement in drill and blast operations. In this case the standpipes 10 are destroyed during blasting and mined out during excavation.

[0118] In tunnelling operations that use a tunnel boring machine (TBM), the standpipes 10 are installed around the tunnel so that the TBM cutting head does not hit the steel of the standpipes 10

[0119] It is envisaged that the pilot holes 16 and the grout holes 96 could be drilled with a machine, such as, for example a hydraulic driller machine or a drilling jumbo or formed by other means.

[0120] It is envisaged that the delivery tube 12 and shutoff valve of the standpipe 10 could be unthreaded from the swage tube 14 after the grout curtain has set. In this way, the pipes 12 and the shutoff valves can be retrieved from the standpipes 12, cleaned out to remove the grout that is set in them, and reuse in subsequent tunnelling operations.

EXAMPLES

[0121] The following numbered examples are further embodiments of the present invention.

1. The standpipe 10 described herein above, wherein the expansion tool is a high energy rate device (HERD) capable of rapidly expanding the swage tube 14 into contact with the interior wall of the pilot hole 16.

2. The standpipe 10 described in example 1 , wherein the HERD is high pressure liquid, such as water, explosively injected into the swage tube 14.

3. The standpipe 10 described in example 1 , wherein the HERD is an explosive charge located in the bore 44 of the swage tube 14 and detonated to cause the swage tube 14 to expand into contact with the pilot hole 16.

4. The standpipe 10 described in example 1 , wherein a blowout preventor (BOP) is attached to the upstream end of the standpipe 10 for providing “wellhead control” by allowing management of high-pressure ground water encountered during underground exploration boreholes, such as in mining or construction or tunnelling. In this example drill-through blow-out preventers and shut-off valves, known in the art, are also required for controlling flow of water from boreholes in the ground formation 22.

INDUSTRIAL APPLICABILITY

[0122] The grout free expandable standpipe 10 of the present invention, and its method of use, are suitable for use in injecting grout into a ground formation 22 for producing a grout curtain to protect the construction of a tunnel in the ground formation 22 and for stabilising ground formations 22 in subterranean mining operations and the like. [0123] The grout free expandable standpipe 10 of the present invention, and its method of use, reside and operate in the fields of civil and mechanical engineering and more particularly in the field of underground tunnel construction and more particularly in the field of strata consolidation.

[0124] The consequence of the use of the grout free expandable standpipe 10 of the present invention, is that grout is not needed for sealing and anchoring standpipes into pilot holes and hence tunnels can be made more quickly since the time to install the grout free expandable standpipe 10 is less than about 30 minutes, as compared to up to around 24 hours required for grouting of conventional standpipes into pilot holes.

REFERENCE SIGNS [0125] The specification uses the following reference signs:

10 grout free expandable standpipe 61 high-pressure pump

12 pipe 62 top connector

14 swage tube 64 push rod

16 pilot hole 66 inflatable packer

18 rock wall 70 central flow path

20 blind end 72 lift rings

22 ground formation 76 bore

30 pin ends 80 packer mandrel

32 pin ends 82 ferrule

40 tube 84 ferrule

42 rubber cover 86 packer element

43 swage seal 87 top sub

44 bore 88 cavity

46 in-ground end 90 inflation galleries

48 centraliser 92 sliding end sub

50 connector 96 grout hole

52 flange 98 blind end

54 hole 100 rock drill

60 swage packer tool ADVANTAGES

[0126] The grout free expandable standpipe 10 and methods of the present invention have the advantage that they do not require grout for the anchoring and sealing of the standpipe 10 into the ground formation 22. This has the advantage of reducing the time for setting the standpipe from up to around 24 hours for prior art standpipes that require grout, to less than about 30 minutes. This time saving represents significant cost savings in the process of excavation and construction.

[0127] Also, the delivery tubes 12 and shutoff valves can be unthreaded from the swage tubes 14 and retrieved for further and later use, after grout curtains have cured, thus saving further cost, and to avoid the standpipe protruding into the excavation area.

[0128] The grout free expandable standpipe 10 and methods of the present invention have the further advantage of allowing drillers to control any high-pressure water encountered during drilling (referred to as “wellhead control”), by attaching a blowout preventor (BOP) to the standpipe 10.

[0129] The grout free expandable standpipe 10 and methods of the present invention have the further advantage that sealing, and anchoring is maintainable without having to maintain pressure to an inflatable packer element or energy to a mechanical packer element. Using inflatable or mechanical packer elements for sealing a standpipe into a pilot hole 16 have the disadvantage that if they leak then high-pressure water can be allowed to flow back into the tunnel area, which is dangerous.

[0130] The grout free expandable standpipe 10 and methods of the present invention have the further advantage that it can withstand much higher ground water pressure situations than mechanical packer type standpipes.

[0131 ] The inflatable packer 66 of the grout free expandable standpipe 10 of the present invention has the advantage that it can be reused in the installation of multiple standpipes, whereas prior art mechanical packers, used to set prior art standpipes, are single use only, with one mechanical packer being used for each prior art grout sealed standpipe.

MODIFICATIONS AND VARIATIONS

[0132] It is to be understood that reference to "one example" or "an example" of the invention, or the like (e.g. "such as") herein, is not made in an exclusive sense. Various substantially and specifically practical and useful exemplary embodiments of the claimed subject matter are described herein, textually and/or graphically, for carrying out the claimed subject matter.

[0133] Accordingly, one example may demonstrate certain aspects of the invention, whilst other aspects are demonstrated in a different example. These examples are intended to assist the skilled person in performing the invention and are not intended to limit the overall scope of the invention, in any way, unless the context clearly indicates otherwise.

[0134] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0135] Variations (e.g. modifications and/or enhancements) of one or more embodiments described herein may be employed. For example, other grades of ductile metal could be used for the components of the grout free expandable standpipe 10. Also, other dimensions of the grout free expandable standpipe 10, the pilot hole 16 and the grout hole 96 could be used. Still other alternatives are contemplated.