Note: Descriptions are shown in the official language in which they were submitted.
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GROUT FREE EXPANDABLE STANDPIPE
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,
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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;
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= "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.
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[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.academa.eciuI$ SJ2$$/PreExcavatonGuthqiRocknnieioQ P-e Exc.:ay
ation Grouting in Rook Tunnelino). 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
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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.
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[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
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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.
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[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;
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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;
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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
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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.
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[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;
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[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.
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[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
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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.
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[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 0-
ring seals indicated in figure 2 as small square black elements. The 0-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
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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.
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[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.
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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.
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[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 (IBM), 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.
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[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
blind end 72 lift rings
22 ground formation 76 bore
pin ends 80 packer mandrel
32 pin ends 82 ferrule
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
connector 96 grout hole
52 flange 98 blind end
54 hole 100 rock drill
swage packer tool
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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
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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.
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