Note: Descriptions are shown in the official language in which they were submitted.
CA 02502065 2005-03-23
METHOD FOR IN SITU REPAIR OF TIMBER PILES
USING SYNTHETIC REINFORCING FABRIC
FIELD OF THE INVENTION
The present invention relates in general to methods for in situ repair of
ground-
penetrating wooden structural elements, such as timber piles and utility
poles, that have
been damaged by fungi or other causes.
BACKGROUND OF THE INVENTION
It is well known to use timber piles to support buildings and other
structures.
Timber piles are commonly driven into pre-drilled pilot holes, or may be
driven directly
into the ground without pre-drilling. Depending on the soil conditions, the
required load-
carrying capacity is developed by driving the piles to a subsurface hardpan or
bedrock, or
to a sufficient depth to develop the required capacity by way of "skin
friction" between
the circumferential surfaces of the piles and the surrounding soil. In some
applications,
the piles must be capable of resisting lateral forces due to wind or other
lateral loads
acting on the supported structure. In such cases, the upper sections of the
piles are
subject to transverse flexural stresses in addition to the vertical
compressive stresses
induced by the weight of the supported structure.
Timber piles are preferably treated with creosote or other preservatives to
prevent
or inhibit deterioration due to fungal attack. Various fungi that are
naturally prevalent in
the environment will consume organic material provided that the requisite
conditions of
oxygen, moisture, and temperature are present. These conditions are commonly
present
(particularly in the spring) in the upper few feet of soil under structures
supported by
timber piles, particularly where there is an air space between the piles and
the supported
structure (e.g., buildings with crawl spaces). Where the piles are
inadequately protected
against fungal attack, or where the piles' preservative treatment has
deteriorated or has
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been impaired for some reason, the piles will be susceptible to rot or decay,
particularly
near the ground surface.
Such rot or decay causes serious impairment of the piles' capacity to resist
both
vertical and transverse structural loads. This effect is particularly
pronounced with
S respect to the piles' flexural resistance, since the loss of material
thickness from the outer
surface of a structural member causes an exponential reduction in flexural
strength and
stiffness. For these reasons, it is critically important to repair or replace
timber piles that
have been damaged by fungal attack or other phenomena, in order to ensure that
the piles
will have sufficient strength to resist all loads that may be imposed by the
supported
structure, and with an adequate factor of safety. It is also highly desirable
to be able to
repair the piles in situ.
There are a number of known methods for dealing with the problem of decayed
timber piles, including underpinning methods that involve the installation of
new piles to
replace the damaged piles. The main object of the present invention is to
provide an
improved method for in situ repair of timber piles to restore all or part of
the structural
integrity and strength that has been lost due to decay or other damage.
BRIEF DESCRIPTION OF THE INVENTION
In general terms, the present invention is a method for repairing, in situ, a
timber
pile that has experienced deterioration due to fungal attack or other type of
damage. In
one aspect, the invention is a method for repairing a damaged timber pile in
situ,
comprising the steps of:
(a) removing unsound material from a damaged timber pile within a selected
repair section, so as to expose a core section of sound material;
(b) installing a grout form enclosing the repair section of the pile so as to
form
a grout space within the form, said form having a grout opening and being
configured so as to generally correspond to the original surface contours
of the pile in the repair section;
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(c) introducing a fluid grout into the grout space through the opening in the
grout form, so as to substantially fill the grout space;
(d) allowing the grout to solidify;
(e) removing the grout form, thus exposing the grouted area; and
(f) bonding a first layer of non-biodegradable reinforcing fabric to the
exposed surface of the grouted area using an impregnation resin.
In a second aspect, the invention is a method for repairing a damaged,
substantially vertical timber pile in situ, comprising the steps of:
(a) exposing a portion of the pile, including the damaged region plus a
portion
extending below the damaged region to a ground surface;
(b) cutting off an upper portion of the pile by severing the pile at a
substantially horizontal cutting plane located below the damaged region,
leaving a pile stub projecting above the ground surface, said pile stub
having a substantially horizontal top surface and a circumferential outer
surface;
(c) forming a plurality of substantially vertical grooves in the
circumferential
outer surface of the pile stub, each said groove being of a selected length
and extending downward from the top surface of the pile stub;
(d) forming a hole at or near the lower end of each groove in the pile stub,
each said hole extending radially into the pile;
(e) providing a round timber infill section of selected length, said infill
section having an upper end, a lower end, and a circumferential outer
surface, said lower end having a substantially planar bearing surface
oriented substantially transverse to the longitudinal axis of the infill
section, with the diameter of said infill section substantially matching the
diameter of the pile stub;
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(f) forming a plurality of substantially vertical grooves in the
circumferential
outer surface of the infill section, each said groove being of a selected
length and extending upward from the lower end of the pile stub, with the
number and circumferential spacing of said grooves matching the number
and spacing of the grooves in the pile stub;
(g) forming a hole at or near the upper end of each groove in the infill
section,
each said hole extending radially into the stub;
(h) positioning the infill section upon the pile stub, such that the lower
bearing
surface of the infill section bears on the top surface of the pile stub, with
the vertical grooves in the infill section being aligned with the vertical
grooves in the pile stub, thus forming a plurality of tension bar channels
each comprising an infill section groove and a matching groove in the pile
stub plus their corresponding radial holes;
(i) for each tension bar channel, providing a double-hooked tension bar
having a straight elongate center section and having a hooked section at
each end, said hooked sections being substantially perpendicular to the
center section, with the distance between the hooked sections matching the
distance between the radial holes of the corresponding tension bar
channel;
(j) applying grout to the radial holes in the infill section and the pile
stub;
(k) before the grout has set, inserting a double-hooked tension bar into each
tension bar channel such that the center section of each tension bar is
disposed substantially completely beneath the circumferential outer
surfaces of the infill section and the pile stub, and such that each hooked
section of the tension bar is extends into one of the tension bar channel's
radial holes forming part of the tension bar channel, said step of inserting
the tension bars into the tension bar channels causing displacement of
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grout such that there remains a layer of grout substantially surrounding
each hook within its corresponding radial hole;
(1) bonding a first layer of non-biodegradable reinforcing fabric to the
circumferential surfaces of the infill section and the pile stub using an
impregnation resin, said first layer of reinforcing fabric being of sufficient
dimensions to substantially cover all of the tension bars.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described with reference to the
accompanying figures, in which numerical references denote like parts, and in
which:
FIGURE 1 is a conceptual depiction of a damaged timber pile prior to
being repaired in accordance with a first aspect of the present invention.
FIGURE 2 depicts the repair section of the damaged timber pile of Figure
1, after removal of unsound material.
FIGURE 3 illustrates the repair section of the pile of Figure 2 with the
grout form in place.
FIGURE 4 illustrates the repair section of the pile of Figure 2 after
application of grout and reinforcing fabric.
FIGURE 5 is an elevation of a damaged timber pile repaired in
accordance with a second aspect of the present invention, illustrating a
grooved infill section positioned on the grooved pile stub of a timber pile
that has been cut off below the zone of damage.
FIGURE 6 is an exemplary cross-section through either the infill section
or the pile stub in Figure 5, further illustrating the grooves formed therein.
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FIGURE 7 is an exemplary illustration of a double-hooked tension bar for
use in the method of the second aspect of the invention.
FIGURE 8 is an enlarged cross-sectional detail through one of the tension
bars after completion of a pile repair in accordance with the method of the
second aspect of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
1. First Aspect of the Invention
Figure 1 illustrates a timber pile 10 supporting an elevated structure S,
where the
pile 10 has experienced decay or damage near the ground surface. The
particular
structural arrangement shown in Figure 1 is for exemplary purposes only. The
method of
the present invention is readily adaptable for use in the repair of damaged
timber piles in
other types of structural systems, and also for use in repair of other timber
foundation
elements including utility poles.
After excavating as required to expose the damaged section 20 of pile 10,
unsound material is removed from pile 10 so as to expose undamaged pile
material, thus
creating a repair section 12. As shown in Figure 2, the repair section 12 must
include a
core section 18 by which pile 10 maintains at least a minimal degree of
structural
continuity across the repair section 12. The repair section 12 is preferably
prepared with
a bevelled section 16 adjacent to and on each side of core section 18, and a
transition
section 14 between each bevelled section 16 and adjacent undamaged portions of
pile 10.
The prepared surfaces of repair section 12 do not need to be uniform or
smooth, and in
fact a certain degree of surface irregularity may be beneficial to enhance the
effectiveness
of the bond with the grout that is to be applied in repair section 12.
The primary purpose of transition sections 14 is to provide for a minimum
thickness of grout within repair section 12, and for this purpose it may be
necessary to
remove a certain amount of undamaged pile material. Each transition section 14
preferably will preferably be at least 150 millimetres long, as shown in
Figure 2. The
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primary purpose of bevelled sections 16 is to eliminate or minimize the stress-
raising
effects of abrupt changes in cross-sectional configuration of the grout to be
applied in
repair section 12. Preferably, bevelled sections 16 will be conically bevelled
at an angle
between 30 and 45 degrees relative to horizontal, as shown in Figure 2.
However, other
bevel angles may be used, and in fact it is not essential that bevelled
sections 16 be
completely conical in configuration; for instance, bevelled sections 16 could
include
curvilinear portions (as viewed in elevation). Whatever configuration bevelled
sections
16 may take, it will typically be necessary to remove a certain amount of
undamaged pile
material to obtain the desired geometrical configuration for the bevelled
sections 16.
In the preferred embodiment of the method, the timber in the repair section
prior
to the introduction of grout, preferably such that the moisture content in the
repair section
is reduced to approximately 18 per cent by weight, or less.
After repair section 12 has been prepared as described above, it is ready to
be
grouted. In the preferred embodiment of the method, the surfaces within repair
section
1 S 12 that will be in contact with grout are coated with a suitable bonding
agent. As shown
in Figure 3, the next step in the method is to place a grout form 30 around
repair section
12, thereby forming a grout space 34 between the inner surfaces of grout form
30 and the
surfaces of repair section 12. Grout form 30, which incorporates a grout
opening 32, is
preferably configured to generally match the original shape of pile 10 in
repair section
12, such that the introduction of grout into grout space 34 will restore pile
10 to
substantially its full original section within repair section 12. Grout form
30 may be
fashioned in any suitable way, in accordance with apparatus and methods well
known in
the art of formwork, such that it will be readily removable after completion
of the
grouting process. For example, in the preferred embodiment of the method,
grout form
30 is a two-piece steel form that may be clamped in place around repair
section 12.
When grout form 30 is in place, a fluid grout material 40 is introduced
through
grout opening 32 so as to substantially fill grout space 34 with grout 40.
Preferably,
grout 40 is an epoxy grout, such as Sikadur 42 Multiflo.TM After grout 40 has
sufficiently
cured and solidified, grout form 30 is removed to expose grout surface 42.
Next, a first
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layer of non-biodegradable reinforcing fabric 50 is bonded over grout surface
42, using a
suitable adhesive resin (such as Sikadur 300TM) that will bond to grout
surface 42 and
will also impregnate and bond with fabric 50. In the preferred embodiment of
the
method, fabric 50 is a carbon fiber fabric having unidirectional primary
fibers (such as
Sikawrap 103CTM). In the sense used in this specification, primary fibers are
the fabric
fibers that are particularly adapted and oriented so as to receive and resist
tensile stresses
(as opposed to secondary fibers that have comparatively less significant
structural
strength and function). Preferably, the process of bonding fabric 50 to grout
surface 42
involves first applying a coat of resin to grout surface 42, then tightly
wrapping fabric 50
over grout surface 42 so that the resin becomes dispersed within the fibers of
fabric 50.
To enhance the effectiveness of the bond, fabric 50 may receive a coat of
resin before
being wrapped over grout surface 42. Preferably as well, a further coat of
resin is applied
to fabric 50 after it has been applied over grout surface 42.
The first layer of fabric 50 may be applied to repair section 12 of pile 10
with its
1 S primary fibers either parallel or perpendicular to the axis of pile 10. In
cases where pile
10 is subject to vertical loading only, a satisfactory repair may be achieved
using a first
layer of fabric 50 with its primary fibers perpendicular to the pile axis. In
cases where
pile 10 is subject to axial compressive stress only (i.e., no bending
stresses), it is desirable
for the primary fibers of the reinforcing fabric 50 to be wrapped
circumferentially around
the pile so as to provide "hoop strength" to hold grout 40 in place so that it
can absorb
imposed compressive loads and transfer them to undamaged sections of pile 10
below
repair section 12.
When a structural member is subject to bending stresses, the member will be
under longitudinal tensile stresses on one side of the member, and
counteracting
longitudinal compressive stresses on the opposite side. The magnitude of these
tensile
and compressive bending stresses is greatest at the outermost surfaces of the
member
(i.e., farthest from the member's neutral axis). In the case of a laterally-
loaded pile,
therefore, one side of the pile is under longitudinal tensile stress, with the
stress intensity
being greatest at the outer surface of the pile. Decay or other damage to the
surface of a
timber pile thus removes material that would otherwise have been available to
resist these
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tensile bending stresses, making it necessary for any repair method to restore
longitudinal
tensile strength across the repair zone.
Accordingly, in cases where pile 10 is also subject to lateral loadings that
will
induce flexural stresses in pile 10, the method of the present invention
preferably
provides at least one layer of reinforcing fabric 50 with its primary fibers
oriented parallel
to the axis of pile 10. It may be sufficient in some cases for this layer of
fabric 50 to be
the only layer of fabric used in the repair (for example, where the damaged
pile retains
sufficient capacity to safely carry all anticipated vertical loads, but the
decay or other
damage has seriously impaired the pile's lateral bending strength). In most
cases,
however, it will be preferable to use two layers of fabric 50 - one with its
primary fibers
substantially perpendicular to the pile axis, and one with its primary fibers
substantially
parallel to the pile axis. In such cases, the second layer is applied in
substantially the
same way as previously described with respect to the first layer.
Where two layers of fabric 50 are applied to pile 10, it is not critical for
them to
be applied in any particular order. In other words, the first layer may be
applied with its
primary fibers perpendicular to the pile axis, with the primary fibers of the
second layer
being parallel to the pile axis, or, alternatively, the first layer may be
applied with its
primary fibers parallel to the pile axis, with the primary fibers of the
second layer being
perpendicular to the pile axis.
Beneficial structural effects may also be achieved by applying any one or more
layers of fabric 50 with their primary fibers obliquely oriented (e.g.,
diagonally). Using
this method of fabric application, it may be possible (depending on the loads
acting on
the pile in question) to achieve a satisfactory degree of structural repair
and
reinforcement for purposes of both vertical and lateral loadings, using only a
single layer
of fabric 50. This is due to the fact that an obliquely-oriented primary fiber
can be
resolved, in accordance with well known structural engineering principles,
into two
components, one being oriented parallel to the pile axis and the other being
perpendicularly oriented relative to the pile axis.
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In an alternative embodiment of the method, the reinforcing fabric 50 has bi-
directional primary fibers; e.g., with two sets of primary fibers disposed
substantially
perpendicular to each other. Using fabric of this type facilitates timber pile
repairs that
require the application of only one layer of fabric 50, while obtaining the
structural
benefits of two layers of fabric 50 having unidirectional primary fibers as
described
above. In other words, bi-directional fabric 50 will provide primary fibers
that are
effective for purposes of both hoop strength and flexural strength, regardless
of the
fabric's orientation. Bi-directional fabric 50 may be applied to pile 10 with
one set of
primary fibers parallel to the pile axis, and the other set perpendicular to
the pile axis.
Alternatively, the desired structural benefits may also be achieved by
applying bi-
directional fabric 50 with its two sets of primary fibers oriented obliquely
(e.g.,
diagonally) relative to the pile axis.
2. Second Aspect of the Invention
The first aspect of the present invention, as described above, is directed to
repairing damaged timber piles in which the damage is surficial only; i.e.,
where there
remains a continuous core of undamaged timber along the full length of the
pile. The
second aspect of the invention is directed to repairing a timber pile in which
the damage
is so extensive that the pile does not retain a sound, undamaged core, or
where any such
undamaged core is too small to provide sufficient residual structural strength
to make a
repair according to the first aspect of the invention a practical option.
In such situations, the damaged pile may be repaired using an alternative
method
in accordance with the second aspect of the invention, which is illustrated in
Figures 5-8.
In accordance with this method, a portion of the damaged pile 10 is exposed
(excavating
as required) down to a grade level G for a selected distance below the damaged
region of
the pile 10. Pile 10 is then cut off on a substantially horizontal plane C
located below the
damaged region, leaving a pile stub 60 extending upward from grade level G and
having
a length Lla (length Lla being a selected distance that will provide adequate
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room for completion of the repair, as further described hereinbelow). Pile
stub 60 has a
substantially horizontal top surface 61 and a circumferential outer surface
63.
Next, a plurality of substantially vertical grooves 62 are formed in the
circumferential outer surface 63 of pile stub 60, extending downward from the
top
surface 61 of the pile stub for a distance Llb (the determination of which is
discussed
below). At or near the lower end of each groove 62, a radially-oriented hole
64 is drilled
into the pile stub 60 to a depth L3a.
A round timber infill section 70, having a length appropriate to the repair
being
carried out, is then provided. Infill section 70 has an upper end, a lower end
(which has a
substantially planar bearing surface 71 oriented substantially transverse to
the
longitudinal axis of infill section 70), and a circumferential outer surface
73. Infill
section 70 has a nominal diameter substantially corresponding with that of
pile stub 60.
A plurality of substantially vertical grooves 72 are formed in the
circumferential outer
surface 73 of infill section 70, extending upward from the lower end of infill
section 70
for a distance Llc (the determination of which is discussed below). At or near
the upper
end of each groove 72, a radially-oriented hole 74 is drilled into infill
section 70 to a
depth L3a. For purposes which will be explained, the circumferential spacing
of grooves
72 in infill section 70 substantially matches the circumferential spacing of
grooves 62 in
pile stub 60.
The preceding description suggests that grooves 72 and radial holes 74 may be
formed in infill section 70 on site, after infill section 70 has been
positioned on pile stub
60. Alternatively, however, grooves 72 and radial holes 74 may be pre-formed
in infill
section 70. Those skilled in the art of the invention will appreciate that the
particular
stage or location at which grooves 72 and radial holes 74 are formed in infill
section 70 is
not critical to the method.
In Figure 5, grooves 62 and 72 are shown in a staggered pattern, with the ends
of
adjacent grooves offset a selected distance L4. This is preferred in order to
minimize
stress concentrations in pile stub 60 and infill section 70, but it is not
essential. Grooves
62 and 72 may be non-staggered without departing from the scope of the method.
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Once grooves 72 and radial holes 74 have been formed, infill section 70 is
positioned on top of and in substantially coaxial alignment with pile stub 60,
such that the
lower bearing surface 71 of infill section 70 bears on top surface 61 of pile
stub 60, with
each vertical groove 72 in infill section 70 being aligned with a
corresponding vertical
groove 62 in pile stub 60, thus forming a plurality of tension bar channels 78
each
comprising a pile stub groove 62 and a corresponding infill section groove 72,
along with
their corresponding radial holes 64 and 74. As illustrated in Figure S, each
tension bar
channel 78 has an overall length L2a. Figures 5, 6, and 8 show a total of
eight tension
bar channels 78, but this is exemplary only; the actual number will depend on
the
particular structural requirements of the pile repair.
In a preferred alternative embodiment of the method, as shown in Figure 5, a
layer
of a suitable fluid grout 75 (such as Sikadur 42 MultifloTM) is disposed
between bearing
surface 71 and top surface 61 to provide enhanced uniformity of vertical load
transfer
from infill section 70 to pile stub 60, and also to facilitate the proper and
desired
alignment of infill section 70 relative to pile stub 60, particularly in cases
where bearing
surface 71 and top surface 61 do not have sufficiently uniform and matching
contours to
ensure satisfactory load transfer and axial alignment.
The next step in the method is to install a double-hooked tension bar 80 in
each
tension bar channel 78. Each tension bar 80 has an elongate center section 82
having an
overall length L2b, and a hooked section 84 at each end of (and substantially
perpendicular to) center section 82, with each hooked section 84 having an
overall length
L3b. Prior to installation of tension bars 80, a suitable amount of fluid
grout 85 is
deposited into radial holes 64 and 74, the diameter of which is greater than
that of hooked
sections 84. As best seen in Figure 8, a tension bar 80 is then installed in
each tension
bar channel 78, until center section 82 is substantially fully disposed within
grooves 62
and 72 of the corresponding tension bar channel 78, with the hooked sections
84 of
tension bar 80 being inserted into the radial holes 64 and 74 of the tension
bar channel 78,
thus partially displacing the grout 85 within radial holes 64 and 74 so as to
substantially
fill any spaces between hooked sections 84 and the interior surfaces of radial
holes 64
and 74. Any excess grout 85 extruded out of radial holes 64 and 74 during the
insertion
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of hooked sections 84 is preferably removed and discarded. After the grout 85
remaining
inside radial holes 64 and 74 has cured, the hooked sections 84 of each
tension bar 80
will be firmly embedded within the pile stub 60 or the infill section 70 (as
the case may
be).
S From the foregoing discussion, it will be appreciated that the depth L3a and
cross-sectional dimensions of radial holes 64 and 74 must be sufficient to
receive hooked
sections 84 while also allowing space for grout 85. Furthermore, in the
preferred
embodiment, the cross-sectional dimensions of grooves 62 and 72 will be such
that the
center section 82 of tension bar 80 can lie largely or completely beneath the
circumferential surfaces 63 and 73 of pile stub 60 and infill section 70
respectively.
Lengths Llb, Llc, L2b, and L3b are determined or selected according to well-
known structural engineering principles, to suit the anticipated maximum
tensile load in
each tension bar 80, and to suit the structural properties of the construction
materials used
for the tension bars 80, pile 10, and infill section 70.
In the preferred embodiment of the method, additional fluid grout 87 is
deposited
along grooves 62 and 72 prior to the installation of tension bars 80. As
tension bars 80
are being installed, and their hooked section 84 are being inserted into
corresponding
radial holes 64 and 74, the center sections 82 of tension bars 80 press into
and become at
least partially jacketed by grout 87. Excess grout 87 squeezed out of grooves
62 and 72
is preferably removed and discarded. The provision of grout 87 in grooves 62
and 72 is
generally desirable to enhance the solidity of the anchorage of tension bar 80
to pile stub
60 and infill section 70. However, grout 87 is not essential to the method.
The primary
consideration in the anchorage of tension bars 80 is for their hooked sections
84 to be
anchored to pile stub 60 and infill section 70 with sufficient solidity that
tensile loads in
tension bars 80 can be transferred to pile stub 60 and infill section 70 by
way of the
hooked sections 84, without the consequent development of any significant
axial
displacement between pile stub 60 and infill section 70.
After grout 85 (and grout 75 and/or grout 87, as the case may be) has cured
and
hardened, a first layer of non-biodegradable reinforcing fabric 90 (such as
Sikawrap
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103CTM) is wrapped around and bonded to the circumferential surfaces of pile
stub 60
and the infill section 70 using a suitable impregnation resin (such as Sikadur
300TM).
First fabric layer 90 preferably will be large enough to substantially cover
all of the
tension bars 80, and preferably will extend beyond the end of each tension bar
80 for a
selected distance L5, which is preferably at least 50 mm. First fabric layer
90 provides
desirable general protection to the repair area, but a more fundamental
function is to
securely retain and prevent dislodgement of tension bars 80.
As with the method of the first aspect of the present invention, the
reinforcing
fabric may have predominately unidirectional primary fibers, and it may be
applied to the
repair area with its primary fibers oriented either transversely or
longitudinally relative to
the axis of pile 10. Alternatively, the primary fibers may be oriented
obliquely. In a
preferred embodiment of the method, two layers of fabric are used, with one
layer having
its primary fibers oriented transversely and the other layer having its fibers
oriented
longitudinally, and with the two layers being bonded to each other using a
suitable
l S impregnation resin. Other variations of the reinforcing fabric and its
application,
described previously in connection with the first aspect of the present
invention, will be
equally applicable with respect to the method of the second aspect of the
invention.
Tension bars 80 may be fabricated from a metallic or other structural material
capable of safely carrying the design tension forces (which are determined on
a case-by-
case basis in accordance with established structural engineering principles).
Tension bars
80 could be made of carbon steel, but in that case would preferably be
galvanized, coated,
plated, or otherwise protected to resist corrosion. In the preferred
embodiment of the
method, tension bars 80 are made of fiber reinforced polymer (FRP), which has
excellent
tensile characteristics and will not corrode when buried in the ground or
otherwise
exposed to moisture. Alternatively, tension bars 80 may be fashioned from
stainless
steel.
It will be readily appreciated by those skilled in the art that the use of any
of the
described embodiments of the method of the invention may entail the further
step of
providing temporary shoring for any structure supported by the timber pile or
piles being
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repaired. However, shoring will not necessarily be required in all cases. For
example,
the pile to be repaired might retain an undamaged core section having
sufficient structural
strength to withstand the weight imposed on it by the supported structure
during the
repair procedure, and in such a case the pile may be repaired in accordance
with the first
aspect of the invention, without need for shoring (although shoring might be
optionally
provided as a safety enhancement).
In cases where the pile does not have a substantial or any undamaged core, the
pile will have to be repaired in accordance with the second aspect of the
invention, and it
will commonly be necessary to use temporary shoring during the repair
procedure. Even
in such cases, however, shoring might not be required if the supported
structure can
safely bridge the damaged pile and temporarily redistribute the load that
would have been
supported by the pile under repair to other support elements. In summary, the
need for
temporary shoring will depend at least in part on the characteristics of the
supported
structure.
It should be understood that the term "timber pile", as used in this patent
document, is not intended to be limited to piles that support loads from a
building or
other substantial structure. The term is intended to have a broad meaning that
includes
any timber member embedded in the ground in a substantially vertical
orientation,
regardless of whether it is so embedded by being driven into the ground (using
pile-
driving equipment), by being inserted into an excavated or augered hole and
backfilled,
or by any other means. Understood in this sense, the term "timber pile" covers
not only
piles for supporting substantial structures, but also utility poles, flag
poles, soldier piles,
and analogous structural elements.
It will also be readily appreciated that various modifications of the present
invention may be devised without departing from the essential concept of the
invention,
and all such modifications are intended to be included in the scope of the
claims
appended hereto.
In this patent document, the word "comprising" is used in its non-limiting
sense to
mean that items following that word are included, but items not specifically
mentioned
CA 02502065 2005-03-23
are not excluded. A reference to an element by the indefinite article "a" does
not exclude
the possibility that more than one of the element is present, unless the
context clearly
requires that there be one and only one such element.
16
