U.S. patent application number 15/216126 was filed with the patent office on 2017-05-11 for telescopic mine roof support.
The applicant listed for this patent is BURRELL MINING PRODUCTS, INC.. Invention is credited to Charles C. Lash, Michael T. Shook.
Application Number | 20170130580 15/216126 |
Document ID | / |
Family ID | 58664019 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170130580 |
Kind Code |
A1 |
Shook; Michael T. ; et
al. |
May 11, 2017 |
TELESCOPIC MINE ROOF SUPPORT
Abstract
A longitudinally yieldable support for underground roof support
includes a first support section with a first elongate outer shell
partially filled with a solid compressible filler material and a
second support section at least partially filled with a second
solid compressible filler material. The second support section is
at least partially disposed within the first elongate outer shell
and is telescopically extendable relative thereto. A bladder is
interposed between the first and second support sections that is
fillable in situ to cause extension of the second support section
relative to the first support section when filled under pressure
with a filler material.
Inventors: |
Shook; Michael T.; (New
Kensington, PA) ; Lash; Charles C.; (Apollo,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BURRELL MINING PRODUCTS, INC. |
NEW KENSINGTON |
PA |
US |
|
|
Family ID: |
58664019 |
Appl. No.: |
15/216126 |
Filed: |
July 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14659086 |
Mar 16, 2015 |
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15216126 |
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14508032 |
Oct 7, 2014 |
9347316 |
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14659086 |
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13599428 |
Aug 30, 2012 |
8851805 |
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14508032 |
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61954746 |
Mar 18, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21D 15/523 20130101;
E21D 15/18 20130101; E21D 15/48 20130101 |
International
Class: |
E21D 15/18 20060101
E21D015/18; E21D 15/14 20060101 E21D015/14 |
Claims
1. A longitudinally yieldable support, comprising: a first support
section comprising a first elongate outer shell partially filled at
a first end portion with a first solid compressible filler material
and defining a opening at a second end of the first elongate outer
shell between a second end and a top of the first solid
compressible filler material; and a second support section
comprising a second elongate outer shell at least partially filled
with a second solid compressible filler material positioned in the
opening of the first outer shell, the second elongate outer shell
having an outer diameter that is slightly smaller than a diameter
of the first elongate outer shell to allow the second elongate
outer shell to slide relative to the first elongate outer shell; a
port in communication with a space between the top of the first
compressible filler and a bottom of the second compressible filler
configured for filling the space with a third filler material under
pressure to cause the second support section to rise relative to
the first support section in order to span a space between a floor
and a roof of an underground entry.
2. The support of claim 1, wherein the first and second elongate
outer shells are comprised of steel and wherein the first and
second solid compressible filler materials are cast in the first
and second elongate outer shells respectively.
4. The support of claim 3, wherein the second elongate outer shell
is movable in a telescopic manner from a first position in which
the second elongate outer shell is at least partially disposed
within the first elongate outer shell to a second position in which
a portion of the second elongate outer shell is maintained within
the second elongate outer shell and a top of the second elongate
outer shell is in contract with a roof of a mine entry.
5. The support of claim 1, wherein the first and second
compressible filler materials have substantially the same
density.
6. The support of claim 5, wherein the third compressible filler
material is comprised of a solidified material having a second
density that is greater than the densities of the first and second
compressible filler materials.
7. The support of claim 1, further comprising a fillable bladder
interposed between the top of the first compressible filler
material and a bottom of the second compressible filler material,
the fillable bladder having an inlet accessible through the port
for filling the bladder in situ.
8. The support of claim 7, further comprising a one-way valve
coupled to the inlet of the bladder to allow the filler material to
enter the bladder but prevent the filler material from escaping
from the bladder.
9. The support of claim 8 wherein the port is positioned proximate
the top of the first compressible filler of the first support
section.
10. The support of claim 5, wherein the first and second
compressible filler materials have a density of between about 40
and 50 lb/ft.sup.3 and the third filler material has a density of
between about 50 and 60 lb/ft.sup.3.
11. The support of claim 5, wherein the bottom end of the first
support section and the top end of the second support section will
yield under load before a center portion of the support where the
third filler material resides begins to yield.
12. The support of claim 1, wherein the first and second support
section are capable of supporting a load of at least 100,000
lbs.
13. The support of claim 12, wherein the first and second support
sections are capable of supporting a load of between approximately
100,000 lbs and 300,000 lbs as the first and second support section
yield under load.
14. The support of claim 10, wherein the first and second outer
shells will fold upon themselves as the first and second support
sections yield.
15. A method of installing a longitudinally yieldable support in an
underground entry, comprising: providing a first support section
comprising a first elongate outer shell partially filled at a first
end portion with a first solid compressible filler material and
defining a opening at a second end of the first elongate outer
shell between a second end and a top of the first solid
compressible filler material; providing a second support section
comprising a second elongate outer shell at least partially filled
with a second solid compressible filler material positioned in the
opening of the first outer shell, the second elongate outer shell
having an outer diameter that is slightly smaller than a diameter
of the first elongate outer shell to allow the second elongate
outer shell to slide relative to the first elongate outer shell;
and pumping a third filler material through a port in communication
with a space between the top of the first compressible filler and a
bottom of the second compressible filler configured for filling the
space with a third filler material under pressure to cause the
second support section to rise relative to the first support
section until the support abuts against a roof of an underground
entry.
16. The method of claim 1, further comprising providing the first
and second elongate outer shells of steel and separately casting
the first and second solid compressible filler materials into the
first and second elongate outer shells respectively.
17. The method of claim 16, further comprising moving the second
elongate outer shell in a telescopic manner from a first position
in which the second elongate outer shell is at least partially
disposed within the first elongate outer shell to a second position
in which a portion of the second elongate outer shell is maintained
within the second elongate outer shell and a top of the second
elongate outer shell is in contract with a roof of a mine
entry.
18. The method of claim 15, further comprising providing the first
and second compressible filler materials with substantially the
same density.
19. The method of claim 18, further comprising providing the third
compressible filler material as a solidified material having a
second density that is greater than the densities of the first and
second compressible filler materials.
20. The method of claim 15, further comprising providing a fillable
bladder interposed between the top of the first compressible filler
material and a bottom of the second compressible filler material,
the fillable bladder having an inlet accessible through the port
for filling the bladder in situ.
21. The method of claim 20, further comprising providing a one-way
valve coupled to the inlet of the bladder to allow the filler
material to enter the bladder but prevent the filler material from
escaping from the bladder.
22. The method of claim 21, further comprising providing the port
in a position proximate the top of the first compressible filler of
the first support section.
23. The method of claim 18, further comprising providing the first
and second compressible filler materials with a density of between
about 40 and 50 lb/ft.sup.3 and the third filler material with a
density of between about 50 and 60 lb/ft.sup.3.
24. The method of claim 18, further comprising configuring the
support so that the bottom end of the first support section and the
top end of the second support section will yield under load before
a center portion of the support where the third filler material
resides begins to yield.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 14/659,086, filed on Mar. 16, 2015, which
claims priority to U.S. Provisional Patent Application No.
61/954,746, filed on Mar. 18, 2014, and is a continuation of U.S.
patent application Ser. No. 14/508,032, filed on Oct. 7, 2014,
which is a continuation of U.S. patent application Ser. No.
13/599,428, filed on Aug. 30, 2012, now U.S. Pat. No. 8,851,805,
the entirety of each of which is incorporated by this
reference.
BACKGROUND
[0002] Field of the Invention
[0003] The present invention relates generally to an underground
mine roof support for supporting the roof, and, more particularly,
to a yieldable mine roof support that allows for adjustment of the
overall length of the mine roof support to fit between a roof and a
floor of a mine entry.
[0004] Description of the Related Art
[0005] Over the past several years, Burrell Mining Products, Inc.
of New Kensington, Pa. has successfully marketed and sold a mine
roof support product sold under the trademark THE CAN.RTM.. THE CAN
support is comprised of an elongate metal shell that is filled with
aerated concrete. The use of aerated concrete in THE CAN support
allows the support to yield axially in a controlled manner that
prevents sudden collapse or sagging of the mine roof and floor
heaving. THE CAN support yields axially as the aerated concrete
within the product is crushed and maintains support of a load as it
yields.
[0006] A typical size of THE CAN support is approximately six feet
(1.8 meters) in height and two feet (0.6 meters) in diameter. The
overall height of THE CAN supports is based on the average size of
the mine entry with each support being of a height that is less
than an average height of the mine entry in which the supports are
to be installed. In order to install each support, wood planks (or
other appropriate cribbing materials such as aerated concrete
blocks) are placed beneath THE CAN support to level the support and
additional wood planks or other cribbing materials are placed on
top of the support until the space between the support and the roof
is filled. Essentially, the cribbing materials are tightly wedged
between the support and the roof so as to cause each THE CAN
support to bear a load of the roof upon installation. Even though
these cribbing materials can be installed by mine personnel in a
manner that ensures that each support begins bearing a load of the
mine roof upon installation, there still exists a need in the
industry to provide a mine roof support that is capable of being
installed in a manner that substantially fills the space between
the mine roof and the mine floor without requiring the installation
of cribbing materials above the roof support. In addition, even
though cribbing materials may be tightly inserted between the top
of the mine roof support and the roof of the mine, there is still
an amount of movement of the mine roof relative to the mine floor
(or vice versa in the case of floor heaving) that can occur before
the mine roof support is able to fully bear the load. Thus, there
still exists a need in the art to provide a mine roof support that
is capable of bearing a load of the mine roof support shortly after
installation but before the roof begins converging toward the floor
or vice versa.
[0007] Thus, it would be advantageous to provide a mine roof
support that is installable within a mine entry that substantially
fully extends between the mine roof and the mine floor when
properly installed. It would be a further advantage to provide a
mine roof support that is installable within a mine entry that is
capable of bearing a load of the mine roof shortly after
installation without the need of cribbing materials placed above
the support in order to decrease installation time and to increase
the initial load bearing capacity of the mine roof support.
[0008] These and other advantages will become apparent from a
reading of the following summary of the invention and description
of the illustrated embodiments in accordance with the principles of
the present invention.
SUMMARY OF THE INVENTION
[0009] Accordingly, a support is comprised of first elongate tube
partially containing a crushable or compressible core material in a
bottom portion thereof that allows controlled yielding of the
support along its length. A second elongate tube is telescopically
received within the first elongate tube. The second elongate tube
is movable in a telescopic manner relative to the first elongate
tube and is filled with a crushable or compressible core material
of the same consistency as the material in the first elongate tube.
A fillable bag or bladder is inserted between the first elongate
tube and the second elongate tube with a filling port or nozzle
extending through a side wall of the first elongate tube. The bag
or bladder is then filled under pressure in situ with a crushable
or compressible core material that causes the second elongate tube
to rise relative to the first elongate tube in a telescopic manner
until the upper end of the second elongate tube contacts a roof of
a mine entry in which the support is positioned. Once the core
material in the bag or bladder cures, the support allows controlled
yielding of the support along the second elongate tube as the
compressible core material compresses due to convergence of the
mine entry roof and floor. By being able to raise the second tube
relative to the first tube, the support of the present invention is
provided with a length adjustment feature.
[0010] In one embodiment, the support is comprised of a first outer
steel shell formed in the shape of a first elongate tube. An
aerated or other lightweight concrete or cement is poured into the
bottom of the first elongate tube to fill a portion thereof. Once
the lightweight concrete is set, the lightweight concrete will bond
to the inside surface of the first elongate tube so as to prevent
the concrete from disengaging from the tube during transport or
use. The use of a lightweight cement containing lightweight
aggregate or air pockets allows the cement to be crushed within the
first outer shell thus allowing axial yielding of the support along
its length as the lightweight concrete is compressed. The support
is further comprised of a second outer steel shell formed the shape
of a second elongate tube. Aerated or other lightweight concrete is
poured into the second outer steel shell so that the second outer
steel shell is completely filled from top to bottom with
lightweight concrete. The outer diameter of the second outer steel
shell is slightly less than an inner diameter of the first outer
steel shell so that the second outer steel shell can be slid into
the first outer steel shell but that restricts lateral movement of
the second outer steel shell relative to the first outer steel
shell under load.
[0011] A fillable bag or bladder is positioned within the first
outer steel shell and on top of the compressible filler contained
in the first outer steel shell. The fillable bag or bladder may
have a generally cylindrical shape when filled with a diameter
approximately equal to the inner diameter of the first outer steel
shell. The bladder has an filling port or nozzle that extends
through a hole or aperture formed in a sidewall of the first outer
steel shell to allow the bladder to be filled in situ from outside
the first outer steel shell. The second outer steel shell that has
been filled with the compressible filler is positioned at least
partially within the first outer steel shell and on top of the
bladder.
[0012] Filling the bladder under pressure with a filler material,
such as cement, lightweight cement, grout or other materials known
in the art that can be pumped into the bladder, causes the second
outer steel shell to rise relative to the first outer steel shell
from a first position to a second position where the top of the
second outer steel shell abuts against a roof of a mine entry.
[0013] In another embodiment, the second elongate outer shell is
partially filled with a compressible filler in an upper portion
thereof and is disposed over the first elongate outer shell that is
completely filled with the compressible filler. The bladder is
disposed within the second outer shell between the compressible
filler in the second outer shell and the top of the compressible
filler within the first outer shell. This provides less
compressible filler above the bladder and thus less weight that
must be lifted as the bladder expands to raise the second outer
shell relative to the first outer shell.
[0014] In still another embodiment, the compressible filler
material in the first and second outer shells is formed from the
same material and thus has substantially the same density. The
filler material in the bladder may have a density that is
substantially the same as or greater than the compressible filler
material in the first and second outer shells. This ensures that
the support when installed will yield in a controlled and
predictable manner by allowing the top and bottom portions of the
support to yield before the center section containing the bladder
begins to yield.
[0015] In yet another embodiment, rather than employ the use of a
bladder, the filler materials contained in the first and second
outer shell sections are spaced apart to form an air gap between
the upper surface of the filler material in the bottom section and
the bottom surface of the filler material in the upper section. The
filler materials may be spaced apart with blocks of the filler
material. The filling nozzle is in fluid communication with the air
gap so that filler material in liquid form can be pumped under
pressure into the air gap to force the upper section away from the
lower section, thus causing the upper section to rise. By
maintaining a relatively close tolerance between the inner diameter
of the first shell and the outer diameter of the second shell and
providing the filler material in an uncured and liquefied form
having a particle size that is greater than a gap between the first
and second shells, the filler material will cause the upper section
of the support to rise without substantially flowing through the
gap. Once the upper section abuts the roof of the mine entry, the
filling process can cease.
[0016] In another embodiment, the precast compressible filler
material in the upper and lower sections has a density of between
about 40 and 50 lb/ft.sup.3 and the compressible filler material
that is pumped into the support in situ has a density of between
about 50 and 60 lb/ft.sup.3.
[0017] In yet another embodiment, the top and bottom ends of the
support will yield first under load until the precast filler
materials have yielded and then the filler material filled in situ
will yield.
[0018] In another embodiment, the support is capable of supporting
a load of between approximately 100,000 lbs and 300,000 lbs as the
support yields under load.
[0019] In still another embodiment, the first and second outer
shells will fold upon themselves as each section yields.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The foregoing summary, as well as the following detailed
description of the illustrated embodiments is better understood
when read in conjunction with the appended drawings. For the
purpose of illustrating the invention, there is shown in the
drawings several exemplary embodiments which illustrate what is
currently considered to be the best mode for carrying out the
invention, it being understood, however, that the invention is not
limited to the specific methods and instruments disclosed. In the
drawings:
[0021] FIG. 1 is a perspective side view of a first embodiment of a
support in accordance with the principles of the present
invention.
[0022] FIG. 2 is a perspective side view of the support shown in
FIG. 1 in an unfilled and collapsed state.
[0023] FIG. 3 is a perspective side view of the support shown in
FIG. 1 in an unfilled and collapsed state coupled to a pump
system.
[0024] FIG. 4 is a perspective side view of the support shown in
FIG. 3 in a filled state coupled to a pump system.
[0025] FIG. 5 is a perspective side view of a bladder in an
unfilled and collapsed state in accordance with the principles of
the present invention.
[0026] FIG. 6 is a perspective side view of the bladder of FIG. 5
in a filled and expanded state.
[0027] FIG. 7 is a cross-sectional side view of a nozzle port in
accordance with the principles of the present invention.
[0028] FIG. 8 is a cross-sectional side view of the nozzle shown in
FIG. 7 coupled to a nozzle in accordance with the principles of the
present invention.
[0029] FIG. 9 is a perspective side view of an embodiment of a
support in an expanded and non-collapsed state installed in a mine
entry in accordance with the principles of the present
invention.
[0030] FIG. 10 is a perspective side view of the support
illustrated in FIG. 8 in an expanded and partially collapsed state
installed in the mine entry.
[0031] FIG. 11 is a perspective side view of the support
illustrated in FIG. 9 in an expanded and further partially
collapsed state installed in the mine entry.
[0032] FIG. 12 is a perspective side view of the support
illustrated in FIG. 9 in an expanded and still further partially
collapsed state installed in the mine entry.
[0033] FIG. 13 is a perspective side view of the support
illustrated in FIG. 9 in an expanded and substantially fully
collapsed state installed in the mine entry.
[0034] FIG. 14 is a perspective side view of a second embodiment of
a support in accordance with the principles of the present
invention.
[0035] FIG. 15 is a cross-sectional side view of a third embodiment
of a support in accordance with the principles of the present
invention in a collapsed state.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0036] FIG. 1 illustrates a first embodiment of a mine roof support
in expanded form, generally indicated at 10 in accordance with the
principles of the present invention. The support 10 may be utilized
in various underground support situations including without
limitation underground mine roof support, various tunnel
applications or the like. The support 10 is comprised of a lower
support section 12 that is comprised of an outer shell 14 in the
form of a tube that is partially prefilled with a first
compressible filler material 16, such as an aerated concrete
aerated grout, foam or other suitable material known in the art and
an upper support section 18 that is coupled to the lower support
section 12 in a telescopic manner. The outer shell 14 may be
comprised of a sheet of metal, such as steel, that is rolled into a
cylinder and welded along a seam 15 that extends the longitudinal
length of the outer shell 14. The upper support section 18 is
comprised of an outer shell 20 that is substantially prefilled with
a second compressible filler material 22. The second filler
material may be of the same composition as the first compressible
filler material. The upper support section 18 is also comprised of
a sheet of a metal, such as steel, that is rolled into a cylinder
and welded along a seam 19 that extends the longitudinal length of
the outer shell 20.
[0037] The lower support section 12 also include a nozzle port 30
that is coupled to the lower support section 12 and in fluid
communication with the inside of the lower support section 12
through a hole formed in the outer sell 14. The nozzle port 30 is
configured to be coupled with a filling nozzle (as further
described herein) for filling a bladder 32 positioned between the
lower and upper filler materials 16 and 22, respectively. Once the
support 10 is positioned in a desired location within a mine entry
to support the roof of the mine and control convergence between the
floor and the roof of the mine entry, the upper section 18 can be
expanded relative to the lower section 12 in a telescopic manner by
inflating the bladder 32 with filler material pumped through the
nozzle port 30 until the top 24 of the upper section 18 abuts
against the roof of the mine entry.
[0038] The upper support section 18 is thus lifted to be in contact
with the roof of the mine entry as the space between the filler
materials 16 and 22 is filled with a filler material 34 such as
aerated concrete, aerated grout, foam or other suitable materials
known in the art. The filler materials 16, 22 and 34 provide the
principle load bearing capabilities of the support 10 while the
outer shells 14 and 20 provide upper longitudinal or load bearing
support while also maintaining adequate hoop strength of the mine
support 10 to prevent any significant lateral or radial expansion
of the filler materials 16, 22 and 34 as the support 10 is
compressed. Thus, the tubes 12 and 18 and filler materials 16, 22
and 34 work in tandem as the support 10 yields under load to allow
vertical or longitudinal compression of the support 10 while
maintaining support of the load. That is, the support 10 will
longitudinally yield for a given displacement or yield dimension
without catastrophic failure under load.
[0039] Aerated or "foamed" concrete or cement is particularly
beneficial because it can be cast in the outer shells 14 and 20 as
necessary and the strength or compressibility characteristics of
the foamed concrete can be controlled and relatively uniform and
predictable to produce a desired compressive strength to weight
ratio. The use of foamed concrete, in which small air cells are
formed within the concrete, in the bottom portion 36 of the lower
support section 12 and in the entire upper section 18 is well
proven and has been reliably used in roof supports for years. In
addition, foamed concrete once cured forms a solidified, unitary
structure that will remain contained within the outer shell 14
during handling and will not settle within the outer shell 14, as
may be the case when using loose materials, such as saw dust or
pumas. In a support application, settling of the filler materials
16 and 22 is a major concern since any settling will result in
larger displacement or yielding of the support before the support
begins to carry a load.
[0040] As previously mentioned, while cylindrical supports in the
form of the support sections 12 and 18 have been successfully used
in underground mines for a number of years, the space between the
top of the support and the roof must be occupied with a material
that will transfer the forces applied by the roof to the support
without any significant lag between when the roof moves and the
support begins bearing a load. Most commonly, wood planks have been
stacked on top of supports and effectively wedged to the best
extent possible between the roof and the support. As movement
within the mine entry occurs, the wood planks are compressed until
they effectively begin bearing a load and can fully transfer that
load to the support. Moreover, as the space between the support and
the roof increases, more wood is required between the roof and the
support. As more wood is stacked upon the support, the roof of the
mine can move a greater distance before the support will begin
fully supporting the load. Ideally, a load supported by a support
should be fully supported within approximately the first inch (2.5
centimeters) of movement.
[0041] In order to maximize the load bearing capability of the
support 10 of the present invention while also making the support
10 adjustable in length, the upper support section 18 is
telescopically coupled to the lower support section 12. In use (as
will be described in more detail), the upper support section 18 is
lifted relative to the lower support section 12 until the top 24 of
the upper support section 18 abuts against the roof. The overall
length of the upper support section 18 is such that when raised
relative to the lower support section 12, the bottom portion of the
upper support section 18 is still engaged with the lower support
section 12. The upper support section 18 is raised by pumping
filler material into the support 10 through the nozzle port 30.
[0042] The filling port 30 may comprise a one-way valve that allows
the filler material to be pumped into the outer shell 14 while
preventing the filler material 22 from exiting through the port 30
when the nozzle being used to fill the outer shell 20 is removed.
By using a nonflammable filler material, such as aerated concrete,
lightweight grout, self-hardening foam or other materials known in
the art, the support 10 provides a significant improvement over
prior art supports that utilize wood products alone or in
combination with other nonflammable support structures. In the case
of a fire, any supports that are made in whole or in part from wood
could fail as the fire burns any flammable materials from the
support. With the present invention, the supports are more likely
to remain in place and continue to support the roof even during a
fire. Furthermore, use of filler materials that are not susceptible
to shrinkage continue to support the roof even after long periods
of time.
[0043] Until the filler material pumped through the nozzle port 30
has cured, attachment members may be provided that are formed from,
for example, elongate steel straps that are bent and wrapped around
the bottom edge of the outer shell 20 with the distal ends upwardly
extending within the outer shell 20. The proximal ends extend to
the top end 24 of the outer shell 20 and are outwardly bent to form
attachment tab portions. The attachment tab portions are provided
with a hole so that the proximal ends can be bolted to the roof at
least until the filler material that has been pumped through the
nozzle port 30 has adequately cured so as to hold the upper section
18 in position.
[0044] Referring now to FIG. 2, there is illustrated the support 10
in a pre-expanded position where the outer shell 20 of the upper
support section 18 is positioned or disposed at least partially
within the lower support section 12 and the bladder 32 is collapsed
and not yet filled with a filler material. The outer shell 20 of
the upper support section 18 may be fully, substantially (i.e.,
with a small portion or few inches of the outer shell 20 exposed)
or partially disposed (i.e., with several inches of the outer shell
20 exposed) within the lower support section 12. The outer shell 20
has an outer diameter that is slightly smaller (e.g., 0.125-0.5
inch smaller or less) than the inner diameter of the outer shell 14
of the lower support section 12, thus forming a small annular gap
28 between the outer shell 14 and the outer shell 20. This allows
the support 10 to be transported and moved into position while
protecting the outer shell 20 of the upper support section 18 from
being damaged and to provide the support 10 in a more compact
state. The bladder 32 is in a compressed state and "sandwiched"
between the upper and lower sections 18 and 12.
[0045] Once placed on a support surface, such as the floor of a
mine entry where the support 10 is to be installed, the upper
support section 18 can be lifted in a telescoping manner relative
to the lower support section 12 until the top edge 24 of the upper
support section 18 abuts against the roof (not shown). Lifting of
the upper support section 18 relative to the lower support section
12 may be facilitated by lubricating the sides of the outer shell
20 during the manufacturing process. Such lubricants may include
non-flammable lubricants such as those made from synthetic
materials, such as polyolefin or polytetrafluoroethylene, or other
lubricants approved for use in the industry. The support 10 is
configured to rest directly on the support surface 32 without the
need for wood cribbing or the like in order to provide a
non-flammable support 10 over its entire length when installed in a
mine entry or other underground tunnel where support is required.
While a substantial portion of the upper support section 18 is
shown protruding from the lower support section 12, it is
contemplated that the upper support section 18 in it pre-expanded
state could be entirely contained in the upper portion 38 of the
lower support section 12. Also, because the upper support section
18 is prefilled with a compressible filler and contained within the
upper portion 38 of the lower support section 12, the upper support
section 12 provides internal structural support to the upper
portion 38 of the lower support section 12. As such, during
transport or installation, it is less likely that damage will occur
to the hollow upper portion 38 that could otherwise prevent the
upper support section 18 from being extendable relative to the
lower support section 12. That is, an inadvertent impact to the
outer shell 14 of the lower support section 12 that could dent the
outer shell 14 is resisted, if not prevented, by the added support
from the outer shell 20 and compressible filler 22 contained in the
upper support section 18.
[0046] As further illustrated in FIG. 3, once the support 10 is
moved into position between the roof 40 and the floor 42, a pump
system, generally indicated at 44, is coupled to the support 10 via
the nozzle port 30. The pump system 44 includes a nozzle 46
configured for coupled to the nozzle port 30, a hose 48 coupled
between the nozzle 46 and a pump 50. The pump 50 is in fluid
communication with a filler material supply vat or tank (not shown)
that contains the filler material in liquid form so as to be pumped
with the pump system 44 into the bladder 32 under pressure. This
operation is performed in situ with the support 10 in the desired
position to provide support between the roof 40 and floor 42.
[0047] As shown in FIG. 4, once the pump system 44 is engaged and
filler material is pumped into the bladder 32 under pressure, the
filler material 52 causes the bladder 32 to expand and forces the
upper support section 18 away from the lower support section 12 in
a telescopic manner. The upper support section 18 is lifted until
the top 24 of the upper support section 18 abuts against the roof
24. By utilizing a relative quick setting filler material 52, the
support 10 can begin bearing a load in a relatively short period of
time (e.g., 1 to 2 hours). Obviously, the filler material 52 is
made not to cure too rapidly so that larger batches of the filler
material can be prepared in advance for installing several supports
10 at a time before the batch of filler material starts to cure.
For example, a batch of filler material 52 that cures in two hours
allows those installing supports to premix enough filler material
52 to adequately install a significant number of supports during
that time (e.g., ten supports) before a new batch of filler
material is needed. Also, this provides enough curing time to allow
the pump system 44 to be properly cleaned between batches so that
the filler material does not cure inside the pump system 44.
[0048] FIGS. 5 and 6 illustrate a bladder 60 in accordance with the
principles of the present invention. In FIG. 5, the bladder 60 is
shown in a pre-expanded state and in FIG. 6, the bladder is
illustrated in an expanded state. The bladder 60 is comprised of a
flexible bag portion 62 and a nozzle port 64 coupled to the bag
portion 62 at a lower end thereof. The bag portion 62 may have a
generally cylindrical shape with a diameter approximately equal to
the inside diameter of the lower support section. The bag portion
62 may be of a baffle-type design as illustrated or a simple
cylindrical shape. The bag 62 is formed from a flexible yet strong
material having a thickness capable of maintaining pressure exerted
on the bag 62 when filled so as to prevent rupture of the bag 62
during the filling process and until the filler material pumped
into the bag 62 cures. As shown in FIG. 6, when filled, the bag 62
has a generally cylindrical shape so as to fill the space between
the upper and lower support sections as previously described. It is
also contemplated that the bladder 60 may have a maximum filling
capacity to limit the extension of the upper support section
relative to the lower support section. Typically, the distance
between the roof and the floor of a mine entry are known and the
support is manufactured in sizes to match the distance. As such,
the required extension of the upper support section relative to the
lower support section may only require about six to eighteen inches
of extension of the upper support section. As such, the bladder 60
could have a maximum expansion of approximately twenty-four inches
so that there is a limit to the expansion between the upper and
lower support sections. Once the bag 62 of the bladder 60 is fully
filled, a pressure sensor on the pump system will cause the pump to
disengage, alerting the user that a maximum bladder expansion has
been reached. This feature is also useful to alert the user that
the support is sufficiently expanded between the floor and the
roof. That is, when the pump senses sufficient pressure, as when
the upper support section has been expanded until it firmly abuts
against the roof, the pump will shut off to alert the user that the
support has been properly installed.
[0049] FIG. 7 illustrates a nozzle port 80 is attached to the outer
shell 14 of the lower support section 12 in a hole 82 formed
therein. The nozzle port 80 is comprised of an externally threaded
tube 84 to which first and second nuts 86 and 88 attach the tube 84
to the outer shell 14 and nuts 88 and 90 attach the nozzle port to
the bag 62 of the bladder 60. A one way valve 92 comprised of a
flexible plate 94 is attached in a cantilevered manner to the end
of the tube 84 that allows filler material to flow into the bag 62
but that prevents the filler material from flowing back out through
the tube 84. As sown in FIG. 8, when pressurized filling material
flows through the tube as indicated by the arrow, the filling
material forces the flexible plate to bend away from the tube
allowing the filling material to flow into the bag 62 only in one
direction as indicated by the arrow. When the nozzle 96 is removed
from the tube 84, the valve 92 closes to prevent the filler
material from escaping through the tube 84.
[0050] Referring now to FIG. 9, once the support 10 is positioned
and the outer shell 20 of the upper support section 18 is raised
using the filling nozzle 96 shown in FIGS. 7 and 8 is used to
engage with the orifice or port 80 so that the upper support
section 18 can be lifted with a compressible filler material, such
as a lightweight grout or cement, a foam or other materials known
in the art. The port 80 is positioned proximate the top surface 100
of the precast filler material 102 in the bottom portion of the
lower support section 12. As such, the bladder 60 can rest upon the
top surface of the filler material 102 while being filled. The
bladder 60 is filled until the filler material forces the upper
support section 18 into engagement with the roof 40. Once it is
evident that the upper support section 18 is sufficiently engaged
with the roof, the nozzle 96 can be removed. By using a filler
material that is in an at least partially liquefied form that will
relatively quickly harden once pumped into the upper support
section 18, once cured, settling of the filler material can be
minimized if not eliminated. It is also contemplated that once the
bladder is filled with a filler material, the orifice or port 80
can simply be plugged with a tapered plug that will prevent any
filler material from escaping from the port 80. Those of skill in
the art will appreciate that other mechanisms and/or structures may
be used to effectively close the port once the filling process is
completed to prevent the filler material from escaping through the
port and such other mechanisms and/or structures are incorporated
herein.
[0051] In order to prevent over extension of the upper support
section 18 relative to the lower support section 12, the upper
support section 18 may include a brightly colored indicator ring
104 that may be pained around the upper support section a
predetermined distance from the bottom edge 105 of the upper
support section 18. That is, if the upper support section 18 were
extended to a point where the upper section 18 could easily
disengage from the lower support section 12, the support 10 may not
provide support in a predicted manner by allowing the upper support
section from fully or partially disengaging from the lower support
section. The indicator ring 104 provides a visual indicator when
the upper support section has reached its maximum safe extension
position, even if the upper support section 18 has not yet engaged
the roof. In such a situation, the support 10 should be removed and
a longer support utilized or the space between the top of the
support 10 and the roof should be filled with wood timbers or other
approved materials.
[0052] FIG. 9 illustrates a support 10 according to the present
invention in a fully extended position with the bottom end 107 of
the support 10 in contact with the floor 42 and the upper end 24 of
the support 10 engaging the roof 40. Once the center section 109 of
the support that was filled in situ with filler material 111
through the nozzle port 80 as previously described has adequately
cured, the support 10 can begin bearing a load as the roof 40 and
floor 42 converge as is typically the case in underground mine
entries.
[0053] As shown in FIG. 10, as the roof 40 and floor 42 converge,
either by the roof moving toward the floor or the floor heaving
toward the roof, the support 10 will begin to collapse upon itself
in a controlled and predictable manner. That is, the upper and
lower ends 24 and 107 of the support 10 will begin to yield as the
filler material is compressed and the outer shells 14 and 20 fold
upon themselves in an accordion-like manner. More specifically, the
upper and lower sections 18 and 12 will yield along their length
typically from the ends 24 and 107 toward the center.
[0054] As previously discussed, the lower and upper support
sections 12 and 18 are at least partially prefilled with a first
filler material 22, such as a lightweight concrete, having a
predetermined load bearing capability while yielding. The center
section 109 of the support 10 is filled in situ with a second
filler material 115 having a load bearing capability that is at
least as great as the load bearing capability of the first filler
material 22. By providing the center section 109 of the support 10
with a second filler material 115 that has a greater load bearing
capacity than the first filler material 22 additional benefits and
load bearing characteristics are realized. As shown in FIGS. 10 and
11, as the support 10 first begins to yield, the support 10 is more
likely to begin yielding from the top and bottom ends 24 and 107 of
the support 10. The outer shells 14 and 20 will begin folding upon
themselves in an accordion-style manner due to plastic deformation
of the outer shells 14 and 20 as illustrated and the filler
material 22 begins crushing to form sections within the
accordion-style folds 119 of higher density as illustrated. Because
the center support section 109 that is filled in situ is filled
with a filler material 111 of higher density it will likely not
begin yielding until the precast portions of the upper and lower
sections 18 and 12 have undergone significant yielding. It is also
less likely that the central section of the support 10 where the
outer shells 14 and 20 overlap will yield initially since an
effective double wall is formed that will provide additional load
bearing strength along this section.
[0055] As illustrated in FIG. 12, the upper and lower sections 12
and 18 will continue to yield along their lengths while the outer
shells 14 and 20 maintain sufficient hoop strength to contain the
compressed filler 22 without bulging or lateral buckling. Once the
lower and upper sections 12 and 18 have substantially been
compressed as shown in FIG. 12 and a first yield limit has been
reached, the center section 109 will then begin yielding until a
second yield limit is reached as shown in FIG. 13. Again the outer
shells 14 and 20 will begin folding upon themselves in an
accordion-style manner due to plastic deformation of the outer
shells 14 and 20 as illustrated and the second filler material 111
will begin crushing to form another section of higher density. Once
the center section 109 begins to yield, as can be visibly observed,
mine operators are alerted that complete failure of the support 10
is approaching and that all personnel and mining equipment should
be removed from the area. The support 10 will continue to yield to
the second yield limit until the filler material contained in the
bladder is substantially fully compressed causing either the
support 10 to fail or the support 10 to effective punch through the
roof or the floor in which case the roof will collapse around the
support 10. At this point, however, the support has effectively
performed as expected.
[0056] As shown in FIG. 14, a second embodiment of a support,
generally indicated at 200, is illustrated. The support 200 has a
configuration similar to the configuration of the support 10
illustrated in FIG. 1, but rather than having a bladder system
interposed between the upper and lower support sections 202 and
204, an air space 206 is formed between the precast filler
materials 208 and 210 of the upper and lower support sections 202
and 204, respectively. A small block 220 of filler material may be
interposed between the precast filler materials 208 and 210 of the
upper and lower support sections 202 and 204, respectively, to form
the air space gap 206 therein between. As another filler material
225 in liquid form is pumped through the port 226 as previously
described, the filler material 225 will first completely fill the
gap 206 and then subsequently cause the upper support section 202
to rise relative to the lower support section 204 until adequately
extended between the floor and roof of a mine entry or other
underground tunnel.
[0057] While the foregoing illustrated embodiments show the outer
shell of the upper support section being disposed within the lower
support section, it is equally contemplated, as shown in FIG. 15
that a support 300 according to the present invention may comprise
an outer shell 302 of an upper support section 301 that is disposed
over the outer shell 304 of the lower support section 303. In this
case, the upper support section is precast with a filler material,
inverted and then placed over the top of the lower support section.
This configuration has the advantage that the upper support section
301 will have less weight that the upper section previously
described herein as only a portion of the upper section 301 is
filled with compressible filler material. In addition, if the
support 300 is stored outside prior to use, the gap between the
outer shell 302 of the upper support section 301 and the outer
shell 304 of the lower support section 303 will not accumulate
water as may be the case when the support is inverted. Effectively,
the support 300 is the same as the support 10 but simply inverted.
Thus, while reference has been made to upper and lower support
sections, it is noted that the orientation of the resulting support
is not critical and can properly function in either
orientation.
[0058] The supports of the present invention are designed to carry
an average load of at least approximately between about 100,000 lbs
and about 350,000 lbs depending on the size of the support. The
upper and lower support section includes a precast filler material
formed from foamed concrete having density of approximately 40 to
50 lb/ft.sup.3. The central support section, which may include the
bladder of the present invention, includes a filler material formed
from lightweight cement, grout our other materials known in the art
having density of approximately 50 to 60 lb/ft.sup.3. Each support
section is comprised of an outer tube that is formed by sheet
rolling techniques to form a tube from a flat sheet of steel. Such
steel may have a thickness of approximately 0.075 to 0.09 inches of
1008 steel. The tube is then welded at a seam along the entire
length of the tube. Likewise, each section may be formed by an
extrusion process or other methods known in the art. The support
generally will longitudinally yield when subjected to a
longitudinal force or load. The support will yield in one or more
yield zones by allowing the outer tubes or shells to fold upon
themselves in a plurality of folds as the filler materials
compress. Thus, the support longitudinally yields without releasing
the load.
[0059] Various fillers and combinations of fillers may be employed
in the supports. For example, the filler material may comprise
aerated concrete mixtures of one or more densities. Likewise, the
upper and lower support sections may include compressible fillers,
such as pumas or hollow glass spheres that may be encapsulated
within other binding agents or other materials, such as cement,
grout or foam to hold the filler material together and to the
inside of the outer shells.
[0060] By way of example of the loads that can be supported by a
support in accordance with the present invention, several tests
have illustrated the impressive load supporting capabilities of the
mine support in accordance with the present invention. Supports
comprised such filler materials such as with a lightweight concrete
have been subjected to vertical force tests in the NIOSH mine
simulator to compress the support sand record the load bearing
capability of each support. Typically, after less than 2 inches of
compression, the supports are able to support a load of over 200
kips and continue to maintain that load bearing capacity over its
entire range of yielding up to 22 inches of vertical displacement.
As illustrated by such tests, such supports are able to support a
significant load within 2 inches of compression. Prior art supports
that use wood planks to fill the gap between the top of the support
and the roof will typically allow more movement before the same
load bearing capacity is reached.
[0061] Accordingly, each test support will behave in a predictable
manner and continue to yield while supporting at least a particular
load. Moreover, such supports will only yield a short distance
before a significant load bearing capacity is realized. This allows
mine engineers to place the supports at various locations and
distances throughout a mine entry where the loads to be supported
are relatively predictable, with the assurance that very little
movement of the roof will occur before the support is fully loaded.
Moreover, because each support gradually increases in load bearing
capacity while continuing to yield, there is no unexpected drop in
load bearing capacity of the supports that could result in a
localized failure. Such tests often reveal data with a sine-type
wave pattern where the load bearing capacity varies as the support
is compressed. This is a result of the folding of the outer shell
of the support. That is, when the outer shell of the support is
experiencing plastic deformation when the shell is forming a fold,
the load bearing capacity will decrease slightly until the fold is
complete at which point the load bearing capacity will slightly
increase. This repeats with each successive fold of the outer shell
of the support until the support has reached its maximum
compression (typically about half its original height). However,
while the occurrence of each fold changes the load bearing capacity
of the support, the upper and lower load bearing capacity of the
support during and after a fold is within a relatively constant
range, again producing a predictable load bearing capacity of the
support even as the support yields.
[0062] The supports according to the present invention can also
maintain a support load of even during several inches of vertical
displacement of the upper end of the support relative to the bottom
end. This allows the support to continue to bear a load even if the
floor and roof of the mine entry laterally shift relative to one
another. Thus, even in a condition where horizontal shifting of the
mine roof or floor occurs, the mine support according to the
present invention continues to support significant loads.
[0063] While the present invention has been described with
reference to certain illustrative embodiments to illustrate what is
believed to be the best mode of the invention, it is contemplated
that upon review of the present invention, those of skill in the
art will appreciate that various modifications and combinations may
be made to the present embodiments without departing from the
spirit and scope of the invention as recited in the claims. It
should be noted that reference to the terms "shell" or "tube" are
intended to cover shells or tubes of all cross-sectional
configurations including, without limitation, round, square, or
other geometric shapes. In addition, reference herein to a use of
the support in a mine entry or underground mine according to the
present invention is not intended in any way to limit the usage of
the support of the present invention. Indeed, the support of the
present invention may have particular utility in various tunnel
systems or other applications where a yieldable support post is
desired. The claims provided herein are intended to cover such
modifications and combinations and all equivalents thereof.
Reference herein to specific details of the illustrated embodiments
is by way of example and not by way of limitation.
* * * * *