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,
another conduit
needs to be positioned in the bore hole and retracted slowly as cement is
injected in the
bore hole.
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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.
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
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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;
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;
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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
penetrating head 11. Therefore, when the soil penetrating head 11 is withdrawn
from the
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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
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
25
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 thereto
in a similar
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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 secure the
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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
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example, bentonite cement solution or other similar chemical mixtures which
are left in the
bore hole to harden whereby to 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.
Date Recue/Date Received 2020-06-02
