Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02883868 2015-03-06
METHODS AND APPARATUSES OF SUPPORTING AND BRACING A UTILITY
POLE
TECHNICAL FIELD
[0001] This document relates to methods and apparatuses of supporting and
bracing a
utility pole.
BACKGROUND
[0002] Utility poles are used to support overhead power lines and other
public
utilities. Traditional methods of supporting a utility pole include using one
or more guy wires
at the upper end of the utility pole to laterally brace the upper end of the
utility pole in the
vertical position. In some environments, such as soft soils, guy wires may be
ineffective in
bracing utility poles. Over time, wind loading on insufficiently braced
utility poles has
caused utility pole tipping, resulting in the weight of the conductor failing
the line.
SUMMARY
[0003] A bracket comprising: a plate having bolt holes and a utility pole
mount; a
clamp secured to the plate, the clamp comprising cooperating screw pile shaft
receiving parts
having laterally extending flanges, the flanges having fastener receiving
openings for
securing the clamp around a screw pile.
[0004] A combination comprising: a bracket; a utility pole extended from a
ground
surface, in which the plate is bolted to the utility pole through the bolt
holes in the plate; and
a screw pile fastened to the clamp and penetrating the ground surface.
[0005] A combination comprising: a bracket comprising a plate and a clamp;
a utility
pole extended from a ground surface, in which the plate is secured to the
utility pole; a screw
pile fastened to the clamp and penetrating the ground surface along an axis
that is parallel to
a utility pole axis; and a lateral stabilizer connected to the utility pole;
in which the utility
pole is positioned above or partially within unstable soil, and the unstable
soil is one or more
of permafrost, soils with ice lensing, muskeg, soil with organics, water
saturated soils, silts,
sands, peat, hog fuel, wood chips, and weak alluvial soils.
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[0006] A method is disclosed of supporting a utility pole that is erected
relative to a
ground surface and defines a utility pole axis, the method comprising:
inserting a first screw
pile and a second screw pile below the ground surface; and connecting each of
the first screw
pile and the second screw pile to the utility pole; in which the first screw
pile is parallel to
the utility pole axis and the second screw pile is at a non zero angle to the
utility pole axis.
[0007] A method is disclosed of bracing a utility pole that is erected
relative to a
ground surface and defines a utility pole axis, in which a first screw pile is
connected to the
utility pole and extended below the ground surface parallel to the utility
pole axis, the
method comprising: inserting a second screw pile below the ground surface at a
non zero
angle to the utility pole axis; and connecting the second screw pile to the
utility pole
[0008] An apparatus is disclosed comprising: a utility pole erected
relative to a
ground surface and defining a utility pole axis; a first screw pile connected
to the utility pole
and extended, parallel to the utility pole axis, from the utility pole to
below the ground
surface; and a second screw pile connected to the utility pole and extended,
at a non zero
angle to the utility pole axis, from the utility pole to below the ground
surface.
[0009] In various embodiments, there may be included any one or more of
the
following features: At least one of the cooperating screw pile shaft receiving
parts is fused to
the plate. The utility pole mount is a channel formed by the plate and having
a C-shaped
cross-sectional shape. The clamp defines a screw pile shaft axis, which is
parallel to a utility
pole axis defined by the channel. A series of stiffeners located within the
channel. Each
stiffener has a utility pole contacting edge that is curved to follow a
portion of an outer
circumferential surface of a utility pole. Each stiffener comprises a utility
pole penetrating
pin. The clamp comprises a series of clamps axially aligned and spaced from
one another
along the plate. A screw pile thrust stop secured to the plate. The screw pile
thrust stop
comprises a plate positioned across a screw pile shaft axis defined by the
clamp. Bolts
securing the bracket to the utility pole or fastening the screw pile to the
clamp are installed to
an installation torque at or above 150 Newton meters. The utility pole is
positioned above or
partially within unstable soil, and the nstable soil is one or more of
permafrost, soils with
ice lensing, muskeg, soil with organics, water saturated soils, silts, sands,
peat, hog fuel,
wood chips, and weak alluvial soils. The screw pile is a first screw pile, and
further
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comprising a second screw pile penetrating the ground surface and secured by
bracket to the
utility pole at a base of the utility pole above the ground in a batter pile
configuration relative
to the utility pole, in which the first screw pile is mounted parallel to a
utility pole axis. The
second screw pile comprises plural second screw piles secured at various
radially spaced
locations about a utility pole circumference. The first screw pile and the
second screw pile
are both screw piles sized for the utility pole. The first screw pile and the
second screw pile
are helical piers. Inserting comprises screwing. Inserting comprises
monitoring torque
applied to the second screw pile during insertion and stopping insertion after
the torque
applied exceeds a predetermined value. Connecting comprises connecting the
second screw
pile to the utility pole through a bracket. The soil adjacent the utility pole
is unstable soil.
The unstable soil is one or more of permafrost, soils with ice lensing,
muskeg, soil with
organics, water saturated soils, silts, sands, peat, hog fuel, wood chips, and
weak alluvial
soils. The second screw pile is connected at a vertical connection distance
from the ground
surface and at an angle with respect to the utility pole sufficient to
laterally brace the upper
end of the utility pole. The method may include erecting the utility pole
relative to the
ground surface. The first screw pile is connected adjacent to a base of the
utility pole.
Connecting further comprises connecting the second screw pile to restrict
relative
movement, in all axes of direction, between the utility pole and the second
screw pile. A
bracket connects the second screw pile and the utility pole. The bracket has a
guide, and the
bracket has at least a configuration in which the guide allows relative axial
displacement
between the bracket and the second screw pile. The utility pole is a utility
pole.
[0010] These and other aspects of the device and method are set out in the
claims,
which are incorporated here by reference.
BRIEF DESCRIPTION OF THE FIGURES
[0011] Embodiments will now be described with reference to the figures, in
which
like reference characters denote like elements, by way of example, and in
which:
[0012] Fig. 1 is a side view of a known method of supporting a utility
pole with a
screw pile and guy wire.
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[0013] Fig. 2 is a side view illustrating a system and method of
supporting or bracing
a utility pole.
[0014] Fig. 3 is a perspective view of a bracket used in the method of
Fig. 1.
[0015] Fig. 4 is a perspective view of a pair of the brackets of Fig. 3
connected to the
utility pole of Fig. 1 and each supporting a screw pile.
[0016] Fig. 5 is a perspective view of a utility pole mounting plate taken
from the
bracket of Fig. 3.
[0017] Fig. 6 is bottom plan view of the bracket of Fig. 3.
[0018] Fig. 7 is a perspective view of an embodiment of a bracket used in
the method
of Fig. 1.
[0019] Fig. 8 is a perspective view of another embodiment of a bracket
used to
connect a screw pile to a utility pole.
[0020] Fig. 9 is a top plan view of the bracket of Fig. 8.
[0021] Fig. 10 is a side elevation view of the bracket of Fig. 8.
[0022] Fig. 11 is a bottom plan view of the bracket of Fig. 8.
[0023] Fig. 12 is an end elevation view of an outer screw pile receiving
part of the
clamp of the bracket of Fig. 8.
[0024] Fig. 13 is an end elevation view, in section, of the clamp of the
bracket of Fig.
8 used to clamp a screw pile shaft.
[0025] Fig. 14 is a top plan view of the inner screw pile receiving part
of the clamp
of the bracket of Fig. 8, with dashed lines used to illustrate plates used to
secure the part to
the bracket plate.
[0026] Fig. 15 is an end elevation view of the inner screw pile receiving
part of Fig.
14, with a screw pile shaft shown in dashed lines.
[0027] Fig. 16 is a side elevation view of the inner screw pile receiving
part of Fig.
14.
[0028] Fig. 17 is an end elevation view of a stiffener located within the
plate channel
of the bracket of Fig. 8.
[0029] Fig. 18 is a side elevation view of a system and method of
supporting a utility
pole with the brackets of Fig. 7 and
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[0030] Fig. 19 is a section view taken along the 19-19 section lines in
Fig. 18.
[0031] Fig. 20 is a side elevation view of the brackets from Fig. 8 used
on utility
poles that make up a distribution or transmission tower.
DETAILED DESCRIPTION
[0032] Immaterial modifications may be made to the embodiments described
here
without departing from what is covered by the claims.
[0033] Referring to Fig. 1, utility poles 11 are used to support overhead
power lines
40 and various other public utilities, such as cable, fiber optic cable, and
related equipment
such as transformers and street lights. Utility poles may be referred to as
telephone, power,
hydro, telegraph, or telegraph posts or utility poles, depending on
application. Electrical
cable may be routed overhead as an inexpensive way to keep it insulated from
the ground 12
and out of the way of people and vehicles. Utility poles may be made of wood,
metal,
concrete, composites such as fiberglass, or other suitable materials. Utility
poles may be fifty
or ninety feet tall in some cases, and may support hundreds of feet of wire.
Utility poles are
often placed in areas where fences and other infrastructure cannot be placed
due to unstable
soil conditions. A poorly supported utility pole may fall over and cause a
forest fire or other
devastation.
[0034] Figure 1 shows a depiction of a utility pole 11. Utility pole 11
may extend
below ground surface 12, but is founded by a vertically drilled screw pile,
such as a helical
pier 22. Pier 22 is driven into ground surface 12 adjacent and parallel to
utility pole 11, and
secured to a base 48 of utility pole 11 using bolts 31 past through holes (not
shown) blown
through utility pole 11 and pier 22. An upper end 17 of utility pole 11 nay be
laterally braced
using one or more guy wires 15, which are anchored below ground surface 12 at
guy
insertion points 44 spaced a sufficient lateral distance from a utility pole
entry point 46 in
ground surface 12. Although shown in a 60-90 degree cable installation, guy
wires are
similarly used in other utility pole 11 cable installations, such as tangent
or dead end cable
installations.
[0035] As seen in Figure 2, in particular embodiments, an apparatus 10 is
illustrated.
Apparatus 10 may include a utility pole 11, a first screw pile 16, and a
second screw pile 18.
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Utility pole 11 may be erected relative to a ground surface 12 to define a
utility pole axis 14.
The first screw pile 16 may be connected to the utility pole 11, for example
using a series of
bolts 31. Screw pile 16 may also be extended, parallel to the utility pole
axis 14, for example
vertically, from the utility pole 11 to below the ground surface 12 as shown.
The second
screw pile 18 may be connected to the utility pole 11, for example using a
suitable securing
mechanism such as a bracket 24. Screw pile 18 may be extended, at a non-zero
angle 20 to
the utility pole axis 14, from utility pole 11 to below the ground surface 12
as shown.
[0036] The use of the second screw pile 18 may give tensile lateral
support to the
utility pole 11 similar to a guy wire, but also gives compression support to
the utility pole 11.
The first screw pile 16 and the second screw pile 18 may both be screw piles
sized for the
utility pole 11 as shown. Even though screw pile 16 is illustrated as founding
the utility pole,
screw pile 18 is also of sufficient dimensions and strength to found the
utility pole 11 by
occupying the founding position of screw pile 16. This means the same
equipment can be
used to install both screw piles 16 and 18. Using one or more screw pile 18 is
advantageous
because screw piles are cheaper and more efficient to install than are guy
wires. Installing
guy anchors requires use of specialized tools as well as the cost of the guy
anchor and wire
itself.
[0037] In some embodiments, the first screw pile 16 and the second screw
pile 18
may be helical piers 22 as shown. Helical piers 22 may comprise a shaft 25
with one or more
helical flights 23 protruding laterally from the shaft 25 at or near a pointed
drive end 27 of
the pier 22, or at various locations along the length of the shaft 25. Screw
piles include
ground screws, foundation anchors, anchor rod anchors, rod drive anchors, and
helical piles.
Using screw pile 18 may also eliminate the need for guying the utility pole
11. Elimination
of guying is advantageous for reasons given above and because guy wires give
the utility
pole 11 a larger lateral footprint than do screw piles 18, compare footprints
103 and 104 in
Fig. 18 for example. A smaller footprint is particularly useful if space
around utility pole 11
is restricted, for example if located adjacent roadways, pipelines, or thick
vegetation.
[0038] As shown in Figs 3-7, the apparatus may comprise a bracket 24
connecting
one or more of the screw piles, for example screw pile 18, to the utility pole
11. The bracket
24 may be designed to withstand forces greater than the breaking strength of
the utility pole
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11. Bracket 24 may be formed of one or more parts, for example a base, such as
a plate 37,
and a screw pile mount such as a clamp 38. The plate 37 may have bolt holes,
such as holes
66 and 70 (Fig. 5), and a utility pole mount such as a channel 65 formed by
the plate 37 and
having a C-shaped cross-sectional shape (Fig. 5).
[0039] The clamp 38 may be secured to the plate 37, and may comprise
cooperating
screw pile shaft receiving parts 35, for example semi-cylindrical part 35 as
shown. Parts 35
may cooperate to form a guide, for example an axial passageway 41 sized to fit
screw pile 18
and open at both axial ends 39 (Figs. 3-4). Passageway 41 allows the bracket
24 to have at
least a configuration in which the guide 34 allows relative axial displacement
between the
bracket 24 and the second screw pile 18. Screw pile 18 may be axially
displaced through
bracket 24 along direction lines 33 as shown in Fig. 4, at least before being
secured into
place in the bracket 24.
[0040] Screw pile receiving parts 35 may be connected together by a
suitable
mechanism. For example, parts 35 may have laterally extending flanges 58, for
example
laterally extended from the edges 81 of C-shaped screw pile contacting
portions 59. The
flanges 58 may have fastener receiving openings, such as bolt holes 63, for
securing the
clamp around a screw pile, for example using bolts 50, nuts 52, and spring
clips 54, passing
through cooperating flanges 58 as shown (Fig. 3). A further bolt 51 may be
passed through
an opening 45 in portion 59 to contact and secure screw pile 18 from axial
movement once
positioned within bracket 24 (Fig. 4).
[0041] One or more of screw pile receiving parts 35 may connect to plate
37, for
example through a base plate 60 and flange plate 61 (Fig. 7). Clamp 38 may
also be adapted
to pivot or move relative to plate 37. Pivoting may be accomplished via a
suitable pivoting
mechanism. For example, base plate 60 may include one or more C-shaped holes
62 that
allow one or more bolts 64 to loosely secure plate 60 to plate 37 through bolt
holes 66, while
allowing bracket 24 to pivot, for example about an axis 49 perpendicular to
the plate 37
(Figs. 3, and 5-6). In other cases, plate 37 includes C-shaped holes 62. Plate
37 may also be
designed to allow relative movement with utility pole 11 once partially
secured to utility pole
11, to permit the fine-tuning of the position of the bracket 24 prior to
securing to the utility
pole 11. For example, plate 37 may include a pair of holes, one being a slide
hole 68 and the
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other being a standard bolt hole 70 (Figs. 3 and 5). Once a bolt 36 is loosely
passed through
slide hole 68 into utility pole 11, bracket 24 may be vertically moved
relative to utility pole
11 as far as permitted by the dimensions of slide hole 68. Once in position,
bolts 36, 72, 64,
and 51 may be fully secured to prevent further relative movement. These and
other
mechanisms may be used to allow relative movement between bracket 24 and
utility pole 11
or bracket 24 and screw pile 18 to allow fine positional adjustments after
rough positioning
and partial securing. Allowing relative movement between utility pole 11 and
bracket 24
makes installation of apparatus 10 more convenient because small errors in
initial
positioning can be corrected without having to remove the bracket 24 from the
utility pole
11. For example, if screw pile 18 is driven into ground surface 12 first, and
then bracket 24
installed partially upon utility pole 11, slide hole 68 and bolt 36 allow the
proper vertical
height of bracket 24 to be obtained after partially securing to utility pole
11. Similarly, holes
62 allow bracket 24 to assume the proper angle for receiving screw pile 18 and
connecting to
utility pole mount 37.
[0042] Referring to Fig. 2, a method of supporting a utility pole 11 is
also illustrated.
The method may begin with utility pole 11 being erected relative to a ground
surface 12 and
defining a utility pole axis 14. In a first stage, a first screw pile 16 and a
second screw pile 18
may be inserted, for example by screwing, below the ground surface 12. In a
second stage,
each of the first screw pile 16 and the second screw pile 18 may be connected
to the utility
pole 11. After connection, the first screw pile 16 may be parallel to the
utility pole axis 14
and the second screw pile 18 may be at a non-zero angle 20 to the utility pole
axis 14.
[0043] As described above inserting may comprise screwing, for example if
helical
piers 22 are used. Screwing is beneficial because it minimally disrupts the
ground and thus
negates the need to allow the ground to settle after installation. When
working with unstable
soils, the ability to avoid excavation and backfilling followed by settling is
further
advantageous, as the strength of the soil is already weak to begin with.
[0044] Inserting may further comprise monitoring torque applied to the
first or
second screw pile during insertion and stopping insertion after the torque
applied exceeds a
predetermined value. The torque may be monitored directly, through for example
a torque
gauge 47, or indirectly, for example by counting the number of rotations. An
exemplary
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predetermined torque value may be 1000 foot pounds averaged over 3 feet,
although other
suitable torques may be used depending on application. In some cases the
predetermined
torque may be selected to make the foundation as strong as if the pole 11 were
mounted in
firm soil conditions. Monitoring torque gives a user an objective way to
measure the holding
strength of the screw pile 18. By comparison, there is no way of testing the
holding strength
of a guy anchor once installed, despite the requirement in many jurisdictions
that holding
strength must be of a predetermined minimum value.
[0045] Inserting screw pile 18 to a predetermined torque means that soil
strength is
not be a factor because the pull-out strength is determined by the applied
torque. If after
insertion, the predetermined torque value has not been met, extension screw
pile sections can
be added to screw pile 18 to increase the length of screw pile 18 so that
enough screw pile 18
can be inserted into ground 12 to meet the predetermined torque value. As
shown in Figs 2-
5, in particular embodiments, connecting may further comprise connecting the
first or second
screw pile to the utility pole through a bracket 24.
[0046] The utility pole 11 may itself be inserted into the ground 12, or
may be
positioned on top of or above the grot:nd 12. In some embodiments, either the
first screw pile
16 or the second screw pile 18 or both may connect to the utility pole 11
above ground 12,
for example by connecting to base 48 of utility pole 11, the base 48 being
contrasted with the
middle 28 and upper end 17 portions of utility pole 11. As shown in Fig. 18,
the base 48 may
only have a height 101 that is a fraction of the height 102 of the utility
pole 11 itself, with
height 101 being within reach of an adult in most cases. Thus, installation of
the bracket 24
and screw pile 22 can be accomplished without special ladders, cherry pickers,
or climbing.
In other embodiments the first screw pile 16 or the second screw pile 18 or
both may connect
to the utility pole 11 below ground 12.
[0047] The soil 26 adjacent to the utility pole 11 may be unstable soil
26, such as one
or more of permafrost, soils with ice lensing, muskeg, soil with organics,
water saturated
soils, silts, sands, peat, hog fuel, wood chips, and weak alluvial soils. Soil
strength may be
determined using a geotechnical analysis, for example incorporating a standard
penetration
test. A worker may dig a hole for utility pole 11, log geotechnical
information for that hole,
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and fill out a log chart. If there is a meter or more of unstable or weak soil
at the surface,
vertical stabilization and lateral stabilization may be used as described in
this document.
[0048] Referring to Fig. 2, the first and second screw piles 16 and 18 may
be
connected at a vertical connection distance 19 from the ground surface 12 and
at an angle 20
with respect to the utility pole sufficient to laterally brace the upper end
17 of the utility pole.
For example distance 19 may be 1-2 meters above grade, for example 1.5 meters
above
grade, although other distances 19 may be used. Vertical connection distance
19 may be
positioned above base height 21 of screw pile 16 in some cases. For example,
angle 20 may
be thirty to sixty degrees, although other angles may be used.
[0049] The method may further comprise erecting utility pole 11 relative
to the
ground surface 12, for example before, during, or after the first stage and
before or during
the second stage. In some embodiments, the first screw pile 16 may be
connected adjacent to
a base 48 of the utility pole 32. In an exemplary embodiment, connecting may
further
comprise connecting the second screw pile 18 to restrict relative movement, in
all axes of
direction, between the utility pole 11 and the second screw pile 18.
[0050] In another embodiment, a utility pole 11 may be braced, the utility
pole 11
already having a first screw pile 16 connected to the utility pole 11 and
extended below the
ground surface parallel to the utility pole axis 14. Second screw pile 18 may
be inserted
below the ground surface 12 at a non-zero angle 20 to the utility pole axis
14. The second
screw pile 18 may then be connected to the utility pole 11. Such a method
allows existing
installations comprising utility pole 11 founded by screw pile 16 to be
improved via
installation of screw pile 18 in the manner described. Such a method may be
used to laterally
brace utility pole installations in areas of unstable soils. In other cases,
no vertical first pile
16 may be present or connected to utility pole 11, such that the second screw
pile 18 is the
only such pile used to stabilize the utility pole 11.
[0051] Referring to Fig. 7 another embodiment of a bracket 24 is
illustrated, with
plate 37 and screw pile receiving parts 35 provided as independent pieces.
Extended from
plate 37 is a neck plate 61 that may be connected, for example by fillet
welding, to receiving
part 35. The neck 61-plate 60 connection may be made before or after plate 37
is connected
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to the utility pole. A swivel pin 13 may be mounted between plate 37 and plate
60 to assist in
aligning plate 60 and plate 37 together before securing bolts 64. The swivel
pin 13 may be
provided as part of plate 60, plate 37, or as an independent part. To install
the bracket 24 to a
utility pole 11, holes (not shown) are drilled through the utility pole 11,
and bolts 36 passed
through corresponding bolt holes 70 in the plate 37 and the holes in the
utility pole 11. Nuts
73 and washers 67 may be used to complete the bolted connection to the utility
pole 11. The
utility pole mount of plate 37 is a channel 65 formed by the plate 37 and
having a C-shaped
cross-sectional shape, for example defined by a base part 69 and side walls
71. The width of
side walls 71 may increase from a utility pole contacting edge 74 to base part
69, to reinforce
the plate 37. The edges 74 may be textured (not shown) to grip the utility
pole 11 in use.
[0052] In some cases the disclosed methods and apparatuses provide a
buttress pile
in a manner that it will work for the compression holding forces and also the
opposing
tension holding forces at the base of a power pole, so as to provide a base
support to the pole
in soft soil. Such a structure eliminates the need to guy and anchor in two
opposing
directions the top of the structure. In some cases a power pole is provided
the support at the
base of the structure that it could obtain if it were set in stable soil
conditions, such as dry
compactable clay, albeit using a relatively decreased footprint while taking
advantage of the
compression and tension holding cap'city, and with a footprint on one side of
the power pole
only in some cases. Conventional guying requires two opposing anchors attached
at the top
of a pole and the footprint would be a minimum of 6-10 meters (3-5 meters
either side).
[0053] Fig. 1 discloses a conventional way to laterally brace a utility
pole anchored
by a helical pier 22 parallel to the pole axis. The pole is laterally braced
using guy wires 15.
There are several drawbacks with guy wires. Firstly, there is no effective way
to test the
holding strength of the guy against tensile forces. Second, guy wires take up
a relatively
large lateral footprint (see Fig. 18) as the guy wires must be extended a
distance from the
pole and are connected near the upper end of the pole. Third, guy wires do not
resist
compressive loading. Thus, two guy wires in opposition are required to
laterally brace in
opposing directions. Fourth, over time the guy wires stretch and sag, leading
to weakened
lateral stabilizing.
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[0054] By contrast, guy wires can be replaced with a second screw pile
screwed in at
a non-zero angle to the utility pole axis. Several advantages may be realized
over guy wires.
Firstly, lateral brace loading strength can be quantified and tested by
monitoring torque
applied to the screw piles 18 during insertion and stopping insertion after
the torque applied
exceeds a predetermined value. Second, the angled screw pile takes up less
lateral space and
gives a relatively smaller footprint as a result, see Fig. 18 for example.
Such a result may be
particularly important for example if the pole is adjacent roadways,
pipelines, or thick
vegetation. Such a result is also possible because the screw pile can be
connected near the
base of the pole and simply screwed far enough into the ground until the
desired holding
strength is achieved. Third, screw piles resist tensile and compressive
loading. Screw piles
may have flights 23 or other lateral protrusions like threads, which grip the
soil to resist
tensile (pull out) and compressive (push in) loading. Fourth, screw piles are
rigid and do not
sag or stretch over time. Fifth, screw piles used in the disclosed methods and
apparatuses are
cheaper and more efficient to install than a comparable guy wire arrangement.
Sixth, the
labor costs for guy wire installation are relatively higher, in some cases
seventy percent
higher, than for a screw pile. In some cases there is also a difference of
about forty percent
decrease in production time when installing a screw pile as opposed to
installing two guy
anchors and extension rods in unstable or soft soil.
[0055] Referring to Figs. 8-1C, a further embodiment of a bracket 24 is
illustrated.
The clamp 38 comprises a series of clamps 38 axially aligned and spaced from
one another
along the plate 37 (Fig. 8). The clamps 38 may collectively define a screw
pile shaft axis 76,
which may be parallel to a utility pole axis 75 defined by the channel 65. In
use in this
example the utility pole axis 75, the screw pile shaft axis 76, and the axis
14 of the utility
pole 11 itself after installation, are all parallel to one another. The
channel 65 runs from a
first end 77 to a second end 78 of the plate 37, with the clamps 38 being
spaced along the
plate 37 from first to second ends 77 and 78. The length of channel 65 from
end to end 77-78
may be five feet in one example. The dimensions of the channel 65 may be
selected such that
the edges 74 contact the utility pole 11 in use, while a portion of the base
part 69 of the
channel 65 may or may not contact the utility pole 11. Thus, all or a
substantial portion of
the gripping force of the bracket 24, excepting the force from the bolts 91,
may be focused
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along the relatively narrow surface area of the edges 74, leading to a
stronger bite along
edges 74 than if the force were dispersed across a surface area the size of
the base part 69.
[0056] Referring to Figs. 12-16, the structure of the clamp 38 is
illustrated. At least
one of the screw pile shaft receiving parts, in this case 35', may be fused to
the plate 37, for
example by welding or other integral connection. In the example shown parts
35' and 35"
include first and second omega-shaped pieces 79' and 79", respectively.
Referring to Fig.
12, the second omega piece 79" is shown and described, although the first
piece 79' shares
many common features with piece 79- in this example. Piece 79" has a pipe
receiver 80
with a C-shaped cross-section, and connected along both edges 81 of pipe
receiver 80 are
laterally extending flanges 58. Omega piece 79" has a back surface 83 and a
pipe gripping
inner surface 84. Omega pieces 79 may be formed by bending a single piece of
metal in
some cases. Referring to Fig. 13, omega piece 79' may be reinforced by one or
more plates
82 extended, for example welded, perpendicularly from respective back surfaces
83 of
omega pieces 79. Referring to Figs. 13, 14, and 16, in the example shown two
spaced fins or
plates 82 are extended perpendicularly between back surface 83 of omega piece
79', and an
outer surface 85 of plate 37. A plate, such as a flat bar 86, extends, for
example by welding,
between plates 82 for further reinforcement. Referring to Fig. 15, each plate
82 may connect
to back surface 83 of piece 79' along the entire width of the pipe receiver 80
and at least part
of each flange 58. Referring to Figs. 13 and 14, each flange 58 carries a
fastener receiver
opening, such as bolt holes 63, for receiving bolts 50, which may be secured
using nuts 52.
In use, the size of the opening provided by clamp 38 for screw pile 22 is
selected such that
fastening the flanges 58 together produces compressive forces against screw
pile 22, to apply
a friction hold on pile 22 against axial thrusting.
[0057] Referring to Figs. 9, 10, 11, and 15, a series of stiffeners 90 may
be located
within the channel 65. Referring to Fig. 15, each stiffener 90 may be a plate
as shown,
extended, for example by welding, perpendicularly across channel 65. Each
stiffener 90 may
have a utility pole contacting edge 92 that is curved to follow a portion of
an outer
circumferential surface of a utility pole 11. Each stiffener may comprise a
utility pole
penetrating pin or pins 94. Pins 94 act like nails, and allow the bracket 24
to be initially
secured to utility pole 11 by for example pressing pins 94 into utility pole
11 by suitable
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force such as hammering plate 37. Stiffeners 90 and pins 94 act as sheep dogs
that take some
axial load off of bolts 91 (Fig. 11). Referring to Fig. 11, stiffeners 90 and
bolt holes 70 may
be staggered along the length of the plate 37 from first end 77 to second end
78. Bolts 91
pass through holes 70 and corresponding holes in utility pole 11, emerging
from the opposite
side of utility pole 11 where nuts 93 and washers 95 may be used to secure
bolts 91, and
plate 37, in place. Pins 94 also prevent sliding of the plate 37 along the
utility pole 11.
[0058] Referring to Figs. 8-10, bracket 24 may have a screw pile thrust
stop, such as
a plate 96, secured to the plate 37. Plate 96 may be positioned across the
screw pile shaft axis
76 defined by the clamp 38. Thus, plate 96 blocks or limits the axial travel
of a shaft 25 of
screw pile 22 through clamps 38. The plate 96 may effectively cap the shaft
conduit defined
collectively by the clamps 38. The plate 96 may be reinforced by one or more
brace plates 97
extended, for example by welding, between plate 37 and plate 96, for example
perpendicular
to both plates 37 and 96. The plate 96 prevents vertical thrust of the screw
pile 22 relative to
the utility pole 11, and allows the utility pole 11 to effectively sit on top
of the pile 22.
[0059] Referring to Fig. 18, a combination of a bracket 24', utility pole
11, and screw
pile 22' is illustrated. The bracket 24' is secured to the utility pole 11,
for example by bolting
as described above. The screw pile 22' is fastened to the clamps 38 and
penetrates the
ground surface 12 vertically, parallel to the utility pole 11. A lateral
stabilizer, such as the
combination of a second screw pile 22- and the bracket 24" described in Figs.
2-7, may be
connected to the utility pole 11. Other later stabilizers may be used, such as
one or more guy
wires 15. The utility pole 11 is positioned above or partially within unstable
soil 26, and the
unstable soil is one or more of permafrost, soils with ice lensing, muskeg,
soil with organics,
water saturated soils, silts, sands, peat, hog fuel, wood chips, and weak
alluvial soils.
Insertion of screw pile 22' into soil 26 may be carried out before or after
securing the plate
37 to the utility pole 11, for example using bolts 91 as described above. Once
the plate 37 is
secured to the utility pole 11, and the screw pile 22' inserted into the soil
26 with sufficient
torque to found the base 48 of the utility pole 11, the pile 22' may be
connected to the
clamps 38, for example as described above. The bracket 24' may be positioned
such that a
top end 98 of the screw pile 22 contacts the plate 96 of the thrust stop
mechanism. In some
cases the thrust stop plate 96 may be connected in a fashion that allows fine
positioning of
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the stop relative to the plate 37, or relative to the utility pole 11, after
the plate 37 is secured
to the utility pole 11. In some cases the thrust stop plate 96 may be
connected to plate 37
after securing the plate 37 to the utility pole 11. Bolts, such as bolts 91
and 50, may secure
the bracket 24' to the utility pole 11 or fasten the screw pile 22 to the
clamps 38 with an
installation torque at or above 150 Newton meters.
[0060] Referring to Fig. 18, a second screw pile 22- may penetrate the
ground
surface 12 and be secured by bracket 24" to the utility pole 11 at a base 48
of the utility pole
11 above the ground in a batter pile configuration relative to the utility
pole 11 as shown.
Referring to Fig. 19, plural second screw piles 22" may be secured at various
radially spaced
locations about a utility pole 11 circumference. For example, three piles 22"
are positioned
at 120 degree intervals about a utility pole 11 circumference.
[0061] Referring to Fig. 20, a transmission or distribution tower 99
mounted in
unstable soils is illustrated, with base utility poles 11 each with a bracket
24 secured to the
utility pole 11 and mounting a vertical screw pile 22. The lateral connections
100 between
utility poles 11 may provide lateral stabilization to the utility poles 11,
while the screw piles
22 provide thrust, sinking, and lateral strength to the tower 99. The
disclosed method of
founding a distribution or transmission tower is a replacement for previous
methods of
founding such towers, for example using more complicated and expensive bucket
pile
foundation methods.
[0062] Using a vertical bracket such as bracket 24' may be more expensive
than the
traditional vertical support method illustrated in Fig. 1 with bolts 31.
However, additional
strength is added to the screw pile 22 in the axial and lateral directions. In
addition, the
strength of the screw pile 22 itself is not comprised because there is no need
to drill holes in
the screw pile itself when using bracket 24'. The bracket 24' also spaces
screw pile 22 a
distance away from pole 11, as opposed to directly adjacent pole 11,
increasing the lateral
support provided by the pile 22, and making installation of screw pile 22
easier to
accomplish because the pile 22 is not directly adjacent the pole 11. Bracket
24' also
distributes load off of bolts 91 used to secure screw pile 22 to pole 11, thus
increasing shear
resistance and longevity.
CA 02883868 2015-03-06
[0063] All of the methods disclosed here may be used for permanent or
temporary
installation of screw piles 16 and 18 to brace utility pole 11. One or both of
screw pile 16 or
18 may be telescopic. The first and second screw piles 16 and 18,
respectively, may be
inserted at the same time or in a suitable order of insertion. Screw piles 16
and 18 may be
connected to the utility pole 11 at the same time or in a suitable order of
connection. The
utility pole 11 may be installed after one or both of screw piles 16 and 18
are inserted. The
position of screw pile 16 as being parallel to the utility pole 11 includes at
least nominal
deviations from parallel. In some cases screw pile 16 need not be parallel,
and may be at a
non-zero angle relative to the utility pole axis.
[0064] Use of screw piles 16 and 18 restricts lateral utility pole tipping
as well as
vertical jacking. The apparatus 10 may be designed to withstand a lateral
force greater than
the breaking strength of the utility pole 11. The first screw pile 16 may be
positioned
underneath the utility pole 11 as a foundation base. Wherever mechanisms such
as bolts or
other securing mechanisms are discussed, it should be understood that other
suitable
connection mechanisms may be used, for example welding, nailing, adhesive, and
others.
Although described above with respect to a utility pole, other utility poles
may be used in the
apparatuses and methods disclosed here. Screw pile 18 may in some cases be
installed
through a bracket 24 after bracket 24 is partially secured to utility pole 11.
Apparatus 10 in
Fig. 2 is set up for a tangent installation relative to the conductor wire,
although other
installations may be used. In some embodiments, inserting may comprise
extending or
pounding. An insertion hole (not shown) may be drilled prior to insertion of
either screw
piles 16 or 18.
[0065] The word plate in this document is not limited to a flat object.
Other non-bolt
fasteners may be used to secure flanges 58. In some cases a hinge may be
provided between
two cooperating flanges 58, with the opposite cooperating flanges 58
connecting by bolting
or another suitable fastening mechanism. Vertical includes nominal deviations
from vertical
and is used as a relative word. C-shaped includes U-shaped. The utility pole
11 may have a
circular cross sectional shape.
[0066] In the claims, the word "comprising" is used in its inclusive sense
and does
not exclude other elements being present. The indefinite articles "a" and "an"
before a claim
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feature do not exclude more than one of the feature being present. Each one of
the individual
features described here may be used in one or more embodiments and is not, by
virtue only
of being described here, to be construed as essential to all embodiments as
defined by the
claims.
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