Note: Descriptions are shown in the official language in which they were submitted.
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MINE SHAFT LINER PLATE SYSTEM AND METHOD
CROSS-REFERENCES
[0001] This application claims the benefit of U.S. Provisional Application
Serial
Nos. 61/301,316, filed February 4, 2010, 61/369,856, filed August 2, 2010 and
61/394,800
filed October 20, 2010, the entire specification of each of which is
incorporated herein by
reference.
TECHNICAL FIELD
[0002] This application relates generally to liner systems for vertical mine
shafts
and underground tunnels and, more particularly, to liner plate system and
method for
providing a waterproof shaft or tunnel.
BACKGROUND
[0003] Vertical mine shafts often encounter issues with water penetration,
particularly when one or more vertical sections of the mine shaft pass through
porous
ground water containing layers. Prior attempts to address this issue include
cast iron
tubbing, welded steel panels, composite bolted systems and others. However,
such
technologies have proven expensive and timely to install.
[0004] Accordingly, it would be desirable and advantageous to provide a system
and method of sealing vertical mine shafts and other types of tunnels that
facilitates
installation.
SUMMARY
[0005] In one aspect, a liner plate structure for use in lining shafts and
tunnels
includes a primary plate portion and at least one flange disposed at a side
edge of the
primary plate portion. A thermoplastic fusion element extends along an
exterior surface of
the flange.
[0006] In another aspect, in the liner plate structure according to the
preceding
aspect, the thermoplastic fusion element of the flange is disposed within a
recess of the
exterior surface of the flange.
[0007] In another aspect, in the liner plate structure of one of the preceding
aspects,
the thermoplastic fusion element of the flange includes a multi-layer assembly
including at
least one thermoplastic fusion layer at the outer side of the recess and at
least one elastic
polymer layer below the thermoplastic fusion layer for permitting compression
of the
thermoplastic fusion element within the recess.
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[0008] In another aspect, in the liner plate structure of one of the preceding
aspects,
the thermoplastic fusion layer protrudes slightly above the exterior surface
of the flange.
[0009] In another aspect, in the liner plate structure of one of the preceding
aspects,
at least one electrofusion chord element is embedded within the thermoplastic
fusion layer.
[0010] In another aspect, in the liner plate structure of one of the preceding
aspects,
the thermoplastic fusion element has a width that is less than a width of the
recess.
[0011] In another aspect, in the liner plate structure of one of the preceding
aspects,
a sub-recess is located to one side of the recess.
[0012] In another aspect, in the liner plate structure of one of the preceding
aspects,
the sub-recess has a depth that is less than the depth of the recess, and the
sub-recess has
one side edge in communication with the recess.
[0013] In another aspect, in the liner plate structure of one of the preceding
aspects,
the sub-recess includes at least two spaced apart extensions, each of which
extends to an
inward facing edge of the flange.
[0014] In another aspect, in the liner plate structure of one of the preceding
aspects,
the thermoplastic fusion element includes at least one electrofusion chord
element with end
portions extending inward through an opening or openings in the flange and
terminating at
an interior side of the liner plate structure.
[0015] In another aspect, in the liner plate structure of one of the preceding
aspects,
first, second, third and fourth flanges circumscribe the primary plate
portion, each flange
has a corresponding recess and electrofusion element, the recesses align to
form a
circumscribing recess and the electrofusion elements are joined to form a
circumscribing
electrofusion element.
[0016] In another aspect, in the liner plate structure of one of the preceding
aspects,
the primary plate portion has a height and length, the length larger than the
height, the
primary plate portion is curved in the lengthwise direction. A structural
member protrudes
from an inner side face of the primary plate portion, the structural member
extends in the
lengthwise direction and is also curved.
[0017] In another aspect, in the liner plate structure of one of the preceding
aspects,
the primary plate portion and flange are both formed of metal plate material,
the flange
metallurgically welded to the primary plate portion.
[0018] In another aspect, in the liner plate structure of one of the preceding
aspects,
the primary plate portion has a height and length, the length larger than the
height, the
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primary plate portion is curved in the lengthwise direction. First, second,
third and fourth
flanges circumscribe the primary plate portion, each flange has a first
portion extending
outwardly beyond an outer side face of the primary plate portion and a second
portion
extending inwardly beyond an inner side face of the primary plate portion.
[0019] In another aspect, in the liner plate structure of one of the preceding
aspects,
the flanges are welded to the primary plate portion, the first portion of each
flange is
substantially smaller than the second portion.
[0020] In another aspect, in the liner plate structure of one of the preceding
aspects,
the primary plate portion includes at least two holes extending from an inner
side face to an
outer side face of the primary plate portion, each of the holes including
threads.
[0021] In a further aspect, a liner structure within a shaft or tunnel
includes at least
first and second liner plate members assembled together, the liner plate
members formed of
metal plate material having respective metal surfaces in contact with each
other along a
plate joint. A thermoplastic fusion seal arrangement is located along the
plate joint.
[0022] In another aspect, in the liner plate structure of the immediately
preceding
aspect, each metal surface includes a respective recess, the thermoplastic
fusion seal
arrangement formed by respective thermoplastic fusion elements within each
recess, the
thermoplastic fusion elements fused to each other.
[0023] In another aspect, in the liner plate structure of one of the two
immediately
preceding aspects, a coating seal material is located at an exterior surface
of the assembled
liner plate members.
[0024] In another aspect, in the liner plate structure of one of the three
immediately
preceding aspects, a grout material located within a spaced between the
coating seal
material and a wall of the shaft or tunnel.
[0025] In another aspect, in the liner plate structure of one of the four
immediately
preceding aspects, each liner plate member includes a structural member
protruding from
an inner side face of the liner plate member. An inner liner system is
connected to the
structural members of the liner plate members.
[0026] In yet a further aspect, a method of lining a mine shaft bore includes
the
steps of. providing a plurality of liner plate members, each liner plate
member having a
curved shape; assembling a first set of liner plate members into a first ring
structure;
assembling a second set of liner plate members into a second ring structure;
mounting the
second ring structure in abutting contact with the first ring structure; and
forming at least
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one seal between the first ring structure and the second ring structure.
[0027] In another aspect, in the liner plate structure of the immediately
preceding
aspect, the forming step involves energizing electrofusion chord members
located on both
the first ring structure and the second ring structure.
[0028] In another aspect, in the liner plate structure of one of the two
immediately
preceding aspects, the forming step includes applying a coating along an
exterior surface of
the joined first and second ring structures.
[0029] In another aspect, in the liner plate structure of one of the three
immediately
preceding aspects, a further step includes applying a grout material into a
space between
the exterior of the joined ring structures and the mine shaft bore.
[0030] In still another aspect, a liner plate structure for use in lining
shafts and
tunnels includes a primary plate portion having a length and height, the
length greater than
the height, the primary plate portion further including first, second, third
and fourth side
edges. First, second, third and fourth flanges respectively disposed at the
first, second,
third and fourth side edges, each flange having a plurality openings therein
for facilitating
connection to another liner plat structure. A structural member is connected
to and
protrudes from an inner side face of the primary plate portion, the structural
member
extending in the lengthwise direction and located in a central region along
the height of the
primary plate portion.
[0031] In another aspect, in the liner plate structure of the immediately
preceding
aspect, the primary plate portion includes at least one hole extending from
the inner side
face to an outer side face of the primary plate portion, the hole including
threads for
receiving a threaded plug.
[0032] In another aspect, in the liner plate structure of one of the two
immediately
preceding aspects, each flange includes a first flange portion overhanging the
interior side
face of the primary plate portion and a second flange portion overhanging and
exterior side
face of the primary plate portion, the overhang of the first flange portion
larger than the
overhang of the second flange portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Fig. I illustrated one embodiment of a liner plate structure;
[0034] Fig. 2A shows one embodiment of a cross section of the liner plate of
Fig. 1
along line 2-2;
[0035] Fig. 2B shows another embodiment of a cross-section of the liner plate
of
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Fig. 1 along line 2-2;
[0036] Fig. 3 shows a cross-section of the liner plate of Fig. 1 along line 3-
3;
[0037] Fig. 4 shows an enlarged partial view of the corner of the cross-
section of
Fig. 2A;
[0038] Figs. 5A-5C show alternative fusion chord configurations in cross-
section;
[0039] Figs. 6A and 6B show partial cross-sections of one embodiment of fusion
joints at adjacent liner plate flanges;
[0040] Figs. 7A and 7B show partial cross-sections of another embodiment of
fusion joints at adjacent liner plate flanges;
[0041] Figs. 8A and 8B show exemplary liner plate assembly configurations;
[0042] Fig. 9 show another embodiment of a liner plate structure including
openings to facilitate assembly;
[0043] Fig. 10 shows a cross-section of the liner plate of Fig. 9 taken along
line 10-
10;
[0044] Fig. 11 shows another embodiment of a liner plate structure;
[0045] Fig. 12 shows another embodiment of a liner plate structure;
[0046] Fig. 13 shows an assembly of liner plates in a vertical mine shaft bore
installation;
[0047] Fig. 14 shows another embodiment of a liner plate structure in partial
cross-
section view;
[0048] Fig. 15 shows a side elevation view of the liner plate of Fig. 14;
[0049] Fig. 16 shows the liner plate of Fig. 16 with anchor structure added;
[0050] Figs 17A and 17B show assembled liner plate structures during
electrofusion welding;
[0051] Fig. 18 shows a partial cross-section of assembled liner plates
according to
Fig. 16 with an interior liner assembly added;
[0052] Fig. 19 shows another embodiment of a liner plate structure in partial
cross-
section view;
[0053] Fig. 20 shows a side elevation view of the liner plate of Fig. 19;
[0054] Fig. 21 shows multiple liner plates according to Fig. 19 with an
interior liner
assembly added;
[0055] Figs. 22-24 show a partial cross-section of a flange recess and
electrofusion
chord and extrusion assembly;
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[0056] Fig. 25 shows a partial cross-section of a corner section of an
extrusion;
[0057] Fig. 26 shows a schematic cross-section of an extrusion ring structure;
[0058] Fig. 27 shows a schematic layout of one arrangement of electrofusion
chord;
[0059] Fig. 28 shows a schematic partial cross section of the electrofusion
chord
arrangement of Fig. 27;
[0060] Fig. 29 shows another embodiment of a liner plate structure including a
secondary sealing recess;
[0061] Fig. 30 shows a partial cross-section of the liner plate of Fig. 29;
and
[0062] Fig. 31 shows a cross-section view of an arrangement of liner plates
including an exterior polyurea coating.
DETAILED DESCRIPTION
[0063] Referring to Fig. 1 an exemplary liner plate 10 is shown and includes a
primary plate portion 12 of arcuate (or other curvature) configuration with
peripheral top,
bottom, left and right side flanges 14, 16, 18 and 20 located at respective
side edges of the
plate portion. The plate and flanges are preferably formed primarily of a
strong material
such structural carbon steel or aluminum. To form the liner plate a generally
flat piece of
plate material may be curved into an arcuate shape and generally flat pieces
of flange
material may be formed or cut into corresponding arcuate shapes. It is
recognized that
corrugations could be incorporated into plate portion 12 for increased
strength and/or
inwardly facing vertical or lateral ribs could be formed in or applied to the
plate portion 12
for increased strength. The top and bottom arcuate flange portions may then be
welded to
the arcuate plate portion. Left and right side flange portions may then be
welded to plate
ends as well. Any suitable metal welding technology may be used. In another
embodiment, the flat plate could be cut to include the flange portion (e.g.,
by removing
corner sections), the flange portions folded relative to the base plate
portion, the structure
formed into an arcuate shape and then the flange portions welded to each other
at the
corners. In still other embodiments a stamping operation, forging operation or
metal
casting operation may be used to form the liner plate. Alternatively, a
material other than
steel or other alloy is used, such as concrete, in which case the liner plates
may be formed
by casting.
[0064] The dimensions of the liner plate may vary depending upon the size of
the
mine shaft or tunnel into which the liner plates will be assembled, as well as
other factors.
However, it is contemplated that the thickness of the plate portion 12 may
generally be in
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the range of about 1/4" to 1" or more (e.g., such as in the range of about 2"
to 5"). In
applications where the liner plate is installed to provide structural support
for the shaft or
tunnel wall, the plate thickness may be higher. The arcuate length or extent
of a typical
liner plate may be in the range of about 36" to 72" or more, such as up to
about 216" and
the arc encompassed by that length may typically be in the range of about 18
to 36 degrees
or more (e.g., such as about 40 to 180 degrees). The height of each liner
plate may
typically be in the range of about 24" to 36" or more (e.g., such as between
about 42" to
96"). The radial depth of the liner plates may be in the range of about 5" to
10" or more
(e.g., such as in the range of about 10" to 18"). Variations on these
dimensions are
possible. In some embodiments, the thickness of the flanges 14, 16, 18 and 20
will match
that of the arcuate plate 12. In other embodiments the thickness of the
flanges may be
more or less than that of the arcuate plate.
[0065] Referring to Figs. 2A and 2B, exemplary cross-sections of the liner
plate 12
are shown. Fig. 2A shows a cross-section in which the outer surface of each of
the arcuate
plate 12 and top and bottom flange 14 and 16 has a polypropylene layer 22, 24
and 26
bonded thereto. Other suitable thermoplastics that can be thermally bonded
could be used
to form the layers, such as polyethylene. In order to form a continuous
polypropylene layer
it may be applied after the plate and flanges are formed and welded. However,
embodiments in which the polypropylene layer is coated onto the plate and
flanges prior to
the components being welded together may be possible. Fig. 2B shows an
embodiment in
which only the top and bottom flanges 14 and 16 include a polypropylene layer.
In either
implementation (Fig. 2A or Fig. 2B), both the left and right flanges 18 and 20
would
include corresponding polypropylene layers 28 and 30 as well, as shown in Fig.
3. By way
of example, the polypropylene layers may typically have a thickness in the
range of about
1/8" to 1/2", but variations are possible. The primary purpose of the
polypropylene layers
is to provide a sealing function when liner plates are abutted against each
other and
assembled into a cylindrical liner for a mine shaft or tunnel.
[0066] In this regard, and referring to Fig. 4, the flange portions of the
liner plate
may include one or more thermoplastic fusion elements (e.g., such as electro-
fusion joining
elements) extending therealong. The illustrated electro-fusion joining
elements 32 include
a generally planar resistive element 34 coated in polypropylene and the
elements are
applied directly to the outer surface of the polypropylene layer (e.g., per
Fig. 5A).
However, the shape of the elements 32 could vary, such as the oval or round-
shaped
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elements shown in Figs. 5B and 5C. For example, electrofusion chord as
described in U.S.
Patent No. 5,407,514 could be used. Energization of the resistive elements of
the chord
heats the thermoplastic and causes the fusion to take place. Preferably, the
electro-fusion
elements are incorporated into the liner plates prior to installation of the
liner plates in the
field, but in field of application of the electro-fusion elements may be
possible. In this
embodiment, when two liner plates are abutted against each other as shown in
Fig. 6A, the
electro-fusion elements 32 are sandwiched between the polypropylene layers 24
and 26 of
the two liner plates. By passing current through the resistive elements 34 the
two layers 24
and 26 are effectively joined or bonded together by electro-fusion welding of
the material
of the layers 24 and 26 and the material of the elements 32, per Fig. 6B.
Thus, multiple
sealing lines may be formed along the radial thickness or depth of the
flanges,
corresponding to the number of spaced apart sealing elements disposed
depthwise along the
flanges. In another embodiment, according to Fig. 7A, the electro-fusion
element may be
formed of a lattice-type resistive element that extends along substantially
the entire flange
depth, to produce a relatively continuous bond and seal along the depth of
adjoining
flanges per Fig. 7B. Other variations are possible. Although not shown,
similar electro-
fusion bonds would be formed between abutting left and right side flanges of
side-by-side
liner plates.
[0067] A plurality of like liner plates are assembled together to form, for
example,
a cylindrical mine shaft liner that is sealed against penetration by
groundwater. Other mine
shaft liner geometries are possible as well, such as oval, elliptical or
rectangular of other
polygonal shapes. In one example, the liner plates are assembled in aligned
columns and
rows per Fig. 8A, but a preferred assembly configuration offsets the liner
plates from row
to row as shown in Fig. 8B. In either case, by electro-fusion bonding the
adjacent flange
portions of the liner plates, a sealed cylindrical structure can be formed
(i.e., sealed along
its entire height for a full 360 degrees).
[0068] Various structures may be used to assemble adjacent liner plates
together.
In one example, per Fig. 9, openings 40 are provided in the flanges so that
the openings of
adjacent flanges align and nut and bolt assemblies can be used. At least one
or more of the
electro-fusion sealing elements, or portions thereof should, in such cases,
extend along the
external side of the opening (i.e., between the opening and the cylindrical
outer surface of
the arcuate plate 12).
[0069] In order to provide desired sealing and suitable assembly, it is
contemplated
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that in some embodiments a typical liner plate may include electro-fusion
elements along
only two flanges (e.g., one of the top and bottom flanges and one of the left
or right
flanges). For example, referring to the cross section of Fig. 10, one or more
electro-fusion
elements extend along the outer surfaces of polyethylene layers 28 and 26 of
the left and
bottom flanges, but not along the other surfaces of the polypropylene layers
24 and 30 of
the top and right flanges. When properly assembled, a left flange with element
32 will
always abut a right flange without element 32 so that the adjacent
polypropylene layers can
be sealed by electro-fusion, and a bottom flange with element 32 will always
abut a top
flange without element 32 so that the adjacent polypropylene layers can be
sealed by
electro-fusion. In such embodiments, it may be desirable to provide some
structure on the
liner plates that forces them to be assembled in the proper orientation (e.g.,
with the top
flange always facing up and not inadvertently facing down).
[0070] In one example, such a forced assembly arrangement could be achieved by
non-symmetrical placement of the openings 40 on, for example the left and
right flanges 18
and 20. Specifically, referring to Fig. 11, upper side flange openings 40a are
spaced a
distance dl from the top edge of the liner plate and lower side flange
openings 40b are
spaced a distance d2 from the bottom edge of the liner plate, where d2 is
greater than dl.
As long as side-by-side liner plates are always arranged in the same top up
orientation, the
side flange openings will be centered on each other to facilitate receiving
the nut and bolt
assemblies. However, if one liner plate is arranged in a top up orientation
and an adjacent
side located liner plate is accidentally arranged in a top down orientation,
the side flange
openings will not align properly, preventing receiving of the nut and bolt
assemblies, and
thus alerting an installer to the improper orientation of one of the liner
plates. Of course,
other structures could be provided or used to force proper orientation of the
liner plates
during assembly. For example, per Fig. 12, the left flange 18 of each liner
place could be
bowed slightly outward about its vertical axis and the right flange 20 of each
liner plate
could be correspondingly bowed slightly inward along its vertical axis to
achieve a mating
relationship between left and right flanges when place side-by-side. Other
variations are
possible.
[0071] Referring to Fig. 13, an exemplary installation of assembled liner
plates 12
to form a cylindrically extending liner 50 of a vertical mine shaft 51 is
shown. Grout (e.g.,
cementious grout) or other filler material 54 may be delivered into the gap or
spacing 52
between the external surface of the cylindrical liner and the inward facing
surface or wall
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of the mine shaft bore 51 itself. In this regard, the arcuate plate portions
of the liner plates
may be formed with grout openings for purpose of feeding grout into the space,
in which
case suitable plug structures could be provided for such openings.
[0072] The ends of each electro-fusion chord should terminate so they are
accessible from the inward facing side of the liner plate (e.g., radially
inward of the arcuate
plate), making them accessible from the inside of the assembled ring of liner
plates when
installed. The chord ends can protrude through the gap between mating plastic
sheets or
extended through openings or holes in the flange or flanges and terminate at
the radially
inner side of the flanges of the liner plate.
[0073] Preferably, the electro-fusion process is performed after full rings of
liner
plates have been assembled (e.g., each time one ring is assembled or each time
a specified
number of rings are assembled), but could alternatively be performed as
individual liner
plates are assembled into place.
[0074] In an alternative embodiment, electro-fusion chords may be eliminated
and
adjacent flanges of the assembled/installed liner plates could be field welded
in place using,
for example, a down-hole field extrusion gun that applies a thermoplastic
material. In other
embodiments, the a true metallic weld may be applied to adjacent flanges
(e.g., at the
radially inner edges of the abutting flanges).
[0075] Referring to the embodiment of Figs. 14-16, the electro-fusion chords
may
also be placed within a perimeter recess 80 formed in the flanges 14, 16, 18
and 20. Such a
construction facilitates steel to steel contact between adjacent liner plates
for better
structural support by the installed liner system. In this regard, as will be
described in more
detail below, the electro-fusion chord installed in the recess may protrude
slightly outward
of the flange surfaces so as to assure contact with the chord of an adjacent
liner plate. In
one embodiment, the electro-fusion chord may include a compressible rubberized
thermoplastic or rubber core and a thermoplastic exterior, making the chord
more readily
compressible when adjacent plates are bolted together.
[0076] The liner plates may also include a structural member 82 on the primary
plate portion 12. In the illustrated embodiment, the structural member is a T-
shaped
member, with the base 84 of the T-shaped member welded to the inner face of
the arcuate
plate portion 12 and the cross or head 86 of the T disposed radially inward of
the arcuate
plate portion. The T-shaped structural member has a curved configuration that
matches the
curve of the liner plate as best seen in Figs. 17A and 17B. The configuration
of the
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structural member could vary. By way of example, other possibilities include
wide flange
beams, tubes, channels, standing ribs, etc. Referring again to Fig. 16, anchor
loops 88 may
be connected to the external face of the arcuate plate portions 12 (e.g., by
welding) to
provided an integrated connection with the grout or other filler material that
is delivered
into any gap or spacing between the external surface of the cylindrical liner
and the inward
facing surface of the mine shaft bore itself. The anchor loops may, by way of
example be
formed of curved rebar structure, such as #5 rebar. In this regard, the
primary plate portion
12 includes one or more holes 90 and 92 (Fig. 17A) for delivering the grout
into the space
at the external surface of the liner. The holes 90 and 92 may be threaded to
enable easy
installation of a threaded plug to assure sealing of the holes (gaskets or
thread dope may be
used in connection with the plugs).
[0077] In another embodiment as shown in Figs. 19-2 1, the flanges 14, 16, 18
and
20 may be connected (e.g., welded) to the main plate structure 12 so as to
extend radially
outward beyond the outer side face of the plate portion 12 slightly (e.g., 1/8
inch to 1 inch
or more) as shown at locations 94, 96 and 98. These overhanging portions act
to assist in
anchoring the plates to the fill grout to provide an integrated connection
with the grout or
other filler material, in which case the anchor loops may be eliminated in
certain
implementations. In addition, the overhanging arrangement facilitates use of a
filet weld to
secure the flanges 14, 16, 18 and 20 to the main plate portion 12.
[0078] As seen in Figs. 18 and 21, in some embodiments, an inner liner system
100
may be connected to the plate structures upon installation and after
thermoplastic fusion
weld sealing. By way of example, the aforementioned T-shaped structural member
may
include a series of bolt openings 102 for connecting a smooth inner liner
plate 104 formed
of metal, plastic or other suitable material. Bolt and nut assemblies 105
secure the liner to
the structural member. The inner liner members may also have an inward and
downward
facing hook structure 106 that overlaps and rests atop the upper edge of the T
portion 86 of
the structural member 82. Moreover, each inner liner structure may be formed
with an
inwardly (Fig. 18) or outwardly (Fig. 21) offset lower edge or flange 108 that
receives the
upper edge of an immediately adjacent lower liner structure. Alternatively,
the upper edge
could include the inwardly or outwardly offset flange to receive the lower
edge of an
immediately adjacent upper liner structure.
[0079] Where the liner plates are made for structural support of the shaft or
tunnel
wall, the thickness of the steel plate making up the arcuate plate and flanges
may, for
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example, be on the order of two to four inches, but other variations are
possible. In one
embodiment the thickness of the arcuate plate portion is between 25% and 75%
thicker
than the thickness of the flanges (e.g., 50% thicker). The arcuate length or
extent of a
typical structural liner plate may be in the range of about 72" to 190", such
as about 110" to
150", such as about 125" to 135", but variations in the range of 36" to 216"
are envisioned
as well. The arc encompassed by each plate may be in the range of about 40 to
80 degrees,
such as about 50 to 70 degrees, such as about 60 degrees, but variations are
possible,
including in the range of about 40 to 180 degrees.
[0080] The radial depth of the flanges may be on the order of about 5" to 15"
depending on the application, such as about 8" to 12" (e.g. about 10"), but
variations in the
range of 5" to 18" are envisioned as well. The width or radial depth of the
recess to receive
the electro fusion chord will typically vary according to the radial depth of
the flanges. By
way of example, the width or radial depth of the recess may be on the order of
about 10%
to 30% of the radial depth of the liner plate flanges.
[0081] Referring to Figs. 22-25, where the chord is applied in a recess 80,
the
electrofusion chord 120 may be incorporated into an extrusion that is placed
in the recess
80. In one example, a multi-layer gasket extrusion 122 of polypropylene top
layer 124 (it
is recognized that other materials may be used, particularly thermoplastic
materials that are
capable of heat fusion), an elastic polymer intermediate layer 126 (e.g., EPDM
(ethylene
propylene diene Monomer (M-class) material)) and a bottom layer of material
128 (e.g.,
such as sanoprene) that will bond to metal at the bottom of the recess in the
presence of
heat is created (e.g., via a co-extrusion process or via multiple layered
extrusions). The
polyproylene layer 124 may be formed with spaced apart recesses 130 (e.g.,
generally
semicircular in form) that will receive the electrofusion chord 120 (e.g.,
chord that is
circular in cross-section). The extrusion 122 is then cut to lengths to
facilitate formation of
a rectangular ring structure that can circumscribe the continuous,
circumscribing recess 80
formed by aligned recesses of all flanges on a liner plate. As show in Fig.
25, end portions
of extrusion strips 122 may be cut with a fourty-five degree taper and then
bonded together
(e.g., via heating) to form the right angle turns needed to transition from
one flange to the
next. A rectangular ring structure 134 with three fused corners 136 and one
unfused corner
138 is formed (e.g., per the schematic cross-section of Fig. 26), enabling the
ring structure
to be applied into the recess 80 of a liner plate. Once applied, the corner
138 can be fused
to hold the ring structure in place. Heat may then be applied at the inner
surfaces of the
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flanges in the vicinity of the recesses to cause layer 128 to bond to the
metal. In an
alternative embodiment an adhesive (e.g., one that does not require heat)
could be used to
bond the ring structure in the recess 80.
[0082] In one implementation, all extrusions 122 making up the ring structure
are
straight and the upper and lower extrusions are flexible enough to take the
shape of the
curved recess portions of the top and bottom flanges 14 and 16 of the liner
plate. In
another implementation, the top and bottom extrusions may be cold rolled into
the desired
curvature prior to forming the ring structure 134. Of course, other techniques
for placing
the extrusion in the liner plate recess may be used, such as extrusion
directly into the
recess.
[0083] Once the base extrusion 122 is placed in the recess, the fusion chord
120 is
then applied into extrusion recesses 130. In this regard, numerous
configurations for the
placement pattern of the chord are possible. In one embodiment, as best seen
in Fig. 27,
the recess 80 of each flange is fitted with two distinct fusion chord loops as
outer and inner
loops 140 and 142. Transverse recesses are cut into the extrusion ends to
receive the lateral
portions 144 and 148 of the chords. These lateral portions 144 and 148 may be
curved
portions rather than straight portions. Each fusion chord loop 140, 142 is
terminated with
loop ends 150 in proximity to each other and loop ends 152 in proximity to
each other.
The loop ends 150 are displaced relative to loop ends 152 by some distance. As
best seen
in the schematic view of Fig. 28, at the location of the loop ends 150 and 152
holes 160 and
162 are drilled through the flange and the fusion chord fed through the holes
so that each
fusion chord loop has end portions 164, 166 that are accessible at the
internal side of the
liner plate to facilitate connection of the power supply for the fusing
operation.
[0084] Referring to Figs. 23 and 24, once the chord is applied to the recesses
130 of
the extrusion ring, an overlayer 170 of polypropylene is applied (e.g., via
extrusion) over
the top to hold the chord in place. In one embodiment, as shown in Fig. 24,
the end result
is a thermoplastic fusion element in the form of a multi-layer fusion assembly
180 applied
in the recess 180 with upper layer 170 extending slightly above the exterior
surface or side
face of the flange 182, and with one or both of the side edges of the assembly
spaced from
the side edges of the recess. The raised nature of layer 170 assures good
contact with a
similar raised layer of an adjacent liner plate flange when two plates are
secured together
with flanges surfaces 182 contacting each other. The side to side spacing
provides
sufficient room for the assembly 180 when it is compressed (e.g., downward
compression
13
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WO 2011/097201 PCT/US2011/023290
of the multi-layer assembly results in some outward bowing of the sides of the
assembly
180). In one example, the height HA of the assembly 180 before compression is
between
about 10% and 20% greater than the overall recess height HR (e.g., for a
recess having a
depth of about 1/4" to 3/4" the assembly may protrude by about 0.025" to
0.15"), but
variations are possible. Likewise, the width (or radial depth) WA of the
assembly 180
before compression may be between about 2% and 8% less than the width (or
radial depth)
WR of the recess (e.g., for a recess having a width or radial depth of about
1.75" to 2.25"
the width or radial depth of the assembly may be between about 1.60" and
2.20"), but
variations are possible.
[0085] In one process, the height of the fusion assembly 180 above the surface
182
of the flange may be defined by implementing a post installation trimming
operation. That
is, the assembly 180 may be fully formed in the recess 80 such that layer 170
extends
higher than desired. A planing type device may then be run along the surface
182 to trim
the layer down to the desired height. However, other techniques could also be
used.
[0086] During a fusion process, as the resistive elements in the fusion chords
120 of
adjacent fusion assemblies 180 are energized and heating takes place, the
polyproylene
layers 170 and 174 are heated and fusion of abutting layers 170 takes place.
In some
embodiments, the heating may also cause the exterior sides of the layers 170
and 174 to
bond to the side walls of the recess 80.
[0087] Referring now to Figs. 29 and 30, a secondary or back-up sealing system
may also be enabled by providing a small recess or sub-recess 200 in the
flanges at the
radially internal side of the recess 80 and extrusion assembly 180 (e.g., in
the illustrated
embodiment immediately adjacent to the recess with one side of the sub-recess
in
communication with the recess 80). This sub-recess 200 (e.g., about 1/16 to
3/16 inch
depth and 1/8" to 1/2" wide (or radial depth), such as, about 1/8" deep and
1/4" wide) on
the flanges would align with a similar recess on adjacent flanges of adjacent
liner plates to
create a continuous recess (e.g., 1/4" by 1/4" in total) that could be filled
with grout or
other sealant (e.g., via a radially inward extending portion 202 or portions
of the sub-recess
that extend to the inward facing side edges of the flange). By providing
multiple radially
inwardly extending sub-recess portions 202 on each flange that can be
selectively and
temporarily plugged, the location of a leak along a given plate structure or
circumferential
extension of plate structures can be identified. Specifically, the method of
testing for a leak
may involve plugging two spaced apart sub-recess extensions 202 (e.g.,
inserting a
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WO 2011/097201 PCT/US2011/023290
temporary plug the sealingly abuts against the thermoplastic fusion element)
and then
applying pressurized air to a sub-recess extension located between the two
plugged
extensions. If the sub-recess holds the pressure, then the thermoplastic
fusion seal is
deemed sound in the region between the two plugged sub-recess extensions. If
the sub-
recess does not hold the pressure, then the thermoplastic fusion seal is
deemed imperfect or
leaking in the region.
[0088] As a matter of practice, the secondary recess 200 may be filled with
grout
only in situations where a leak is identified. Alternatively, the secondary
recess 200 may
always be filled with grout to provide the secondary or back-up seal for the
installation.
[0089] Referring now to Fig. 31, an embodiment including a two or three stage
sealing system is shown. Specifically, the electrofusion chord assembly seal
210 is
provided between adjacent flanges of the liner plates. At the external surface
of the
assembled liner plate structure a polyurea coating 212 is also applied for
sealing purposes.
The polyurea coating may be applied by suitable spray process and may, by way
of
example, have a thickness of between about 1/10" and 1/2", but variations are
possible.
The third stage sealing could be by way of the grout seal mentioned above.
[0090] In terms of overall assembly process, in one method, the liner is
assembled
in a top down manner in the case of a vertical mine shaft installation. A
series of liner
plates are assembled together with nut and bolt assemblies within the shaft to
form a ring.
That ring is then raised upward and connected via nut an bolt assemblies to
the lower side
of a previously installed ring. The exterior of the joined rings is then
sprayed with
polyurea to provide the first sealant barrier. Suitable equipment capable of
reaching the
exterior side of the assembled liner plate rings may be used for this purpose.
Additional
ring layers may be added in a similar fashion (by repeating the foregoing
steps) to achieve
the desired depth of the liner plate structure. Periodically (e.g., after
every ring or every
few rings are assembled), grout may be applied to the exterior of the polyurea
layer in the
space 52 between the bore or shaft 51 and the liner assembly by providing a
temporary
form structure at the bottom of the lowest ring layer and pumping grout 220
upward into
the space 52 between the liner plate assemblies and the mine shaft bore wall
50. The
electrofusion sealing may also be performed periodically by delivering power
to the leads
of the electrofusion chords. In this regard, reference is made to Figs. 17A
and 17B, where
Fig. 17A contemplates energization of the chords on the vertical plate flanges
and Fig. 17B
contemplates energization of the chord on the horizontal plate flanges. The
exact number
CA 02788349 2012-07-26
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of chords energized at any one time and the overall sequence of energization
could vary.
[0091] It is also recognized that in any given application a mine or tunnel
shaft liner
system could be made up of a combination of liner plate structures with
thermoplastic
fusion seals and liner plate structures without thermoplastic fusion seals.
For example,
certain sections of the liner system could utilize the thermoplastic fusion
seals in those
regions where groundwater is an issue and other sections could be installed
without the
thermoplastic fusion seals in regions where groundwater is not an issue.
[0092] While particular embodiments have been illustrated and described, it is
to be
clearly understood that the above description is intended by way of
illustration and
example only and is not intended to be taken by way of limitation, and that
changes and
modifications are possible.
[0093] What is claimed is:
16
