Note: Descriptions are shown in the official language in which they were submitted.
CA 02369310 2002-O1-30
SOIL STABILIZING SYSTEM
Field of the Invention
The invention pertains to structures and methods for stabi-
lizing soil, including soil held by a retaining wall or soil on a slope or in
a sub-base.
Background of the Invention
Retaining walls are used in a wide variety of civil engineer-
ing and landscaping applications, for example to support slopes and
embankments for highways and railways, support noise barriers, control
erosion, reinforce sub-bases, etc. Retaining walls are commonly made
having a supporting face structure made of interconnecting blocks or
sandbags with soil placed and compacted in back of the wall, and with
sheets of geogrid laid in the fill at various levels, extending back from
the wall. Geogrid is attached to the wall, typically by means of posts or
pins which project through holes in the geogrid. As soil is packed
around and over the geogrid, soil particles fill the holes in the geogrid,
helping the sheet to resist movement in the soil and thereby stabilize the
backfill behind retaining wall and the sub-base soil. However, geogrid
sheets are relatively thin so their resistance to horizontal movement is
limited. There exists a need in the field of soil stabilization for a
structure which provides greater soil stabilizing properties than that
afforded by geogrid sheets.
In cases where geogrid is used, there exists a need for a
system with the capability of anchoring the geogrid sheets to the soil or
rock so that they provide greater stability and resistance to movement of
the backfill and wall.
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With respect to the stabilization and reinforcement of soil
on sloping ground, where a retaining wall is not used, the soil at the
surface of the slope is susceptible to erosion by reason of the forces of
gravity, wind and water flow down the slope. There exists a need for
stabilizing the soil on such slopes and ground.
There also exists a need for a soil stabilizing system which
can be used in place of geogrid in a wide variety of applications, with or
without a retaining wall, but which can be readily assembled from
components either at the factory or the job site.
Summary of Invention
It is an object of the invention to provide a soil stabilizing
system for stabilizing the soil held by a retaining wall, or in a sub-base.
It is a further object of the invention to provide a system for
stabilizing ground by means of a gridwork of cells which helps to
interlock soil particles together and thereby reinforces the soil.
It is a further object of the invention to provide an anchor-
ing system for retaining walls and an anchoring system for geogrid used
in conjunction with retaining walls and slopes. The anchoring system
can be used with or without grout.
It is a further object of the invention to provide a soil
stabilizing system for stabilizing the soil on slopes.
It is a further object of the invention to provide a soil
stabilizing system which can be used for the applications for which
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geogrid is conventionally used, but which comprises components which
can be readily assembled at either the factory or the job site.
According to one embodiment of the invention, there is
provided a soil stabilizing system comprising strip members affixed
together at right angles to each other in a generally rectangular grid.
When used in conjunction with a retaining wall, one set of the strip
members is attached to the retaining wall.
1 ~ According to a further embodiment of the invention, there
is provided a soil stabilizing system comprising strip members affixed
together at right angles to each other in a generally rectangular grid,
with connecting members affixed at the intersections of the strip mem-
bers and soil retaining bars attached between the connecting members
along one set of parallel strip members so as to form parallel elongate
cells. When used in conjunction with a retaining wall, the set of parallel
strip members that is perpendicular to the soil retaining bars is attached
to the retaining wall.
According to a further embodiment of the invention, there
is provided a soil stabilizing system comprising strip members affixed
together at right angles to each other in a generally rectangular grid,
with interconnecting members affixed at the intersections of the strip
members and soil retaining bars attached between the connecting mem-
hers along the strip members so as to form a grid of rectangular cells.
The cells can be made in a variety of sizes, to suit a particular applica-
tion. When used in conjunction with a retaining wall, one set of parallel
strip members is attached to the retaining wall.
According to a further embodiment of the invention, there
is provided an anchoring system which can be used for anchoring
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retaining walls in conjunction with the soil stabilizing systems of the
invention or with geogrid systems. The anchoring system comprises
anchor posts which can be filled with grout and used for the injection of
grout into the soil, and which can be attached to the soil stabilizing
systems or to geogrid.
According to a further embodiment of the invention, there
is provided a system for stabilizing a retaining wall comprising strip
members affixed to a retaining wall and anchored into backfill supported
by the wall or to a slope, by means of the anchoring system.
According to further embodiment of the invention, there is
provided a soil stabilizing system comprising strip members adapted to
be affixed to a retaining wall at horizontally spaced positions along the
wall, extending into soil supported by the wall and anchored into said
soil or to a slope behind the back fall. Soil stabilizing members are
affixed to the strip members at spaced positions thereon, the soil stabi-
lizing members having a plurality of radially-extending arms.
According to a further embodiment of the invention, there
is provided a system for anchoring geogrid in soil. The system includes
an anchor post for affixing in the soil having a longitudinal bore through
the post, and a retaining pin for inserting through a hole in the geogrid
and into the bore in the post, the pin being capable of affixing the
geogrid to the anchor post. The anchoring system can be used with or
without grout.
According to further embodiment of the invention, there is
provided a kit for making a soil stabilizing system adapted to be at-
tacked to a retaining wall. The kit comprises a set of strip members for
attachment to a retaining wall at horizontally spaced positions along the
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wall and to extend into soil supported by the wall, a set of soil retaining
bars and a set of connecting members adapted to be affixed to the strip
members at spaced intervals thereon. The connecting members are
adapted to hold the soil retaining bars on the strip members so as to
form rectangular cells with the connecting members at the corners and
the soil retaining bars at the sides of the cells. The kit can be assembled
at the factory or the job site to make a soil stabilizing system.
According to a further embodiment of the invention, there
is provided a method for making a soil stabilizing structure. Two sets
of strip members are attached at generally right angles to each other so
as to form a rectangular grid which lies on and is filled with and cov-
ered by soil. Preferably, connecting members are affixed to the strip
members at their points of intersection, the connecting members being
adapted to hold soil retaining bars on the strip members between adja-
cent connecting members. Preferably, soil retaining bars are attached
between the connecting members on either one set of parallel strip
members, to form elongate parallel cells, or on both sets of strip mem-
bers, to form a grid of rectangular cells. When used in conjunction with
a retaining wall, one set of parallel strip members is attached to the
wall.
These and other embodiments, objects, advantages and
features of the invention will be apparent from the following descriprion
of the preferred embodiments, considered along with the accompanying
drawings.
Brief Description of the Drawings
Figure 1 is a perspective view of a first embodiment of a
soil stabilizing system according to the invention.
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Figure 2A and 2B show connectors used with the embodi-
ment of Figure 1.
Figure 3 is a perspective view of a second embodiment of a
soil stabilizing system according to the invention.
Figure 4A is a perspective view of a connecting member.
Figure 4B is a perspective view of alternative embodiments
of the connecting member.
Figure 5 is a perspective view of a third embodiment of a
soil stabilizing system according to the invention.
Figure 6A is a cross-sectional view of an embodiment of
the invention attached to a retaining wall.
Figure 6B is a perspective view showing the connection of
a strip member of the soil stabilizing system to an interconnecting plate
of a sandbag-type retaining wall.
Figure 7 is a perspective view of the soil stabilizing system
of Figure 5 used in conjunction with a retaining wall.
Figure 8A is a partly cutaway view of an anchor post
insertion device.
Figure 8B shows two views of an anchor post, assembled at
left and disassembled at right.
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Figure 9 is a cross-sectional view of an anchor post at-
tacked to a connecting member and strip member.
Figure 10 is a perspective view of the soil stabilizing
system of Figure 3 used in conjunction with anchor posts.
Figure 11 is a cross-sectional view of an embodiment of the
soil stabilizing system, with a set of anchored strip members attached to
a retaining wall.
Figure 12 is a perspective view of a further embodiment of
the soil stabilizing system, attached to a retaining wall.
Figure 13 is a perspective view of an alternative embodi-
meat of the connecting member.
Description of the Preferred Embodiments
Figure 1 illustrates a first embodiment of the soil stabilizing
system of the invention. In this specification, "soil" includes soil, sand,
gravel and other fill materials that may be used in conjunction with
retaining walls or which require stabilization or reinforcement in a
particular application. Referring to Figure l, the soil stabilizing system
comprises principally strip members 10, which, when connected to-
gether, form a grid which holds soil particles.
A first set of strip members is laid generally parallel to each
other and spaced apart on soil 24. A second set of strip members 10 is
laid over it, preferably at approximately right angles to the first set.
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The strip members 10 and the other components of the soil
stabilizing system are preferably made of strong and corrosion resistant
plastic or metal that will be durable when buried in the soil.
Strip members 10 are generally rectangular in cross-section
and preferably have a series of bores 28 spaced along their length.
Alternatively, strip members 10 may be made of a relatively thin mate-
rial and bores 28 may be punched or drilled in them at selected positions
on site as the soil stabilizing system is assembled. Strip members 10 are
preferably a flexible material which is wound into a coil and cut to
length as required.
The strip members 10 are connected together at their points
of intersection, which are arranged to coincide with the alignment of a
bore 28 in each strip member, by inserting pin 11 through the aligned
bores . As shown in Figure 2A, pin 11 has a head 13 and shaft 15. The
diameter of the shaft is such that it fits snugly in bore 28, and the
diameter of the head is larger than the diameter of bore 28. It will be
understood that various forms of connector for connecting the strip
members 10 can be used in place of pin 11. An alternative form of
connector is shown in Figure 2B. Connector 17 has an upper and a
lower section which attach firmly together, providing a head at either
end with a diameter larger than the diameter of bore 28.
The attachment together of strip members 28 forms a
generally rectangular grid 19 having rectangular cells 21. The cells
have a height equal to the thickness of strip members 10. In use for
reinforcing soil, the soil 24 fills cells 21 and covers grid 19.
Figure 3 shows a second embodiment of the invention. As
in the embodiment of Figure 1, a first set of strip members 10 is laid
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generally parallel to each other and spaced apart on soil24. A second
set of strip members 10 is laid over it at approximately right angles.
Connecting member 12, best seen in Figure 4A, is a planar element,
generally cross-shaped, with a bore 34 at its centre. Four pairs of
parallel arms 14, separated by slots 36, extend radially out from the
centre at right angles. A connecting member 12 is placed at each point
of intersection of strip members 10, with bore 34 aligned with two bores
28, and pin 11 is pressed through the bores to attach the connecting
member and strips together. Bore 34 is the same diameter as bore 28
and shaft 15 of the pin fits snugly in it.
Soil retaining bars 16 are members that are generally
rectangular in cross-section, dimensioned to fit snugly in slot 36 be-
tween the parallel arms 14 of a connecting member 12. The soil retain-
ing bars 16 are fitted into slots 36 of adjacent connecting members 12
along one set of parallel strip members 10. They lie on and are sup-
ported by strip members 10. The soil retaining bars thus form a set of
parallel cells 22, having a depth equal to the height of the soil retaining
bars 16. In use for reinforcing soil, the soil 24 fills cells 22 and covers
grid 19. The width of the cell 22 is equal to the spacing between
parallel soil retaining bars, and the length will be as long as desired for
a particular application, depending on the number and spacing of the
strip members 10 that are perpendicular to the soil retaining bars .
The resistance to lateral movement of a connecting member
12 itself provides some soil stabilization. The connecting members may
be of various thicknesses and sizes. A thicker connecting member will
provide greater resistance to movement and therefore greater stabiliza-
tion than a thinner one. A cap (not shown) may be provided on the
connecting member 12 to hold the soil retaining bar in place in slot 36.
Alternative forms of the connecting member 12 are shown in Figure 4B .
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The sizes of cells 22 can be different for different applica-
tions. Their depth may be varied by selecting soil retaining bars 16 of
different heights. Their length and width may also be varied by select-
ing different spacing for the strip members 10. The soil retaining bars
are therefore provided in various lengths.
To facilitate the fitting together of cells 22, the connecting
members 12 may be provided with more than one bore 34. Such other
bores may be positioned at various points across the body of a connect-
ing member 12 including its arms 14. Any such bore may be selected
for a alignment with a bore 28 of a strip member 10 and attachment by
means of a pin 11. This enables the connecting members to be posi-
tinned so as to best align with each other for formation of cells 22.
Figure 5 shows a further embodiment of the soil stabilizing
system. This embodiment differs from that shown in Figure 3 by the
addition of soil retaining bars 16 perpendicular to those shown in Figure
3, so as to form rectangular cells 25. The length and width of cells 25
is accordingly equal to the spacing of the strip members 10, which
support the soil retaining bars 16.
Each of the embodiments of Figures 1, 3 and 4 may be
constructed and used either without a retaining wall, for example where
the structure is used to stabilize or reinforce sub-base soil or soil on a
slope, or with a retaining wall. Where they are used with a retaining
wall, one end of a set of the parallel strip members 10 is affixed to the
retaining wall.
The soil stabilizing system is attached to a retaining wall as
it is being built, at various levels as required for a particular application.
For example, it can be attached at every third or fourth horizontal
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course of the blocks or sandbags that are used to construct the retaining
wall .
Figure 6A shows a grid 19 of Figures 1, 3 or 4 attached to
a retaining wall built with wall-building units, eg. blocks or sandbags,
held together with interconnecting plate members as described in WO
00/61880, published October 19, 2000. Retaining wall 33 is formed of
horizontal courses of sandbags 32 which support soil (backfill) 24 on
ground 38 in back of the wall. The sandbags 32 are affixed together by
interconnecting plate members 35, which have projections or hooks 30
thereon. Such projections are conventionally used for the attachment of
geogrid, but, in the present application, they are used for connection of
strip members 10. As shown in Figure 6B, a strip member 10 is looped
through and attached to connector ring 37. The loop is closed by a pin
39 or an suitable conventional attachment means, such as a rivet, staple,
binding ring, etc. Connector 37 is fitted over hook 30 and is held in
place by the sandbag 32 in the adjacent upper course. Alternatively, an
interconnecting plate member can be provided which has no hook or
projection but instead has a bore through which strip member 10 can be
looped for attachment thereto.
Alternatively, the retaining wall 33 may be built of blocks
having convention attachment means of the kinds well known in the art
for attaching sheets of geogrid to retaining wall blocks. For example,
the blocks may have posts on their upper surface which fit through bore
28 near the ends of strip members 10. Or the blocks may have bores
into which a retaining pin can be inserted to hold the strip member to
the blocks. The soil stabilizing systems of the present invention can
accordingly be used in conjunction with any conventional blocks or
retaining wall structures of the type to which geogrid can be affixed.
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A perspective view of the soil retaining structure of Figure
5; used in conjunction with a retaining wall 33, is shown in Figure 7.
When the embodiment of Figure 3 is used in.conjunction with a retain-
ing wall, the soil retaining bars are oriented so as to be generally paral-
let to the wall.
Strip members 10 are affixed to the retaining wall blocks or
sandbags 32 generally parallel to each other and along the full length of
wall 33. The strip members 10 extend a length behind the wall that is
optimal for soil stabilization in a given application, for example 10 or 20
feet. As the retaining wall is built and the soil stabilizing system at a
given level is covered with soil, the cells 22 or 25 are filled with soil.
As the retaining wall is built higher, further soil stabilizing systems are
assembled at selected levels and are filled and covered with soil.
Cumulatively, the structures hold the retaining wall and the soil behind
it together and stabilize the wall and soil.
The soil stabilizing systems of Figures 1, 3 and 4, whether
used with or without a retaining wall, can, with minor modification, be
used with an anchoring system as described hereunder.
Referring to Figure 8A, anchor post insertion device 62
comprises tube 64 and spike assembly 66. The spike assembly com-
prises shaft 68 with point 70 at one end and plate 72 proximate the other
end. Spike assembly 66 is moveable longitudinally within tube 64 and
is held in place therein by pin 74. The anchor post insertion device 62
is inserted in the soil in which an anchor post is fo be affixed, for
example by drilling or driving. The pin 74 is then removed and spike
assembly 66 is removed from the tube 64 so that an anchor post can be
inserted. Figure 8B shows the anchor post 50 in assembled and disas-
sembled views. Anchor post 50 are preferably made of sturdy plastics
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or metal material, resistant to corrosion. Anchor post 50 has a longitu-
dinal bore 52 extending therethrough. Anchor post 50 is preferably
cylindrical in cross-section, though it may also be rectangular or other
shapes, provided that the anchor post insertion device has a correspond-
s ing shape. The anchor post has a pointed tip 54 which is affixed to its
lower end by means of a short post 58 on the upper end of the tip which
is press-fitted into bore 52 of the post. Alternatively, tip 54 may be
made integrally with post 54. Tip 54 has a plurality of holes 56 on its
lower surface which are open to bore 52 of the anchor post 50. In use,
tip 54 is fitted to the anchor post 50 and the anchor post is inserted in
tube 64 of the anchor post insertion device which is embedded in the
soil. The tube 64 is then pulled up out of the soil and the soil is com-
pacted around the anchor post. Grout, eg. concrete, can be injected
down through bore 52 and out through holes 56 in the anchor tip to
form a ball of grout at the base of the anchor.
In use, a grid 19 of Figures 1, 3 or 4, or a strip member
10, is affixed to an anchor post. Figure 9 illustrates the attachment of a
connecting member 12 and strip member 10 to an anchor post 50. A
retaining;pin 38 is used for this purpose instead of a pin 11. Retaining
pin 38 has enlarged ends 40 with flanges 42. The outer diameter of
ends 40 is slightly larger than the diameter of bores 34, 28, but the ends
40 are sufficiently compressable that end 40 can be pressed through the
bores. The flanges 42 then hold the connecting member 12 and strip
member 10 from slipping off the pins 38. Pins 38 preferably have a
longitudinal bore 44 whereby the grout can be injected through the bore
and into the anchor post. The lower end of retaining pin 38 is driven
into bore 52. The bulbous end 40 of the retaining pin forms a snug fit
within bore 52, securing the retaining pin and the connecting member
and strip member to the upper end of the anchor post 50. Preferably,
grout is injected through bore 44 of the retaining pin 38, through bore
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52 of the anchor post and out through holes 56 into the soil around the
base of the anchor post.
Figure 10 shows a soil stabilizing system of the type illus-
trated in Figure 5 attached to anchor posts 50 by means of the mode of
attachment illustrated in Figure 9. Grout has been injected through the
anchor posts and forms grout balls 51 at the base thereof.
The anchoring system of Figures 8 and 9 can be used with
or without grout. It can also be used with the grid of Figures 1, 3 and 4
whether the grid is used in conjunction with a retaining wall or on its
own. The anchoring system can also be used to anchor a retaining wall
by means of affixing it to a strip member 10 or a plurality of strip
members, attached to a retaining wall but where no grid 19 is employed.
In such an embodiment, illustrated in Figure 11, a set of strip members
10 is attached to a retaining wall 33 as described above along selected
horizontal courses of blocks or sandbags 32 as the wall is constructed, at
spaced intervals along each such course and extending into the backfill
in back of the wall. Each strip 10 is affixed to an anchor post 50 by the
means illustrated in Figure 9 and grout is injected into and through the
anchor post, forming grout ball 51. Where there is a restricted depth of
backfill behind a retaining wall, the anchor posts can be placed directly
into a rock face or unexcavated soil behind the backfill and the retaining
wall can be anchored directly thereto by means of strip members 10.
In a further embodiment of the soil stabilizing system of the
invention, shown in Figure 12, strip members 10 are attached to a
retaining wall as described above and connecting members 12 are
affixed thereto, by the mode of attachment described above, at selected
positions along their length. Here, the soil stabilization is provided
primarily by the resistance to movement in the soil of the connecting
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members 12. The arms 14 of the connecting members 12 may be of
various lengths, with greater resistance to movement being provided by
connecting members 12 having longer arms 14; Likewise; the connect-
ing members 12 may be of various thicknesses. In this embodiment,
connecting member 12 may be termed a soil stabilizing member.
Further, since arms 14 are not used in this embodiment to
attach soil stabilizing bars, slot 36 can be eliminated and the soil stabi-
lizing member can be in the form of a simple cross.
In a further embodiment of the invention, the connecting
members are adapted to hold the soil retaining bars at an angle to the
strip members that is other than vertical. Referring to Figure 13,
connecting member 112 has arms 114 angled to define a slot 136, that is
angled relative to the longitudinal axis of bore 34. A soil retaining bar
held in slot 136 is therefore angled relative to a strip member 10 which
supports it. This is useful in certain applications. For example, in the
embodiment of Figure 3, when used in conjunction with a retaining
wall, angling the soil retaining bar so that the upper edge thereof tilts
towaxds the retaining wall will provide greater resistance to forward
movement of the wall. Also, where the embodiment of Figure 3 is used
to stabilize soil on a slope, angling the upper edge of the soil retaining
bars toward the top of the slope will provide better soil-holding proper-
ties.
According to a further embodiment of the invention, there
is provided a soil stabilizing system for anchoring geogrid in the soil.
As is well known in the art of retaining walls, geogrid has a web-like
structure, full of holes, and is affixed to retaining walls at various levels
during the construction, extending into the soil supported by the retain-
ing wall. However, because the geogrid is relatively thin, typically less
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.than about 1 mm, its resistance to lateral movement is limited. The
anchoring system of the present invention provides means for anchoring
the geogrid int the soil so as to substantially increase its resistance to
movement. To anchor geogrid, retaining pin 38 is fitted through a hole
in the geogrid and into bore 52 of anchor post 50, which is embedded in
the soil under the geogrid. The end 40 of the retaining pin 38 is sized
so as to snap into a hole in the geogrid and hold the retaining pin se-
curely to the geogrid. Preferably, grout is injected into the anchor post
as described above in order to further anchor it in the soil. To stabilize
a sheet of geogrid, as many anchor posts as may be required for a
particular application are driven into the soil as described above. The
geogrid sheet, attached to the retaining wall by conventional means, is
lain over the anchor posts and affixed to them as described above.
Although the invention has been described in terms of
various embodiments, it is not intended that the invention be limited to
these embodiments. Various modifications within the scope of the
invention will be apparent to those skilled in the art. The scope of the
invention is defined by the claims that follow.
