NZ618804B - Modified stone column drill - Google Patents
Modified stone column drill Download PDFInfo
- Publication number
- NZ618804B NZ618804B NZ618804A NZ61880413A NZ618804B NZ 618804 B NZ618804 B NZ 618804B NZ 618804 A NZ618804 A NZ 618804A NZ 61880413 A NZ61880413 A NZ 61880413A NZ 618804 B NZ618804 B NZ 618804B
- Authority
- NZ
- New Zealand
- Prior art keywords
- drill
- stone column
- section
- granular stone
- guide channel
- Prior art date
Links
- 239000004575 stone Substances 0.000 title claims abstract description 58
- 238000006073 displacement reaction Methods 0.000 claims abstract description 72
- 230000010006 flight Effects 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims description 12
- 229910000906 Bronze Inorganic materials 0.000 claims description 7
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 239000010974 bronze Substances 0.000 claims description 7
- 239000000919 ceramic Substances 0.000 claims description 7
- 238000005755 formation reaction Methods 0.000 claims description 7
- 229920000642 polymer Polymers 0.000 claims description 7
- 238000003780 insertion Methods 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 239000000314 lubricant Substances 0.000 claims description 4
- 230000014759 maintenance of location Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 238000005056 compaction Methods 0.000 description 3
- 230000000295 complement Effects 0.000 description 3
- 238000005553 drilling Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000002783 friction material Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000001050 lubricating Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 230000003068 static Effects 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Abstract
618804 A granular stone column drill which includes a first drill 10, a second drill 11 and a displacement device 20, where the first drill 10 includes a tube within which the second drill 11 at least partially, coaxially, lies, and the displacement device includes a displacement unit 20 and at least one guidance means 26. The second drill 11 includes a drill flight 14 and first terminal end. The displacement unit 20 includes a guide channel 22 and an exposed wall such that the guide channel 22 extends into the exposed wall. The exposed wall lies approximately parallel to a centreline of the second drill 11. At least one guidance means 26 is located within the guide channel 22. The guide channel 22 is a continuous circumferential channel that follows a wave like path. Either the guidance means 26 or the displacement unit is releasably or permanently attached to the second drill 11. st one guidance means 26. The second drill 11 includes a drill flight 14 and first terminal end. The displacement unit 20 includes a guide channel 22 and an exposed wall such that the guide channel 22 extends into the exposed wall. The exposed wall lies approximately parallel to a centreline of the second drill 11. At least one guidance means 26 is located within the guide channel 22. The guide channel 22 is a continuous circumferential channel that follows a wave like path. Either the guidance means 26 or the displacement unit is releasably or permanently attached to the second drill 11.
Description
TITLE OF INVENTION : MODIFIED STONE COLUMN DRILL
Technical Field: The present invention relates to modifications to a drill used to
form in ground piles for supporting buildings or other structures.
Background Art
Any discussion of the prior art throughout the specification is not an admission that
such prior art is widely known or forms part of the common general knowledge in the
field.
The formation of in ground granular stone columns can be accomplished by a number
of means, one means uses a drill which includes an auger within a hollow tube. When
the drill is at the desired depth the aggregate is fed into the centre of the hollow tube
and the auger rotated to form the granular stone column. As the aggregate is a
granular material it can bridge and partially or completely block the flow of aggregate
into the stone column. To overcome this bridging it is possible to manually clear this
bridging but this can be time consuming and can affect the quality of the granular
stone column formed.
To minimise bridging and allow the drill to be more easily extracted from the ground as
the granular stone column is formed the auger can be driven in the opposite direction
to the hollow tube. One method proposed for this uses an epicyclic gear, with the
auger permanently attached to the sun gear and the annulus (annular gear) driven. In
some variations, to prevent the auger being continuously driven, the sun gear is
disengaged from the planetary gears. If the sun gear is disengaged during the initial
drilling it needs to be properly aligned then engaged with the planetary gears before
the granular column can be formed, this can be time consuming and if misaligned with
power applied it could damage or break the teeth or gears. It should be noted that the
reverse direction of the auger and the hollow tube still bridges, this bridging then
needs to be cleared before continuing.
In addition to the bridging problems that can increase the time taken to prepare a
granular stone column there is also a need to compact the aggregate during formation
of granular stone column. The feed rate of aggregate, rpm of the drills and extraction
rate of the drill from the ground can all be varied, but even then it can be difficult to
achieve the required compaction. To improve compaction the completed stone
column can be mechanically vibrated, but this is an additional step.
In some ground environments the drill can ‘stick’ during extraction which can increase
the time taken to form each granular stone column, or in some cases require additional
machinery to clear.
It is an object of this invention to overcome or mitigate one or more of the deficiencies
highlighted above, and/or to at least provide the consumer with a useful choice.
Disclosure of Invention
The present invention provides a granular stone column drill which includes a first drill,
a second drill and a displacement device, where
- the first drill includes a tube within which the second drill at least partially, co-
axially, lies;
- the second drill includes a drill flight and first terminal end;
- the displacement device includes a displacement unit and at least one
guidance means;
- the displacement unit includes a guide channel and an exposed wall such that
the guide channel extends into the exposed wall;
- the exposed wall lies approximately parallel to a centreline of the second drill;
- the at least one guidance means are located within the guide channel;
such that the guide channel is a continuous circumferential channel that follows a
wave like path, and either the at least one guidance means or the displacement unit is
releasably or permanently attached to the second drill.
Preferably the guide channel follows a smooth wave like path. In a highly preferred
form the guide channel is approximately sinusoidal.
Preferably the guide channel is between 1 and 100 (inclusive) wavelengths in length.
Preferably the number of wavelengths is between 1 and 10.
In an alternative preferred form the guide channel is made up of a plurality of partial
waves or a superposition of waveforms. Preferably the guide channel is made up of
one or more of the following:- different wavelengths, different waveforms, waves with
different peak to trough dimensions, non-sinusoidal wave forms, sinusoidal
waveforms, discontinuities and whole wavelengths.
In a further form the guide channel is a superposition of two or more separate
subsidiary waveforms, each subsidiary waveform having a different wavelength and/or
peak to trough distance.
Preferably the guide channel has a peak to trough distance of between 1mm and
400mm. In a highly preferred form the peak to trough distance is 25mm to 100mm. In
a still more preferred form the peak to trough distance is 50mm.
Preferably the granular stone column drill includes a gearbox which is attached to or
adapted to be driven by the first drill, such that the second drill includes a drive section
and the gearbox includes an engagement section, where the drive section and
engagement section are adapted to co-operate to transfer rotational motion in the first
drill to the second drill, or from a rotary head to the first and/or second drill.
Preferably the drive section includes a pair of parallel opposing first sides and the
second drill includes a shaft, and the engagement section includes at least one pair of
first contact means, such that the distance between said first sides is the same as the
diameter said shaft, and the distance between said first contact means is also the
same as the diameter of said shaft. Preferably the engagement section includes a
parallel pair of second contact means and the drive section includes a pair of parallel
opposing second sides. Preferably the second sides and second contact means are
dimensioned similarly to the first sides and first contact means respectively.
Preferably the contact means are selected from a surface, an extended rotatable
member a combination of these. In a highly preferred form each contact means is a
cylindrical roller or wheel. In an alternative preferred form the contact means are
surfaces or strips of one or more materials selected from bronze, a low friction metal, a
low friction polymer and a low friction ceramic; noting that the low friction properties
may come from a lubricant or be an inherent property of the material used. In a
preferred form the cross section of the engagement section is a polygon with the
contact means forming the sides of the polygon.
In an alternative form the drive section is essentially rectangular, or preferably
essentially square in cross section and includes at least one drive unit extending from
each face of the drive section,
Preferably the engagement section includes a first aperture which has a cross section
that is the combination of a cross with all arms equal in length and a circle, where the
cross and the circle are concentric. Preferably the arms of the cross form four drive
channels dimensioned to accept at least one drive unit.
Preferably each drive unit can rotate freely about a centreline that is approximately
perpendicular to the face from which it extends.
Preferably the engagement section is a socket for the drive section. Preferably each
drive unit is selected from a surface, an extended rotatable member a combination of
these. In a highly preferred form each drive unit is a cylindrical roller or wheel. In an
alternative preferred form one or more drive unit is a surface or strip of one or more
materials selected from bronze, a low friction metal, a low friction polymer and a low
friction ceramic; noting that the low friction properties may come from a lubricant or be
an inherent property of the material used.
The present invention also includes a preferred method of forming a granular stone
column which includes the following steps in order:
- a first or insertion step where the granular stone column drill is inserted into
the ground;
- a second step where the engagement section and drive section are
engaged and the gearbox drives the second drill;
- a third or formation step where the displacement device is engaged.
Preferably the gearbox includes an epicyclic gear set, and the engagement section
forms part of a sun gear.
Preferably the drive section is quadrilateral in cross section. Preferably the
quadrilateral is a square. In an alternative form the cross section of the drive section is
a regular polygon.
Brief Description of Drawings
By way of example only, a preferred embodiment of the present invention is described
in detail below with reference to the accompanying drawings, in which:
Figure 1 is a pictorial view of a drill assembly for forming in ground granular
stone columns attached to a drilling rig;
Figure 2 is a cross sectional side view of the drill assembly and the support
frame;
Figure 2a is an enlarged section of Figure 2 showing the optional displacement
unit in more detail;
Figure 2b is an enlarged section of Figure 2 showing the epicyclic gear and
optional drive section in more detail;
Figure 3 is a side view of the displacement unit;
Figure 4 is a plan view of an epicyclic gear;
Figure 5 is a side view of the portion of the second drill that includes the drive
section;
Figure 5a cross sectional view A-A through the shaft of the second drill;
Figure 5b cross sectional view B-B through the drive section of the second drill;
Figure 6 plan view of the sun gear with the engagement section;
Figure 6a cross sectional view C-C through the sun gear with the drive socket;
Figure 7 side view of a portion of the second drill and sun gear with the drive
section disengaged from the engagement section;
Figure 7a cross sectional view D-D through the shaft of the second drill with the
drive section disengaged from the engagement section;
Figure 8 side view of a portion of the second drill and sun gear with the drive
section and engagement section engaged;
Figure 8a cross sectional view E-E through the engagement section with the drive
section and engagement section engaged;
Figure 9 is a side view of a second embodiment of the column assembly without
hopper or crane excavator;
Figure 9a is an enlarged view of a first variation of the displacement unit of the
second embodiment;
Figure 9b is an enlarged view of a second variation of the displacement unit of the
second embodiment;
Figure 10 is a plan view of the sun gear of the second embodiment;
Figure 11 is a partial side view of the secondary section of the second drill,
including an alternative variant of the drive section. Of the second
embodiment;
Figure 12 is a cross sectional plan view, through G-G, of the secondary section of
the second embodiment;
Figure 13 is a cross sectional view of the sun gear of the second embodiment with
the an alternative variant of the drive section engaged;
Figure 14 is a partially cross sectional view of the second embodiment of the
column assembly without hopper or crane excavator in a first (insertion)
position;
Figure 15 is a partially cross sectional view of the second embodiment of the
column assembly without hopper or crane excavator in a second
position;
Figure 16 is a partially cross sectional view of the second embodiment of the
column assembly without hopper or crane excavator in a third
(formation) position;
Definitions
Aggregate: when used herein is construction aggregate above about 0.1 mm in size
(including sand, stones, crushed rock, crushed concrete, slag, etc).
Auger: when used herein includes a flight without a central shaft, similar to a
corkscrew.
Flight: when used herein is a strip of material following a helical path like a spiral
staircase.
Tube: when used herein a tube is meant to indicate a long hollow member whose
outer cross sectional profile may be circular or any other shape (triangular, square,
hexagonal, elliptical, etc) and whose inner cavity is circular (or approximately
circular/elliptical) in cross section.
Please note the drawings are representative only and the relative dimensions may be
exaggerated for clarity.
FIRST EMBODIMENT OF THE INVENTION
Referring to Figure 1 a first embodiment of a column assembly (1) including a drill
assembly (2), a hopper (3) and a support (4) is shown. The column assembly (1) in
use is attached to a crane or excavator (5). The crane/excavator (5) is of a known
type used in the industry and it provides the support and services to the column
assembly (1).
The drill assembly (2) includes a first drill (10) and a second drill (11) and is used for
forming in ground granular stone columns.
Referring to Figure 2 the column assembly (1) is shown in cross section. The first drill
(10) is essentially a hollow tube with the second drill (11) lying coaxially aligned, and at
least partially within, said first drill (10).
The second drill (11) includes a primary section (12) and a secondary section (13),
where one terminal end of the primary section (12) is coterminous with a first terminal
end (14) of the second drill (11), and one terminal end of the secondary section (13) is
coterminous with a second terminal end (15) of the second drill (11). The first terminal
end (14) and second terminal end (15) are the opposite terminal ends of the second
drill (11). The primary section (12) is the end of the second drill (11) that is located
closest to the primary end (15a) of the first drill (10), where the primary end (15a) is
the open terminal end of the first drill (10) that enters the ground first.
The hopper (3) is a container for the aggregate to be used to form the granular
column. In this case it is essentially a truncated cone with a cylindrical section
extending from the cone’s base, the truncated end forming the base of the hopper (3).
The column assembly (1) further includes a movement device (16) and a gearbox (17).
Where the movement device (16) is attached to the support (4) and indirectly to the
secondary section (13) and/or second terminal end (15), and the gearbox (17) is
configured or adapted to drive, when in use, either one or both drills (10,11).
The movement device (16) is most likely to be a pneumatic or hydraulic ram of known
type, but, it could be any device that can move the second drill (11) longitudinally
within the first drill (10).
The primary section (12) is an auger which includes a drill flight (18) one end of which
is coterminous with the first terminal end (14). The drill flight (18) may extend along
part or all of the length of the primary section (12).
For clarity two enlarged sections are shown as Figure 2a and Figure 2b, in Figure 2a
the second drill (11) includes, or is attached to, a displacement unit (20) and in Figure
2b the secondary section (13) of the second drill (11) includes a drive section (21).
The second drill (11) may include either, one of, or both, the displacement unit (20)
and the drive section (21).
Referring to Figure 2a and Figure 3 a portion of the secondary section (13) of the
second drill (11) with one variant of the displacement unit (20) is shown. In this variant
the displacement unit (20) is rigidly connected to, or is formed as part of the secondary
section (13) of the second drill (11). The displacement unit (20) may be permanently
attached (welded onto the second drill (11) for example), formed as part of the second
drill (11) or releasably attached (for example keyed and/or bolted to the second drill
(11)).
In Figures 2a and 3 the displacement unit (20) is shown as a cylinder co-axially
aligned with the second drill (11) which includes a guide channel (22). The guide
channel (22) is a continuous circumferential channel in the surface of the displacement
unit (20) that follows a smooth wave like path. The waveform of the guide channel
(22) is likely to be approximately sinusoidal (or the superposition of a plurality of
approximately sinusoidal waveforms) and have a peak to trough distance of between
1mm and 400mm, though it is felt it will most likely be between 20mm and 100mm.
The figures show a guide channel (22) two wavelengths in length, but this will likely
depend on the rotational speed of the second drill (11), the size of the aggregate and
the peak to trough distance of the guide channel (22). The length of the guide channel
(22) will be at least 1 wavelength and likely fall within the range of between 1 and 10
wavelengths for most applications. It is felt that the waveform will consist of a whole
number of waves of the same waveform and frequency but some applications may
benefit from a variable waveform consisting of a number of partial or whole
wavelengths of the same or different waveforms and/or frequencies. The guide
channel (22) may also benefit from discontinuities. It should be noted that the
waveform can be a superposition of different waveforms, where those superimposed
waveforms have different frequencies and/or peak to trough heights. For example a
wave with a periodicity of 1 with a peak to trough of 25mm could be combined with a
wave with a periodicity of 5 and a peak to trough of 1mm, so the displacement unit
imparts a slow large movement combined with a faster short displacement at the same
time.
The guide channel (22) includes channel walls (23,24) that are the side walls of the
guide channel (22).
The support (4) includes a retention structure (25) and guidance means (26), where
the retention structure (25) is a framework designed to hold the guidance means (26)
within the guide channel (22). In this case the guidance means (26) are freely rotating
rollers or wheels of a known type that are dimensioned to fit between the channel walls
(23,24) of the guide channel (22). It should be noted that the guidance means (26)
may be any device that can move freely along the guide channel (22) between the
channel walls (23,24), for example wheels, rollers, blocks of material, constructs with
one or more low friction surfaces, constructs with balls or rollers contacting one or
more of the channel walls (23,24), etc. One guidance means (26), in this case each is
shown as a wheel, is located within the guide channel (22) on two diametrically
opposed sides of the displacement unit (20).
In use the guidance means (26) operate cooperatively with the guide channel (22) to
move the displacement unit (20) and the second drill (11) co-axially with respect to the
first drill (10). This motion has been found to minimise or eliminate the bridging of the
aggregate when the column assembly (1) is used in a manner similar to that described
in for forming a granular stone column.
In other words, when the displacement unit (20) is in use, the second drill (11) rotates
with the displacement unit (20) but the guidance means (2) remains in a fixed position
attached to the retention structure (25). This means that as the second drill (11)
rotates each guidance means (26) moves along the guide channel (22) parallel to one
or both channel wall (23, 24). As the guidance means (26) moves along the length of
the guide channel (20) the second drill (10) is co-axially displaced in relation to the first
drill (10).
The speed and magnitude of the co-axial displacement between the first and second
drill (10,11) is determined by the waveform of the guide channel (20) and as such this
can be optimised for specific applications.
It should be noted that the guidance means (26) may be solid and formed of a low
friction material (bronze, polytetrafluoroethylene, polymers, ceramics, etc) or be a
device containing one or more rotating members that contact one or both of the
channel walls (23,24). The guidance means (26) are dimensioned and designed to act
co-operatively with the guide channel (22) to move the displacement unit (20) and the
second drill (11) to which they are attached, or formed as part of, co-axially with
respect to the first drill (10).
As can be seen in Figure 3 the second drill (11) may extend beyond the displacement
unit (20), as such the second terminal end (15) is not necessarily co-terminous with
the displacement unit (20).
Referring to Figures 2 and 2a it can be seen that the movement device (16) is
indirectly connected to the second drill (11) by the guidance means (26), as these
engage with but are not directly attached to the displacement unit (20). In addition the
movement device (16) may include an isolator (27) to co-axially rotationally isolate the
movement device (16) from the first drill (10) or second drill (11), this isolator (27) may
be a bearing (roller/ball), bushes, or anything similar.
Referring to Figure 4 a standard epicyclic gear (30) is shown, the epicyclic gear (30)
includes an annulus or ring gear (31), planetary gears (32) and a sun gear (33). The
sun gear (33) is centrally located with, in this case, three planetary gears (32)
distributed evenly around and enmeshed with the sun gear (33). The annulus or ring
gear (31) is a ring gear with the teeth on the inner surface, the annulus or ring gear
(31) is meshed with all of the planetary gears (32).
The gearbox (17) shown in Figure 2b includes an epicyclic gear set (30) with an
annulus or ring gear (31), more than one planetary gears (32) and a sun gear (33).
Referring to Figure 5 the section of the second drill (11) that includes the drive section
(21) is shown in more detail. In this case the drive section (21) is located between the
primary section (12) and the secondary section (13) of the second drill (11).
Referring to Figures 5, 5a and 5b, where Figure 5a is a cross section of the drive
section (21) in the direction of arrows A-A in Figure 5, and Figure 5b is a cross
sectional view of the primary section (12) of the second drill (11) in the direction of
arrows B-B in Figure 5. In this case the cross section of the primary section (12) is
circular and the same as the secondary section (13). The cross section, A-A, of the
drive section (21) is a square with the distance between opposing faces equal to the
diameter of the circular cross section, B-B, of the primary section (12).
Referring to Figure 6 the sun gear (33) includes an engagement section (39). The
engagement section (39) includes a pair of first contact means (40) and a pair of
second contact means (41) is shown in plan view with the sun gear (33) lying on the x-
y plane. .Each contact means (40) is a cylindrical roller on a co-axial shaft.
In this view the first contact means (40) are parallel and the second contact means
(41) are parallel but the first contact means (40) lie perpendicular to the second
contact means (41). The distance between the pair of first contact means (40) is equal
to the diameter of the primary section (12) with each first contact means (40)
equidistant from the centre of the sun gear (33). Likewise the distance between the
pair of second contact means (40) is equal to the diameter of the primary section (12)
with each second contact means (40) equidistant from the centre of the sun gear (33).
Noting that if cross-section A-A is not a square then the distance between respective
pairs of contact means (40,41) will depend on the faces of the drive section (21) each
pair of contact means (40,41) is intended to engage with.
Figure 6a is a cross sectional view in the direction of arrows C-C through the sun gear
(33). Figure 6a is a cross sectional view of the sun gear (33) viewed in the x-z plane.
In Figure 6a the first contact means (40) are parallel to each other and the centreline
of the sun gear (33). In Figure 6a the second contact means (41) are approximately
perpendicular to each other and the centreline of the sun gear (33). Where the contact
means (40,41) incorporates a long rotatable member (cylindrical roller in this case) to
reduce friction, this rotatable member must be either parallel to, or angle with respect
to, the centreline of the sun gear (33) to minimise scuffing. The optimum angle of the
contact means (40,41) with respect to the centreline of the sun gear (33) will depend
on the diameter of the contact means (40,41) and the diameter of the primary section
(12).
One preferred means of using the drive section (21) is shown in Figure 7, 7a, 8 and
8a; where Figures 7a and 8a are cross section views in the direction of arrows D-D
and E-E respectively.
In Figures 7 and 7a the drive section (21) is not engaged with the engagement section
(39) and as such the sun gear (33) is free to rotate with respect to the second drill (11).
In Figures 8 and 8a the movement device (16) has moved the drive section (21) with
respect to the sun gear (33). The drive section (21) and engagement section (39) now
co-operate to transfer the rotation of the sun gear (33) to the second drill (11) or vice
versa, depending on which is being driven.
When forming a granular stone column the drill assembly (2) is rotated and inserted
into the ground during insertion it may be desirable to keep the first and second drills
(10,11) rotating the same way. When the drill assembly (2) reaches the required
depth the aggregate forming the granular stone column needs to be fed to the base of
the drill assembly as the drill assembly (2) is removed. In this case it may be desirable
to rotate the first and second drills (10,11) in opposite directions. If the second drill
(11) incorporates the drive section (21) and a sun gear (33) with the engagement
section (39) is used this opposite rotation can be easily accomplished. Without the
engagement section (39) and drive section (21) present two separate drive means,
one for each drill (10,11), are likely to be required.
In further embodiments the gearbox may not be an epicyclic gearbox but the
engagement section (39) may still be present in one of the gears.
In alternative embodiments (not shown) the cross section A-A need not be square it
can be any polygon where the distance between at least one pair of opposing parallel
faces is equal to the diameter of the primary section (12). For example the cross
section A-A could be a regular hexagon, a rectangle or any other suitable shape.
In further embodiments (not shown), where contact means (40) are present the
contact means (40) may simply be the inner walls of a socket that is internally
dimensioned to engage with the drive section (21). In this case the contact means
(40) could be bronze or a self lubricating, and/or low friction, solid material (metal,
polymer or ceramic for example).
In further embodiments (not shown), where the contact means (40) are present they
may simply be blocks or strips of suitable material, in this case they are likely to be a
self-lubricating and/or low friction material, such as bronze, a polymer or a ceramic.
Alternatively each contact means (40) may simply include one or more rotating
member that contacts the surface of the primary section (12) or drive section (21).
In a further embodiment (not shown), where a displacement unit (20) is present, the
guide channel (22) could be formed into a ring of material attached to the retention
structure (25) and the guidance means (26) attached to the second drill (11). The
guidance means (26) would still move along the guide channel (22) but they would
rotate with the second drill (11) whenever it was being driven rather than remain static
with regards to the column assembly (2).
BEST MODE OF CARRYING OUT THE INVENTION
Referring to Figure 9 a second embodiment of the column assembly (1) is shown with
the hopper (3) and the crane excavator (5) removed for clarity. In this case a rotary
head (50) of known type is shown, this rotary head (50) is configured to rotate the first
drill (10).
In this second embodiment the first drill (10) includes an expanded section (51)
located close to or at the primary end (15a). The expanded section (51) is essentially
two truncated cones separated by a cylindrical section, where the bases of the cones
are coterminous with the ends of the cylinder.
Figure 9 shows optional alpha and beta first flights (52, 53), which are flights on the
outside of the first drill (10). The alpha and beta first flights (52, 53) may have the
same handedness or opposite handedness, and either may be the same handedness
as the drill flight (18).
In Figure 9 the displacement unit (20) is shown within a displacement device (55) with
two engagement tabs (56, 57) extending from an outer casing (6). Where the outer
casing encloses (60), at least partially, the moving parts of the displacement device
(55).
Referring to Figure 9a and 9b an expanded view of two variations of the displacement
device (55) are shown, with the interior exposed or in cross section for clarity. The
displacement device (55) includes the displacement unit (20) and the guidance means
(26) housed within the outer casing (60). In both variations the movement device (16)
is attached to the outer case (60) by an isolator (27). The isolator (27) rotationally
isolates (co-axially) the movement device (16) and outer case (60) which means the
electrical, hydraulic or pneumatic connections to the movement device (16) do not
need to account for this. As indicated in the first embodiment the isolator (27) is most
likely to be a roller bearing, ball bearing, bush or similar, but anything that co-axially,
rotationally, isolates the movement device (16) from the drills (10, 11), either directly or
indirectly can be used.
The first variation of the displacement device (55) is shown in Figure 9a and in this
variation the displacement unit (20) is essentially the same as described for the first
embodiment, with the guide channel (22) circumferentially cut into the outer surface of
a cylinder attached to, or formed as part of, the second drill (11), but the guidance
means (26) extend from an inner wall of the outer casing (60). It should be noted that
the guidance means (26) may be attached to the outer casing (60) of the displacement
device (20) directly or indirectly.
In Figure 9b a second variation of the displacement device (55) is shown in cross
section, in this second variation the guidance means (26) are attached to the surface
of the second drill (11) and the displacement unit (20) is attached to or formed as part
of the outer casing (60). In this second variation the displacement unit (20) is a ring
with the guide channel (22) circumferentially cut into the inside wall (61).
There is a displacement space (62), which is a void, between the second terminal end
(15) of the second drill (11) and the outer casing (60) to allow the second drill (11) to
be displaced relative to the displacement (55) when the displacement device (55) is in
use. The dimensions of the displacement space (62) are such that when in use the
second drill (11) cannot contact the outer casing (60).
In Figure 10 the sun gear (33) with an engagement section (39) including a first
aperture (65) is shown in plan view. In this second embodiment the first aperture (65)
passes through the entire thickness of the sun gear (33). In this view the first aperture
(65) is the combination of a cross with all arms equal in length and a circle, the centres
of the cross, the circle and the sun gear (33) are coincident. The arms of the cross
form four drive channels (66) through the sun gear (33). The diameter of the circle is
Referring to Figures 11 and 12 a portion of the secondary section (13) and a cross
sectional view of the drive section (21) respectively, are shown. In this second
embodiment the second drill (11) shaft in the drive section (21) is essentially square in
cross-section with a maximum diagonal dimension of d2, where d2 is less than or at
most equal to d1.
The drive section (13) further includes 4 pairs of drive units (67), where one drive unit
(67) of each pair is located on diametrically opposed faces of the second drill (11)
shaft to the other. Each drive unit (67) is a wheel or roller configured to rotate on a
drive rod (68) to which it is attached. Each drive rod (68) is a shaft that extends
approximately perpendicularly from a face (69) of the drive section (21). In some
cases the drive rod (68) will extend through the second drill (11) shaft joining pairs of
drive units together.
There are two drive units (67) shown located on each face of the drive section (21),
these are spaced apart along the length of the drive section (21). The centreline of
each drive rod (68) is perpendicular to, and passes through the centreline of the
second drill (11).
Figure 13 shows a cross sectional view of the sun gear (33) and drive section (21) of
the second embodiment engaged in the drive position. In the drive position the sun
gear (33) can rotationally drive the second drill (11).
In the drive position the drive units (67) have been pushed into a complementary drive
channel (66), as such each drive unit (67) is dimensioned to fit within the associated
drive channel (66).
One preferred method of using the second embodiment will now be described with
reference to Figures 14, 15 and 16 where the column assembly (1) is shown with the
hopper (3) and the crane excavator (5) removed for clarity.
In Figure 14 the column assembly (1) is shown in a first or insertion position, where the
displacement device (55) is disengaged and the second drill (11) is not being driven by
the gearbox (17). In this position the drill assembly (2) is inserted into the ground to
start the formation of a granular stone column, the first drill (10) is rotated by the rotary
head (50) and it is forced into the ground. The second drill (11) may be stationary or
rotated during this step (for example with the first drill (10)).
Located and attached to one side of the gearbox (17), the side closest to the
movement device (16), is a lock device (70). The lock device (70) is a thick walled
tube that lies co-axial with the second drill (11) which includes engagement apertures
(71). Each engagement aperture (71) is a slot that extends into the lock device (70)
that is dimensioned and configured to accept an engagement tab (56, 57).
When the drill assembly (2) is at the required depth and the stone column is to be
formed the movement device (16) pushes the second drill (11) relative to the first drill
(10). The movement device (16) then causes the first terminal end (14) to extend
away from the primary end (15a).
The movement device (16) continues to push the second drill (11) through the first drill
(10) until, as shown in Figure 15, the drive units (67) are engaged with the drive
channels (66), in this second position the gearbox (17) can drive the second drill (11)
to feed any aggregate within the first drill (10) out of the primary end (15a) to form a
stone column as the drill assembly (2) is withdrawn from the ground.
In Figure 16 the movement device (16) has pushed the second drill (11) into a third
(formation) position, in this position each engagement tab (56, 57) has been pushed
into full engagement with the complementary engagement aperture (71). The second
drill (11) is also pushed further through the first drill (10), extending the first terminal
end (14) still further from the drill assembly (2).
The displacement device (55) can now displace the first and second drills (10, 11)
relative to each other as the drill assembly is withdrawn from the ground. The
differential lengthwise motion of the second drill (11) relative to the first drill (10)
minimises the chance of the aggregate bridging helping to produce a uniform quality
stone column. The displacement device (55) is also believed to assist with the
compaction of the stone column.
Though it is preferred that there are engagement tags (56, 57) on the displacement
device (55) they are optional and an alternative method of engaging the displacement
device (55) can be used.
In some embodiments (not shown) the drive channels (66) may have a different cross
section, for example the cross section may be semi-circular. In this case the drive
units (67) will have a complementary shape.
In some embodiments the drive units (67) are permanently attached to the associated
drive rod (68) and this configured to rotate. In still other embodiments the drive units
(67) are not configured to rotate, they act merely as drive keys.
Though the gearbox (17) is described as an epicyclic gearbox it can be any suitable
form of gearbox (17) that allows the rotary head (50) to directly drive the first drill (10)
and indirectly, via the gearbox (17), drive the second drill (11).
There are preferably two guidance means (26) present but in some cases there may
be one, or more than two.
In use the guidance means (26) operate cooperatively with the guide channel (22) to
move the displacement unit (20) or guidance means (26) and the second drill (11) co-
axially with respect to the first drill (10).
Key
1. Column assembly;
2. Drill assembly;
3. Hopper;
4. Support;
5. Crane excavator;
. First drill;
11. Second drill;
12. Primary section (of second drill);
13. Secondary section (of second drill)
14. First terminal end;
15. Second terminal end;
15a. Primary end (of first drill);
16. Movement device;
17. Gearbox;
18. Drill flight;
20. Displacement unit;
21. Drive section (of second drill);
22. Guide channel;
23. Channel wall (side wall of guide channel);
24. Channel wall (side wall of guide channel);
25. Retention structure;
26. Guidance means;
27. Isolator (rotationally isolates movement device and displacement device);
. Epicyclic gear set;
31. Annulus or ring gear;
32. Planetary gear;
33. Sun gear;
39. Engagement section;
40. First contact means;
41. Second contact means;
50. Rotary Head;
51. Expanded section (of first drill);
52. Alpha first flight;
53. beta first flight;
55. displacement device;
56. engagement tab (on enclosed displacement device);
57. engagement tab (on enclosed displacement device);
60. outer casing (of the enclosed displacement device)
61. inside wall (of displacement unit when it is a ring);
65. first aperture (cross shaped aperture through sun gear);
66. drive channels (through sun gear, second embodiment);
67. drive units (second embodiment);
68. drive rod (second embodiment connects pairs of drive units);
70. lock device (to engage with displacement device);
71. engagement aperture;
Claims (29)
1. A granular stone column drill which includes a first drill, a second drill and a displacement device, where 5 - the first drill includes a tube within which the second drill at least partially, co- axially, lies; - the second drill includes a drill flight and first terminal end; - the displacement device includes a displacement unit and at least one guidance means; 10 - the displacement unit includes a guide channel and an exposed wall such that the guide channel extends into the exposed wall; - the exposed wall lies approximately parallel to a centreline of the second drill; - the at least one guidance means are located within the guide channel; 15 such that the guide channel is a continuous circumferential channel that follows a wave like path, and either the at least one guidance means or the displacement unit is releasably or permanently attached to the second drill.
2. A granular stone column drill as claimed in claim 1 wherein, the guide channel 20 follows a smooth wave like path.
3. A granular stone column drill as claimed in claim 1 or claim 2 wherein, the guide channel is approximately sinusoidal. 25
4. A granular stone column drill as claimed in any one of claims 1 to 3 wherein, the guide channel is at least 1, and up to 100, wavelengths in length.
5. A granular stone column drill as claimed in claim 4 wherein, the number of wavelengths is between 1 and 10 inclusive.
6. A granular stone column drill as claimed in claim 1 or claim 2 wherein, the guide channel is made up of a plurality of partial waves or a superposition of waveforms.
7. A granular stone column drill as claimed in claim 6 wherein, the guide channel is a 35 superposition of two or more separate subsidiary waveforms, each subsidiary waveform having a different wavelength and/or peak to trough distance.
8. A granular stone column drill as claimed in any one of the preceding claims wherein, the guide channel has a peak to trough distance of between 1mm and 400mm.
9. A granular stone column drill as claimed in claim 8 wherein, the peak to trough distance is 25mm to 100mm.
10. A granular stone column drill as claimed in claim 8 or 9 wherein, the peak to 10 trough distance is 50mm.
11. A granular stone column drill as claimed in any one of the preceding claims wherein, the granular stone column drill includes a gearbox which is attached to, or adapted to be driven by, the first drill, such that the second drill includes a drive 15 section and the gearbox includes an engagement section, where the drive section and engagement section are adapted to co-operate to transfer rotational motion in the first drill to the second drill or from a rotary head to the first and/or second drill.
12. A granular stone column drill as claimed in claim 11 wherein, the gearbox includes 20 an epicyclic gear set, and the engagement section forms part of a sun gear.
13. A granular stone column drill as claimed in claim 11 or 12 wherein, the drive section includes a pair of parallel opposing first sides, the second drill includes a shaft, and the engagement section includes at least one pair of first contact 25 means, such that the distance between said first sides is the same as the diameter said shaft, and the distance between said first contact means is also the same as the diameter of said shaft.
14. A granular stone column drill as claimed in claim 13 wherein, the engagement 30 section includes a parallel pair of second contact means and the drive section includes a pair of parallel opposing second sides.
15. A granular stone column drill as claimed in claim 14 wherein, the second sides and second contact means are dimensioned similarly to the first sides and first 35 contact means respectively.
16. A granular stone column drill as claimed in any one of claims 13 to 15 wherein, the contact means are independently selected from the group consisting of a surface, an extended rotatable member and a combination of these. 5
17. A granular stone column drill as claimed in any one of claims 13 to 16 wherein, each contact means is a cylindrical roller or wheel.
18. A granular stone column drill as claimed in any one of claims 13 to 16 wherein, at least one contact means is a surface or strip of one or more materials selected 10 from the group consisting of bronze, a low friction metal, a low friction polymer and a low friction ceramic; such that the low friction properties may come from a lubricant or be an inherent property of the material used.
19. A granular stone column drill as claimed in any one of claims 13 to 18 wherein, 15 the cross section of the engagement section is a polygon with the contact means forming the sides of the polygon.
20. A granular stone column drill as claimed in claim 11 or 12 wherein, the drive section is essentially rectangular in cross section and includes at least one drive 20 unit extending from each face of the drive section.
21. A granular stone column drill as claimed in claim 20 wherein, the drive section is essentially a square with rounded corners in cross section. 25
22. A granular stone column drill as claimed in claims 20 or claim 21 wherein, the engagement section includes a first aperture which has a cross section that is the combination of a cross with all arms equal in length and a circle, where the cross and the circle are concentric. 30
23. A granular stone column drill as claimed in claim 22 wherein, the arms of the cross form four drive channels dimensioned to accept at least one drive unit.
24. A granular stone column drill as claimed in any one of claims 20 to 23 wherein, each drive unit can rotate freely about a centreline that is approximately 35 perpendicular to the face from which it extends.
25. A granular stone column drill as claimed in any one of claims 20 to 23 wherein, each drive unit is selected from a surface, an extended rotatable member a combination of these. 5
26. A granular stone column drill as claimed in claim 25 wherein, each drive unit is a cylindrical roller or wheel.
27. A granular stone column drill as claimed in claim 25 wherein, each drive unit is a surface or strip of one or more materials selected from the group consisting of 10 bronze, a low friction metal, a low friction polymer and a low friction ceramic; such that the low friction properties may come from a lubricant or be an inherent property of the material used.
28. A granular stone column drill as claimed in any one of claims 11 to 27 wherein, 15 the engagement section is a socket for the drive section.
29. A method of using the stone column drill as claimed in any one of the preceding claims which includes the following steps in order: - a first or insertion step where the granular stone column drill is inserted into 20 the ground; - a second step where the engagement section and drive section are engaged and the gearbox drives the second drill; - a third or formation step where the displacement device is engaged.
Publications (2)
Publication Number | Publication Date |
---|---|
NZ618804A NZ618804A (en) | 2014-01-31 |
NZ618804B true NZ618804B (en) | 2014-05-01 |
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