Note: Descriptions are shown in the official language in which they were submitted.
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GEOTHERMAL FLEXIBLE CONDUIT LOOP SINGLE PASS
INSTALLATION SYSTEM FOR DENSE SOILS AND ROCK
TECHNICAL FIELD
The present invention relates to a geothermal flexible conduit loop single
pass installation system for dense soils and rock.
BACKGROUND ART
In the parent patent application, I describe the construction of a soil
penetrating head of various configurations which is driven into the soil and
simultaneously draws a geothermal conduit loop. The soil penetrating head and
conduit
loop remain in the soil after it is driven thereinto by a force transmitting
shaft, such as
driven by a drill or a percussion apparatus. This method of disposing conduit
loops into
the ground greatly facilitates the installation of the loop in soft soil and
reduces costs
considerably.
In my U.S. Application Ser. No. 12/497,560, filed on July 3, 2009, and
entitled "Soil Penetrating Plate Assembly To Position Geothermal Conduit Loops
In
Soil", I disclose other embodiments of soil penetrating plate assemblies to
draw the
flexible geothermal conduit loops into the soft soil and to release them
therein. With
many of these installation procedures, the boring head and the soil
penetrating plates to
which the conduit loops are attached are simply left buried into the soft soil
by detaching
the force transmission shaft assembly therefrom. This has proven to be a good
procedure for soft soil conditions but not feasible for hard soils where a
drill head is
required to bore into the soil.
When boring in dense soil and rock, the procedure to install geothermal
conduits is to firstly bore a hole and retract the drill head and install a
conduit loop hook
to draw a conduit loop in the bore hole and again retract the shaft and head
attachment.
A filler material, such as cement, is then introduced in the bore hole. This
is a time
consuming task as these bore holes may be up to 500 feet deep and the shaft
may be
in five foot sections requiring at least two assemblies and disassemblies.
Such
installations are therefore very costly. Also, if the cement is injected from
the bottom,
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another conduit needs to be positioned in the bore hole and retracted slowly
as cement
is injected in the bore hole.
SUMMARY OF INVENTION
It is therefore a feature of the present invention to provide a geothermal
flexible conduit loop single pass installation system wherein the boring head
and the
attachment device to draw the conduit loops can be withdrawn from the soil
without
damaging the conduit loops released in the bored hole.
Another feature of the present invention is to provide a geothermal flexible
conduit loop single pass installation system for dense soil or rock equipped
with a
boring head capable of boring a hole in hard soil or rock while simultaneously
releasing
a pressurized medium from the boring head into the soil to facilitate
displacement of the
boring head and one or more flexible conduit loops drawn behind the boring
head as it
bores into the soil. The pressurized medium also cools the boring head,
evacuates the
drilled soil out of the bore hole and injects fluid streams to maintain the
bore hole open.
Another feature of the present invention is to provide a geothermal flexible
conduit loop single pass installation system for dense soil or rock wherein a
pressurized
bentonite cement solution is injected into the bore hole from the soil
penetrating head
as the head is retracted to the top of the bored hole.
According to the above features, from a broad aspect, the present
invention provides a geothermal flexible conduit loop single pass installation
system for
dense soil or rock comprised of a hollow force transmission shaft having a
soil
penetrating head secured to a boring end of the shaft. Conduit means is
provided in
the soil penetrating head in communication with a passageway formed in the
hollow
force transmission shaft for the passage of pressurized medium therein.
Attachment
means is secured behind the soil penetrating head and has hook means adapted
to
hook a loop end portion of a flexible conduit loop and draw same in a bore
hole being
formed by the soil penetrating head as it descends in the soil under the
influence of a
downward force applied to the hollow force transmission shaft and a boring
displacement of the soil penetrating head. The medium is being released in the
bore
hole through the soil penetrating head as the bore hole is being formed. Means
is
provided to withdraw the hollow force transmission shaft, the soil penetrating
head and
the attachment means without interference with the flexible conduit loop drawn
into the
bore hole whereby the flexible conduit loop remains in the bore hole by
surrounding soil
and/or a pressurized medium released in the bore hole.
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According to a further broad aspect of the present invention, there is
provided a method of installing a geothermal flexible conduit loop in dense
soil or rock
in a single pass, the method comprising the steps of: 1) providing a hollow
force
transmission shaft having a soil penetrating head secured to a boring end of
the shaft,
conduit means in the soil penetrating head in communication with a passageway
formed in the hollow force transmission shaft for the passage of a pressurized
medium
therein, attachment means secured behind the soil penetrating head and having
engageable means adapted to engage a loop end portion of a flexible conduit
loop, ii)
boring a hole in the soil and simultaneously drawing the flexible conduit loop
spaced
behind the soil penetrating head and engaged by the attachment means, and iii)
withdrawing the force transmission shaft and at least the attachment means,
the step of
withdrawing also including simultaneously disengaging the attachment means
from the
loop end portion, the flexible conduit loop being installed in the bore hole
simultaneously
with the step (ii) whereby the boring and conduit loop installation is
effected
simultaneously in a single pass of the soil penetrating head in the soil.
BRIEF DESCRIPTION OF DRAWINGS
A preferred embodiment of the present invention will now be described
with reference to the accompanying drawings in which:
FIG. 1 is a fragmented end view illustrating the basic component parts
of the geothermal flexible conduit loop installation system and comprised of a
soil
penetrating head, a conduit loop attachment soil penetrating plate, a pair of
conduit
loop end portions and a hollow force transmission shaft;
FIG. 2A is a fragmented side view showing a modification of the
attachment means for the loop end portion of a flexible conduit loop;
FIG. 2B is another fragmented side view showing another example of
the attachment means for the loop end portion of a flexible conduit loop;
FIG. 3A is a fragmented side view showing a further embodiment of an
attachment plate and wherein the conduit loop is connected to the attachment
plate by
a releasable interconnection;
FIG. 3B is a fragmented perspective view showing a protection head
secured to the loop end of the conduit loop;
FIG. 4 is a simplified section view showing another
configuration of the
soil penetrating head for the installation of one or more flexible conduit
loops into a hole
being bored;
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FIG. 5 is a
simplified schematic top view of the soil penetrating head of
Figure 4 showing its orientation prior to being withdrawn from a bored hole;
FIG. 6 is a
simplified schematic view illustrating the recovery of
pressurized bentonite cement solution during the boring process of the soil
penetrating
head into the soil;
FIG. 7A is a
simplified schematic view illustrating the use of a sacrificial
bore head which is releasable at the bottom of the bore hole; and
FIG. 7B is an end view of the coupling.
DESCRIPTION OF PREFERRED EMBODIMENTS
A preferred embodiment of the present invention will now be described
with reference to the accompanying drawings in which Figure 1 illustrates the
basic
component parts of the geothermal flexible conduit loop installation system.
The
system comprises a hollow force transmission shaft 10 which is connected to a
soil
penetrating boring head 11 secured to a boring end of the shaft. The soil
penetrating
head 11 is rotated by the hollow force transmission shaft, as indicated by
arrow 12 and
percussions may also be transmitted into the shaft, in a manner well known in
the art,
whereby the soil penetrating head will bore into dense soil or rock. As
hereinshown, the
soil penetrating head 11 is provided with a plurality of small conduits 13
through which a
pressurized medium exits whereby to loosen and displace the soil or rock
particles as
the soil penetrating head bores into the dense soil or rock and rotated by a
suitable
drive, also well known in the art. The soil penetrating head is also provided
with a
conduit 14 which connects to a passageway 15 provided in the hollow shaft for
the
passage of a pressurized medium. Abrasive means is usually embedded in the
outer
surface of the head.
As also shown in Figure 1, an attachment means, herein in the form of a
soil penetrating plate 16, is secured behind the soil penetrating head and is
provided in
a lower edge 17 thereof with a hook formation 18. The hook formation 18 is
dimensioned to hook a loop end portion 19 of a flexible conduit loop, as
described in my
aforesaid U.S. Patent Applications, and draws the loop from a top end of a
bore hole
into the bore hole being formed by the soil penetrating head as it descends
into the soil
under the influence of a downward force applied to the hollow force
transmission shaft
10. As the bore hole is being formed, the conduit loop is being installed in a
single
operation or single pass of the boring assembly.
As shown in solid lines in Figure 1, the loop end portion 19 of the flexible
conduit loop 20, only a lower portion being shown herein, is drawn behind the
soil
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penetrating head 11. Therefore, when the soil penetrating head Ills withdrawn
from
the bore hole, as will be described later with reference to Figure 6, the soil
penetrating
head 11 would contact the loop end portion 19 of both flexible conduit loops
20 and 20'
and this may cause damage to the conduit loop. In order to overcome this
problem, the
soil penetrating plate is extended to its configuration as shown in phantom
lines
indicated by reference numeral 16' whereby the hook formation 18' is disposed
outside
the outer periphery of the soil penetrating head 11. This is workable when the
soil
density permits the bore hole to be made of larger diameter and the boring
head by the
pressure of the medium, herein water, released under pressure and excavating
the soil
surrounding the bore head. Therefore, the conduit loop end portions as shown
at 19'
are spaced apart sufficiently whereby the soil penetrating head may be
withdrawn
without interference with the conduit loops. When it is withdrawn, the soil
penetrating
plates 16' are located in the spacing between the opposed conduits 21 and 21'
of the
flexible conduit loops 20 and 20' and therefore will not damage the conduit
loops.
As hereinshown, the soil penetrating plates 16' have a slope top leading
edge 22' to facilitate the withdrawing thereof in the bore hole. The leading
edge 22'
may also be sharpened to facilitate this withdrawing. Further, these soil
penetrating
plates are secured to the hollow force transmission shaft 10 by a sleeve 23
provided
with a bearing support connection 29 whereby rotation of the force
transmission shaft
10 is not transmitted to the soil penetrating plates 16'. As hereinshown, the
soil
penetrating plate has opposed wing portions 24' which extend diagonally
aligned with
one another and project to opposed sides of the soil penetrating head. These
wing
portions 24' extend in a common vertical plane with respect to the force
transmission
shaft 10. Restraining means in the form of a bushing 25 is immovably secured
to the
outer periphery of the force transmission shaft 10 to maintain the soil
penetrating plates
16' about the shaft to prevent vertical displacement thereof with the shaft.
As also
shown in Figure 1, the hook means may be provided by a through hole 26 formed
in the
soil penetrating plates 24' adjacent an outer edge thereof. As also shown in
Figure 1,
the hollow force transmitting shaft 10 is composed of shaft sections
threadedly
interconnected together by a screw end portion 27 and a threaded bore portion
28
formed at adjacent ends of the force transmitting shaft portions,
respectively.
Referring to Figure 2A, there is shown an example of a further attachment
means to secure the loop end portion of the flexible conduit loop to the force
transmission shaft. As hereinshown, it is provided by a connecting arm
projection 30
extending transversely from the sleeve 23 and provided with a hook formation
31
thereunder, adjacent the free end 32 thereof. The loop end portion 19 is
secured
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thereto in a similar fashion as previously described with respect to Figure 1
The arm
30 extends within the bore hole. The boring head 11 is preferably a detachable
sacrificial boring head.
Figure 2B shows another modification of the attachment means and as
hereinshown, there is provided a connecting arm projection 35 also extending
transversely to the sleeve 23 and having at a free end thereof a projection
shield 36
which has a soil penetrating leading end formation 37. The shield 36 is
pivotally
connected to the arm 35 by a pivot pin 39. A projection extends behind the
soil
penetrating leading end formation to protect the loop end from material into
the hole as
it is being bored by the soil penetrating head 11. When the hollow force
transmission
shaft is withdrawn, the end formation 37 pivots towards the side wall 9' of
the bore hole
9 to clear the loop end 19 and the connecting arm projection 35 is displaced
along the
space between the spaced-apart conduits 21 and 21'of the flexible conduit loop
20.
Referring now to Figure 3A, there is shown a still further embodiment of
the attachment means and as hereinshown, there is provided a soil penetrating
plate 40
as described in my co-pending Application Ser. No. 12/497,560. This soil
penetrating
plate 40 is provided with an angulated leading edge 41 as well as an upwardly
angulated rear edge 42 permitting easy insertion and withdrawal of the soil
penetrating
plate 40 into the soil. A hook formation 43 is provided in the top end portion
of the
leading edge 41 and it is adapted to receive a releasable interconnection
means which
is a connecting chain link 44. The chain link 44 is formed of a predetermined
tensile
strength whereby to break and disconnect when the tensile force therein is
exceeded if
the resistance or tension in one or two of the conduit loops being drawn
exceeds the
predetermined tensile force of the chain link 44. This prevents damage to the
conduit
loops and releases them at a depth where this resistance or tension in the
loop exceeds
the predetermined tensile force of the connecting chain link 44.
The conduit loop 20 can also be connected to a through bore 46 formed in
the soil penetrating plate 40. To do so, the connecting chain link 44 of
predetermined
tensile strength is formed with a disconnectable portion in the form of a
threaded sleeve
45, which is well known in the construction of chain link loops, wherein the
threaded
sleeve is rotated on a threaded portion 47 of the chain link 44 to provide
access to a
space 48 whereby the chain link 44 may be positioned within the through hole
46.
Figure 3B illustrates another embodiment wherein the loop end portion 19
is protected in a protective head casting 49, herein made of resin and shaped
to be
pulled into the soil by a soil penetrating plate or other means. A hole 49' is
provided to
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secure the chain link 44 thereto. The protective head casting 49 could also be
made by
aluminum casted plates to sandwich the loop end portion 19 therebetween.
Referring now to Figures 4 and 5, there is shown a further embodiment of
the construction of the soil penetrating head. As hereinshown the soil
penetrating head
50 is a retractable rotating head formed by two or more branch arms 51 and
51', each
provided with a nozzle 52 and 52' respectively, which constitutes the conduit
means for
release of the pressurized medium therefrom. Each of the branch arms 51 and
51'
extend at a downward angle and spaced in a common plane (see Figure 5) whereby
it
can be retracted without interference with the flexible conduit loops released
in the bore
hole when oriented at a predetermined position parallel to the conduit loops
20 and 20',
as shown in Figure 5. The orientation of the branch arms 51 and 51' is
determined
from the top of the bore hole by suitable means, such as a position indication
marking
57 on the force transmission shaft. As also hereinshown, there is provided a
central
branch arm 53 which extends axially with the hollow force transmission shaft
10 and is
also provided with a nozzle end 54. Accordingly, the pressurized medium 55 is
released in a cone to excavate the soil thereunder and release the soil
upwards in the
direction of arrows 55 towards a top end of the bore hole.
As also shown in Figure 4, the soil penetrating plate 56 positions the
conduit loops 20 behind the bore head 50. As shown in Figure 5, the branch
arms 51
and 51' lie in a common diametrical plane and when withdrawing the soil
penetrating
head 50, it is firstly positioned substantially parallel to the conduit loops
20 and 20'
whereby not to interfere with these as the soil penetrating head 50 and the
soil
penetrating plate 56 is withdrawn. The soil penetrating plate is withdrawn in
the area
between the spaced-apart conduits 21 and 21' of the conduit loops 20 and 20'.
Referring now to Figure 6, there is schematically illustrated a typical
method of installation of the geothermal flexible conduit loops 20 and 20' in
a bore hole
60 as it is being formed by the soil penetrating head 11 or 51, in a single
pass. A
suitable rotation and/or percussion drive 61 is secured to a top end portion
of the hollow
force transmitting shaft and a pressurized medium is fed into the hollow shaft
by a
pump 62 connected to a supply reservoir 63. The flexible geothermal conduit
loops 20
and 20' are wound on spools 64 and 65, respectively, and positioned on opposed
sides
of the bore hole 60. At a convenient location beside the top end of the bore
hole 60,
there is provided a medium collection basin 66 for collection of a backflow of
the
pressurized medium for re-injection into a top end of the hollow force
transmitting shaft
by the pump 62, if such medium is, for example, bentonite cement solution or
other
similar chemical mixtures which are left in the bore hole to harden whereby to
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immovably secure the conduit loops therein. The medium may also be air, water
or
other liquids.
Referring now to Figures 7A and 7B, there is illustrated an embodiment
wherein the boring head 70 is a sacrificial boring head, that is to say it is
released in the
bore hole 71 when reaching the desired boring depth. For this purpose, the
lower end
72 of the boring shaft 73 is provided with a coupling 74 which may have a
hexagonal
shape 75 to import rotation to the boring head 70 through its hexagonal
connector 76.
As the boring head descends to bore through the soil, the force on the shaft
73 keeps
the coupling 74 engaged with the shaft 76 of the boring head. When reaching
the
bottom of the bore hole, the shaft 73 is retracted and the coupling releases
the boring
head 70 and retracts the soil penetrating mechanism 77 which engaged with the
conduit loops 20 and 20' to draw them in the bore hole being formed in a
single pass.
With the bore head 70 disconnected there is no possible damage to the conduit
loops
by having to retract this type of bore head, the circumference of which spans
the
position of the conduit loops in the bore hole. Also, as hereinshown,
bentonite cement
is controllably released in the bore hole 71 from the open end of the shaft 73
as it is
retracted and as illustrated by arrows 78.
It is within the ambit of the present invention to cover any obvious
modifications of the preferred embodiment described herein provided such
modifications fall within the scope of the appended claims.
