Note: Descriptions are shown in the official language in which they were submitted.
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RETAINED EARTH STRUCTURE
ND METHOD OF MAKING SAME
Inventor: Edgar Davis
Background of the Invention
Field of the Invention
The present invention relates to retained
earth structures in general and in particular to a
retained earth structure comprising a plurality of
interlocked facing wall modules connected to elongated
wire mesh reinforcing panels by means of a novel
clevis and bolt assembly.
Description of the Prior Art
A retained earth structure comprises a wall
for retaining earth and/or other backfill material
placed behind the wall. Elongated members extend from
various locations on the back surface of the wall into
the backfill material. The elongated members are
captured by the backfill material and prevent the wall
from buckling outwardly.
The wall may comprise a uniform, unbroken
expanse of concrete or the like which is poured on
site. Alternatively, the wall may comprise a
plurality of interlocking precast modules or wall
members which are assembled on site.
The use of precast modules tends to be less
expensive than on-site poured concrete because the
installation and removal of the forms required when
concrete is poured on site and the transportation to
and pouring of large amounts of concrete on site are
generally not required. Moreover, the amount of labor
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required for assembling the modules is generally less
than that re~uired for poured concrete walls.
Initially, the elongated members used for
preventing the outward buckling of the wall in
retained earth structures comprised elongated straps
of material having a generally rectangular
cross-section. Outward movement of the wall and the
straps from the backfill material was prevented by
means of friction between the backfill material and
the straps.
Several methods and apparatus have been
provided in the past for attaching the strap members
to individual wall modules. For example, in U.S.
Patent No. 3,686,873, there is disclosed a number of
structures comprising a plurality of individual strap
members which are attached to a plurality of wall
modules. In one such structure one or more U-shaped
members having widely spaced legs are anchored in each
one of the wall modules. The ends of each leg of each
U-shaped member extends beyond the back surface of the
module. A bolt and nut assembly is used to attach one
end of each strap member to the end of each of the
legs of each of the U-shaped members.
In another one of the structures disclosed
in the patent, one or more ring-shaped members are
anchored in each of the modules and one end of each
strap member is passed through the ring-shaped member,
folded back on itself and bolted or riveted to an
underlying section thereof.
In still another one of the structures
disclosed in the patent, the end of each strap member
is attached to the modules by passing a rod or pin
used for interlocking the modules together through a
hole provided therefor in the end of the strap member.
In U.S. Patent No. 4,449,857, there is
disclosed a structure comprising a plurality of wire
mesh panels which are attached to a plurality of wall
modules by means of threaded female fittings anchored
in the wall modules and threaded male fittings movably
mounted to the end of each elongated wire in the wire
mesh panel.
In each panel there is provided a plurality
of four to six elongated parallel 1/2" to 3/8" wires
which are spaced six inches apart and interconnected
by crossbars which are welded perpendicularly to the
wires on 24-inch centers.
The advantage that the wire mesh panels have
over the previously described straps is that, in
addition to friction forces, outward movement of the
panels and the wall modules attached thereto is
further restrained by the crossbars which engage the
backfill material bearing downwardly thereon.
Disadvantages of the prior known wire mesh
panel structures are that the threaded female and male
fittings used for attaching the wire mesh panels to
the wall modules are relatively expensive to make; the
threading of each male fitting into each female
fitting during installation is relatively time
consuming; and the strength of each attachment
corresponds to the relatively limited strength of an
enlarged protuberance located at the end of each wire
in the panel for retaining the male part of the
fitting.
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Summary of the Invention
In view oi the foregoing, principal objects
of the present invention are a method and apparatus
for building a retained earth structure comprisins a
plurality of interlocking facing wall modules
connected to elongated wire mesh reinforcing panels by
means of a novel clevis and bolt assembly.
In accordance with the above objects, there
is provided a clevis formed from a section of
reinforcing bar. The section of reinforcing bar is
bent to form a U-shaped member. The ends of the legs
of the U-shaped member are folded back on themselves
to form a loop or hole. Another straight section of
reinforcing bar i5 then welded to the interior of the
U-shaped portion of the member and extends above and
below the plane of the legs of the member in a
direction generally perpendicular thereto.
Each of the wall modules is precast. In the
course of precasting each of the wall modules, a
plurality of 4 to 6 clevises are anchored in a line in
the module. Depending on the size of the module, a
plurality of parallel rows of clevises may be anchored
in a module.
In addition to the clevises, there is
provided a plurality of elongated generally
rectangular wire mesh panels. Each of the panels
comprises a plurality of elongated parallel spaced
wires. Spaced crossbars are welded to the wires in a
direction generally perpendicular thereto. One end of
each of the wires is folded back on itself for forming
a loop or hole.
In one embodiment of the present invention,
to connect each of the wires in a panel to a clevis,
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there is provlded a bolt and nut assembly. The bolt
has a threaded shaft of sufficient length to pass
through both legs of the clevis and the wire loop
located therebetween and to have the nut threaded
thereon. Extending from the head of the bolt there is
provided a tear-shaped shoulder. The tear-shaped
shoulder is provided to be inserted in the hole formed
in one of the legs of the clevis so as to prevent
rotation of the bolt when the nut is threaded thereon.
In another embodiment of the present
invention, an elongated pin is provided for attaching
the ends of the wires in each wire mesh panel to a
corresponding number of clevises. The ends of the pin
are bent to prevent the wires from becoming detached
from the clevises.
In use, a course of wall modules, with the
ends of the legs of each of the clevises projecting
from the rear surface thereof, are assembled on a
level foundation. Soil or backfill material is then
placed behind the wall up to the level of the first
row of clevises. A reinforcing pane~ is then spread
across the backfill rearwardly of the wall. Each of
the wires in each panel is then attached to a
corresponding clevis by means of the bolt and nut
assembly or the elongated pin. ~fter the attachment
of the panels of the first course is completed,
additional backfill material is placed over the panels
in the first course up to a level just below the next
highest row of clevises. The above-described
attachment of panels to the next highest row of
clevises is repeated, followed by the placing of
additional backfill material on the next highest row
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of panels. This procedure is repeated until the wall
achieves its desired height.
The advantage of the apparatus and method Gf
the present invention is that conventional materials
are used for forming the clevis and panel members and
the means for attaching the panels to the clevises is
relatively inexpensive, quick and eas~.
Brief Description of the Drawing
Other objects, features and advantages of
the present invention will become apparent upon a
consideration of the following detailed description
and the accompany drawings, in which:
Fig. 1 is an elevation view of a number of
modular facing panels arranged in a retaining wall
according to the present invention;
Fig. 2 is a schematic cross-sectional view
of the retaining wall of Fig. 1, illustrating
connected mesh reinforcement panels embedded in soil;
Fig. 2A is a side elevation view of the end of one
of the wires in the mesh of Fig. 2;
Fig. 3 is a rear elevation view of a modular
facing panel illustrating embedded clevis members in
accordance with the present invention;
Fig. 4 is an enlarged side cross-sectional
view taken in the direction of lines 4-4 of Fig. 3 of
a portion of the modular facing panel, clevis and a
portion of a reinforcement panel according to the
present invention;
Fig. 5 is a cross-sectional view of a
portion of the modular facing panel and a clevis taken
in the direction of lines 5-5 of Fig. 3;
Fig. 6 is a side elevation view of a clevis
according to the present invention;
Fig. 7 is a top plan view of Fig. 6;
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Fig. 8 ls an end elevation view of Fig. 6;
Fig. 9 is a side elevation view of a bolt
according to the present invention;
Fig. 10 is an end elevation view of Fig. 9;
Fig. 11 is an end elevation view of a nut
according to the present invention;
Fig. 12 is a side elevation view of Fig. 11;
Fig. 13 is a top plan exploded view of the
apparatus of Figs. 4 and 5;
Fig. 14 is a top plan exploded view of
another embodiment of the present invention; and
Fig. 15 is a top plan view of the assembled
parts of Fig. 13.
Detailed Description of the Invention
Referring to Figs. 1 and 2, a retained earth
retaining wall system is illustrated in accordance
with the present invention. It includes an upright,
typically vertical, retaining wall, generally
designated by the number 10, formed of interlinked
modular facing full panels 12 and half facing panels
14 to be described more fully below. Extending from
the backside of panels 12 and 14 in a generally
horizontal direction are wire mesh soil reinforcement
panels 16, embedded into the soil, generally
designated by the number 18. A mesh reinforcement
panel includes a plurality, generally four to six, of
generally parallel spaced metal wires 20
interconnected by parallel spaced crossbars 22,
preferably by welding at crossover points. Crossbars
22 are generally perpendicular to wires 20.
Referring to Fig. 2A, one end of each of the
wires 20 is terminated with a tear-shaped hole 21.
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The hole 21 is formed by bending a section 23 of thc
end of each of the wires 20 back on itself.
Typically, a machine is provided for bending the ends
of all of the wires in a panel simultaneously to form
the whole 21.
As set out below, the soil reinforcement
panels are attached to the soil retaining wall facing
panels in spaced horizontal layers from the bottom to
the top, with soil being layered above the lowermost
one up to a level at which the next unit in order is
attached to the retaining wall. In this manner, the
mesh reinforcement panels are embedded into the soil.
The nature of this system is such that soil
reinforcement panels 16 accept soil pressure against
crossbars 22 in bearing (i.e., soil against bar).
This bearing pressure is transferred to the lateral
parallel wires 20. This system is an improvement over
the use of strips in that strips require the
development of tensile strength through frictional
contact with the soil which, in turn, requires that
strict limits be maintained on the embankment soil and
its placement in the soil mass.
Any number of different spacing of wires 20
and crossbars 22 may be employed in accordance with
known practice. One suitable type of unit includes
3/8 in. diameter wires 20 and crossbars 22 forming a
grid typically with 6 inches between wires and 24
inches between crossbars. The welds between the wires
and crossbars should be sufficient to develop the full
yield strength of the longitudinal wires and to
develop a shear strength equal to or greater than 50%
of the longitudinal wire yield strength.
B
Referrlng to Figs. 2 and 3, a suitable
modular facing panel 12 is illustrated. It is
hexagonal in shape and is suitably formed by casting
concrete into the desired shape. Each unit includes
holes 24 for receiving vertical linking pins 25 which
project through adjacent panels to interlock the
facing panels together into retaining wall 10. In
addition, tongues 26 are provided at the edges of the
panels for mating with corresponding grooves 27 in
adjacent panels for alignment and stability.
A suitable panel measures 5 feet between
facing end walls. However, larger panels may prove
more suitable for larger wall projects. To provide a
level wall, half-panels 14 are interlinked alternately
at the top and bottom of the wall as illustrated in
Fig. 1.
Referring to Fig. 3, such a half-panel is
suitably formed from a full panel cut in half along
the line X-X. Other panel configurations will be
necessary to interlock with full and half panels when
the upper edge of the wall is required to be sloped
instead of flat relative to a horizontal line.
Alternately, panel segments may be cased individually.
A main feature of the present invention is
the provision of a convenient mode of connecting
retaining wall facing panels 12, half-panels 14 and
other applicable panel configurations to soil
reinforcement panels 16.
Referring to Figs. 4-13, an assembly
generally designated by the number 30 is utilized to
provide such a connection. In assembly 30 there is
provided a clevis 31, a bolt 40 and a nut 41. Clevis
31 comprises a pair of leg members 32 and 33 which
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extend from a U-shaped section 34. In the interior of
the U-shaped section 34, there is provided a straight
rod-shaped member 35. The member 35 is rigidly
attached to the section 34, as by welding, and extends
in opposite directions and perpendicular to the plane
of the legs 32 and 33. On their free ends, each of
the legs 32 and 33 is provided with a tear-shaped hole
36. The hole 36 is formed by bending a section 37 of
each of the legs 32 and 33 back on itself and rigidly
attaching the end thereof 38 to the underlying leg, as
by welding. Typically, each of the clevises 31 is
formed from sections of reinforcing bar material
having the same structural and physical
characteristics of the material used for making the
reinforcing panels 16.
Referring to Figs. 9-12, in the bolt 40
there is provided an elongated shaft portion 42. At
one end of the shaft portion 42 there is provided a
head member 43. At the opposite end of the shaft
portion 42 there is provided a plurality of external
threads 44. Extending from the head 43 there is
provided a tear-shaped shoulder 45. The shape of the
shoulder 45 corresponds to the tear-shaped hole 36 in
each of the legs 32 and 33 of the clevis 31.
In the nut 41 there is provided a flange 47.
Extending from the flange 47 there is provided an
hexagonal member 48 which is adapted to be engaged by
a wrench for threading the nut 41 onto the bolt member
40, as will be further described below.
In a preferred embodiment, the clevises 31
are cast in place within the concrete facing panels 12
and 14, as illustrated in Figs. 3-5. Specifically,
the clevises 31 are mounted such that a predetermined
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length of each of the legs 32 and 33, including the
tear-shaped hole 36, extend beyond the back surface of
the modules 12 and 14 so that one of the nut and bolt
assemblies 40, 41 can be used to couple the ends of
each of the wires 20 to the corresponding clevis. In
practice, a plurality of clevises 31 are mounted in a
row side by side with a spacing corresponding to the
spacing between the wires 20 and each of the panels
16. For full-sized modules such as the module 12,
there are generally two rows of clevises provided in
each module, such as shown in Fig. 3. For half-size
modules such as module 14, generally one row of
clevises 31 is sufficient. Also, it may be noted that
in some applications, especially in the upper portions
of a wall, it may be sufficient for alternate modules
to be anchored to panels 16 if the interlocking
features of each of the module are sufficiently strong
enough to withstand the forces tending to buckle the
module outwardly.
One suitable procedure for forming the
overall soil retaining system of the present invention
is as follows. The soil is first leveled at the
desired depth. Then a leveling pad 44 (typically
formed of concrete 1 ft. wide x 0.5 ft. deep) is
placed on the soil. A bottom layer of upright,
alternating full and half-facing panels, illustrated
in Fig. 1, is then placed on the leveling pad. These
panels are supported and held vertically by temporary
braces on the front or finished side of the wall.
Pins 25 are placed in holes 24 interlocking adjacent
panels to provide additional support. The panels are
disposed in the manner illustrated in Figs. 3 and 4,
so that the clevis 31 extends toward the soil in
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spaced horizontal relationship. The soil is then
backfilled up to the lowermost row of clevises 31 of
the panels 12, 14. The holes 21 in the ends of the
wires of a first panel 16 are slid between the holes
36 in the ends of the legs 32 and 33 of each clevis 31
in a row. The wires of panels 16 are then attached to
the clevises 31 by means of a corresponding number of
bolts 40 and nuts 41.
Referring to Figs. 14 and 15, alternatively,
a single pin member 50 having a shaft 51 which is long
enough to pass through all of the holes 21 and 36 in a
row of clevises may be used for attaching each of the
panels 16 to their respective clevises, eliminating
the need for a separate nut and bolt for each clevis.
The opposite ends 52, 53 of the shaft 51 are bent to
prevent the wires 20 from becoming detached from the
clevises 30.
Preferably, there is a two to one
relationship between rows of clevis 31 and facing
panels 12 so that each full facing panel has two mesh
reinforcement panels attached to its back face.
However, if desired, a less or greater number of
reinforcing panels may also be employed.
In the nex~ step, soil is placed above the
first tier of soil reinforcing panels to a level at
which a second tier of reinforcing panels may be
conveniently laid to rest in the clevises 30.
In the next step, another series of panels
is interlinked with the base series of facing panels
by conventional means. In the illustrated embodiment,
pins are placed in holes 24 to provide additional
alignment capabilities. In addition, the grooves of
mating units interlink with each other. Other
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techniques may be employed for reinforcing the modular
units as is conventional in the retaining wall and
precast concrete fields. The above steps are repeated
with respect to connecting soil reinforcement panel 16
in a tiered horizontally spaced series as illustrated
in Fig. 2 until the desired height of the retaining
wall is achieved. In the top layer half-panels are
alternately positioned as illustrated in Fig 1. The
soil is conventionally compacted in horizontal layers
approximately 2/3 foot in height as the wall is
erected.
As set out above, a soil retaining system
with the foregoing welded wire soil reinforcement mesh
panels 16 resists soil stress through soil bearing on
the crossbars which then transfer this stress in shear
to the welded tension wires. The circular section of
the wires provides the optimum end-to-surface area
ratio for corrosion resistance. Overall, this is a
highly effective reinforced earth retaining wall
system with a particularly simplified method of
attachment of the reinforcement panels to the
retaining wall.
A number of modifications of the present
system may be made without departing from the scope of
the invention. For example, while the modular units
are illustrated in a hexagonal configuration, it
should be understood that other modular units may also
be employed, for example, of a star-shaped or
rectangular configuration, without departing from the
scope of the invention. Furthermore, the number,
spacing and material of the mesh reinforcement panels
may be modified depending upon the characteristics
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desired for the overal] system. This would result in
corresponding modification of the connecting units.
It is apparent from the foregoing that a
unique connecting system has been provided for the
interconnecting of modular soil retaining walls with
wire mesh reinforcement panels which have the unique
advantages of significantly reducing the labor
required in the field compared to conventional
techniques and which, thus, significantly reduces the
costs of the system
The foregoing description of the preferred
embodiment of the present invention has been presented
for purposes of illustration and description. It is
not intended to be exhaustive or to limit the
invention to the precise form disclosed. Obviously,
many modifications and variations will be apparent to
practitioners skilled in this art. The embodiment was
chosen and described in order to best explain the
principles of the invention and its practical
application, thereby enabling others skilled in the
art to understand the invention for various
embodiments and with various modifications as are
suited to the particular use contemplated. It is
intended that the scope of the invention be defined by
the claims appended hereto and their equivalents.
