Note: Descriptions are shown in the official language in which they were submitted.
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SEGMENTAL RETAINING WALL SYSTEM
FIELD OF THE INVENTION
The invention relates generally to earth retaining walls. More particularly,
the
invention relates to a segmental retaining wall= system comprising retaining
means for
attaching reiriforcement members to the retaining wall.
BACKGROUND OFTHE INVENTION
Segmental retaining walls commonly comprise courses of modular units
(blocks). The blocks are typically made of conerete. The blocks are typically
dry-
stacked (no mortar or grout is_ used), and often include one or more features
adapted to
properly locate adjacent blocks and/or courses with respect to one another,
and to
provide resistance to shear forces from course to course. The weight of the
blocks is
typically in the range of ten to one hundred fi8y pounds per unit. Segmental
retaining
walls commonly are used for architectural and site development applications.
Such
walls are subjected to high loads exerted by the soil behind the walls. These
loads are
affocted by, among other things, the character of the soil, the presence of
water,
temperature and shrinkage efffects. and seismic loads. To 6andle the loads,
segmental
rctaining wall systems often comprise one or more layers of soil reinforcement
material extending from between the course.s of blocks back into'the soil
behind the
blocks. The reinforcement material is typically in the form of a geogrid or a
geofalmc. Geogrids often are configured in a lattice azrangement and are
constructed
of polymer fibers or processed plastic sheet material (punched and stretched
such as
described, for example, in U.S. Patent No. 4,374,798). while reinforcement
fabrics are
constructed of woven, nonwoven, or knitted polymer fibers or plastics. These
reinforcement members typically extend rearwardly from the wall and into the
soil to
stabilize the soil against movement and thereby create a more stable soil mass
which
results in a more slructurally secure retaining wall. In othcr instances, the
reinforcement members comprise tie-back rods that are secured to the wall and
which
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similarly extend back into the soil.
Although several different forms of reinforcement members have been
developed, opportunities for improvement remain with respect to attachment of
the
reinforcement members to the facing blocks in the retaining wall systems. As a
general proposition, the more efficient the block/grid connection, the fewer
the layers
of grid that should be required in the wall system. The cost of reinforcing
grid can be
a significant portion of the cost of the wall system, so highly efficient
block/grid
connections are desirable.
Many segmental retaining wall systems rely primarily upon frictional forces to
hold the reinforcement material between adjacent courses of block. These
systems
may also include locating pins or integral locator/shear resistance features
that
enhance the block/grid connection to varying degrees. Examples of such systems
include those described in U.S. Patent Nos. 4,914,876, 5,709,062. and
5,827.015.
These systems cannot take advantage of the full tensile strength of the common
reinforcement materials, however, because the block/grid holding forces that
can be
generated in these systems is typically less than the tensile forces that the
reinforcing
materials themselves can withstand.
One of the many advantages of segmental retaining wall systems over other
types of retaining walls is their flexibility. They do not generally require
elaborate
foundations, and they can perform well in situations where there is
differential settling
of the earth, or frost heaving, for example, occurs. Even so, these types of
conditions
might result in differentials in the block/grid connections across the wall in
systems
that rely primarily on fricitional connection of blocks to grid.
In an effort to improve the grid/block connection efficiency, several current
retaining wall systems have been developed that mechanically connect the
reinforcement members to the blocks. In several such systems, rake shaped
connector
bars are positioned transversely in the center of the contact area between
adjacent
stacked blocks with the prongs of the connector bars extending through
elongated
apertures provided in the geogrid to retain it in place. Examples of this type
of svstem
are shown in U.S. Patent Nos. 5,607,262 (FIGS. 1-7), 5,417,523, and 5,540.525.
These systems are only effective if the geogrid used is of a construction such
that the
cross-members that engage the prongs of the connector will resist the tensile
forces
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exerted on the grid by the soil. There are only a few such grids currently
available
and, thus, the wall builder or contractor has to select geogrid products from
a limited
number of reinforcement member manufacturers when such an attachment system is
used. These systems also rely upon the prongs of the rake connectors being in
register
Aith the apertures in the grid material and in contact with the grid cross
members. If
the connector prongs do not line up with the grid apertures, installation
becomes a
problem. Variability in the grid manufacturing process means that the
apertures in this
type of grid frequently are not perfectly regular. A solution to this problem
has been
to use short connector rakes that only engage several grid apertures, rather
than long
connectors that engage all of the apertures in a row across the grid layer.
This
solution eases installation problems, but would appear to make the connection
mechanism less efficient, with the consequence that the full strength of the
grid
cannot be taken advantage of in the design of the wall system. These devices
are
subject to the same criticisms as the pure friction connector systems.
A third type of connector system uses a channel that, in cross-section, has a
relatively large inner portion and a very narrow opening out of that portion.
The grid
is provided with a bead or equivalent enlargement along its leading edge. The
grid is
then threaded into the channel from the side, so that the grid layer extends
out through
the narrow channel opening, but the bead is captured in the larger inner
portion. An
example of this type of connection is shown in FIGS. 9-10 of U.S. Patent No.
5.607,262. While this system overcomes differential settling concerns, it is
very
difficult to use in the field, and relies upon special grid configurations.
A modification of the third type of connector system described above is one in
which the channel into which the bead fits is formed by a combination of the
lower
and adjacent upper block, so that the enlarged/beaded end of the grid can
simply be
laid in the partial channel of the lower blocks, and will be captured when the
upper
blocks are laid. This system simplifies installation, but does not resolve the
aforementioned performance concerns. In a variation of this system, the end of
a
panel of geogrid material is wrapped around a bar, which is then placed in a
hollowed-out portion of the facing unit which is provided with an integral
stop to
resist pullout of the bar. Rather than being held in place by the next above
facing
unit, the wrapped bar is then weighted down with earth or gravel fill dumped
on top
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of it in the hollowed out portion of the facing unit. This system is shown in
U.S.
Patent No. 5,066,169. Not only is the facing unit of this system extremely
complex
and difficult to make, but the installation process is diffcult and requires
the use of
very narrow panels of grid material.
From the above, it can be appreciated that it would be desirable to have a
segmental retaining wall system comprising a facing block of a relatively
simple
shape to facilitate high speed mass production, and wherein the block can' be
mechanically connected to the reinforcement material in a fashion that is
highly
efficient, so that a higher percentage of the full design strength of the
reinforcement
can be taken advantage of, wherein the system can be used with a wide variety
of the
commonly available geogrids and fabrics, wherein the grid/block connection
mechanism is secure even in differential settling conditions, and wherein the
system is
easy to work with in the field during installation.
SUMMARY OF THE INVENTION
Briefly described, the present invention relates to a wall block for use in a
segmental retaining wall system. The wall block comprises an interior face for
forming an interior surface of a segmental retaining wall, an exterior face
for forming
an exterior surface of the segmental retaining wall, first and second sides
that extend
from the exterior face to the interior face, and a top surface and a bottom
surface.
Further provided in the wall block is a channel defined by a front wall. a
rear wall,
and an arcuate bottom surface. The channel extends across one of the faces and
surfaces and the rear wall of the channel preferably includes an inwardly
extending
shoulder.
In one preferred embodiment, the channel is formed transversely in the top
surface of the wall block and the front wall of the channel includes an
inwardly
extending shoulder. Preferably, the rear wall shoulder is defined by an
arcuate curve
and a planar portion while *the front wall shoulder is defined by first and
second
substantially planar surfaces.
In a further preferred embodiment, the block further comprises a flange that
is
sized and configured so as to mate with a channel of another of the blocks.
Typically,
this flange is formed transversely along the bottom surface of the wall block.
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The invention may also comprise a layer of reinforcement material (i. e.,
geogrid or fabric) laid across the top of the block, so that a portion of the
reinforcement material lays in the channel formed in the top of the block.
The invention may also comprise a retaining bar adapted to fit into the
channel
and to engage the layer of reinforcement material in such a manner as to
mechanically
connect the reinforcement material to the block.
The features and advantages of this invention will become apparent upon
reading
the following specification, when taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. I is a perspective view of an example retaining wall formed in accordance
with the present invention.
FIG. 2 is a perspective front view of a wall block used in the wall shown in
FIG.
FIG. 3 is a perspective rear view of the wall block shown in FIG. 2.
FIG. 4 is a detail view of a channel provided in a top surface of a wall
block.
FIG. 5 is a detail view of a flange provided on a bottom surface of a wal l
block.
FIG. 6 is an end view of a first embodiment of a reinforcement member
retaining
bar.
FIG. 7 is a partial side view of a wall block depicting insertion of the
retaining
bar shown in FIG. 6 over a reinforcement member within a channel of the wall
block.
FIG. 8 is a cross-sectional side view of an example retaining wall constructed
in
accordance with the present invention.
FIG. 9 is a detail view showing the retention of a reinforcement member
between
adjacent stacked wall blocks.
FIG. 10 is an end view of a second embodiment of a reinforcement member
retaining bar.
FIG.11 is a perspective front view of an alternative walI block.
FIG. 12 is a perspective rear view of the wall block shown in FIG. 11.
FIG. 13 is a detail view of a channel provided in a top surface of the wall
block
shown in FIGS. I 1 and 12.
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FIG. 14 is a detail view of a flange provided on a bottom surface of a wall
block
shown in FIGS. 11-13.
FIG. 15 is a side view of a third embodiment of a reinforcement member
retaining bar_
FIG. 16 is a partial side view of a wall block shown in FIGS. 11-14 depicting
insertion*of the retaining bar shown in FIG. 15 over a reinforcement member
within a
channel of the wall block.
FIG. 17 is a detail view showing the retention of a reinforcement member
between adjacent stacked wall blocks.
DETAILED DESCRIPTION
Referring now in more detail to the drawings, in which like numerals indicate
corresponding parts throughout the several views. FIG. 1 illustrates the
general concept
of a segmental retaining wall 10 constructed in accordance with the present
invention.
As depicted in this figure, the retaining wall 10 comprises a plurality of
wall blocks 12
that are stacked atop each other in ascending courses 14. When stacked in this
manner,
the wall blocks 12 together form an exterior or decorative surface 15 which
faces
outwardly away from the soil, and an interior surface 17 which faces inwardly
toward
the soil.
Generally speaking, the standard wall blocks.12 that comprise the majority of
any given wall are substantially identical in size and shape for ease of block
fabrication
and wall construction. Accordingly, each block 12 typically is configured so
as to mate
with vertically adjacent blocks 12 when the blocks 12 are stacked atop one
another to
form the retaining wall 10. Referring to FIGS. 2 and 3, each wall block 12
comprises an
exterior face 24, an opposed interior face 26, a top surface 28, a bottom
surface 30, and
two opposed sides 32. Because the exterior faces 24 of the blocks 12 form the
exterior
surface 15 of the retaining wall 10, the exterior faces 24 typically are
provided with an
ornamental texture or facing to create a visually pleasing facade. Also, the
exterior face
24 of each wall block 12 is preferably sloped inwardly from the bottom surface
30 to the
top surface 28 in an incline ratio of approximately 30 to 1. This inward slope
of each
block exterior surface 15 creates an aggregate inward slope effect over the
entire
retaining wall 10 which counteracts the outward leaning impression which can
be
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created by such waIIs when viewed by the observer. Contrary to the exterior
faces 24,
the interior faces 26 of the wall blocks 12 preferably are configured in an
upright or
vertical orientation and, therefore, form an upright, yet stepped (FIG. 8),
interior surface
17 of the retaining wall 10.
The top and bottom surfaces 28 and 30 of each block 12 are preferably, but not
necessarily, parallel to each other so that, when stacked on top of one
another, an upright
wall 10 is formed. As shown most clearly in FIGS. 2 and 3, a curved edge 33 is
preferebly formed at the junction of the top surface 28 and the interior
surface 26 tD
avoid abrasion of rqinforcement members that will be secured to the wall
formed by the
blocks 12. Similar to the top and bottom surfaces 28 and 30, the opposed sides
32 are
preferably, but not necessarily, parallel to each other. However, as known in
the art, the
opposed sides 32 can be inwardly or outwardly tapered from the exterior face
24 of the
block 12 to the interior face 26 of the block 12 to form curved walls of
nearly any shape.
Preferably, the wall blocks 12 fiuther include intezior openings 34 which
reduce the
amount of concrete or other materials needed to fabricate the blocks 12 and
reduce the
weight of the blocks 12 to simplify wall constrtxlion. Although depicted in
the figures
as being arranged in a horizontal orientation, these openings 34 could be
arranged in a
vertical orientation, if desired. In either case, the openings 34 are sized so
as to
maximize the strength of the blocks while still permitting space for
connecting tie-back
reinforcement members (not shown) to the wall. One tie-back system
particularly well-
suited for walls constructed with the inventive blocks 12 is that disclosed in
U.S. Patent
No. 6,168,351. .
As mentioned above, the wall blocks 12 comprise retaining means for auaching
reinforcement members (e.g., geogrids) to the retaining wall 10. Preferably,
these
retaining means include a ehannel 16 that is fonned in each block 12.
Preferably, each
block 12 has a channel 16 provided in its top surface 28 as shown in FIGS. 2
and 3,
ahhongh altemative placetrtent is feasible. By way of example, the channel 16
altetnatively could be provided in the bottom surface 30 or the interior face
26 of the
wall block 12. When provided in the interior face 26 of the block 12, the
channe116 can
be arranged either horizontally or vertically therein, although horizontal
placement is
preferred. When the channel 16 is provided in the top surface 28 as ilhutrated
in FIGS.
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2 and 3, however, the channel 16 preferably extends transversely across the
block 12
from one side 32 of the block 12 to the other, usually parallel to the
interior surface 26 of
the block 12. As illustrated most clearly in FIG. 4, the channel 16 is defined
by a front
wall 36, a rear waI138, and a bottom surface 40. The front wall 36 preferably
includes a
shoulder 42 that extends inwardly toward the interior face 26 of the wall
block 12. In a
preferred embodiment, the shoulder 42 is defined by two substantially planar
surfaces 43
and 44. The first planar surface 43 extends inwardly from the top surface 28
of the block
at an angle of approximately 90 . The second planar surface 44 extends from
the first
planar surface 43 at an oblique angle toward the exterior face 24 of the block
12. By
way of example, the second planar surface 44 can extend from the first planar
surface 43
at an angle of approximately 45 . Preferably, however, the oblique angle will
range
from approximately 20 to approximately 70 .
Positioned opposite the front wall 36, the rear walI 38 of the channel 16
preferably includes an inwardly extending shoulder 45. However, the rear wall
shoulder
45 preferably is arranged as a radiused curve so as to form a substantially
arcuate edge
46 and an oblique planar portion 47. As shown in FIG. 4, the bottom surface 40
of the
channel 16 can also be formed as a radiused curve. In a preferred embodiment,
this
curve comprises a radius of curvature of approximately 2 inches. This
curvature
provides room for the flanges 18 of blocks 12 of upper courses during wall
construction
and space for a retaining bar (FIG. 7) when a reinforcement member is secured
to the
wall. Although the channels 16 have been described herein as being arranged in
specifically defined configurations, it will be apparent from the present
disclosure that
these channels 16 could be arranged in altemative configurations. As is
discussed
hereinafter, an important consideration is that the channel 16 be
appropriately situated
and configured to work in conjunction with a reinforcement retaining bar 22
(described
in more detail hereinafter) to facilitate mechanical clamping of reinforcement
members
such as geogrids. with limited opportunity for block failure. A further
consideration is
that the channel 16 can be situated and configured to work in conjunction with
a mating
flange of a block in an adjacent course to properly locate the courses with
respect to each
other, to provide resistance to shear forces tending to displace the adjacent
courses with
respect to each other, and to provide resistance to overturning rotation of
the upper block
with respect to the adjacent lower block. Depending upon the particular
implements used
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to retain the reinforcement members, the placement of the channel 16, and the
degree of
course-to-course engagement of blocks desired, the walls 36, 38 of the channel
16 can be
formed without shoulders to simplify block construction.
Where a high degree of engagement between blocks in adjacent courses is
desired (particularly to prevent the upper block from rotating or overturning
during wall
construction), as in the preferred embodiment, the front wall shoulder 42 is
specifically
adapted to receive a flange 18 that extends from substantially each block 12.
Most
preferably, the flange 18 is provided on the bottom surface 30 of the block 12
and, like
the channel 16, extends transversely from one side 32 of the block to the
other side 32.
As is illustrated in FIG. 5, the flange 18 is defined by a front surface 48, a
rear surface
50, and a bottom surface 52. Both the front surface 48 and the rear surface 50
extend
obliquely toward the exterior face 24 of the wall block 12 such that the
entire flange 18
extends towards the exterior face 24 of the block. When the front wall 36 of
the block
channels 16 comprise first and second planar surfaces 43 and 44 as described
hereinbefore, the front surface 48 of the flange 18 comprises mating first and
second
planar surfaces 55 and 57. As with the like named surfaces of the channel 16,
these first
and second planar surfaces 55 and 57 are arranged with the first planar
surface 55
extending from the block at an angle of approximately 90 while the second
planar
surface 57 extends obliquely from the first planar surface 55 at an angle of
approximately 45 . To provide for the engagement between vertically adjacent
wall
blocks 12. the blocks 12 can be placed on top of lower wall blocks 12 such
that the
flanges 18 extend into the channels 16. Once so situated, the upper wall
blocks 12 can
be urged forwardly along the lower blocks 12 so that the front surfaces 48
and, in
particular, the first planar surfaces 43 and 55 and the second planar surfaces
44 and 57
abut each other. This abutment prevents the blocks 12 from rotating forward or
overturning and also provides some resistance to shear forces which may be
exerted on
the wall structure. In the presently preferred embodiment, the flange measures
about
1.30 inches from its juncture with the block body to its bottom surface 52,
and is about
1.48 inches thick in the plane of its juncture with the block body. These
dimensions give
adequate strength to the flange.
The relative front to-back locations of the flange 18 and channel 16 establish
the
appropriate location of adjacent courses of block. In the preferred wall
structure, the
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wall has a batter of about 4 degrees. These translates to a course-to-course
setback of
about 1 inch with blocks of the preferred dimensions- The presently preferred
dimensions of the block are about 15 inches from top face to bottom face,
about 8 inches
from side to side. and about 12 inches from front to back. The preferred
weight is about
75 to 85 pounds. As is known in the art, altennative locating means can be
used.
Examples of altemative locating systems include those of U.S. Patent Nos.
4,914,876,
5,257,880, 5,607,26,') and 5,827,015.
Preferably, the block of the present invention is made from a high strength
concrete block mix, which meets or exceeds the ASTM standard for segmental
retaining
wall blocks, ASTM C 1372-97, with the additional requirements that the
allowable
maximum 24 hour cold water absorption is 7%, and the minimum net area
compressive
strength is about 3500 psi. It is preferably made in a standard concrete
block, paver, or
concrete products machine, by a process generally described in, for example,
U.S- Patent
No. 5,827,015. The shape of the blocks of the
present invention are such that they readily can be made with such equipment.
They will
preferably be cast on their sides so that the critical channels and flanges
are formed by
fixed steel mold parts. When cast on their sides, the blocks are of such a
configuration
as to be easily stripped from the molds.
The retaining means of the disclosed system typically further include a
. 2C reinforcement member retaining bar 22, shown most clearly in FIG. 6. As
indicated in
this figure, the retaining bar 22 is specifically sized and configured to fit
within the
channel 16. In a preferred arrangement, the retaining bar 22 has a plurality
of different
surfaces: a top surface 54, a bottom surface 56, a front surface 58, and a
rear surface 60.
Preferably, the top surface 54 is substantially planar in shape while the
bottom surface 56
is arcuate in shape. In particular, the bottom surface 56 is adapted to follow
the contours
of the bottom surface 40 of the channel 16. The front surface 58 and the rear
surface 60
preferably are planar in shape. Preferably, the front.surface 58 extends
perpendicularly
downward from the top surface 54 so as to mate with the front wall 36 of the
channel 16
and the rear surface 60 extends obliquely from the top surface 54 to likewise
mate with
the rear wall 38. The preferred dimensions of the bar are about 0.6 inch thick
at its
thickest location, about 0.18 inch at its thinnest location, and about 2
inches from leading
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edge to trailing edge. Preferably, the bar is 64 inches long, but shorter
lengths may be
required for tight radius curves.
It is presently preferred that the bar has the solid configuration shown in
FIG. 6.
However, the bar can have a hollow configuration, such as that shown in FIG.
10. As is
; illustrated in this figure, the retaining bar 22' similarly includes top,
bottom, front. and
rear surfaces 54'-60', but the interior of the bar 22' includes a plurality of
voids 61.
Through provision of such voids 61, both the volume of the materials and
weight of the
bar 22' can be reduced.
The retaining bar 22, 22' can be constructed of a polymeric or other material.
The material needs to be such that its long-term performance in the prevailing
environment will be suitable. The presently preferred material for the bar is
regrind
CPVC, available from Inteic Plastics, Inc. We understand this material to
comprise about
80% CPVC, about 10% weatherable PVC, and about 10% rigid PVC. Presently, for
the
preferred bar dimensions, we prefer a material that meets or exceeds the
following
properties: Young's Modulus = 60,000 psi; Engineering Yield Stress = 2,048,000
psi;
Engineering Strain = 3.41 x 10'2 in/in. Different properties may be
appropriate if
different dimensions or materials are used for the bar. As shown in FIG. 7,
the retaining
bar 22 can be positioned on top of a reinforcement member 20 in the channel 16
by
inserting the retaining bar 22 into the channel 16 by twisting the bar 22
downwardly into
place within the channel 16. The channel 16 needs to be dimensioned to accept
the bar
16, the flange 18, and a layer of reinforcement material. In the presently
preferred
embodiment, a dimension of 0.06 inches is assumed for the thickness of the
reinforcement material. This dimension is about that of the thickest geogrids
presently
known. If the channel is sized to accommodate reinforcement material of this
dimension, it can then function with a wide range of reinforcing materials.
Once correctly inserted within the channel 16, the retaining bar 22, 22' is
securely held within the channel 16 and, in turn, securely holds the
reinforcement
member 20 in place. The retaining bar 22, 22' bears against the rear wall 38
of the
channel and also contacts the bottom surface 52 of the flange 18 of a block
situated
above (FIG. 9) when a tensile load is applied to the reinforcement member 20.
The
retaining bar 22, 22' therefore prevents the reinforcement member 20 from
being pulled
out from the retaining wall 10. More specifically, when a tensile force is
applied, to the
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reinforcementmember 20 from the soil side of the retaining wall 10, the
retaining bar 22,
22' is pulled upwardly in the channel. Contact with the flange inserted into
the channel
causes the bar to rotate and move further upwardly and backwardly within the
channel
i 6, clamping the reinforcement member 20 between the retaining bar 22 and the
rear
wall of the channel 16.
This clamping system creates a highly efficient connection between block and
grid. In a standard connection test of the type which is well-known to those
of skill in
the segmental retaining wall art, the following connection strengths were
achieved using
TC Mirafi 5XT geogrid:
Normal Load (lb/ft) Peak Connection (Ib/ft) Service Connection (Ib/ft)
241 3199 1509
798 3289 1911
1851 3247 2222
2869 2731 2488
3860 2649 2425
The long term design strength of the Mirafi 5XT grid, according to the NCMA
design methodology is 1084 !bs/ft, so it is apparent that the connection
strength
generated by the current clamp system is highly efficient.
Testing with TC Mirafi IOXT geogrid (NCMA long tenn design strength of
2602 lbs/ft) yielded the following results:
Normal Load (lb/ft) Peak Connection (lb/ft) Service Connection (Ib/ft)
261 3536 2735
908 4438 3016
1837 4548 3322
2910 4128 3320
3874 4493 3634
The system of the present invention can be used to construct any number of
different configurations of segmental retaining walls. FIG. 8 illustrates
another example
of such a retaining wal166. To construct such a wall 66, a leveling pad 68 is
normally
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laid to provide a foundation upon which to build the wall 66. Typically, this
leveling
pad 68 comprises a layer of compacted, crushed stone that is embedded under
the soil to
protect the wall foundation. Once the leveling pad 68 is laid and compacted, a
plurality
of foundation blocks 70 are aligned along the length of the pad 68.
Preferably, each of
the foundation blocks 70 is solid and provided with a channe116 in its top
surface. Since
there are no lower courses with which to engage, the foundation blocks 70 are
normally
not provided with flanges. Additionally, as depicted in the figure, the-
foundation blocks
70 can be relatively short in height, for example, approximately half as tall
as the
standard wall blocks 12 that comprise the majority of the wall 66. Although
such
foundation blocks 70 typically are used in the first course of the retaining
wall 66, it is to
be noted that the standard wall blocks 12 could be used to form this course,
if desired.
After the first. or foundation, course has been fonned with either the
foundation
blocks 70 or wall blocks 12; the next course of blocks 12 can be laid. The
wall blocks 12
are placed on top of the blocks 70 of the foundation course with the flanges
18, if
provided, extending into the channels 16 of the lower blocks 70. As can be
appreciated
from FIG. 8, and with reference to FIGS. 4 and 5, the front surfaces 48 of the
flanges 18
mate with the front wall shoulders 42 of the channels 16 such that each flange
18 extends
underneath the shoulders 42. This mating relationship holds the wall block 12
in place
atop the lower blocks 70 and prevents the wall blocks 12 from tipping forward,
thereby
providing integral locking means for the blocks 12.
Once the first normal wall course has been formed atop the foundation course,
backfill soil, S. can be placed behind the blocks 12. Typically, a non-woven
filter fabric
72 is provided between the wall 66 and the backfill soil to prevent the
introduction of
particulate matter between the courses of blocks 12 due to water migration
within the
soil. Alternatively, a layer of gravel aggregate can be provided between the
wall and the
soil to serve the same function. Additional ascending courses thereafter are
laid in the
manner described above. Although alternative configurations are possible, a
reinforcement member 20 typically is laid between every other course of blocks
12 as
indicated in FIG. 8. It will be appreciated, however, that greater or fewer
reinforcement
members 20 can be provided depending upon the particular reinforcement needs
of the
construction site. Preferably, these reinforcement members 20 are composed of
a
flexible polymeric materials. As described above, the reinforcement members 20
are
13
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WO 01/00932 PCT/US00/02148
positioned so that they extend from the exterior surface 15 of the retaining
wall 66, into
the channel 16, and past the interior surface 17 of the retaining wall 66 to
extend into the
soil. As shown most clearly in FIG. 9, a reinforcement member retaining bar 22
is
placed on top of the reinforcement member 20 in the channel 16. When the next
course
of blocks 12 is laid, the flanges 18 of the upper blocks 12 extend into the
channels 16 in
which the retaining bar 22 is disposed.
Construction of the retaining wall 66 continues in this manner until the
desired
height is attained. As indicated in FIG. 8, the setback of the wall blocks 12
creates a net
inward setback appearance of the retaining wall 66. Additionally, the
configuration the
blocks 12 creates an aesthetically pleasing stepped appearance for the
exterior surface of
the wall 66. Where the full height of a wall block 12 is unnecessary or not
desired, short
wall blocks 74 can be used to form the top or other course. Preferably, these
short wall
blocks 74 are solid and approximately half the height of the standard wall
blocks 12.
Once the retaining wall 66 has been raised to the desired height, cap blocks
76 can be
used to complete the wa1166. As shown in FIG. 8, these cap blocks 76 can be
provided
with a flange 18, but do not have an upper channel in that further
construction will not be
conducted. The cap blocks 76 can be fixed in position with concrete adhesive
and
provided with an ornamental pattem similar to the exterior faces of the blocks
12, if
desired. By way of example, the cap blocks 76 can be designed to extend out
over their
subjacent blocks 74 to provide an aesthetic lip as illustrated in FIG. 8.
Additionally, a
subsurface collector drain 78 can be provided within the backfill soil to
remove excess
water collected therein.
FIGS. 11-17 depict an alternative wall block 100 constructed in accordance
with
the present invention. In that the alternative block 100 shares many common
features
with the preferred wall block 12, the following description of the wall block
100 is
focused upon the differences of this block 100. As illustrated in FIGS. 11 and
12, each
wall block 100 comprises an exterior face 102, an opposed interior face 104, a
top
surface 106, a bottom surface 108, and two opposed sides 110. As with the
preferred
block 12, the exterior faces 102 of the blocks 100 typically are provided with
an
ornamental texture or facing that is sloped inwardly from the bottom surface
108 to the
top surface 106. Also like the preferred block 12, the interior faces 104 of
the wall
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blocks 100 preferably are configured in an upright or vertical orientation.
Preferably, the
wall blocks 100 further include interior openings 112.
As with the preferred blocks 12, the wall blocks 100 each preferably comprises
a
channel 114. Preferably, once such channel 114 is provided in the top surface
106 of
each block 100, although alternative placement is feasible. The channel
extends
transversely across the block 100 from one side I 10 of the block 100 to the
other side
I 10. As illustrated in FIG. 13, the channel 114 is defined by a front wall
118, a rear wall
120, and a channel bottom surface 122. The front wall 118 can include a
shoulder 124
that extends inwardly toward the interior face 104 of the wall block 100. As
indicated in
FIG. 13, the shoulder 124 can be arranged as a curved lip such that the
channel 114
comprises a first substantially arcuate edge 126.
Positioned opposite the front wall 118, the rear wal1120 of the channel 114
also
preferably includes an inwardly extending shoulder 128. The rear wall shoulder
128
preferably is arranged as a curved lip so as to form a second substantially
arcuate edge
130 of the channel 114. Although the shoulders 124, 128 have been described
herein as
being arranged as curved lips, it will be apparent from the present disclosure
that
alternative arrangements are feasible. Indeed, depending upon the particular
implements
used to retain the reinforcement members, the placement of the channel 114,
and the
degree of course-to-course locking desired, the walls 118, 120 can be formed
without
such shoulders 124, 128 to simplify block construction.
Where a high degree of block engagement in adjacent courses is desired, the
channel 114 is specifically adapted to receive a flange 116 that extends from
the block
100. Preferably, the flange 116 is provided on the bottom surface 108 of the
block 100
and extends transversely from one side 110 of the block 100 to the other side
110. As is
illustrated in FIG. 14, the flange 116 is defined by a front surface 132, a
rear surface 134,
and a top surface 136. Both the front surface 132 and the rear surface 134
extend toward
the exterior face 102 of the wall block 100. With this configuration, the
blocks 100 can
be placed on top of lower wall blocks 100 such that the flanges 116 extend
into the
channels 114. Once so situated, the courses of blocks 100 wi11 resist shear
forces in
similar manner to courses containing the preferred blocks 12.
When the alternative wall block 100 is used to form a retaining wall,
preferably a
third embodiment of a reinforcement member retaining bar 138 is used. Shown
most
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clearly in FIG. 15, the retaining bar 138 comprises a plurality of different
surfaces: a top
surface 140, a bottom surface 142, a first upright surface 144, a second
upright surface
146, a first oblique surface 148, and a second oblique surface 150.
Preferably, the top
surface 140 and the bottom surface 142 are parallel to each other as are the
first oblique
surface 148 and the second oblique surface 150. Similarly, the first upright
surface 144
and the second upright surface 146 preferably are parallel to each other such
that the first
upright surface 144 extends perpendicularly from the top surface 140 and the
second
upright surface 146 extends perpendicularly from the bottom surface 142.
Configured in this arrangement, the retaining bar 138 can be positioned on top
of
a reinforcement member 20 in the channels 114 by inserting the retaining bar
138 into
the channels 114 in the manner depicted in FIG. 16. In that the bar 138 is
designed to fit
closely between the front and rear walls 118 and 120 of the channels 114 when
in place.
a longitudinal notch 152 can be provided in the channel 114 to accommodate the
second
upright surface 146 during the downward insertion of the bar 138, as
illustrated in both
FIGS. 16 and 17.
While preferred embodiments of the invention have been disclosed in detail in
the foregoing description and drawings, it will be understood by those skilled
in the art
that variations and modifications thereof can be made without departing from
the spirit
and scope of the invention as set forth in the following claims. For instance,
although
particular block configurations have been identified herein, persons having
ordinary skill
in the art will appreciate that the concepts disclosed herein, in particular
the retaining
means described herein, are applicable to prior and future wall block designs.
16
