Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
apparatus and method for insitu culvert rehabilitation
NAME ( S ) OF INVENTOR ( S )
Alan Rabby
Neil Roy Gillard
FIELD OF THE INVENTION
The present invention relates to an apparatus and a method
for insitu culvert rehabilitation.
BACKGROUND OF THE INVENTION
North America is beginning to experience infrastructure
deterioration. The network of highways represents one area
of infrastructure. The culverts which extend under these
highways are rusting and slowly collapsing under the weight of
increased vehicular traffic volumes.
At the present time there is no known method for
rehabilitating culverts insitu to prevent their further
collapse. Culverts experiencing visible signs of deterioration
are replaced. Prior to replacing a culvert, the highway must
be closed. This involves constructing a temporary detour road
and posting warning signs to slow down the flow of traffic as
it approaches the detour road. Once traffic is diverted, a
trench is dug across the highway. The old culvert is removed
from the trench, a new culvert is inserted into the trench and
the highway is repaved. This process disrupts the flow of
traffic, is time and labour intensive and is expensive.
SUMMARY OF THE INVENTION
What is required is an apparatus and method for in situ
culvert rehabilitation.
According to one aspect of the present invention there is
provided a method for culvert rehabilitation. In its most
basic form the method includes a first step of providing a
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tubular body having a first end and a second end with a pulling
attachment secured to the first end. The tubular body is sized
to closely fit through a smallest portion of a culvert to be
rehabilitated. A second step involves positioning the tubular
body at a first end of the culvert to be rehabilitated. A
third step involves positioning a winch at a second end of the
culvert to be rehabilitated. A fourth step involves securing
a line between the pulling attachment and the winch and using
the winch to pull the tubular body into the culvert.
With the method, as described above, the tubular body is
pulled into the deteriorating culvert and serves to take the
culvert. It is preferred that the tubular body be pulled into
the culvert until it sits in situ substantially co-extensive
with the culvert.
Although beneficial results may be obtained through the
use of the method, as described above, a culvert under a
highway is typically 20 to 25 meters in length. This length
of tubular body tends to be unwieldy. For this reason it is
preferred that two or more tubular bodies be securable
together. Beneficial results have been obtained when the first
end of the tubular body serves as a male coupling and the
second end of the tubular body serving as a female coupling.
To prevent ridges at the connection between tubular bodies that
would cause the tubular bodies to become stuck when being
pulled through a culvert, it is preferred that the two or more
tubular bodies, when mated, maintain a consistent exterior
dimension.
Although beneficial results may be obtained through the
use of the method, as described above, even more advantages may
be obtained when the tubular bodies are made of polymer
plastic. A smooth interior surface of polymer plastic provides
such little resistance to water flow, that the interior
diameter of the culvert may be reduced while maintaining
substantially the same flow rate. Rather than rely upon
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mechanical coupling of tubular bodies, polymer plastic tubular
bodies may be secured together by plastic welding. It is, of
course, desirable to use the largest possible size of tubular
body, so as not to reduce flow rates any more than absolutely
necessary. This raises the possibility that the tubular body
may become stuck during insertion. Should a polymer plastic
tubular body become struck while being pulled through the
culvert, the tubular body can be heated with hot air or other
means to deform the polymer plastic.
Although beneficial results may be obtained through the
use of the method, as described above, difficulties can be
experienced in securing a pulling attachment to a polymer
plastic body. If all of the pulling force is concentrated at
several attachment points, the polymer plastic material will
experience fatigue and failure will occur. Even more
beneficial results may, therefore, be obtained when the tubular
body has an integrally formed end wall across at least the
first end to which is secured the pulling attachment. The
preferred form of pulling attachment is a post having a first
end and a second end. The first end is secured to a base plate
and the second end is secured to an attachment ring. The post
extends through an aperture in the end wall at the first end
of the tubular body with the base plate engaging the end wall
and the attachment ring projecting from the tubular body.
Although beneficial results may be obtained through the
use of the method, as described above, even more beneficial
results may be obtained when the tubular body has an integrally
formed end wall across both the first end and the second end.
At least one opening is provided through which fluids are
pumped into the tubular body. This arrangement provides a
number of advantages. If heat is applied to deform tubular
body to get past a tight spot, water or air can be pumped into
the tubular body to expand tubular body outwardly and restore
its shape.
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Although beneficial results may be obtained through the
use of the method, as described above, even more beneficial
results may be obtained when grout is pumped into a space
between an interior wall of the culvert and an exterior wall
of the tubular body. This serves a number of purposes. It
helps to secure the tubular body in position. It fills gaps
to that the only flow is through tubular body. It provides
additional strength to tubular body so that it can withstand
weight loading as further deterioration of the culvert occurs.
According to another aspect of the present invention there
is provided an apparatus for culvert rehabilitation which
includes a tubular body having a first end and a second end.
A pulling attachment is secured to the first end, whereby the
tubular body is pulled into a culvert.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is a side elevation view of a culvert used as a
mould to fabricate an apparatus for rehabilitating culverts in
accordance with the teachings of the present invention.
FIGURE 2 is a side elevation view, in section, of a
tubular body for an apparatus for rehabilitating culverts in
accordance with the teachings of the present invention.
FIGURE 3 is a side elevation view, in section, of several
tubular bodies being coupled to form an apparatus for
rehabilitating culverts in accordance with the teachings of the
present invention.
FIGURE 4 is a side elevation view, in section, of an
apparatus for rehabilitating culverts in accordance with the
teachings of the present invention.
FIGURE 5 is a side elevation view, in section, of the
apparatus for rehabilitating culverts illustrated in FIGURE 4,
being used to rehabilitate a culvert.
FIGURE 6 is a side elevation view, in section, of the
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apparatus for rehabilitating culverts illustrated in FIGURE 4,
being used to rehabilitate a culvert.
FIGURE 7 is a side elevation view, in section, of the
apparatus for rehabilitating culverts illustrated in FIGURE 4,
5 being heated as a means of getting past an obstruction.
FIGURE 8 is a side elevation view, in section, of the
apparatus for rehabilitating culverts illustrated in FIGURE 4,
being pressurized with fluid.
FIGURE 9 is a side elevation view, in section, of the
apparatus for rehabilitating culverts illustrated in FIGURE 4,
in preparation for grouting.
FIGURE 10 is a side elevation view, in section, of the
apparatus for rehabilitating culverts illustrated in FIGURE 4,
with grouting installed.
FIGURE 11 is an end elevation view of the apparatus for
rehabilitating culverts in position in a culvert as illustrated
in FIGURE 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, an apparatus for rehabilitating
culverts generally identified by reference numeral 10, will now
be described with reference to FIGURES 1 through 11.
Referring to FIGURE 4, apparatus 10 includes a polymer
plastic primary tubular body 12 having an interior cavity 13
extending along the length of primary tubular body 12, a first
end 14 and a second end 16. Primary tubular body 12 is a
composite of several secondary tubular bodies, generally
identified herein by reference numeral 18 and specifically by
reference numerals 18a through 18c, as will hereinafter be
further described. The primary tubular body 12 has integrally
formed end walls 24 and 26 across both first end 14 and second
end 16, respectively. End wall 24 at first end 14 has an
aperture 28 extending therethrough. A pulling attachment 30
is secured to the first end 14. Pulling attachment 30 includes
a post 32 having a first end 34 and a second end 36. First end
34 is secured to a base plate 38. Second end 36 is secured
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to an attachment ring 40. Post 32 extends through aperture 28
in end wall 24 at first end 14 of tubular body 12 with base
plate 38 engaging end wall 24. Attachment ring 40 projects
from primary tubular body 12, whereby a line 42 is attached to
pull primary tubular body 12 into a culvert 44 as illustrated
in FIGURES 5 and 6.
Referring to FIGURE l, there is illustrated a mold 50 for
secondary tubular bodies 18. Mold 50 is an actual culvert of
spiral shape with ends 52, 54 secured thereon by means such as
bolts 55 exterior to mold 50. An opening (not shown) is
provided to allow plastic resin from which secondary tubular
bodies 18 are formed to be introduced into mold 50.
Referring to FIGURE 2, there is illustrated secondary
tubular bodies 18 as they come out of mold 50. It is noted
that secondary tubular bodies 18 each have a first end 56 and
a second end 58 closed by a first end wall 60 and a second end
wall 62 respectively. First end 56 has a tubular extension 63
which serves as a male coupling, as will hereinafter be further
described.
Referring to FIGURE 3, there is illustrated how the
secondary tubular bodies 18, illustrated in FIGURE 2, are
joined to form primary tubular body 12. In particular, it is
noted how two or more tubular bodies 18 are securable together.
Tubular extension 63 at first end 56b of the tubular body 18b,
from which first end wall 60 has been removed, serves as a male
coupling. Second end 58a of the tubular body 18a, from which
second end wall 62 has been removed, serves as a female
coupling. Tubular extension 63 at first end 56b of tubular
body 18b is inserted into second end 58a of tubular body 18a.
Tubular bodies 18, when mated as described, maintain a
consistent exterior dimension. There are various means that
could be used for securing them together; plastic welding is
preferred.
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The use of apparatus 10 in accordance with the teachings
of the preferred method will now be described with reference
to FIGURES 1 through 11. Primary tubular body 12 is assembled
from a plurality of secondary tubular bodies 18 each of which
is manufactured as will now be described. Mold 50 is assembled
as illustrated in FIGURE 1. A plastic resin is introduced into
mold 50 and dispersed substantially evenly, to a required
thickness, over the interior surface of mold 50. A suitable
plastic is low density polyethylene which has the properties
of superior hardness and rigidity. The plastic resin is cooled
until it has hardened into the form of secondary tubular body
18 as illustrated in FIGURE 2. Mold 50 is disassembled and
secondary tubular body 18 is removed from the mold. Mold 50
and secondary tubular body 18 have a matching spiral shape
which allows said body 18 to be removed from said mold 50 by
an unscrewing motion. A multiplicity of secondary tubular
bodies 18 are made in preparation for construction of primary
tubular body 12 as will now be described.
With reference to FIGURES 3 and 4, aperture 28 is formed
in first end wall 60 of secondary tubular body 18a to convert
it into end wall 24 of primary tubular body 12. Second end
wall 62 is removed from secondary tubular body 18a to convert
second end 58a into a female coupling, as illustrated in FIGURE
3. Pulling attachment 30 positioned with post 32 extending
through aperture 28 until base plate 38 lies flush against end
wall 24 and attachment ring 40 accessible. First end wall 60
of secondary tubular body 18b is removed to convert end 56b of
secondary tubular body 18b into a male coupling. When two
secondary tubular bodies 18 are sufficient to form the length
of primary tubular body 12 second end wall 62 is not removed
from secondary tubular body 18b. The interconnection of the
first male coupling formed by tubular extension 63 of tubular
body 18b and female coupling at second end 58a of tubular body
18a are welded together. The tubular body 12 formed by so
welding together secondary tubular bodies 18a and 18b has the
advantage of having no protrusions or protruding connectors
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which cause obstruction as tubular body 12 is drawn through
culvert 44. When more than two secondary tubular bodies 18 are
needed to form the length of primary tubular body 12, second
end wall 62 is removed from secondary tubular body 18b to form
a female coupling at second end 58b. End wall 60 is removed
from secondary tubular body 18c and first end 56c inserted into
second end 58b of secondary tubular body 18b. Secondary
tubular bodies 18b and 18c are then welded together.
Additional secondary tubular bodies 18 can be added, as
required, to construct even longer primary tubular body 12.
The preferred method for culvert rehabilitation using
primary tubular body 12 will now be described with reference
to FIGURES 1 through 11. The method will be described with
reference to examples describing different situations.
Example 1 - Culvert with Rust Deterioration
In this first example, a culvert was rehabilitated that
was experiencing rust damage. The culvert was 36 inches in
diameter and 70 feet in length. A slightly small sized culvert
10 feet in length was used as mold 50. Polymer plastic primary
tubular body 12 was constructed as described above. It was
transported in two pieces a first 40 feet in length and a
second 30 feet in length. In such installations, the length
of the pieces will depend upon the clearance around the
culvert. Some installations have very little clearance, which
requires installation on 10 foot section of secondary tubular
body 18 at a time. Referring to FIGURES 3 and 4, pulling
attachment 30 was secured to first end 14 of body 12. The
culvert to be rehabilitated was prepared by digging out the
ends to provide improved access. The ends of the culverts
often have been damaged and must be cut away. Any mud, or
detritus from disintegration of the culvert, which had
accumulated over time are flushed from the culvert using a high
pressure water hose. Referring to FIGURE 5, the first portion
of tubular body 12 was positioned at a first end 66 of the
culvert 44 to be rehabilitated with attachment ring 40 facing
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into culvert 44. A winch 68 was positioned at a second end 70
of the culvert 44. A line 42 was extended from winch 68 and
secured to pulling attachment 40. Winch 68 was used to pull
the first portion of tubular body 12 into culvert 44. The
second portion of tubular body 12 was then plastic welded onto
the first piece of tubular body 12. Winch 68 was then used to
pull tubular body 12 the balance of the way into culvert 44
until it was substantially co-extensive with the culvert 44.
Example 2 - Culvert that Collapsed to an Oval Shape
In this second example, a culvert was rehabilitated that
was in the process of collapsing. The culvert had originally
been 36 inches in diameter, but had slumped in the middle to
approximately 24 inches. A tubular body 12 was prepared as
described with the first example, this tubular body had to be
sized to closely fit through a smallest portion of culvert 44.
Referring to FIGURE 6, tubular body 12 is assembled, attached
to winch 68 and pulled through culvert 44 as with the first
example. However, with a culvert that is collapsing, problems
can be encountered in pulling tubular body 12 through the
restriction 94. To allow tubular body 12 to pass an
obstruction caused by partial compression or collapse of
culvert 44, the tubular body 12 can be rotated about the long
axis to spiral tubular body 12 past the obstruction. If the
spiralling method of passing the obstruction does not succeed
it is necessary to deform tubular body 12 in a controlled
manner, as will now be described. Referring to FIGURE 7, a
draw wire 88 is introduced through first aperture 84 by means
of which a heater system such as a steam wand 90 is drawn
through second aperture 86 into interior cavity 13 of tubular
body 12. The heating section 92 of steam wand 90 is positioned
close to the restriction 94 that is preventing movement of
tubular body 12 through culvert 44. Heat is supplied at said
restriction 94 to the plastic of which tubular body 12 is
constructed to soften said plastic to allow said tubular body
12 to deform sufficiently to pass restriction 94. When tubular
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body 12 is substantially coextensive with culvert 44, it is
desirable to pressurize and then cool tubular body 12 so that
it assumes a desired shape. Referring to FIGURE 8, tubular
body 12 is modified to allow said body to be filled with water
5 and pressurized. A first aperture 84 and a second aperture 86
are formed in first end wall 24 and second end wall 26
respectively of tubular body 12. First aperture 84 is fitted
with a first threaded connection 96 and second aperture 86 is
fitted with a second threaded connection 87. A first valve 98
10 and a second valve 100 are attached to first threaded
connection 96 and second threaded connection 87, respectively
by which water is introduced into tubular body 12. Water
expands tubular body 12 outwardly, while cooling it. The water
also provides weight that causes serves tubular body 12 to
settle down in culvert 44. Unlike the first example, except
in the area of restriction 94, there is considerable space
between tubular body 12 and culvert 44, generally identified
by space 69. Referring to FIGURE 9, a plug 71 is positioned
in space 69 that lies between first end 66 of culvert 44 and
exterior wall 80 at the second end 16 of tubular body 12.
Liquid grout 72 is pumped under pressure through a feed hose
74 into a space 69 along the length of culvert 44 between an
interior wall 78 of the culvert 44 and an exterior wall 80 of
the tubular body 12. Care must be taken in controlling the
pressure of liquid grout 72 or tubular body 12 will be deformed
in a manner that will restrict the flow channel. The completed
installation is as illustrated in FIGURES 10 and 11. Water is
removed from tubular body 12 and first end wall 24 and second
end wall 26 of tubular body 12 are removed to allow unhindered
access to and passage of water through said tubular body 12.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment without
departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
