GROUND COVER MAT

TAPIS DE SOL

Description

CA 02635582 2008-06-20
"GROUND COVER MAT"
FIELD OF THE INVENTION
The present invention relates to a road or ground cover mat, a system
of road or ground cover mats and a method of assembling and disassembling such
a system or arrangement of mats.
BACKGROUND OF THE INVENTION
Most known road mats are limited to large square or rectangular mats
that are designed to be laid directly onto a ground surface prior to being
driven over
by vehicles and equipment. These mats see such service in areas where it is
prohibitively expensive to develop a full-scale roadway and where access is
required and time sensitive, as well as in environmentally sensitive areas
where
development of a full-scale roadway is simply not feasible due to regulations
and/or
environmental concerns. These mats are also used where the ground surface is
incapable of supporting the weight of a motor vehicle, such as in mud, swamp
or
muskeg.
These known road mats are limited by their ability to provide some
form of highly secure mechanical interlocking mechanism to prevent the
shifting of
the mats while being traversed by heavy equipment. If the mats shift for any
reason
and become unhinged, substantial damage may occur to the traversing equipment.
Further, such shifting requires maintenance and realignment of the mats,
substantially increasing costs.

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Common road mats are mainly large steel and wooden mats that are
designed to be laid over the surface to be traversed. In order to reduce axial
movement, road mats are commonly manufactured with mating engagements at
either end. Such mats generally use a rudimentary L or J shaped reversing or
reciprocating style end joint or coupling end that is easily joined upon
placement,
but provides for very limited and inherently insecure interlocking capability.
FIG. 1 illustrates one such form of engagement wherein a first "L"
shaped appendage extends outwardly and upwardly from a first end and a second
"L" shaped appendage extends outwardly and downwardly from a second end of
each mat. The engagement of the first "L" shaped appendage with the second "L"
shaped appendage prevents axial movement of connected mats. This engagement
works effectively when the underlying surface is firm. However, when the
underlying surface is soft, spongy or uneven, the engagement is not effective.
On
such surfaces the road mats tend to tip up when weight is exerted upon one end
(see FIG. 1). This tipping movement is encountered both as a motor vehicle
first
drives onto one of the road mats and as the motor vehicle drives off the road
mat.
When subjected to this tipping movement, the road mats tend to separate.
United States patent no. 6,652,183 to Stasiewich, et al. partially
addresses the separation problem and is directed to a road mat designed to be
laid
on a ground surface in end to end relation and driven over by a motor vehicle.
The
Stasiewich et al. mats are secured together by interlocking the first coupling
of one
road mat with the second coupling of another, adjacent road mat. The second
coupling is adapted to engage the first coupling such that a retaining lip of
the
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second coupling engages a retaining lip of the first coupling to prevent
separation
(see FIGS. 2a - 2b). Because there is a gap between the couplings' retaining
lips,
the road mat shown and described in this reference suffers from many of the
problems suffered by other conventional mats, including separation of the
couplings
and creating an uneven surface when weight, such as from a vehicle, is applied
to
the side of the coupling (see FIG. 2b).
United States patent no. 7,160,055 to Beamish, et al. also partially
addresses the separation problem and teaches a more complex form of coupling
mechanism that includes a male member and a female member and wherein
wherein the first coupling end is a reciprocating mirror image of the second
coupling
end (see FIG 3a). Beamish, et al. further teaches how a plurality of mats can
be
connected, side-by-side and end-to-end, to form a "stacked" formation, where
both
the ends and the sides of adjacent mats line up with each other (see FIG. 3c
and
Figure 6 of Beamish, et al.). However, this type of arrangement is unstable
and if a
mat along one end, or along one side, starts to come apart or loose, it has a
tendency to "unzip" the rest of the mats along that entire length, or width,
of the
arrangement of mats (see FIG. 3c); especially if a heavy vehicle starts the
unzipping
process and happens to move along that unzip line.
The mat designs of Stasiewich et al. and Beamish, et al. are also
difficult to separate when rocks, debris and/or ice becomes lodged in the
mated
couplings or joints (see FIGS. 2c and 3b).
As such, the known road mats have one or more of the following
problems: they are restricted in their ability to interlock; they do not
provide for an
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even surface when placed on undulating sub soils; do not create stable
arrangements, they do not provide for load dispersal and weight transfer
between
the structures; they are not very torsion resistant; and they are not designed
for
ease of installation and removal, i.e., unlocking.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side schematic view of a prior art ground cover mat
system, showing two mats coupled to each other and illustrating tipping
movement
as a motor vehicle first drives onto one end of the first mat;
FIG. 2a is a sectional side view of another prior art ground cover mat,
coupled to an adjacent mat;
FIG. 2b is a sectional side view of the coupled prior art ground cover
mats of FIG. 2a, illustrating separation of the coupling when weight, such as
from a
vehicle, is applied to one side of the coupling;
FIG. 2c is a sectional side view of the coupled prior art ground cover
mats of FIG. 2a, illustrating how rocks, debris and/or ice may be lodged in
the
mating couplings;
FIG. 3a is a sectional side view of yet another prior art ground cover
mat, shown as becoming uncoupled from an adjacent mat when weight, such as
from a vehicle, is applied to one side of the coupling;
FIG. 3b is a sectional side view of the prior art ground cover mats of
FIG. 2a, shown in a coupled configuration and illustrating how rocks, debris
and/or
ice may be lodged in the mating couplings;
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FIG. 3c is a top view of a plurality of prior art mats arranged in a
conventional "stacked" formation;
FIG. 4a is a top / side perspective view of one embodiment of a
ground cover mat according to the present invention;
FIG. 4b is side perspective view of the other side of the mat of
embodiment of FIG. 4a;
FIG. 4c is a top / side perspective view of the other side of the mat of
embodiment of FIG. 4a;
FIG. 4d is a top view of the mat of embodiment of FIG. 4a;
FIG. 5a is a sectional side view of one embodiment of a first side
coupling of one mat interlocked with one embodiment of a second side coupling
of a
second mat;
FIG. 5b is a sectional side view of one embodiment of a first end
coupling of one mat interlocked with one embodiment of a second end coupling
of a
second mat;
FIG. 6a is an end perspective view of two mats of the embodiment of
FIG. 4a, with one mat being angularly placed, or connected to, an adjacent
mat;
FIG. 6b is a side view of one embodiment of a first side coupling pin;
FIGS. 6c - 6e are sectional side views of the first and second side
couplings of the embodiment of FIG. 5a, illustrating angular placement of the
first
side coupling's pin within the second side coupling's receptacle;
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FIG. 7a is an side perspective view of an arrangement of mats of the
embodiment of FIG. 4a, with one mat being angularly placed, or connected to,
an
adjacent mat in an adjacent row and, also, to an adjacent mat in the same row;
FIG. 7b is an top perspective view of an arrangement of mats of the
embodiment of FIG. 4a, illustrating how the end couplings and side couplings
of
adjacent mats connect;
FIG. 7c is a top view of an arrangement of mats of the embodiment of
FIG. 4a, illustrating the mats being connected in a staggered row
configuration; and
FIGS. 8a - 8c are top views of an arrangement of mats of the
embodiment of FIG. 4a, illustrating the virtual girder system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description are of a preferred embodiment by way of
example only and without limitation to the combination of features necessary
for
carrying the invention into effect. Reference is to be had to the Figures in
which
identical reference numbers identify similar components. The drawing figures
are
not necessarily to scale and certain features are shown in schematic form in
the
interest of clarity and conciseness.
Referring to FIGS. 4a - 8c, one embodiment of a ground cover mat 10
includes a rectangular body 12 having a top surface 12t, a bottom surface 12b,
a
first end 14, a second end 16, a first side 18 and a second side 20. End
coupling
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means 11 is provided for coupling first end 14 of body 12 to second end 16 of
a like
body. Side coupling means 13 is provided for coupling first side 18 of body 12
to
second side 20 of a like body. Preferably, the top and bottom surfaces 12t,
12b are
made from wood. More preferably, the first and second ends 14, 16 and the
first
and second sides 18,20 are made of steel.
In this embodiment, end coupling means 11 comprises at least one
first end coupling 100 positioned at first end 14 of body 12 which is adapted
to
interlock with a second end coupling 102 at second end 16 of a like body. At
least
one second end coupling 102 is positioned at second end 16 of body 12 which is
adapted to interlock with a first end coupling 100 at first end 14 of a like
body. First
end coupling 100 and second end coupling 102 will be hereinafter described in
relation to FIGS. 4a - 4d and 5b. It will be appreciated, however, that
alternative
forms of end couplings could be used at first end 14 and second end 16 of body
12.
In this embodiment, side coupling means 13 comprises at least one
first side coupling 104 positioned at first side 18 of body 12 which is
adapted to
interlock with a second side coupling 106 at second side 20 of a like body. At
least
one second side coupling 106 is positioned at second side 20 of body 12 which
is
adapted to interlock with a first side coupling 104 at first side 18 of a like
body. First
side coupling 105 and second side coupling 106 will be hereinafter described
in
relation to FIGS. 4a - 4d, 5a, and 6a - 6e. It will be appreciated, however,
that
alternative forms of side couplings could be used at first side 18 and second
side 20
of body 12.
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End couglings:
In this embodiment, first end coupling 100 comprises "L" shaped
appendage 22 extending outwardly and downwardly from first end 14 and second
end coupling 102 comprises "L" shaped appendage 24 extending outwardly and
upwardly from the second end 16 of mat 10. Still referring to FIG. 5b, the
engagement of first "L" shaped appendage 22 of a first mat 10a with second "L"
shaped appendage 24 of adjacent mat 10b prevents axial movement of the mats
10a, 10b. The engagement of first "L" shaped appendage 22 of mat 10a with
second "L" shaped appendage 24 of adjacent mat 10b will also transfer weight
on
mat 10a to mat 10b and transfer any upward force, such as during tipping, from
mat
10b to mat 10a.
Side couglings:
In this embodiment, first side coupling 104 comprises upwardly
directed lug or pin 26 which extends laterally from first side 18 and second
side
coupling 106 comprises opening 28 providing access to a receptacle 30
extending
laterally into second side 20. Interior receptacle 30 is of sufficient
dimensions to
accept all, or substantially all, of the length of pin 26. In this embodiment
first side
coupling 104 comprises a pair of upwardly directed pins 26 and the second side
coupling 106 comprises a pair of openings 28 providing access to a pair of
receptacles 30.
Preferably, the spacing XX between each pair of first side couplings
104 is twice that of the spacing X from a first side couplings 104 to its
closest
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respective end 14, 16 (as the case may be and as more clearly illustrated in
FIG.
4d). More preferably, the spacing XX between each pair of second side
couplings
106 is twice that of the spacing X from a second side couplings 106 to its
closest
respective end 14, 16 (as the case may be and also as more clearly illustrated
in
FIG. 4d). Advantageously, such spacing will allow multiple mats 10 to be
connected
in a staggered configuration (see FIGS. 7b and 7c) reducing or eliminating the
chance that a row of mats will unzip from an arrangement of mats, should one
mat
start to come loose or disengage along an end or side (as is the case with the
prior
art mat configurations).
In an alternate embodiment (not shown), the first side coupling 104 is
provided in the form of a single upwardly directed lug or pin 26 and the
second side
coupling 106 is provided in the form of a single opening 28 providing access
to a
single receptacle 30. In yet an alternate embodiment (also not shown), the
first side
coupling 104 is provided in the form of three upwardly directed lugs or pins
26 and
the second side coupling 106 is provided in the form of three openings 28
providing
access to three receptacles 30.
Referring to FIGS. 5a and 6a - 7a upwardly directed pins 26 of a first
mat 10a engage or enter receptacle 30 of an adjacent mat 10c, through opening
28.
Receptacle 30 is of sufficient dimensions to allow entry of the pin 26 or
substantially
all of the pin 26. Advantageously, the pin 26, opening 28 and receptacle 30
allow
for easy connection and angular engagement of first mat 10a with adjacent mat
10c.
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More advantageously, and once the mats 10a, 10c are connected together, the
pin
26, opening 28 and receptacle 30 assist to both reduce or prevent lateral
axial
separation of the first mat 10a from the adjacent mat 10c and to transfer
weight,
such as that from vehicles, from one mat 10a, 10c to an adjacent mat 10c, 10a.
Preferably, pin 26 has a straight medial portion 26s and an upward
curving end portion 26u. More preferably, opening 28 is of sufficient
dimensions to
allow angular passage or angular placement AP of the pin 26 therethrough, but
not
so large so as to allow axial, or substantially axial, disengagement of the
pin 26
from the receptacle 30 (once adjacent mats are interlocked together. In
particular,
in this embodiment, the dimensions of the pin 26 (including the upward curving
end
portion 26u), the opening 28 and receptacle 30, will initially require the
first mat 10a
to be angled, at an angle A relative to adjacent mat 10c, to allow the upward
curving
end portion 26u to enter the receptacle 30 through the opening 28 (as more
clearly
illustrated in FIGS. 6a, 6c - 6e and 7a). Then, once the upward curving end
portion
26u has entered the receptacle, the first mat 10a is lowered to a planar, or
substantially planar, position (relative to the adjacent mat 10c) and the mats
10a,
10c are axially pushed together to place any remaining straight medial portion
26s
(that has not yet entered the receptacle 30) into the receptacle 30. Once this
is
done, the two mats 10a, 10c are in a "locked" configuration wherein lateral
separation of the mats 10a, 10c is reduced or significantly prevented, unless
the two
mats 10a, 10c become once again angled relative to each other at an angle
approximate to A.

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Advantageously, when the mats 10a, 10c are connected together at
their sides 18, 20, the upward curving end portion 26u of the pin 26 engages
upper
portion of receptacle 30 above the hole 28 at approximately point P, thereby
preventing lateral separation of the first mat 10a from the adjacent mat 10c
when
the mats are subject to axial separating forces LF (see FIG. 6e).
Since the mats 10a, 10c, during operation are generally expected to
remain in a horizontal, or substantially horizontal, position relative to each
other (i.e.
co-planar), and since the side couplings 104, 106 are also effective in
transferring
weight from one mat 10a to an adjacent mat 10c (and vice-versa), this angle A
is
typically not approached unless specific action is taken to remove one mat 10a
from
an adjacent mat 10c (typically requiring explicit and direct lifting of one
side of a
mat).
Preferably the dimensions of the pin 26, the opening 28 and
receptacle 30 are such that the first mat 10a is required to be angled,
relative to
adjacent mat 10c, approximately 30 to 35 degrees, during angular placement AP,
so as to allow entry of the upward curving end portion 26u through the opening
28
and into the receptacle 30. Likewise, an angle of approximately 30 to 35
degrees
would be required to disengage side connected mats from each other. Such an
angle is not typically observed between adjacent mats (even if the ground
itself is
uneven or if heavy vehicles drive over the mats), unless specific removal
action is
taken to disassemble adjacent mats. FIG. 6b illustrates the dimensions of a
preferred embodiment of the pin 26.
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In another embodiment (not shown), pin 26 is simply a straight
horizontal (axial) pin. In such an embodiment, the angle A, required to
connect
and/or disassemble adjacent mats 10 will likely be smaller than the angle A of
a pin
having an upward curving portion. However, even such an embodiment will still
have effectively transfer weight between adjacent mats (in both directions as
described both above and further below) and will provide some resistance to
axial
disengagement of adjacent mats (especially if the pin 26, opening 28 and
receptacle are of close tolerances to provide a friction fit between the pin
26 and the
receptacle 30).
Preferably, the pin 26 further comprises a chamfered or tapered end
26t. Advantageously, the tapered end 26t further reduces or eliminates binding
when separating the mats 10a, 10c from each other in mud or ice environments.
More preferably, the dimensions of the pin 26 and the opening 28 are of close
or
tight tolerance so that weight transfer from either mat 10a, 10c (e g. when
weight,
such as from a vehicle, is applied to one side or the other of the mated side
couplings 104, 106) will be efficient and not create a significant uneven
surface
between the two mats 10a, 10c. Advantageously, a close or tight connection of
the
pin 26 through the hole 28, also reduces or eliminates the possibility of mud,
ice or
debris becoming lodged in the couplings 104, 106.
Lifting Points:
In a preferred embodiment, one or more flush mounted lifting points
35 or lifting lugs are provided to facilitate mat 10 pickup and placement.
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Advantageously, such mats 10 with lifting points 35 do not require use of an
expensive backhoe with a hydraulic "gripping thumb" to manipulate and move the
mats; and less expensive forklifts, along with chains or lifting harnesses,
can be
utilized instead. Preferably, the lifting lugs 35 are rated to 20,000 lbs and
are
countersunk into the top surface 12t of each mat 10 at or along the mat's
center of
gravity.
Operation:
The use and operation of the ground cover mats 10 will now be
described with reference to FIGS. 4a - 7c. Ground cover mats 10 are designed
to
be laid on ground surface (not shown) in end to end relation to form a first
row 40. In
a broad method embodiment, mats 10 in the first row 40 are secured together by
interlocking first end coupling 100 of one road mat 10a with second end
coupling
102 of adjacent mat 10c (as previously described and as shown in FIG. 5b). A
second row 42 of mats 10 is laid beside the first 40, by angular placement AP
of
one side coupling 104, 106 with a respective side coupling 106, 104 of a mat
10 in
the first row 40.
In a first method embodiment, a mat 10 in the second row 42 is angled
to angle A, the pin(s) 26 on the first side 18 of a mat 10 in the second row
42 are
mated to respective opening(s) 28 and receptacle(s) 30 of the second side(s)
20 of
an adjacent mat 10 (or a pair of adjacent mats 10a, 10c) in the first row 40,
and mat
10 in the second row 42 is angularly placed AP or locked with said mat(s) in
the first
row 40 (as previously described above); while at the same time interlocking
first end
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coupling 100 of one road mat in the second row 42 with a second end coupling
102
of any adjacent mat in that second row (see FIGS. 5b, 7a and 7b). Subsequent
rows, such as a third row 44, are laid beside preceding rows in a similar
fashion;
see FIG. 7a which illustrates a mat 10 in a third row 44 positioned adjacent a
second row 42 of mats as well as adjacent a mat already present in the third
row.
In a second method embodiment (not shown), the mat 10 in the
second row 42 is angled to angle A, the opening(s) 28 and receptacle(s) 30 of
the
second side(s) 20 of mat 10 in the second row 42 are mated to respective
pin(s) 26
on the first side 18 of an adjacent mat 10 (or a pair of adjacent mats 10a,
10c) in the
first row 40, and mat 10 in the second row 42 is angularly placed AP or locked
with
said mat(s) in the first row 40 (in a manner similar to that previously
described
above); while at the same time interlocking first end coupling 100 of one road
mat in
the second row 42 with a second end coupling 102 of any adjacent mat in that
second row. Subsequent rows, such as a third row 44, are laid beside preceding
rows in a similar fashion.
Preferably, the multiple mats 10 in each row are connected in a
staggered configuration relative to their adjacent rows (see FIGS. 7b and 7c).
Advantageously, such staggered configuration facilitates efficient and
effective
weight transfer to from one mat 10 to adjacent mats 10, increases the mats 10
overall weight bearing capacity and adds stability to the arrangement or
system of
interlocked mats 10.
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In either method embodiment, disassembly of mats 10 from an
arrangement of mats can be accomplished by reversing the steps used to
assemble
the mats.
Advantageously, the pin(s) 26, the openings, the receptacle(s) 30 and
the two method embodiments described above, allow for a row of mats to be
assembled and/or disassembled from either the first side 18 or the second side
20
of a row; a feat previously difficult or impossible with prior art ground
cover mats.
More advantageously, this two-sided assembly / disassembly allows for an
arrangement or system of mats to be moved (over a period of time) along the
ground surface by disassembling a row of mats from the "rear" side and re-
assembling that row of mats on the "front" side of the arrangement of mats.
Even
more advantageously, this allows the use of a finite number of mats to create
a
moving ground cover mat arrangement that can move along with construction that
might span a significant distance over the duration of the construction
project (such
as oil field pipelining where the construction action moves along the
pipeline's
proposed route).
Virtual Girder:
In a preferred embodiment, the ground cover mat 10 further comprises
three longitudinal support members 50a, 50b, 50c wherein one longitudinal
support
member 50a is the first side 18, another longitudinal support member 50b is
the
second side 20 and the remaining longitudinal support member 50c is positioned

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axially along the longitudinal center of the mat (see FIGS. 4c and 4d).
Preferably,
the support members 50a, 50b, 50c are made of steel.
In this embodiment, the ground cover mat 10 further comprises four
cross-members 52a, 52b, 52c, 52d, oriented perpendicular to the longitudinal
support members 50a, 50b, 50c and wherein one cross member 52a is the first
end
14, another cross member 52b is the second end 16 and the remaining two cross
members 52c and 52d extend substantially between the paired pins 26 one the
first
side 18 and their respective corresponding paired receptacles 30 on the second
side 20 (see FIG. 4d). Preferably, the cross-members 52a, 52b, 52c, 52d are
also
made of steel.
Advantageously, in such an arrangement of mats 10, and even if
arranged in a "staggered" configuration, the cross-members 52a, 52b, 52c, 52d
form a line or "cross-girder" 54 which is continuous in the lateral direction
(across
such an arrangement of mats 10), across all the connected mats 10 via the pins
26
and receptacles 30 (see FIG. 8a). More advantageously, by comprising at least
two
cross members (52c and 52d) in the middle portion of the mat 10, the mat 10 is
further strengthened so as to prevent or reduce torsion or twisting corner-to-
corner.
Even more advantageously, in an arrangement of mats 10, the longitudinal
support
members 50a, 50b, 50c form a line or "longitudinal-girder" 56 which is
continuous in
the longitudinal direction (along such an arrangement of mats 10), across all
the
connected mats 10 via the first and second end couplings 100, 102 (see FIG.
8b).
Together, the cross members 52a, 52b, 52c, 52d and the longitudinal support
members 50a, 50b, 50c, in an arrangement of mats 10, create a "virtual girder
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system" 60 (see FIG. 8c) which adds strength and stability to the entire
arrangement.
Those of ordinary skill in the art will appreciate that various
modifications to the invention as described herein will be possible without
falling
outside the scope of the invention.
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