Note: Descriptions are shown in the official language in which they were submitted.
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REINFORCED ARCH WITH FLOATING FOOTER AND METHOD OF
CONSTRUCTING SAME
Technical Field
[0001] Some embodiments of the present invention pertain to reinforced soil
arch structures. Some embodiments of the present invention pertain to
reinforced
soil arch structures having a yielding footer. Some embodiments of the present
invention pertain to methods of making such structures.
io Background
[0002] Geosynthetic reinforced soil arch structures provide an environmentally
preferable and/or less expensive alternative to more traditional construction
materials used for bridges, culverts, overpasses and the like, e.g. steel
structures,
reinforced concrete structures, plastic structures and the like. Geosynthetic
reinforced soil arches for use in the design of structures such as bridges,
overpasses, snowsheds, landslide or rock fall protection structures, or the
like are
described, for example, in U.S. patent Nos. 6,874,974 and 8,215,869 to
VanBuskirk. Some such arches have a supporting form (typically but not
necessarily an arch form) made from a rigid material such as metal, concrete,
reinforced concrete, plastic or reinforced plastic. A plurality of alternating
layers
of compacted soil and reinforcement made from geosynthetics, plastic, metal,
wood and/or the like are associated with the supporting form. Some such arches
have an archway form, a combination of alternating and interacting layers of
compacted mineral soil and reinforcement material associated with the archway
form, and a plurality of shear resisting devices extending from the exterior
surface
of the archway into the reinforced soil mass. Mineral soil can include clay,
silt,
sand, gravel, cobbles, boulders, broken rock, or mixtures of any of the
foregoing.
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100031 U.S. Patent No. 4,010,617 to Fisher discloses a composite arch
structure
comprising an arched liner with compacted fill material or dense soil
thereagainst
to form a soil arch thereabout. The liner has a foundation comprising yielding
footer means.
100041 There remains a need for improved footers for geosynthetic reinforced
soil arch structures.
lo [0005] The foregoing examples of the related art and limitations related
thereto
are intended to be illustrative and not exclusive. Other limitations of the
related art
will become apparent to those of skill in the art upon a reading of the
specification
and a study of the drawings.
Summary
100061 The following embodiments and aspects thereof are described and
illustrated in conjunction with systems, tools and methods which are meant to
be
exemplary and illustrative, not limiting in scope. In various embodiments, one
or
more of the above-described problems have been reduced or eliminated, while
other embodiments are directed to other improvements.
[0007] One embodiment provides a reinforced soil arch having an archway
form, a plurality of alternating layers of compacted fill and reinforcement
material
associated with the archway form, and a floating footer independent of the
archway
form. The archway form is supported by the floating footer. The floating
footer
can comprise a solid base and a squeeze block, with the squeeze block
interposing
the solid base and the archway form. A load distributing member can interpose
the
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squeeze block and a longitudinal edge of the archway form. The archway form is
not coupled to the load distributing member, the squeeze block or the solid
base.
[0008] One embodiment provides a method of providing a reinforced soil arch
having a floating footer. A floating footer is provided along a first edge of
the
reinforced soil arch. A floating footer is provided along a second edge of the
reinforced soil arch. An archway form is positioned on the floating footers on
the
first and second edges. The archway form is independent of the floating
footers.
A plurality of alternating layers of compacted fill and reinforcement material
io associated with the archway form are provided and the archway form is
allowed to
compress the floating footer.
[0009] In addition to the exemplary aspects and embodiments described above,
further aspects and embodiments will become apparent by reference to the
drawings and by study of the following detailed descriptions.
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Brief Description of the Drawings
[0010] Exemplary embodiments are illustrated in referenced figures of the
drawings. It is intended that the embodiments and figures disclosed herein are
to
be considered illustrative rather than restrictive.
100111 Figure 1 is a cross-sectional view of a first example embodiment of a
reinforced soil arch having a floating footer.
[0012] Figure 2 is a cross-sectional view of an example embodiment of a
floating footer.
[0013] Figure 3 is a cross-sectional view of a second example embodiment of a
reinforced soil arch having a floating footer.
[0014] Figure 4 is a cross-sectional view of a third example embodiment of a
reinforced soil arch having a floating footer.
[0015] Figure 5 shows a plan view of a further example embodiment of a
floating footer.
Description
[0016] Throughout the following description specific details are set forth in
order to provide a more thorough understanding to persons skilled in the art.
However, well known elements may not have been shown or described in detail to
avoid unnecessarily obscuring the disclosure. Accordingly, the description and
drawings are to be regarded in an illustrative, rather than a restrictive,
sense.
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[0017] With reference to Figure 1, a first example embodiment of a reinforced
soil arch with a floating footer 20 is illustrated. Reinforced soil arch 20
has an
archway form 22, a reinforced soil arch structure 24 and a floating footer,
indicated
generally at 26.
[0018] In the illustrated embodiment of Figure 1, reinforced soil arch
structure
24 is formed from a plurality of layers of reinforcement material 28 and
compacted
fill 30 overlying and associated with archway form 22. Reinforced soil arch
structure 24 has a plurality of shear resisting devices 32 secured to the
exterior
io surface of archway form 22. Shear resisting devices 32 cooperate with
proximate
portions of the alternating layers of compacted fill 30 and reinforcement
material
28 to keep archway form 22 in contact with reinforced soil arch structure 24
by
preventing shear and separation between archway form 22 and reinforced soil
arch
structure 24 (i.e. shear resisting devices 32 ensure that the alternating
layers of
compacted fill 30 and reinforcement material 28 remain associated with archway
form 22). In some embodiments, reinforcement material 28 restrains archway
form 22 from moving inwardly (i.e. towards the centre of the opening defined
by
archway form 22) relative to floating footer 26. In some embodiments, the
earth
pressures associated with the construction of the reinforced soil arch 24
restrain
archway form 22 from moving outwardly (i.e. away from the centre of the
opening
defined by archway form 22) relative to floating footer 26. In some
embodiments,
shear resisting devices 32 help reinforced soil arch 24 support archway form
22.
[0019] Archway form 22 can be formed of any suitable material, such as metal,
plastic, concrete, wood, or a composite of two or more of the foregoing. In
one
example embodiment, archway form 22 is formed from structural metal plate.
Archway form 22 can have any suitable shape, for example a semicircle or
shallow
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semicircle, a reentrant arch, a vertical or horizontal ellipse, a pear shape,
a box
shape, or a curved overpass or underpass.
[0020] Reinforcement material 28 can be constructed from any suitable material
including geosynthetics, plastic, metal, wood, or the like. In some
embodiments,
reinforcement material 28 is woven geotextile.
100211 The layers of compacted fill 30 can be formed from any suitable
material.
In some embodiments, the layers of compacted fill 30 are formed from mineral
soil, for example, clay, silt, sand, gravel, cobbles, boulders, broken rocks,
or the
like, or mixtures of any of the foregoing. In some embodiments, the layers of
compacted fill 30 are made from manufactured materials such as: rubber;
plastics;
glass; expanded shale, clay or slate; aggregate; or shredded or chipped wood.
[0022] Shear resisting devices 32 can be any suitable material. In some
embodiments including the illustrated embodiment, shear resisting devices 32
are
angle plates attached to the exterior surface of the archway form. The angle
plates
can be affixed to the archway form in any suitable manner, for example by
welding, bolting or the like. In some embodiments, shear resisting devices 32
are
affixed to archway form 22 so that shear resisting devices 32 extend generally
orthogonally outwardly from archway form 22.
[0023] A floating footer 26 is provided at the base of each edge of archway
form
22, and extends longitudinally for the length or for substantially the length
of
archway form 22. With reference to Figure 2, the illustrated example
embodiment
of a floating footer 26 has a solid base 34 and a compressible squeeze block
36.
Each longitudinal edge 38 of archway form 22 floats on a squeeze block 36, and
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squeeze block 36 is supported on solid base 34. Archway form 22 is supported
on
but independent of squeeze block 36, i.e. archway form 22 is not coupled or
otherwise secured to squeeze block 36 or solid base 34.
100241 In some embodiments, including the illustrated embodiment, a bearing
plate 39 interposes all or a portion of longitudinal edge 38 of archway form
22 and
squeeze block 36, so that the downward force applied as archway form 22
settles is
applied evenly across all or a portion of the upper surface of squeeze block
36. In
some embodiments, bearing plate 39 is omitted or replaced by channel 41,
described below. The dimensions of bearing plate 39 can be selected by one
skilled in the art based on the characteristics of the soil supporting
floating footer
26, solid base 34, and/or squeeze block 36 to provide a desired rate and
extent of
compression of squeeze block 36. Archway form 22 is not secured to bearing
plate
39 or to squeeze block 36, i.e. archway form 22 floats on floating footer 26.
100251 Squeeze block 36 can be formed from any suitable material. In some
embodiments, squeeze block 36 is formed from a material having a known
compressibility. In some embodiments, squeeze block 36 is formed from
expanded polystyrene foam. In some embodiments, squeeze block 36 is formed of
wood (including solid wood, logs, wood chips or chunks, shredded wood or the
like), soil, sand, plastic, rubber, paper, weakly cemented sand and gravel
(engineered concrete), corrugated metal, or liquid- or air-filled bladders. In
some
embodiments, two or more of the foregoing materials may be used to provide
squeeze block 36.
100261 In some embodiments in which the material used to provide squeeze
block 36 is loose material (e.g. soil), a trench or other structure may be
provided to
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hold squeeze block 36 in place. For example, in some embodiments, the soil on
either side of the location where squeeze block 36 is to be provided is
compacted,
leaving uncompacted soil disposed within the trench to provide squeeze block
36.
In other embodiments, the soil at and adjacent to the location where squeeze
block
36 is to be provided is compacted, and then a trench is excavated within the
compacted soil and filled with loose soil or other material to provide squeeze
block
36. In some other embodiments in which the material used to provide squeeze
block 36 is loose, no structure is used to hold squeeze block 36 in place, and
the
material is dispersed across a sufficiently large area to ensure that the
bearing plate
to 39 or other load distributing member is supported on the material
providing
squeeze block 36. For example, in embodiments in which bearing plate 39 is
approximately 0.5 m wide, a zone of loose soil approximately 10-12 cm deep and
50 cm wide or wider can be spread to provide squeeze block 36.
100271 Without being bound by theory, the squeeze block 36 undergoes
deformation, allowing archway form 22 to settle downward at a similar rate to
the
reinforced soil arch structure 24, thus relieving a significant portion of the
load
from archway form 22. Bearing plate 39 and/or channel 41 described below
(where used) cooperate with squeeze block 36, solid base 34, and the
underlying
soil 37 to produce sufficient settlement of archway form 22 so that the
majority of
the dead load of the structure and live loads imposed on the structure are
transferred onto the reinforced soil arch 24. By selecting the material used
for
squeeze block 36 to have desired characteristics of compressibility and
dimensions,
squeeze block 36 can be designed to undergo a controlled deformation as the
load
on archway form 22 is increased as layers of reinforcement material 28 and
compacted fill 30 are built up over archway form 22. The dimensions of squeeze
block 36 are selected based on the engineering properties of the material used
for
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squeeze block 36.
[0028] The dimensions of bearing plate 39 can also be selected to control the
rate of deformation of squeeze block 36. Selecting a larger bearing plate 39
will
cause the downward force on archway form 22 to be distributed across a greater
surface area of squeeze block 36, thereby producing a smaller deformation.
[0029] Solid base 34 can be formed from any suitable material. In some
embodiments, solid base 34 comprises a concrete footing. In some embodiments,
solid base 34 comprises a steel reinforced concrete footing. In some
embodiments,
solid base 34 comprises compacted fill. In some embodiments, solid base 34
comprises native mineral soils. In some embodiments, solid base 34 comprises
wood, including solid wood, logs, pressure-treated wood, or the like. In some
embodiments in which solid base 34 comprises wood, reinforced soil arch 20 is
temporary in nature, since wood may eventually rot, causing additional
settlement.
[0030] The dimensions of solid base 34 are selected based on factors including
the engineering properties of the material selected for solid base 34, the
expected
load, and the allowable bearing capacity of the underlying soil. In some
embodiments, the dimensions of solid base 34, and particularly the width of
solid
base 34, are selected to be sufficiently large to minimize settlement of solid
base
34 relative to the underlying soil. Although solid based 34 has been
illustrated as
being wider than squeeze block 36, this is not necessary in all embodiments.
In
some embodiments, solid base 34 has the same width as squeeze block 36.
[0031] In some embodiments, a channel 41 interposes squeeze block 36 and the
base of each edge of archway form 22 instead of or in addition to bearing
plate 39.
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Channel 41 and bearing plate 39 are examples of load distributing members and
act
to distribute the force applied by the longitudinal edges 38 of archway form
22
more evenly on the surface of squeeze block 36. The bearing plate 39 or
channel
41 cooperate with squeeze block 36, solid base 34, and the underlying soil to
provide sufficient settlement of archway form 22 to transfer the majority of
the
dead load of the structure and the live loads imposed on the structure onto
reinforced soil arch structure 24. In some embodiments, channel 41 is a
uniform
channel. In some embodiments, channel 41 is an unbalanced channel. Archway
form 22 is supported by but independent of, i.e. is not coupled directly to,
the load
distributing member.
[0032] Any suitable material can be used to provide the load distributing
member, for example metal, concrete, wood or other relatively rigid material.
100331 With reference to the example embodiment illustrated in Figure 3 in
which like reference numerals have been used to indicate like parts, in some
embodiments, the solid base is provided by native mineral soils. In such
embodiments, squeeze block 36 is supported directly on the soil or sub-soil
surface
underlying archway form 22, indicated by reference numeral 40. In some
embodiments, the surface 40 is a rigid surface, for example bedrock. In some
embodiments, the surface 40 is compacted mineral soils.
100341 The selection of materials to be used to provide solid base 34 (or
which
can be used to provide surface 40) and squeeze block 36 can be made by one
skilled in the art based on the particular considerations at any given site.
Solid
base 34 or surface 40 should be selected to be relatively more rigid than
squeeze
block 36 to allow compression of squeeze block 36 between solid base
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40 and bearing plate 39/channel 41. In some embodiments, the material used to
provide solid base 34 or surface 40 is between 2 times and 1000 times stiffer
than
the material used to provide squeeze block 36, or any value therebetween, e.g.
10
times stiffer, 100 times stiffer, or the like. The material used to construct
squeeze
block 36 can be selected and made of an appropriate height to provide the
desired
level of compression of squeeze block 36 based on the anticipated load to be
experienced by archway form 22 and the compressibility of the material used to
provide squeeze block 36.
io [0035] Changing the surface area of channel 41 and/or bearing plate 39
that
contacts squeeze block 36 can affect deformation because a smaller deformation
will occur if a larger surface area contacts squeeze block 36 (the load will
be more
evenly distributed across the surface of squeeze block 36, and squeeze block
36
will undergo a correspondingly smaller deformation in the vertical direction).
is Changing the material used to provide squeeze block 36 will affect
deformation
because a stiffer material will undergo a smaller level of deformation than a
less
stiff material.
[0036] In some embodiments, the material used to provide squeeze block 36 and
20 the size of channel 41 and/or bearing plate 39 are selected to provide
an expected
deformation of between about 1% and about 2% of the overall height of
reinforced
soil arch 20. For example, if reinforced soil arch 20 is 2 metres in height,
the
material used to provide squeeze block 36 and the size of channel 41 and/or
bearing plate 39 are selected to provide an expected deformation of between
about
25 2 to 4 centimetres. For a reinforced soil height of 10 metres, the
target deformation
range in some embodiments is in the range of 10 to 20 centimetres. Different
levels of deformation may be desirable depending on the type of soil present
at the
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site where reinforced soil arch 20 is being erected. It has been found that
for
typical soil, deformation of approximately 1% of the overall height of the
structure
is common.
[0037] In one example embodiment of a reinforced soil arch having a 12 metre
arch with 12 metres of fill, the rigid base is concrete overlying bedrock, the
squeeze block is made from expanded polystyrene foam (EPS) and the bearing
plate is made from steel. The deformation of the squeeze block is
approximately
12 centimetres.
[0038] In another example embodiment, the squeeze block is compacted sand
having a height of approximately 10 centimetres and the load distributing
member
is an unbalanced channel. The rigid base is compacted cobbles and boulders and
the deformation of the squeeze block is approximately 5 centimetres.
[0039] In some embodiments, squeeze block 36 is restrained on solid base 34 so
that squeeze block 36 is not displaced when archway form 22 is initially
placed
during construction on squeeze block 36. In the example embodiment of Figure
2,
squeeze block 36 is restrained against lateral movement by a wire mesh form
42.
In other embodiments, geotextile fabric and compacted fill such as compacted
mineral soils or manufactured materials are used to secure squeeze block 36.
Any
other suitable mechanism for restraining squeeze block 36 on solid base 34
during
construction could be used in place of wire mesh form 42, for example plastic
dowels extending between solid base 34 and squeeze block 36, a trench formed
in
the top of solid base 34 that is dimensioned to partially receive squeeze
block 36
therein, adhesive securing squeeze block 36 to solid base 34, soil piled on
either
side of squeeze block 36 to secure squeeze block 36, or the like. In some
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embodiments, the securing of squeeze block 36 is only used as a construction
aid
and does not influence the as-constructed performance of the structure.
[0040] Generally it will be convenient to provide floating footer 26 extending
along the full length or substantially the full length of archway form 22.
However,
floating footer 26 could be provided discontinuously along the length of
archway
form 22 (e.g. a floating footer 26 extending less than half the length of
archway
form 22 could be provided at each longitudinal end of archway form 22, so that
a
middle portion of archway form 22 is not supported on a floating footer, or a
further floating footer 26 could be provided to support a middle portion of
archway
form 22, or the like), so long as floating footer 26 allows archway form 22 to
settle
a desired amount.
[0041] Typically, floating footer 26 will be provided along both edges of
is archway form 22. However, in some embodiments, floating footer 26 could
be
provided only along one edge of archway form 22.
[0042] Figure 4 illustrates an alternative embodiment of a reinforced arch 70
having a floating footer. Reinforced arch 70 has an archway form 72, a
reinforced
soil arch structure 74, and a floating footer generally indicated by reference
numeral 76.
[0043] Reinforced soil arch structure 74 has a plurality of layers of
reinforcement material 78 between a plurality of layers of compacted fill 80.
In the
illustrated embodiment, the plurality of layers of reinforcement material 78
and
compacted fill 80 are associated with archway form 72 via the interconnection
of
reinforcement material 78 with an outside surface 73 of archway form 72. In
some
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embodiments, reinforcement material 78 is interconnected with archway form 72
via securement to welded wire mesh 82, bars, or other means secured to the
outside
surface of archway form 72. Reinforcement material 78 may be connected to
archway form 72 in any suitable manner. In some embodiments, the
interconnection of reinforcement material 78 with outside surface 73 of
archway
form 72 restrains archway form 72 against inward movement relative to floating
footer 76. In some embodiments, the earth pressures associated with the
construction of reinforced soil arch 74 restrains archway form 72 against
outward
movement relative to floating footer 76.
[0044] Reinforcement material 78 and compacted fill 80 can be made from the
same materials as reinforcement material 28 and compacted fill 30. Archway
form
72 can be made from the same materials and comprise the same variety of shapes
as archway form 22.
[0045] Floating footer 76 is generally similar in construction to floating
footer
26 and can be constructed from the same type of materials used to construct
floating footer 26. In the illustrated embodiment, floating footer 76 has a
solid
base 84, a compressible squeeze block 86, and a bearing plate 90. Compressible
squeeze block 86 is supported on solid base 84 and can be supported thereon in
any
suitable manner as described with reference to compressible squeeze block 36.
Bearing plate 90 sits on compressible squeeze block 86, and each longitudinal
edge
88 of archway form 72 floats on one of the bearing plates 90. The longitudinal
edges 88 are supported on but independent of the bearing plate 90, i.e. the
longitudinal edges 88 are not coupled to the bearing plates 90.
[0046] In the example embodiment of a floating footer 26A illustrated in
Figure
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5, the squeeze block is provided discontinuously. A plurality of portions of
squeeze block 36A are supported on a solid base 34 to provide a floating
footer to
support archway form 22. Each portion of squeeze block 36A is separated from
adjacent portions by a gap 44. Squeeze block 86 or other portions of floating
footer 26 or 73 could similarly be provided in discontinuous fashion. Although
gaps 44 have been illustrated in Figure 5 as being of relatively uniform size,
the
discontinuous portions of the floating footer and/or the gaps therebetween
could be
of different sizes.
100471 While a number of exemplary aspects and embodiments have been
discussed above, those of skill in the art will recognize certain
modifications,
permutations, additions and sub-combinations thereof. For example:
= compressible squeeze block 86 could have cross-sectional shapes other
than
square or rectangular;
= while the bearing plate/channel, squeeze block and solid base have been
described as being unconnected, in some embodiments these elements could
be coupled together for convenience of construction.
It is therefore intended that the following appended claims and claims
hereafter
introduced are interpreted to include all such modifications, permutations,
additions and sub-combinations as are consistent with the broadest
interpretation of
the disclosure as a whole.
