Note: Descriptions are shown in the official language in which they were submitted.
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Interlocking Honeycomb-cored Panel System For Construction of Load
Supporting Surfaces
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reusable panel system for the construction
of load
bearing surfaces, such as temporary or semi-permanent roadways and equipment
support and work surfaces laid out over geologically unstable surfaces or over
wet-
land marshes.
2 Description of the Related Art
When performing operations with heavy equipment in a remote location, it is
often
necessary to provide a firm, stable and continuous surface to support such
equipment.
For example, when drilling an oil or gas well in a remote location, it is
often
necessary to provide work surfaces used during the drilling process. It is
also
advantageous to provide one or more roadways to allow access to and from the
well-
site. Such a surface should be able to support the very heavy equipment used
in such
operations and able to withstand sever weather. Often the ground is wet and
they may
include marsh, bog, and/or slippery clay earths. The panels should be easy to
install
and able to provide sufficient support to allow operations under severe and
difficult
ground conditions. The panels may also be easily removable, with minimal
impact to
the surrounding environment.
Historically various solutions have been used to meet these requirements. Each
has
its advantages and disadvantages.
In the past, roadways were made of planks, boards or logs laid out in various
configurations and often nailed together. These roadways required an immense
amount of labor to complete and were essentially impossible to remove. There
are
many areas throughout the wilds of Canada and the United States where evidence
of
these roads can be found 50 or more years after they were initially used.
An improvement on these systems is the construction of wooden mats, often made
of
Oak, constructed and nailed together at a factory location and then
transported to the
field. The mats are then interconnected and nailed together to provide a more
or less
continuous surface. However, the gaps in the materials allow the wet ground
under the
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mat to `pump' material up through the gaps as heavy equipment moves over the
surface. This creates a void in the ground under the mat and causes the mats
to break
and splinter. Further this `pumping' action often causes the mat to be buried,
necessitating the addition of further layers of mats. These shortcomings
result in mats
that are difficult to remove when the work is finished. Another disadvantage
is the
weight of the mats themselves, when new and dry they are often over 2,000 lbs
each,
when used and wet the weight can more than double. This requires the use of
very
heavy equipment to move and position the mats.
A further difficulty with these wood mats is they suffer from significant
rotting
problems. This rotting, coupled with the foresaid difficulty of breaking and
splintering
of individual boards causes significant expense in repairs and maintenance to
the
mats.
Often wooden and other mats systems are not substantially connected together.
As
vehicular traffic moves across the surface the mats may separate or `walk'
apart. The
resulting discontinuous surface creates hazards for transportation and
workers, further
it exacerbates the `pumping' action of the mats.
Recently some polymeric load bearing mat systems have been proposed. For
example,
U.S. Patent No. 4,629,358 to Springston discloses a mat system for the
construction
and repair of airfield surfaces. It is made of fiberglass reinforced plastic
and is filled
with hollow inorganic silica spheres.
U.S. Patent No. 6,695,527 to Seaux et.al. discloses a mat system useful to
create a
load bearing ground surface. The mats of the system are formed to be laid out
over a
surface with overlapping edges. The mats are each formed of two halves, an
upper
half and a lower half. The halves include a surface, which will face outwardly
on the
final mat, and a honeycomb surface, which will be positioned inside the mat
when the
two halves are secured together to form the mat.
SUMMARY OF THE INVENTION
A panel system has been invented for use in the construction of load bearing
ground
surfaces.
In accordance with a broad aspect of the present invention, there is provided
a load
bearing structure comprising a panel having at least three sides. The panel
can be
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formed of a honeycomb core located between the upper and lower surfaces of the
panel. A continuous layer can surround the honeycomb core. One or more
connector
means may be located on at least one side of the panel.
Selected edges of the panel may, in one embodiment, have a wedge-shaped
configuration. In another embodiment, the panel may include a lapping ledge
along
one or more selected edges.
If desired, a panel can be textured, treated and/or coated with a variety of
slip-resistant
and/or chemical and/or fire resistant coatings to meet the needs of various
applications. Furthermore, the panels may be colored to provide high-contrast
surfaces in order to enhance visualization of the ground support.
In a further embodiment, the panel can be modified to include stress-strain
sensors
that can function to give real-time telemetric data useful in determining the
response
of the panel under particular field load scenarios.
A light-weight panel is thereby produced with consequently exceptional
handling
capabilities.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of the invention are illustrated in the following
drawings:
Figure 1 is a top plan view of a load supporting panel having a wedged-shaped
edge
configuration.
Figure 2 is a side elevation view of the panel of Figure 1.
Figure 3 is an end elevation view of the panel of Figure 1.
Figure 4 is a section view of the panel of Figure 1 connected to a second
panel.
Figure 5 is a top plan view of a plurality of load supporting panels connected
together.
Figure 6 is a side view of two load supporting panels connected together.
Figure 7 is a top plan view of an alternative embodiment of a load supporting
panel
having a wedge shaped edge configuration.
Figure 8 is a top plan view of an alternative embodiment of a load supporting
panel
having a wedge shaped edge configuration.
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Figure 9 is a top plan view of a plurality of alternatively configured load
supporting
panels connected together.
Figure 10 is a top plan view of a load supporting panel having a lapping ledge
configuration.
Figure 11 is a side elevation view of the panel of Figure 10.
Figure 12 is an end elevation view of the panel of Figure 10.
Figure 13 is a sectional view along line XIII - XIII of Figures 1 and 10.
DESCRIPTION OF VARIOUS EMBODIMENTS
The panels of the present invention may offer a durable, reusable system for
construction of roadways and other ground support surfaces. The panels can be
assembled to create work surfaces of various dimensions. Because the panels
are
designed to interlock with one another they can be connected together in a
wide
number of combinations to provide the correct alignment for any ground support
application. This flexibility of assembly, along with the durability of the
panels
allows for quick and easy installation, usually requiring only one layer of
panels on
virtually any ground substrate. The panels may be formed to be positively
buoyant to
float on water, to enhance their usefulness.
Referring to Figures 1 to 3, a panel useful in the system is provided with an
expansive
upper surface 10 and a lower surface 12. A panel may include a wedge-shaped
edge
14 along one or more selected edges. In the embodiment shown, all the sides of
the
panels have a wedged-shaped edge. A wedge-shaped edge may be either descending
(from the top to the bottom of the panel) or ascending (from the bottom to the
top of
the panel) in order to permit an edge of one panel to be overlapped or
underlapped
with an adjacent panel. For example, the side edge surface of the panel may
intersect
with the upper and lower surfaces at other than 90 such that the thickness
tapers. It
may be useful to form the panels with corresponding wedge-shaped edges, such
that
they can be fit together.
A panel may be connected to one or more other panels through connector means.
In
one embodiment, the connector means may be located around the perimeter of the
panel, such that each panel can be connected to other panels in a wide array
of
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different configurations. For example, the connector means may be located
between 2
and 14 inches from the outside edge of the panel. In the panel illustrated,
the
connector means are alignment apertures 16 that extend through the panel
between the
upper surface 10 and the lower surface 12 of the panel. Such apertures are
formed to
align with apertures on other panels to be joined together and to accept and
retain a
fastener or other component, such as a screw, bolt, rivet, pin, lock, nail,
stake, wire,
etc. Figure 4 shows a descending wedged shaped edge 14 of one panel and an
ascending wedged shaped panel of a second panel 18 joined by connecting means
that
includes apertures 16 through the panel and an assembly that includes a bolt
20 and a
nut 22 each having flanged edges that engage the panel about the aperture. In
the
illustrated embodiment, apertures 16 are positioned on the wedge shaped edge
14. By
joining the panels, multiple panels become effectively a coacting surface
suitable (as
previously described) for use as road or work platforms on a variety of
terrains. Other
connector means may be used including but not limited to: apertures formed to
accept
and retain lock pins, such as those shown in US Patent application
2002/0187017 or
other pins; pins formed or mounted on one panel edge and holes to accept the
pins on
other panel's edges to be joined together; hook and loop fasteners, such as
VelcroTM;
removable rivets; clips; buckles; clasps; clamps; braces; grips; locks; nails;
stakes;
wires; etc. The connector means may be formed on the panel, connected to the
panel
during manufacture or separable therefrom, as desired, with possible
consideration as
to the form of connector means used.
Referring to Figures 5 and 6, a plurality of panels can be laid over a ground
surface in
a single layer with their edges 14 overlapping. The individual panels of said
system
are restrained from horizontal movement by frictional contact with the
underlying
terrain, by mechanical contact and connection with adjoining panels, as by
engagement by connector means 20 and, where necessary, by affixing the
individual
panels to the ground by other mechanical means such as with stakes.
The panels of the present invention may be impermeable, so that fluids cannot
seep
into or through the body of the panels. This reduces and may eliminate the
`pumping'
action associated with some other work mats as described previously. By
reducing
pumping action the panels may also be easier to pick up for reuse and may
cause only
minimal ground disturbance after they have been removed.
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Each panel may be formed with a continuous outer surface, such that there are
no
gaps or channels for the accumulation of mud, ice and other debris.
The dimensions of the panels of the present invention can easily be varied
with
changes to production tooling. In one embodiment, the panels may be 7.5 feet
by 14
feet so that they can fit into an ISO standard container. The work surface of
each such
panel when assembled with adjacent panels overlaid and attached can be 6.5
feet by
13 feet.
Other sizes and shapes of panels can be easily manufactured in order to
customize the
panels for particular applications. Panels of different dimensions can, for
example, be
constructed to allow for curves, slopes and other deviations in roadways and
other
surfaces. Figures 7 and 8 show for example, a panel having a trapezoidal
configuration having a short end edge 26 and a long end edge 28 and side edges
30. It
should be stressed again that other configurations could be manufactured. All
edge
lengths may be varied as shown between Figures 7 and 8. As well, panels having
various different thickness may be used. Figure 9 shows a plurality of panels
of
different dimensions interconnected to one another so that they can be laid to
form a
curved roadway or other deviated surface.
Figures 10 to 12 refer to an alternative embodiment of the panel. In this
embodiment,
the panel useful in the system may be relatively thin with an expansive upper
surface
36 and lower surface 32. The panel may include a lapping ledge 34 along one or
more selected edges. Lapping ledges 34 may be less than the full thickness of
the
panel to permit an edge of one panel to be overlapped or underlapped with an
adjacent
panel. It may be useful to form the panels with corresponding lapping edges,
such
that they can be fit together. For example, each panel may include a ledge 38
extending from its upper surface 36 on one or more sides and a ledge 34
extending
from its lower surface 32 on one or more other sides. In one embodiment, each
panel
may be formed as a square or rectangle and may include a ledge extending from
its
upper surface on two adjoining sides and a ledge extending from its lower
surface on
the other two sides. These ledges may be substantially one half the panel edge
thickness so that the ledges can be overlapped. The ledges may extend out from
the
panel edge a distance, for example about one foot, that creates some
resistance to mud
and liquids passing through the interface of the lapped ledges.
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Connector means may be molded into the panel or connected to the panel during
manufacture. In the embodiment shown, substantially rigid projections 37 such
as a
pin, bolt, screw, etc, are connected to or form part of the ledge extending
from the
lower surface of the panel. Apertures 16 located on the ledge extending from
the
upper surface of the panel 38 are formed to accept and retain the
substantially rigid
projections 37 of an adjacent panel.
The edges of the panel may also be reinforced to constrain any compression at
the
edge of the panel and to protect the edge of the panel from damage. This edge
reinforcement maybe provided in various ways and from various materials
including
but not limited to: fiber reinforced materials, such as for example, pultruded
fiberglass, polymeric rods, for example various plastics (such as polyolefm),
wood,
steel, aluminum and other commonly available commercial materials suited to
the
requirement. The reinforcement material may be placed at various points of the
edge
of the panel, incorporated into the wedge itself, placed parallel to the wedge
on the
vertical plane, etc.
The present panel may include a honeycomb core and a fiber reinforced layer
thereon.
In one embodiment, a honeycomb core manufactured of polypropylene
thermoplastic
is sandwiched between layers of fiber reinforcements. In other embodiments,
the
honeycomb core material may be selected from a variety of commercially
available
core materials including metal such as aluminum honeycomb, resin reinforced
paper
honeycomb, foam materials (such as for example, polyethylene, polyurethane,
polystyrene, polypropylene) and any other available honeycomb core materials.
The
materials can be used alone or in combination, for example honeycomb core may
include a resin reinforced paper outer covering filled with foam material
(such as
polypropylene). In another embodiment, the core may not be filled. The
reinforced
layer may completely surround the honeycomb-core so that it is not open on the
edges
of the panel, thus forming a continuous layer.
Fiber reinforcements are available in a large number of fiber arrangements
each with
different characteristics that can be used to produce desirable properties in
variants of
the present invention. For example, stitch-fiber matting may be utilized in
order to
increase the compression strength of the panel. Reinforcing fibers may include
fiberglass, carbon fiber, aramid fiber, UHMW PE (Spectra), polypropylene,
metal
fibers or any other available reinforcing fibers can be used alone or in
combination.
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These reinforcing fibers can be impregnated with an adhesive and placed onto
the
honeycomb core, or placed on the honeycomb core and infused with an adhesive.
The
panel may also be manufactured with the use of thermoplastic adhesives.
A panel can be textured, treated and/or coated. Slip-resistant and/or chemical
and/or
fire resistant coatings/treatments may be used to meet the needs of various
applications. Additionally, the materials of the panels, such as the coatings,
may be
colored to provide high-contrast surfaces to enhance visualization of the
ground
support. A panel can be recoated at any time should the coating become
ineffective
due to wear or some other cause.
Referring to Figure 13, a panel is shown in section. The panel includes: a
slip
resistant coating 46, such as sand particles (sand particles 20 mils in
diameter in about
mils of paint, for example); a surface coating 47, such as paint (10 mils of
paint, for
example); a fiber reinforced layer 42 (including two layers of fiber glass mat
in epoxy,
each layer about 1/16 inches thick, for example); a honeycomb layer 40 (4
inches of
honeycomb with 5/16 inches straws, for example); fuzz on top of the honeycomb
core
with epoxy 44 (about 5 mils of epoxy, for example); and barrier film 45 (5
mils of
barrier film, for example) for reducing infiltration to the honeycomb layer
45. It is
important to stress that these are examples and not limitations.
While the present invention provides a panel system for the construction of
load
bearing surfaces, such as roads or work areas on unstable ground surfaces, it
can also
be applied for use over conventional roadways and road and work surfaces to
increase
the load bearing capacity of the surface. The panels are light weight.
Consequently,
with minimal equipment and manpower, the panels can be interlocked to provide
said
work surfaces that may exhibit durability and strength and then can be
disconnected,
picked up and transported to another site for reuse. The panels can be
manufactured
using a variety of techniques, from molded thermoplastics to fiber-reinforced
composite structures made with thermoset resins.
The panels can be altered to make them useful in other applications such as
trench
covers, airport taxiways, floors for portable buildings, walkways, portable
docks,
trench shoring, or other such uses as become apparent. These alterations can
involve
resizing the honey-comb core, the reinforcement layer, or the use of different
outer
coatings.
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To produce a panel, a mold may be manufactured, for example, out of light
gauge
steel. The mold may be tightly sealed to prevent air leakage during the vacuum
phase
of the manufacture. The inside surface of the mold can be textured either by
directly
embossing the steel, or by adding a layer of plastic that has the reverse
image of the
desired surface texture. This mold inside surface forms the top surface of the
panel.
The inside of a vacuum bag used during the vacuum phase of the manufacture
forms
the bottom surface of the panel. This technique is well known in the art as
`vacuum-
bag' layup.
The inside of the mold may be sprayed or waxed with a release compound, which
is a
material to which the adhesives used in the manufacture of the panel will not
easily
stick. This may be done to facilitate removing the panel from the mold after
it has
cured. Reinforcing fiber materials, such as for example, fiber reinforcing
cloth can
then be positioned in the mold. The cloth may be trimmed to fit the inside of
the
mold.
The fibers may be positioned before or after saturation with an adhesive
material,
which may be, for example, an epoxy resin. In one embodiment, a resin system
may
be used that is supplied by Dow Chemical available as Dow Durakane 331
EpoxyTM.
Such a resin may, in one embodiment, be cured using Dow Jeffamine D-320TM with
the addition of an accelerator manufactured by Huntsman Chemical called Accel
399TH
The polypropylene honeycomb core may then be set into the mold on top of the
reinforcing fiber materials. In one embodiment, the honeycomb core may be that
supplied by Plascor and known as PP30-5-2TM Polypropylene Honeycomb Core.
PP30-5-2 has material density of roughly 5 pounds per cubic foot of core. The
core
may be treated for adhesion to the fiber reinforcing material using various
techniques
known in the art. This treatment may be used to increase the adhesion of the
reinforcing fiber to the core and can enhance the physical properties of the
resultant
panel. The honeycomb core extends over most of the finished panel. For
example, in
one embodiment, the honeycomb core can extend to approximately 90-95% of the
overall size of the finished panel.
Prior to setting the honeycomb core into the mold a reinforcing edge may be
applied
to the sides of the honeycomb. This reinforcement may include any of various
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materials. In one embodiment of the present invention, the material used is a
plastic
such as polyolefin thermoplastic, (which can be in a triangular or rectangular
form,
for example), adhered with mastic, for example, made up of the epoxy resin
formula
and INHANCETM PEF fibers made of high-density polyethylene (HDPE) fibers. This
product is manufactured by the Inhance Group of Fluoro-Seal International, LP.
The
fibers will be imbedded in the polyolefin.
With regards to the panel having the wedge shaped edge configuration, the
wedge
may be constructed by machining the honeycomb core to form the wedge
configuration after the reinforcing edge is applied. Other techniques to
forming a
wedge shaped edge may also be employed. For example, a separate wedge could be
constructed from any rigid material, (such as plastic, etc.) and then adhered
to the
sides of the honeycomb layer prior to applying the layer of reinforcing fiber.
This
could involve pultruding the entire wedge and then adhering a corresponding
honeycomb cut profile into the pultrusion. The wedge may then be adhered with,
for
example, mastic to the honeycomb core.
A second layer of reinforcing fiber and adhesive, such as epoxy, may then be
laid on
top of the honeycomb core. Corners and or edges may be finished by folding
them in
on themselves.
One or more materials, may be applied on top of the second layer, as will be
appreciated, to allow the panel to be vacuum bagged and when cured ease the
release
of the various materials from the panel itself. A vacuum may then be applied
to the
panel and the mold. The pressure of the vacuum causes the materials in the
mold to
consolidate and forces any air entrained in the structure to be evacuated. The
vacuum
may be maintained until the chemical exothermic reaction of the epoxy system
is
substantially or fully complete such that the epoxy is substantially or fully
cured.
The panel is then removed from the mold. The panel may then be trimmed to
final
specification.
Thereafter sufficient holes may be cut into the panel to provide apertures
and/or so
that connector hardware, such as aperture reinforcement pins, etc. can be
glued into
place using any of a wide variety of adhesive suitable for that purpose.
The panel may then be coated with an industrial epoxy coating suitable for the
chemical resistance and environmental resistance required for the panel,
depending on
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its intended application. For example, resins and coatings may be selected to
enhance
chemical and/or fire resistance. As another example, coatings or resins may be
selected to control static, should this be required. These coatings may also
be colored.
Anti-static features may also be added to some suitable standard coatings.
Alternately or in addition, a top-coat of anti-slip coating may applied to the
panel.
One coating that may be used for this purpose is supplied by Devoe Coatings
and is
known as DevGripTM. There are various grades of this coating available and the
appropriate grade is selected depending on the end use of the panel. The anti-
slip
coating may be colored as well.
The panel may then be allowed to continue curing. Curing may be conducted
slowly,
for example over a number of days, or may be accelerated, for example, by
putting the
finished panel into a heated environment. In one embodiment, curing may be
conducted at a temperature of 160 F or less for up to 48 hours.
A panel is thereby produced with a reasonable weight and consequently,
reasonable
handling capabilities. For example, in one embodiment a panel measuring 4.29
meters by 2.31 meters by 0.10795 meters may weigh less than 193 kilograms
(14.075
ft by 7.575 ft by 4.25 inches weighing less than 4251bs). The panel of the
present
invention may have a reduced weight over previous panels by the combination of
the
essentially hollow honeycomb core providing spacing between thin lightweight
reinforced layers that have extremely high strength to weight ratios.
As well, the panels of the present invention possess significantly better bulk
properties over previous panels as a result of the materials that used are
used in its
reinforced layer. Bulk properties are the increased physical properties such
as tensile
strength, compressive strength and flexural rigidity. Further, by altering the
density or
materials of the honeycomb core, the cross-sectional thickness of the
honeycomb core
or by altering the characteristics of the reinforced layer such as: changing
the type of
fiber reinforcement, its makeup or the material it is made of, or by changing
the
adhesive resin many of the bulk properties of the panel may be altered. For
example a
panel with more flexural rigidity could handle significantly more load on soft
ground
and could be made by the addition of more fiberglass and resin to the
reinforced layer
of the panel.
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In a further embodiment the panel be modified to include stress-strain
sensors. The
stress-strain sensors can function to give real-time telemetric data useful in
determining the response of the panel under particular filed load scenarios.
This
information could be useful in creating a modified panel to replace a panel or
panels
that are failing under the specific circumstances present in the field at a
unique
location. The stress-strain sensors may be attached to the panel by several
different
means, including but not limited to: encapsulating the sensors into the
coating itself;
or gluing the sensors onto the panel by using any of a wide variety of
adhesives
suitable for that purpose.
It should be understood that even though numerous characteristics and
advantages of
the present invention have been set forth in the foregoing description, the
disclosure is
illustrative only, and changes may be made in detail, especially in matters of
size,
shape and arrangement of parts within the principles of the invention to the
full extent
indicated by the broad general meaning of the terms in which the claims are
expressed.
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