Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02589428 2007-05-17
APPARATUS AND METHOD FOR INSTALLING
UNDERGROUND UTILITY PIPING
FIELD OF THE INVENTION
The present invention relates in general to apparatus and methods for
installing
underground piping such as water and sewer mains, and in particular to
apparatus and
methods for installing such piping in narrow trenches.
BACKGROUND OF THE INVENTION
There are three methods commonly used for installing buried utility piping
such
as water and sewer mains. The "safe trench" method involves excavating a
trench with
its sides sloped at sufficiently shallow angles such that the potential risk
of cave-ins is
effectively eliminated. While providing optimal safety to workers, the safe
trench
method entails excavation of very large volumes of soil, and the placing and
compacting
of corresponding large amounts of backfill. Because of the safe trench's
sloped sides,
this method disturbs and disrupts the use of a comparatively large surface
land area.
The "trench shield" method reduces the necessary amount of excavation by using
a heavy shield or enclosure to protect workers in the trench. The shield is
reinforced to
resist forces and pressures that would be exerted against the shield in the
event of a
cave-in, making it safely feasible to use a trench that is narrower than a
safe trench, and
without needing the trench sides to be backsloped (or at least not as
shallowly as a safe
trench). The shield is moved along the length of the trench as new sections of
pipe are
added to the pipeline, to protect the work area surrounding each newly-added
pipe
section. The trench shield method thus provides safety to workers while
reducing
excavation and backfill requirements, but it has significant drawbacks
nonetheless.
Although the trench can be narrower and less sloped than in the safe trench
method, it
still needs to be quite wide in order to accommodate the shield. Moving the
shield, each
time a new pipe section is added, entails a considerable amount of time,
effort, and
expense. These factors are exacerbated by the fact that the shield is
necessarily quite
-1-
CA 02589428 2007-05-17
heavy, especially if it is made long enough (as is preferable) to protect
along the full
length of a typical pipe section (which is commonly six meters long).
The third conventional method of installing underground piping is by inserting
the
pipe into a pre-bored hole. This method is very expensive, and its practical
feasibility in
a given situation will depend on a variety of variable factors (such as soil
properties).
For the foregoing reasons, there is a need for pipe installation apparatus and
methods that are practically and economically feasible in a broad range of
field
conditions, while requiring less excavation than conventional trenching
methods and
ensuring optimal worker safety. The present invention is directed to this
need.
BRIEF DESCRIPTION OF THE INVENTION
In general terms, the present invention encompasses a method and apparatus for
installing piping (especially jointed piping) in a narrow and substantially
straight-walled
trench, without need for workers to enter the trench. A first piping trench
section is
excavated to a desired length, using conventional equipment such as a track-
mounted
backhoe (also referred to as a trackhoe), with a bucket width typically in the
range of 36
inches. Preferably, the bucket has a "spoon" attachment which forms a narrower
secondary channel (or "sub-trench") centered in the trench, for receiving
piping. An
equipment set-up area (or "working zone"), typically having a length of about
10 meters,
is excavated at one end of the first trench section, for receiving the pipe
installation
apparatus of the present invention. The working zone is excavated in
accordance with
"safe trench" methods, to ensure the safety of workers operating the
apparatus. Sand
bedding is deposited into the trench (or, in the preferred embodiment, into
the sub-
trench), by workers and/or equipment at ground level. This process can be
facilitated by
having bedding sand deposited in small piles along the projected route of the
trackhoe,
prior to trench excavation. Upon completion of excavation of a given section
of trench,
the hoe operator can scoop up some of the piled sand and deposit it in the
trench (or sub-
trench).
-2-
CA 02589428 2007-05-17
A first section of pipe is fed into the pipe installation apparatus, which is
actuated
so as to push the pipe section into the piping trench. The leading end of the
pipe section
is supported on a pipe sled which it pushes over the sand bedding as the pipe
is pushed
into the trench. The leading edge of the pipe sled has an upward curve or is
otherwise
configured to prevent the pipe from digging into the sand bedding, and at the
same time
serves to level and at least partially compact the sand bedding. When the
apparatus has
pushed the first pipe section into the trench, a second pipe section is fed
into the
apparatus and coupled to the first pipe section, and the apparatus then pushes
the joined
pipe sections further into the trench. Additional pipe sections are added
until a pipe
string has been laid along the full length of the first trench section.
A second trench section may then be excavated, along with an associated second
working zone. The pipe installation apparatus is moved to the second working
zone and
is actuated to install a pipe string in the second trench section until it
meets the pipe string
previously laid in the first pipe section, and the two pipe strings are
coupled to each other.
This procedure is repeated as necessary to complete the full pipeline required
for the
proj ect.
The method of the invention also provides for the installation of telescoping
temporary spacers at locations along the finished pipeline where valves, tees,
or other
fittings need to be installed. Provision may be made for the safe installation
of these
fixtures during the trench excavation, by enlarging the trench to "safe
trench" standards
in the intended vicinity of fitting. The locations where temporary spacers
need to be
installed in the pipeline may be determined during pipeline installation
operations using
conventional measuring or surveying techniques. This may be facilitated by use
of a
known device such as a metering wheel or meter tally, mounted to the pipe
installation
apparatus, for measuring the length of pipe that has passed through the
apparatus, thus
enabling workers to make accurate determinations of where spacers should be
installed.
After a given string of piping and associated fittings has been positioned, a
compressive
force is applied to the string to firmly seat all joints between the various
components.
Most conveniently, this compressive force may be applied using the bucket of
the
-3-
CA 02589428 2007-05-17
trackhoe. The trench and all working zones may then be backfilled and
compacted as
required.
The present invention also provides for a novel articulated packer apparatus
especially adapted for compacting backfill in narrow trenches, such as in
accordance with
the method of the invention. The compaction apparatus may be independently
self-
propelled, or it may have a hydraulic drive system served by hydraulic fluid
delivered by
flexible hydraulic lines from the pipe installation apparatus. In preferred
embodiments,
the packer is remotely controlled so that it does not require an onboard
operation, thereby
further enhancing worker safety.
Accordingly, in a first aspect the present invention is an apparatus for
installing
piping in a narrow trench.
In a second aspect, the invention is a packer for compacting backfill in a
narrow
trench.
In a third aspect, the invention is a method for installing piping in a narrow
trench.
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 perspective view of the pipe installation apparatus in
accordance
with a first embodiment of the invention.
FIGURE 2 is a plan view of the apparatus of Fig. 1, showing the outriggers in
a
stowed position.
FIGURE 3 is a plan view as in Fig. 2, but with the outriggers in a deployed
position.
-4-
CA 02589428 2007-05-17
FIGURE 4 is an elevational cross-section showing a pipe being fed through the
pipe drive mechanism of the apparatus of Fig. 1.
FIGURE 5A is an oblique partial section showing a pipe being fed through the
pipe drive mechanism shown in Fig. 4, and illustrating the spring-actuated
biasing means of the mechanism.
FIGURE 5B is an oblique partial section as in Fig. 5A, illustrating the
actuation
of the biasing means when a pipe coupling passes through the pipe drive
mechanism.
FIGURE 6 is a plan view of the apparatus of Fig. 1 positioned in a working
zone and pushing a partially assembled pipe string into a trench.
FIGURE 7A is a cross-section through a trench incorporating a secondary
channel, shown with an optional laser support structure spanning the trench.
FIGURE 7B is a cross-section through a working zone, incorporating a
secondary excavation for housing the pipe installation apparatus of the
present
invention.
FIGURE 8A is a side elevation of the apparatus in operation as in Fig. 6.
FIGURE 8B is a side elevation of the leading end of a pipe string positioned
in
a pipe sled as shown in Fig. 6.
FIGURE 9 is a cross-section through a piping trench during backfilling
operations using a remote-controlled articulated packer in accordance with the
invention.
FIGURE 10 is a side elevation of the packer shown in Fig. 9.
FIGURE 11 is an elevational cross-section of a pipe drive mechanism in
accordance with a second embodiment of the invention.
FIGURE 12 is a side elevation of the pipe drive mechanism of Fig. 11.
-5-
CA 02589428 2007-05-17
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figs. 1, 2, and 3, the pipe installation apparatus of the
invention
(generally designated by reference character 10) has a base structure 20
adapted to rest on
a generally level surface, with a transverse bulkhead 30 mounted to base
structure 20 at a
medial point along the length of base structure 20. In the Figures and in this
specification, bulkhead 30 is representatively shown and referred to as a
solid, plate-like
structure, but that particular configuration is not essential to the
invention. Bulkhead 30
could be of any suitably rigid construction, including an open framework.
Accordingly,
references herein to bulkhead 30 are to be understood in a non-restrictive
sense, and to
include transverse frames of other constructions.
Bulkhead 30 has a front side 30F and a rear side 30R. The configuration and
construction of base structure 20 may take any form suitable for the functions
described
herein. In the illustrated preferred embodiment, base structure 20 is of
generally
rectangular outline (as viewed in plan), with a front end 20F and a rear end
20R. Base
structure 20 has a pair of spaced side rails 21 extending between a front
frame 22F
having a front frame opening 23F, and a rear frame 22R having a rear frame
opening
23R. Openings 23A and 23B are sized to suit the pipe to be laid using
apparatus 10.
Base structure 20 has a longitudinal axis extending between front end 20F and
rear end
20R, approximately midway between side rails 21.
Front frame 22F and rear frame 22R each incorporate support legs 24, which
optionally may include adjustment means (not shown) for adapting to uneven
supporting
surfaces. The adjustment means could comprise manually-operated screw-type or
ratchet-type jacks, hydraulic cylinders, or any other suitable mechanism,
various types of
which are well known in the art. The overall size and proportions of base
structure 20
will depend on selected operational design parameters. In preferred
embodiments,
however, base structure 20 will be configured such that it can be readily
transported in
the box of a half-ton truck.
Bulkhead 30 has a pipe opening 32 generally aligned with front frame opening
23F and rear frame opening 23R. Mounted in association with bulkhead 30 is a
pipe
-6-
CA 02589428 2007-05-17
drive mechanism, for engaging a pipe section 70 passing through pipe opening
32 and
advancing it toward the front end 20F of base structure 20 and through front
frame
opening 23F. The pipe drive mechanism may take any of several different forms.
In the
embodiment shown in Figs. 1-4, the pipe drive mechanism includes a plurality
of drive
wheels 34 spaced radially around pipe opening 32 in association with either
the front side
or the rear side of bulkhead 30. In the preferred embodiment (and as best seen
in Fig. 4),
each drive wheel 34 has its own hydraulic drive motor 36. Drive wheels 34
preferably
will be rubber-tired, to facilitate effective tractive engagement with pipe 70
without
causing damage to the outer surfaces of pipe 70.
The pipe drive mechanism shown in Figs. 1-4 has a total of four drive wheels,
each with its own hydraulic drive motor 36. However, other pipe drive
configurations are
readily conceivable. To provide non-limiting examples of alternative
configurations, the
pipe drive mechanism could have three drive wheels, rather than four as shown.
Another
alternative embodiment could have four pipe-engaging wheels as shown, but with
only
two of the wheels being driven (preferably radially opposing each other) and
with the
other two wheels acting as idlers which help guide the pipe 70 through pipe
opening 32.
Other embodiments could use only a single drive wheel. A further embodiment
(shown
in Figs. 11 and 12, and described in detail later in this specification) would
have six drive
wheels mounted in pairs, with each pair of wheels driven by a single hydraulic
motor by
means of a pair of drive chains.
Simple embodiments of the pipe drive mechanism may have a fixed configuration
for handling pipe of a specific diameter. In preferred embodiments, however,
the pipe
drive mechanism incorporates wheel adjustment means for adapting to different
pipe
sizes. In the embodiment shown in Figs. 1-4, 5A, and 5B, the wheel adjustment
means is
provided by mounting each motor 36 on slide arm 38 which slides within a
sleeve 40
which in turn is pivotably mounted to a bracket 41 connected to bulkhead 30.
The radial
position of slide arm 38 within sleeve 40 may be controlled by means of set
screws or
bolts 44 as illustrated, or by any other suitable and conventional means. The
wheel
adjustment means could of course be provided in various other forms using well-
known
-7-
CA 02589428 2007-05-17
technology. For example, a hydraulic or pneumatic cylinder could be provided
for
adjusting the radial position of each drive wheel 34 to accommodate different
pipe sizes.
As illustrated in Figs. 5A and 5B, the pipe drive mechanism preferably
includes
biasing means for biasing drive wheels 34 against a pipe 70 passing through
pipe opening
32 so as to optimize the grip or traction between drive wheels 34 and pipe 70.
In the
illustrated embodiment, the biasing means for each drive wheel 34 is provided
in the
form of a compression spring 42 disposed between sleeve 40 and bulkhead 30,
radially
outboard of the associated bracket 41. When there is no pipe passing through
pipe
opening 32, spring 42 biases wheel 34 toward (or even against) front face 30F
of
bulkhead 30, with the clear space between opposing drive wheels 34 being
somewhat less
than the diameter of the pipe to be installed. Therefore, when a pipe section
70 is then
passed through pipe opening 32 in a direction toward front frame opening 23F,
it will be
tractively engaged by drive wheels 34 (which are being rotated by their
respective
hydraulic motors 36).
Springs 42 thus promote and maintain effective traction between drive wheels
34
and pipe 70. At the same time, they provide resiliency to accommodate
imperfections in
pipe 70 (for example, out-of-roundness), and to accommodate passage of pipe
couplings
72 at connections between pipe sections where, as is common, the outer
diameter of the
coupling 72 is greater than that of pipe 70. As shown in Fig. 5B, the passage
of a
coupling 72 through pipe opening 32 is accommodated by additional compression
of
spring 42, which remains effective to keep drive wheels 34 in tractive
engagement with
pipe 70 (and coupling 72).
Persons skilled in the art of the invention will readily appreciate that other
effective biasing means may be devised in accordance with known principles and
technologies, without departing from the essential concepts of the present
invention.
Figs. 11 and 12 illustrate an alternative embodiment of the pipe drive
mechanism
having three pairs of drive wheels, with each pair of wheels being driven by a
single
hydraulic motor. A pair of spaced-apart upper wheels 34U are rotatably mounted
in
coplanar relation to a suitable upper beam structure 190U positioned above
pipe opening
-8-
CA 02589428 2007-05-17
32 and extending between bulkhead 30 and a suitable upper support member 192U
connected to or forming part of base structure 20. As shown in Fig. 11, upper
wheels
34U are radially oriented relative to pipe opening 32. Each upper wheel 34U
has a
coaxially-mounted upper wheel sprocket 194U rotatable with upper wheel 34U. An
upper motor support structure 195U is mounted to upper beam 190U at a point
between
upper wheels 34U, and supports an upper hydraulic motor 36U which turns an
upper
drive sprocket 196U lying in the same plane as upper wheel sprockets 194U. A
continuous upper drive chain 198U is disposed around upper wheel sprockets
196U and
upper drive sprocket 196U such that actuation of upper motor 36U will cause
rotation of
upper wheels 34U.
Upper motor support structure 195U may be of any suitable construction, and is
preferably adapted to include or accommodate motor position adjustment means
for
adjusting the position of upper motor 36U relative to upper motor support
structure 195U,
to facilitate tensioning of upper drive chain 198U as may be required. In Fig.
12, the
adjustment means is conceptually shown as incorporating an arm to which upper
motor
36U is mounted and which is slidable within a sleeve member connected to upper
beam
structure 190U. However, persons skilled in the art will appreciate that the
motor
position adjustment means could take various other forms in accordance with
well-known
design principles and techniques.
In simple embodiments, upper beam structure 190U can be rigidly connected to
its end supports (i.e., bulkhead 30 and upper support member 192U), with its
position
being set to accommodate a specific size of pipe 70. In preferred embodiments,
though,
upper beam 190U is mounted to its end supports using suitable wheel height
adjustment
means 199, thus allowing the radial position of upper wheels 34U, relative to
pipe
opening 32, to be adjusted to suit different sizes of pipe 70. In Fig. 12,
wheel height
adjustment means 199 is shown as comprising an upstand connected to upper beam
190U
and slidable within a capped tubular sleeve connected to bulkhead 30 (or upper
support
member 192U), with a coil spring disposed between the upstand and the cap of
the sleeve
to bias upper wheels 34U radially toward a pipe 70 passing through pipe
opening 32. A
bolt 44 or pin passes through a hole (or holes) in the sleeve and through a
vertically slot
-9-
CA 02589428 2007-05-17
(or slots) in the upstand, such that the upstand is retained by and movable
within the
sleeve (to the extent allowed by the slots). Multiple holes can be provided in
the sleeve
to facilitate adjustment of wheel height adjustment means 199 to suit
different pipe sizes.
The construction shown and described in connection with wheel height
adjustment means 199 is for purposes of example only. Persons skilled in the
art will
appreciate that wheel height adjustment means 199 could take various other
forms in
accordance with well-known design principles and techniques.
Below upper beam structure 190U and pipe opening 32, a pair of lower beam
structures 190L extend between bulkhead 30 and a suitable lower support member
194L
connected to or forming part of base structure 20. A pair of spaced-part lower
wheels
34L are rotably mounted to each lower beam 190L in substantially the same
fashion as
described in connection with upper wheels 34U. Each lower whee134L has a
coaxially-
mounted lower wheel sprocket 194L rotatable with lower wheel 34L. A lower
motor
support structure 195L is mounted to each lower beam 190U at a point between
lower
wheels 34L, and supports a lower hydraulic motor 36L which turns a lower drive
sprocket 196L lying in the same plane as lower wheel sprockets 194L. A
continuous
lower drive chain 198L is disposed around lower wheel sprockets 196L and lower
drive
sprocket 196L such that actuation of lower motor 36L will cause rotation of
lower wheels
34L.
As best seen in Fig. 11, the two pairs of lower wheels 34L are preferably
disposed
on either side of pipe opening 32 in a canted radial orientation, such that
all upper wheels
34U and lower wheels 34L can tractively engage a pipe 70 passing through pipe
opening
32, with all wheels' planes of rotation passing through or close to the
longitudinal axis of
pipe 70, thus optimizing tractive efficiency. In alternative embodiments,
however, the
planes of the two pairs of lower wheels 34L could both be vertical.
Although three sets of wheels are used in the embodiment shown in Figs. 11 and
12, it would of course be feasible to use more than three sets. However, the
use of three
sets of wheels is particularly preferred since that configuration helps to
ensure that all
wheels will have substantially uniform contact with pipe 70. Maximum tractive
-10-
CA 02589428 2007-05-17
effectiveness with respect to pipe 70 is achieved by driving all wheels 34U
and 34L, but
this is not essential. In one variant, only lower wheels 34L are driven, with
upper wheels
34U being idlers; in another variant, only upper wheels 34U are driven, with
lower
wheels 34L being idlers.
Persons of ordinary skill in the art will appreciate that other variants of
the drive
mechanism of Figs. 11 and 12 may be readily devised without departing from the
principles of the present invention. To provide one non-limiting example,
pulleys and
drive belts could be used instead of sprockets and drive chains.
The operation of the pipe drive mechanism to advance pipe toward and through
front frame opening 23F will necessarily result in an opposite reactive force
acting
against base structure 20. Accordingly, anchorage means must be provided to
resist this
reactive force in order to prevent rearward displacement of the apparatus 10
(i.e., to
transfer the reactive force to the ground in the vicinity of apparatus 10). It
may be
possible in some operative circumstances, when the magnitude of the reactive
force is
small, for the anchorage means to be effectively provided by frictional or
mechanical
resistance between base structure 20 and the surface upon which it rests. In
preferred
embodiments, however, and as shown in Figs. 1, 2, 3, and 6, the anchorage
means is
provided in the form of a pair of outriggers 26, one on either side of base
structure 20.
One end of each outrigger 26 is mounted to base structure 20 (preferably, but
not
necessarily, near front end 20F thereof) so as to be pivotable about a
vertical axis. The
other end of each outrigger 26 has an anchorage member 27 (such as a steel
plate or
blade) adapted to penetrate into and to be retained within a soil mass. Each
outrigger 26
has a hydraulic cylinder 28 extending from a point near anchorage member 27 to
a
selected connection point on base structure 20. Actuation of hydraulic
cylinder 28 is thus
effective to move outrigger 26 in a generally horizontal plane between a
stowed position
(as shown in Fig. 2) and a deployed position (as shown in Figs. 3 and 6).
Effective
results have been achieved using hydraulic cylinders 28 having a 2-inch bore
and an 8-
inch stroke, with a working pressure of 3,000 pounds per square inch. However,
hydraulic cylinders with other characteristics may be suitable or appropriate
depending
on site conditions and desired operational criteria.
-11-
CA 02589428 2007-05-17
It will be appreciated that the anchorage means described above and
illustrated in
the Figures represents an exemplary embodiment, and other effective anchorage
means
may be devised without departing from the principles of the present invention.
In simpler embodiments of the invention, pressurized hydraulic fluid for
actuating
the hydraulic wheel motors and hydraulic cylinders of the anchorage means
could be
provided from a source external to apparatus 10. In preferred embodiments,
however,
apparatus 10 is a self-contained unit, and therefore includes a power and
control system,
conceptually indicated in Figs. 1, 2, 3, and 6 as comprising a power module 50
and a
control module 60. In the preferred embodiment, power module 50 incorporates a
gas or
diesel engine (with various accessories including a fuel tank), a hydraulic
pump which is
driven by the gas or diesel engine, and a hydraulic fluid reservoir. To
provide one non-
limiting example, beneficial results have been achieved using a 20-horsepower
gas
engine driving a VickersTM Model 45D50A1A122R hydraulic pump with 1-inch
lines.
Control module 60 incorporates hydraulic system accessories such as manifolds,
valves,
and valve actuators for controlling flow of hydraulic fluid between the fluid
reservoir and
hydraulic motors 36 associated with drive wheels 34, via hydraulic hoses 37.
In the
preferred embodiment, power module 50 and control module 60 are mounted to
base
structure 20 in association with auxiliary rails 21 extending between rear
frame 22R and
bulkhead 30, but other mounting arrangements are possible without departing
from the
essential concept of the invention.
Persons skilled in the field of the invention will be sufficiently familiar
with the
principles of power systems and hydraulic drive and control systems so as to
be readily
able to devise one or more embodiments of a power module 50 and a control
module 60
suitable for use with the present invention, without need to set out detailed
hydraulic
schematics or component particulars for purposes of this patent specification.
Figs. 6, 7A, 7B, 8A, and 8B illustrate how the apparatus 10 of the invention
may
be deployed in the field for purposes of installing underground piping. As
shown in Fig.
7A, a piping trench 80 is excavated along a desired path, using suitable
equipment such
as a conventional trackhoe. As may be seen from Fig. 6 and in particular from
Fig. 7A,
-12-
CA 02589428 2007-05-17
trench 80 may be comparatively narrow, with vertical or near-vertical
sidewalls 80W if
the soil is sufficiently cohesive. As indicated by reference characters 81, it
may in some
cases be desirable to backslope the upper regions of sidewalls 80W. If soil
characteristics are such that sidewalls 80W require some amount of
backsloping, the
backslope angle can generally be significantly steeper than would be warranted
when
installing pipe using safe trench methods.
In preferred embodiments of the method, a secondary channel 82 is excavated at
the base of trench 80. Secondary channel 82 may be formed using any suitable
method.
Preferably, secondary channel 82 will be formed concurrently with trench 80,
using a
trackhoe with an auxiliary blade or "spoon" permanently or removably attached
to, and
extending downward from, the cutting edge of the trackhoe bucket. The geometry
of the
"spoon" will be selected to suit the desired cross-sectional dimensions of
secondary
channel 82, which in turn will depend on the size of pipe to be installed in
secondary
channel 82. As desired, a different size of "spoon" may be used for each pipe
size;
alternatively, a given size of "spoon" may be used for a range of pipe sizes.
The depth of trench 80 (and, in the preferred embodiment, secondary channel
82)
needs to be controlled within reasonably close tolerances in order to ensure
that the
installed pipeline will be at the intended grade and slope. This is
accomplished in
accordance with well-known level surveying methods, preferably using a
stationary
surveyor's laser 200. For this purpose, and as may be seen in Fig. 7A, a laser
support
structure 210 may be provided at a convenience location, spanning trench 80,
for
supporting the laser 200, which emits a visible beam in a constant horizontal
plane. As
trench excavation proceeds, a worker carrying a surveyor's rod of suitable
length holds
the rod on the bottom of trench 80 in locations as directed by the trackhoe
operator. The
laser beam intercepts the scale on the rod, enabling the trackhoe operator to
determine the
current depth of trench 80, and to determine the extent to which additional
excavation
may be required.
To prepare for use of the pipe installation apparatus 10 of the present
invention, a
working zone 84 is excavated at the end of trench 80, generally as shown in
Figs. 6 and
-13-
CA 02589428 2007-05-17
7B. The length of working zone 84 (as measured parallel to trench 80) will
preferably be
in the range of 10 meters, but in general will be selected to suit various
practical factors
including the dimensions of apparatus 10 and the desired extent of worker
access space
around apparatus 10. Working zone 84 has sidewalls 84W which are backsloped in
accordance with "safe trench" methods as appropriate to suit soil conditions.
A machine
pit 88, with sidewalls 88W, is excavated at the base of working zone 84 to
accommodate
apparatus 10, leaving a generally level access area 86 adjacent to apparatus
10 as
appropriate. Machine pit 88 is excavated within reasonable tolerances to
facilitate
effective engagement of anchorage members 27 with sidewalls 88W. As best seen
in
Fig. 7B, machine pit 88 is excavated to an appropriate depth such that once
apparatus 10
is positioned therein, front frame opening 23F, rear frame opening 23R, and
pipe opening
32 of bulkhead 30 will be in general alignment, both horizontally and
vertically, with the
base of trench 80 (or, in the preferred embodiment, with secondary channe182).
After working zone 84 and machine pit 88 have been excavated, apparatus 10 is
positioned in machine pit 88 as shown in Figs. 6 and 7B. Outriggers 26 are
then
deployed, by actuation of hydraulic cylinder 28, such that their anchorage
members 27
penetrate and securely engage sidewalls 88W of machine pit 88. As shown in
Figs. 7A
and 8B, a layer of sand bedding 110 is deposited in the bottom of trench 80
(or, in the
preferred embodiment, secondary channel 82). A first pipe section 70A is fed
manually
through rear frame opening 23R and pipe opening 32 so as to engage drive
wheels 34,
which in turn advance first pipe section 70 forward through front frame
opening 23F.
Leading end 72A of first pipe section 70A is then engaged with a pipe sled 90
as shown
in Figs. 6, 7A, and 8B. Pipe sled 90 has a sole plate 92 adapted for sliding
over sand
bedding 110, with a contiguous upturned prow member 94 that prevents pipe sled
90
from digging downward into sand bedding 110. Pipe sled 90 also has a sleeve or
bracket
96, of any suitable configuration, for receiving and retaining leading end 72A
of first pipe
section 70A.
The apparatus 10 is then activated so as to advance first pipe section 70A and
pipe
sled 90 into trench 80, with pipe sled 90 acting to level and to some extent
compact sand
bedding 110 as it passes thereover, and with the horizontal reactive force
induced by this
-14-
CA 02589428 2007-05-17
operation being transferred into sidewalls 88W of machine pit 88 through
outriggers 26
and anchorage members 27. Pipe sled 90 may be suitably heavy or may have
supplemental weighting to enhance its effectiveness for purposes of levelling
and
compacting sand bedding 110.
When the trailing end 74A first pipe section 70A approaches rear frame opening
23R, the forward advance of first pipe section 70 is temporarily stopped so
that a second
pipe section 70B can be coupled to trailing end 74A of first pipe section 70A.
The
apparatus 10 is then reactivated so as to advance the pipe string (comprising
first and
second pipe sections 70A and 70B) further into trench 80. This mode of
operation is
carried on, with additional pipe sections being added as required, until
leading end 72A
of first pipe section 70A has advanced to a desired final position. At that
stage, apparatus
10 may be re-positioned in a second working zone 84 a selected distance back
along
trench 80. A second pipe string is then advanced into the trench until it
meets and is
coupled to the trailing edge of the first pipe string. This procedure is
repeated as required
until the entire pipeline required for the project has been laid in trench 80.
The distance between working zones 84 will be selected to suit a variety of
factors, including but not limited to the size and weight of pipe being
installed and the
mechanical capabilities of the particular apparatus 10 being used. As a
general rule, the
power required to advance a pipe string into trench 80 will be greater for
heavier pipe
sections, and will increase as the length of the string increases. It has been
found that
working zone intervals in the range of 50 to 100 meters are typically
sufficient for
installing 6-inch to 12-inch plastic water mains, using an apparatus 10
compact enough to
be transported on a half-ton truck. However, larger or smaller working zone
intervals
may be practical or desirable for particular combinations of variable design
factors and
project requirements.
At one or more locations along the length of the pipeline being installed, it
will
commonly be necessary to install valves, tees, cleanouts, or other fittings.
To
accommodate such fittings, the method of the invention provides for the
installation of
collapsible spacers (not shown) in such locations. The spacers may be of any
suitable
-15-
CA 02589428 2007-05-17
construction. In the preferred embodiment, however, each spacer comprises a
first pipe
section and a smaller second pipe section which can slide in telescopic
fashion within the
first pipe section. Preferably, each pipe section has a linearly-arrayed
series of pin holes
for receiving a retainer pin. The second pipe section is positioned as desired
within the
first pipe section, with at least one pin hole of each pipe section being in
alignment,
whereupon one or more suitable retainer pins can be dropped through the
aligned pin
hole(s), thus temporarily fixing the length of the spacer (to suit the length
of the fitting to
be installed in the spacer location). One end of the spacer will be a "male"
end and the
other end will be a "female" end, adapted for engagement with typical pipe
sections 70
being laid in trench 80 (or secondary channe182).
The collapsible spacers thus make it possible to install the full length of
the
pipeline, using the apparatus and method of the present invention, in a
continuous fashion
without needing to interrupt pipe-laying operations to install valves and tees
and the like.
After the pipeline has been laid out incorporating all required spacers,
workers can enter
a secondary "safe" working zone which has been excavated around each spacer to
install
the required fitting. The spacer is "collapsed" by removing the retainer
pin(s) and then
telescoping the two spacer sections, thus disengaging the spacer from adjacent
pipe
sections 70 to which the spacer had been temporarily connected. The required
valve or
other fitting is then connected between the adjacent pipe sections 70.
After all spacers have been replaced with their corresponding valves, tees, or
other fittings, the entire pipeline string is ready to be backfilled. Prior to
that step,
however, the connections between the various components are preferably made
more
secure by applying a compressive force to the string, so as to firmly seat all
joints. Such
a compressive force may be applied using the bucket of a trackhoe.
After all required pipeline strings have been positioned and connected as
desired
(and after the pipe installation apparatus 10 has been removed), all trenches
80,
secondary channels 82, working zones 84, and machine pits 88 may be backfilled
and
compacted as appropriate. In many if not most cases, it will necessary or
desirable for
the backfill 115 to be compacted to specified densities to prevent excessive
settlement as
-16-
CA 02589428 2007-05-17
backfill 115 consolidates over time, and methods and equipment for achieving
such
backfill densities are well known. In the interests of worker safety, however,
it is
desirable be able to compact backfill 115 in narrow trenches 80 without the
need for
workers to descend into them.
For this reason, compaction of backfill 115 in trenches 80 is preferably
carried out
using a remote-controlled articulated packer 120 as illustrated in Figs. 9 and
10. In the
preferred embodiment, packer 120 has a front section 120A plus a rear section
120B of
basically construction. Front section 120A has a roller drum 122A mounted to a
peripheral frame 126A by means of suitable bearings 124; similarly, rear
section 120B
has a roller drum 122B mounted to a peripheral frame 126B by bearings 124.
Frames
126A and 126B are coupled by a suitable articulation linkage (conceptually
indicated by
reference character 160) whereby front and rear sections 120A and 120B may
swivel
relative to each other about a substantially vertical axis Z. The articulation
linkage may
incorporate steering means for selectively controlling relative swivelling of
front and rear
sections 120A and 120B. The steering means preferably will include at least
one
hydraulic steering ram, although other types of steering mechanisms may also
be used.
Although not essential, linkage 160 preferably will also provide for at least
a limited
degree of swivelling about a transverse horizontal axis.
Roller drums 122A and 122B are fabricated of steel plate in a fashion similar
to
rollers of known compaction equipment, with a continuous cylindrical outer
plate 123
and circular side plates 125 enclosing an inner chamber 127 that may be filled
with
ballasting material (such as water). In the illustrated embodiment, side plate
125 on roller
drum 122A is inset a suitable distance from the edge of outer plate 123 to
define a a
recess 125F in which a suitable packer drive/braking mechanism (schematically
indicated
by reference character 150) may be disposed. The packer drive/braking
mechanism
could take a variety of forms, only a few of which are described or
illustrated herein.
In preferred embodiments, the packer drive mechanism incorporates a reversible
hydraulic motor having a"neutraP' mode. In the preferred embodiment, the
output shaft
of the hydraulic motor is fitted with a drive sprocket that engages a drive
chain attached
-17-
CA 02589428 2007-05-17
to the outer face of side plate 125 (such as by welding) in a circular
configuration
concentric with the drum's axle, thereby causing the drum to rotate in a
selected
direction. Alternatively, a sprocket could be concentrically mounted to side
plate 125,
and driven by means of a drive chain disposed around the hydraulic motor's
drive
sprocket and the sprocket mounted to side plate 125.
The packer braking mechanism may work on principles analogous to automotive
drum brakes, with one or more brake shoes (with appropriately curved brake
pads) that
may be urged radially outward into contact with the inner face of outer plate
123 within
recess 125F so as to retard and stop the rotation of the associated roller
drum.
The sizes of roller drums 122A and 122B and their associated frames 126A and
126B will be determined to suit the width of trench 80 in which packer 120 is
intended to
be operated, as well as the roller mass required to achieve the desired level
of backfill
compaction. Satisfactory results have been achieved using roller drums having
diameters
of approximately 42 inches.
In the embodiment shown in Fig. 10, front section 120A of packer 120 has a
platform 165 disposed above roller drum 122A and supported from frame 126A by
suitable structural support members 132. The purpose of platform 165 is to
support
auxiliary components (schematically indicated by reference character 170)
associated
with packer drive/braking mechanism 150 and its remote control system. In
preferred
embodiments, the auxiliary components will include a hydraulic pump operably
connected to the hydraulic motor of the packer's drive system, and a gas motor
for
driving the hydraulic pump.
The remote control system for the packer drive/braking mechanism 150 may be
either a wireless (e.g., radio-controlled) or hard-wired system, in accordance
with well-
known technology. In alternative embodiments, the packer may have a seat (and
possibly
a cab) for a riding operator, rather than being remotely controlled.
In preferred embodiments, as shown in Fig. 10, packer 120 has a second
platform
130 carrying a water tank (schematically indicated by reference character
140), which
-18-
CA 02589428 2007-05-17
may be used for adding water to backfill in the trench as may be required to
achieve
desired or required backfill compaction standards.
Also in preferred embodiments, packer 120 may be equipped with an adjustable
"dozer" blade at either or both ends of packer 120 (as schematically indicated
by
reference characters 180A and 180B in Fig. 10). Dozer blades 180A and 180B
will
ideally be adjustable for both blade height and blade angle, by means of
suitable
hydraulic rams operably connected to a hydraulic pump included in auxiliary
components
170. This pump could be the same pump that serves the hydraulic motor
associated with
packer drive/braking mechanism 150, or it could be a dedicated pump serving
only the
dozer blades.
It may be seen from the foregoing that the present invention enables the
installation of utility piping in narrow and substantially straight-walled
trenches, thus
requiring considerably less excavation and backfill than in conventional pipe
installation
methods, while eliminating or limiting the need for workers to enter the
trenches.
It will be readily appreciated by those skilled in the art 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 come within the
scope of the
present invention.
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
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.
-19-
