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Claims  |
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The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. In a composite arch structure of the type comprising a liner with
compacted fill material thereagainst and thereabout to form a soil arch
thereabout, a foundation for said liner comprising yieldable footer means,
and means to control the amount and rate of yielding of said footer means
whereby said liner will settle at a rate at least equal to the rate of
settling of said fill material thereabout.
2. The structure claimed in claim 1 wherein said liner is an arched liner
having two longitudinal edges, each of said longitudinal liner edges being
affixed to a yieldable footer means, each of said yieldable footer means
comprising a first footer element and a second footer element, the
adjacent one of said longitudinal liner edges being affixed to said second
footer element, said second footer element, said second footer element
being in part at least receivable within said first footer element and
being capable of settling therein.
3. The structure claimed in claim 1 including means to shorten the
peripheral dimensions of said arched liner.
4. The structure claimed in claim 2 including means to shorten the
peripheral dimension of said arched liner.
5. The structure claimed in claim 2 wherein said first footer element
comprises an elongated member extending the length of said liner
longitudinal edge and having a top surface with a longitudinal slot
therein, said second footer element comprising an elongated member
extending the length of said liner longitudinal edge, a portion at least
of said second footer element being receivable within said longitudinal
slot of said first footer element with a telescoping fit and being
configured to settle within said longitudinal slot.
6. The structure claimed in claim 2 wherein said first footer element
comprises an elongated trench extending the length of said liner
longitudinal edge, said second footer element comprising an elongated
member extending the length of said liner longitudinal edge, said second
footer element being located in said trench and being capable of settling
therein.
7. The structure claimed in claim 4 including upstanding means affixed to
said second footer part, said upstanding means having a plurality of
vertical slots therein, said adjacent one of said liner edges having a
plurality of corresponding holes therein, said last mentioned liner edge
being affixed to said upstanding means and in spaced relationship to said
second footer means by fastening means passing through corresponding ones
of said liner holes and said slots in said upstanding means whereby said
slots permit relative movement of said last mentioned liner edge toward
said second footer means to shorten the peripheral dimension of said
arched liner.
8. The structure claimed in claim 4 wherein said arched liner is made up of
a plurality of arcuate panels, those adjacent panel edges extending
longitudinally of said liner being lapped, one of those adjacent edges
having holes therein, the other of said adjacent edges having
corresponding slots therein, said adjacent panel edges being joined
together by fastening means extending through said corresponding holes and
slots whereby said slots permit relative movement of said joined panel
edges to shorten the peripheral dimension of said arched liner.
9. The structure claimed in claim 5 including a layer of compressible
material of known compressibility within said elongated slot in said first
footer element, said material being compressible by said second footer
element whereby said material controls said amount and rate of yielding of
said footer.
10. The structure claimed in claim 5 including superposed layers of first
and second compressible materials within said elongated slot in said first
footer element, said first and second materials being compressible by said
second footer element, said first and second materials having known
compressibilities, said first material being more easily compressible than
said second material, whereby said first material initially controls said
amount and rate of yielding of said footer and said second material
thereafter controls said amount and rate of yielding of said footer.
11. The structure claimed in claim 5 including a layer of incompressible
material within said elongated slot in said first footer element, said
portion at least of said second footer element within said slot resting
upon and being supported by said incompressible material and means for
removing said incompressible material from said slot at a predetermined
rate whereby to control said amount and rate of yielding of said footer.
12. The structure claimed in claim 5 wherein said second footer element is
of inverted L-shape configuration, the long leg of said inverted L-shaped
second footer element comprising said portion receivable within said
longitudinal slot of said first footer element with a telescoping fit, the
short leg of said inverted L-shaped second footer element overlying said
top surface of said first footer element adjacent said slot therein, at
least one block of material of known compressibility being located between
said top surface of said first footer element and said short leg of said
second footer element, said block of material being compressible by said
short leg whereby to control said amount and rate of yielding of said
footer.
13. The structure claimed in claim 6 wherein said trench has a pair of
longitudinally extending side walls one located exteriorly of said liner
and the other located interiorly of said liner, means lining said interior
side wall and presenting a smooth planar face substantially parallel to
said longitudinal liner edge portion affixed to said second footer
element, said second footer element having a longitudinal surface parallel
to and in abutment with said lining face, said trench being filled with
compressible material of known compressibility initially maintaining said
second footer element in abutment with the upper part of said lining face,
said compressible material being compressible by said second footer part
whereby to permit settling of said second footer element downwardly along
said lining face and whereby to control said amount and rate of yielding
of said footer.
14. The structure claimed in claim 6 wherein said trench has a pair of
longitudinally extending side walls one located exteriorly of said liner
and the other located interiorly of said liner, means lining said interior
side wall and presenting a smooth planar face substantially parallel to
said longitudinal liner edge portion affixed to said second footer
element, said second footer element having a longitudinal surface parallel
to and in abutment with said lining face, said trench being filled with
incompressible material initially maintaining said second footer element
in abutment with the upper part of said lining face, said incompressible
material being capable of plastic flow at a known rate whereby to permit
settling of said second footer element downwardly along said lining face
and whereby to control said amount and rate of yielding of said footer.
15. The structure claimed in claim 6 wherein said trench is partially
filled with incompressible material, said second footer element being
supported in said trench by said incompressible material and means for
removing said incompressible material from said trench at a predetermined
rate whereby to control said amount and rate of yielding of said footer.
16. The structure claimed in claim 6 wherein said trench is partially
filled with incompressible material, said second footer element being of
an inverted U-shaped cross sectional configuration, the legs of said
inverted U-shaped second footer element being supported in said trench by
said incompressible material, said incompressible material being capable
of plastic flow at a known rate whereby said incompressible material will
flow upwardly between said legs of said inverted U-shaped second footer
element controlling said amount and rate of yielding of said footer.
17. The structure claimed in claim 6 wherein said trench is partially
filled with a compressible material of known compressibility, said second
footer element being supported in said trench upon said compressible
material, said compressible material being compressible by said second
footer element whereby to control said amount and rate of yielding of said
footer.
18. The structure claimed in claim 11 including at least one auger hole
passing through one of said first and second footer elements from said
slot though the top of said one of said footer elements at a point within
said liner whereby said incompressible material may be removed from said
slot at a predetermined rate by auger means.
19. The structure claimed in claim 11 including a passage passing through
one of said first and second footer elements from said slot through the
top of said one of said footer elements, said incompressible material
being capable of plastic flow through said passage at a predetermined rate
whereby to control said amount and rate of yielding of said footer.
20. The structure claimed in claim 11 including a passage passing through
one of said first and second footer elements from said slot through the
top of said one of said footer elements, said incompressible material
being a fluid, means to prevent leakage of said fluid between said first
and second footer elements, means permitting escape of said fluid from
said slot through said passage at a predetermined rate whereby to control
said amount and rate of yielding of said footer.
21. The structure claimed in claim 15 including at least one auger hole
passing through said second footer element from said trench through the
top of said second footer element at a point within said liner whereby
said incompressible material may be removed from said trench at a
predetermined rate by auger means.
22. The structure claimed in claim 15 including a passage passing through
said second footer element from said trench through the top of said second
footer element, said incompressible material being capable of plastic flow
through said passage at a predetermined rate whereby to control said
amount and rate of yielding of said footer.
23. The structure claimed in claim 15 including a passage passing through
said second footer element from said trench through the top of said second
footer element, said incompressible material being a fluid, means to
prevent leakage of said fluid between said trench and said second footer
element, means permitting escape of said fluid from said trench through
said passge at a predetermined rate whereby to control said amount and
rate of yielding of said footer. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a composite arch structure of the type comprising
an arched liner and compacted fill material thereagainst to form a soil
arch, and more particularly to a method and means for providing controlled
settling of the arched liner resulting in an improved soil arch with
greater load supporting capabilities.
2. Description of the Prior Art
The teachings of the present invention are applicable to any type of arch
wherein load transfer to some form of abutment means is contemplated. For
purposes of an exemplary showing, the invention will be described with
respect to its application to composite arch structures of the type
comprising an arched liner with compacted fill material thereagainst to
form a soil arch thereabout. Such structures are used, for example, as
highway or railway culverts, bridges, protective underground structures,
snow sheds and the like. While the arched liner may be made of any
appropriate material including concrete or plastic, again for purposes of
an exemplary showing the invention will be described in terms of the use
of liners made up of relatively thin, flexible, arcuately curved,
corrugated metallic plates. The edges of the arched liner are supported on
footers and the arched liner itself, when viewed in end elevation, may
have any appropriate curved shape such as a truncated ellipse, parabola,
hyperbola or a circle.
U.S. Pat. No. 3,508,406teaches a number of embodiments of composite arch
structures of the type to which the present invention is directed. When
the arched liner is made of relatively thin, arcuately curved, corrugated
metallic plates or the like, it will be understood that the liner will be
relatively flexible and will have sufficient strength to permit the liner
to be properly installed. However, the strength of the liner is not at all
capable of supporting the superimposed load of the completed composite
arch structure. The final strength of the structure resides primarily in
the compacted soil arch about the liner. When the span of the liner is
relatively large, it may be provided with longitudinally extending
buttress means affixed to the liner. The buttress means may be performed
concrete buttresses or may be poured in place during the construction of
the composite arch, as is taught in the above mentioned U.S. Pat. No.
3,508,406. Sand or gravel filled bins similarly affixed to the liner
accomplish the same purpose.
Heretofore, footers for the liner of a composite arch of the type
contemplated were prepared by first digging a trench for each footer
having a width for the size footer desired, based upon the expected load
and the supporting characteristics of the soil beneath the footer. The
trench for each footer ran the entire length of the structure. Concrete
was then poured in each trench to form the desired footers.
If the footers were to extend above the level of the ground, forms were
used for those portions of the footers above ground. A number of methods
were used to attach the edgemost plates of the arched liner to the
footers. One common method entailed the use of L-shaped channels affixed
to and extending the length of the concrete footers. The long wall of the
L-shaped channel of each footer was provided with holes, so spaced as to
align with corresponding holes in the edgemost plates of the arched liner
to permit these plates to be bolted to their respective L-shaped channels.
Frequently, these bolt holes in the long walls of the L-shaped channels
were in the form of horizontal slots so as to permit some leeway in
fitting the edgemost liner plates to their respective L-shaped channels.
The channels were of such width as to accept the corrugations of the liner
plates. The bottom of each channel element carried a plurality of
anchoring lugs embedded in the concrete footer prior to the hardening
thereof.
The basic cross-sectional configuration of the footers varied with the size
and type of structure being built, the angle of entry of the arched liner
edges into their respective channels and like considerations. The footers,
for example, could constitute an integral part of a concrete slab or
roadway extending therebetween.
As will be understood by one skilled in the art, the fill material about
the liner will tend to shift downwardly or settle. This settling is the
result of a number of different factors. During the placement of the back
fill about the liner, compaction will artificially produce a volume change
in the fill material by rolling, vibration, tamping and other momentary
load applications. With the passage of time, a volume change will occur in
the fill material by virtue of consolidation. A static external load will
produce a volume change by compression. Finally, shrinkage may produce a
volume change in the fill material by virtue of capillary stresses during
drying of the fill material. As used herein and in the claims hereafter,
the terms "settle" and "settling", as applied to the fill material, should
be construed broadly enough to encompass any one, any combination or all
of the above noted types of volume change and downward shifting of the
fill material.
The present invention is based upon the discovery that if yielding footer
means are used, permitting controlled settling or peripheral shortening of
the liner, the load upon the liner is relieved and a stronger soil arch
with improved load supporting capabilities results. It will further be
understood by the skilled worker in the art that controlled settling of
the liner will result in a diminishing of the cross-sectional area
encompassed by the liner and the bottom of the tunnel defined thereby. In
this sense, the settling of the liner results in a peripheral shortening
thereof.
While in most such structures the amount of settling falls within a matter
of inches or less, the specific amount and the specific rate of settling
are not the primary considerations. The primary factor, among many, is the
relative rate of settling between the liner and the fill material. The
settling of the liner should be so controlled as to be equal to or greater
than the settling of the fill material.
SUMMARY OF THE INVENTION
The present invention is directed to a composite arch structure of the type
comprising an arched liner with compacted fill material thereagainst to
form a soil arch thereabout. Yieldable footer means are provided for the
liner. The yielding of the footer means is controlled so that the liner
will settle at a rate equal to or greater than the settling of the fill
material thereabout.
In a first embodiment, each footer comprises a two-part structure. The
first part is an elongated member extending the length of the arched liner
and having a longitudinal slot therein. The second part of the footer
comprises a shiftable member, again extending the length of the liner. The
liner edge is affixed to the second part of the footer which is adapted to
be slidably received in the longitudinal slot of the first footer part.
Within the slot of the first footer part there is located a compressible
material which will permit a slow and controlled movement of the second
footer part into the slot.
In another embodiment, the same footer structure is employed. However, an
incompressible material is located in the slot. A plurality of holes
leading from the slot to the interior of the tunnel defined by the liner
are provided either in the first or the second footer part. These holes
may be such that the incompressible material will bleed or extrude up
through them in a controlled manner. Alternatively, the holes may be so
sized as to permit removal of the incompressible material from the slot in
a controlled manner by augur means or the like.
In yet another embodiment of the invention, the footer elements are
identical to those described with respect to the first and second
embodiments, but the incompressible or compressible material is replaced
by a distortable member filled with a fluid. The distortable member has
one or more outlets extending through holes either in the first or the
second footer part to the interior of the tunnel defined by the liner. The
one or more outlets are each provided with valve means by which the fluid
may be released in a controlled manner.
In another embodiment of the invention, the first footer part comprises a
trench-like structure, the inner wall of which is lined with concrete or
other suitable material. The remainder of the trench is filled with a
yielding material. The edge of the arched liner is affixed to a second
footer part or block extending the length thereof. The block is located
against the lined wall of the trench and is capable of shifting downwardly
along the lined wall through the action of the yielding material.
In yet another embodiment of the invention, the second or movable footer
part may have an inverted L-shaped cross-section, the long leg of the
L-shaped cross-section being received within the longitudinal slot of the
first footer part and the short leg of the L-shaped cross-section adapted
to overlie the upper surface of the first footer part. Between the upper
surface of the first footer part and the underside of the short leg of the
second footer part there is located a block of compressible material. As
the block compresses in a predetermined fashion, the second footer part
will slid downwardly within the slot of the first footer part.
In another embodiment of the present invention the footer comprises a
unitary structure located in a trench filled with incompressible material.
The footer may be provided with a plurality of holes passing therethrough
and leading to the interior of the tunnel defined by the liner. These
holes may be so sized as to permit the incompressible material to bleed or
extrude upwardly therethrough in a controlled fashion, or they may be of
such dimension as to permit controlled removal of the incompressible
material by augur or other appropriate means. Alternatively, the unitary
structure could be provided with a void into which the incompressible
material could shift.
In a final embodiment of the present invention the footer is a unitary
structure to which the edge of the liner is affixed. The footer extends
the length of the liner and is located in a trench containing compressible
material. As the material compresses, the footer is enabled to sink into
the trench.
It is also within the scope of the invention, in association with all of
the above described embodiments, to so construct the liner itself as to
permit actual, physical peripheral shortening thereof, as will be
described hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of an exemplary composite arch structure
illustrating one embodiment of the yieldable footers of the present
invention.
FIG. 2 is a fragmentary cross-sectional elevational view of the left-hand
footer of FIG. 1.
FIG. 3 is a fragmentary, side elevational view of an L-shaped channel by
which the arched liner of the composite arch structure is affixed to its
footers.
FIG. 4 is a cross-sectional view taken along the section line 4--4 of FIG.
3.
FIG. 5 is a fragmentary perspective view, partly in cross-section,
illustrating the one edge of the arched liner affixed to the L-shaped
channel of FIG. 3, which, in turn, is affixed to the footer of FIGS. 1 and
2.
FIG. 6 is a fragmentary cross-sectional view similar to FIG. 2 and
illustrating another embodiment of the yieldable footer of the present
invention.
FIG. 7 is a fragmentary, cross-sectional view illustrating yet another
embodiment of the yieldable footer of the present invention.
FIG. 8 is a fragmentary, cross-sectional view similar to FIG. 2 and
illustrating another embodiment of the yieldable footer of the present
invention employing a modified movable footer part.
FIG. 9 is a fragmentary, cross-sectional view illustrating yet another
embodiment of the yieldable footer of the present invention wherein the
footer comprises a unitary structure mounted in a trench containing
incompressible material.
FIG. 10 is a fragmentary, cross-sectional view illustrating a one-piece
footer mounted in a trench having compressible material therein.
FIG. 11 is a fragmentary perspective view illustrating two plates of a
flexible liner bolted together, one plate having slots to receive the
bolts to enable the plates to shift slightly with respect to each other to
reduce their peripheral dimensions.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates an exemplary composite arch structure comprising an
arched liner 1 with compacted fill material 2 thereagainst forming a soil
arch generally indicated at 3 thereabout. As indicated above, the liner
may be made of any suitable material. In a typical embodiment, the liner 1
is made up of relatively thin, corrugated, steel panels joined together by
bolts or other suitable means. The liner is supported by footers generally
indicated at 4 and 5.
The initial ground level is indicated at 6. In the usual construction
procedure, the footers 4 and 5 are first put in place. The edge panels of
the liner are then affixed to their respective footers, the footers
running the full length of the liner. When the liner is complete, it will
have sufficient strength to be free-standing, but by virtue of the
thickness of the panels used and the size of the structure, the liner will
generally be flexible and will not have sufficient strength to sustain, in
and of itself, the weight of the fill material place thereabout. Careful
back filling and compaction of fill material against the liner is then
conducted on both sides of the liner with progress at both sides of the
liner being substantially the same. It will be understood by one skilled
in the art that the strength of the back fill will be added to the liner
as work progresses. Upon completion of the back filling and compaction,
the soil arch 3 is formed and itself sustains the bulk of the forces
thereon. During the construction process, the liner serves primarily as a
form for the soil arch. Upon completion of the structure, the arch liner
serves primarily simply as a lining for the structure.
When the composite arch structure is relatively large and has a relatively
large span, it has been found that back fill and compaction become
difficult at or above those points on the sides of the liner where the
radial forces acting on the liner form an angle of about 45.degree. or
more to the horizontal. Compaction and back fill at or above these points
may bring about the risk of distortion or failure of the liner. As a
consequence, it has been found advantageous to affix to each side of the
liner, at or above those points, longitudinally extending load-spreading
buttress means. Such buttress means are indicated in dotted lines at 7 and
8 on either side of the liner 1. Such buttress means are taught in the
above mentioned U.S. Pat. No. 3,508,406. The buttress means may take any
one of a number of forms. For example, they may be precast concrete
elements affixed to the liner. Alternatively, they may comprise concrete
members affixed to the liner, having been poured in place during the back
filling operation. In yet another form, they may constitute bin-like
structures filled with sand or other known consolidated material.
The present invention is based upon the discovery that if the liner 1 is
permitted to settle in a controlled fashion (i.e., at a rate equal to or
greater than the settling of the fill material), the load pressures above
the liner may be directed away from the steel arch to the back fill
material itself, which is more capable of sustaining the load pressures.
This results in further consolidation and packing of the particles of the
back fill material in closer and tighter formation, thereby increasing the
strength of the soil arch and its load supporting capabilities. It has
been found that the soil arch can be made to sustain 90% or more of the
live load, the liner bearing only 10% or less.
It will be understood that the footer 5 is a mirror image of the footer 4
and is otherwise identical. The footer 4 is best shown in FIG. 2. Footer 4
comprises a first footer part 4a and a second footer part 4b. While the
footer part 4a may be made of any suitable material and in any appropriate
manner, it can readily be poured of concrete in an appropriate size trench
9 at the initial ground level 6 and of a length equal to the length of the
liner 1. Through the use of a suitable form or the like, a longitudinally
extending notch or slot 10 is provided in the footer part 4a, again being
of a length equal to the length of the liner 1. The slot 10 should lie at
an angle to the horizontal substantially equivalent to the angle formed by
the edge of the arched liner 1 to the horizontal.
The second footer part 4b extends the length of the liner 1 and may be made
of any suitable material including metal wood or the like. As shown in
FIG. 2, the part 4b constitutes a precast concrete member. The second
footer part is so sized as to be received in the slot 10 of the footer
part 4a with a sliding fit.
The edge of the liner 1 is affixed to the second footer part 4b by means of
an L-shaped channel 11. The channel 11 is most clearly shown in FIGS. 3
through 5. The channel comprises a tall wall 11a, a short wall 11b and an
intermediate web 11c. The tall wall 11a is provided with a plurality of
perforations in the form of short horizontal slots 12. Finally, the
L-shaped channel 13 has a plurality of anchor tabs formed from the web 11c
and extending downwardly as at 13. During the formation of the second
footer part 4b, the anchor tabs 13 are embedded in the concrete to firmly
affix the channel 11 to the footer part 4b. During the assembly of the
liner, those plates forming the edge of the liner are located in the
L-shaped channel 11 between the tall wall 11a and the short wall 11b and
are bolted to the tall wall. To this end, the liner plates are provided
with bolt holes adapted to align with the slots 12. Bolts 14 affix the
liner plates to the channel 11, as is shown in FIGS. 2 and 5. It will be
evident from FIGS. 4 and 5 that the web 11c of the channel is of such
width as to easily accept the corrugations of the panels of liner 1. In
this way, the liner edge is firmly affixed to the footer part 4b.
Referring to FIGS. 2 and 5, the bottom of the longitudinal slot 10 of
footer part 4a is provided with a compressible material 15. Preferably,
the compressible material runs the full length of the slot 10 and is of
approximately uniform depth. As will be described hereinafter, the
compressible material 15 should be carefully selected to provide the
required settling of the liner. While not so limited, typical compressible
materials suitable for this purpose may include wood, air-entrained
concrete, a synthetic material with suitable compressibility such as
urethane and the like.
As will further be described hereinafter, the footers may be so designed as
to initiate settling of the liner at any desired stage as the fill
material 2 is caused to settle for any of the reasons enumerated above by
appropriate selection of the predetermined limiting load, the exceeding of
which will activate the yielding footer means. Thus, the footers could be
so designed as to initiate settling of the liner during the initial back
filling and top loading of liner 1.
Under most circumstances, however, during the initial back filling and top
loading of the liner 1, the forces will not be sufficient to compress the
compressible material 15. As the forces exceed the predetermined limiting
load, however, the material 15 will compress, causing the liner 1 to
settle. Keeping in mind the nature of the back fill material, the size and
purpose of the structure and the forces involved, the size of slot 10 and
the amount of compressible material with a given compressibility would
determine the controlled settling of the liner 1, including the amount and
rate thereof.
It would also be within the scope of the invention to provide a
compressible element 15 made up of two layers of different material having
different compressibilities. This would provide a load actuated system
capable of triggering a resistance mechanism. Thus, for example, the
initial load actuated settling would take place at a first predetermined
rate dependent upon the more easily compressible layer and thereafter at a
lesser predetermined rate dependent upon the characteristics of the less
compressible layer.
FIG. 2 can also be considered to be an illustration of a second embodiment
of the present invention. This embodiment is substantially the same as the
previously described embodiment with the exception that the material 15 is
incompressible, rather than compressible. The controlled settling of liner
1 is accomplished by controlled removal of the incompressible material 15
from beneath the footer part 4b. To this end, the footer part 4b may be
provided with a plurality of augur holes, spaced along its length. One
such augur hole is illustrated in broken lines at 16 in FIG. 2. The hole
16 is so sized that an augur may be extended therethrough and used to
remove the material 15 at a predetermined rate.
Any appropriate incompressible, cohesionless solid may be used. Clay, or a
clay-sand mixture, would serve as an appropriate incompressible material.
Alternatively, the footer part 4b may be provided with a plurality of
holes, so sized as to permit controlled extrusion or bleeding therethrough
of the incompressible material 15. Hole 16 in FIG. 2 may also be
considered to represent such a bleed hole or extrusion orifice. Valve
means (not shown) may be connected to the upper end of hole 16 to further
control the bleeding or extrusion of the incompressible material 15.
Instead of the holes 16 in footer part 4b, similar holes, serving either
as bleed or augur holes, could be located in footer part 4a as shown in
broken lines at 16a.
When the embodiment of FIG. 2 is provided with incompressible material 15,
substantially the same factors must be taken into consideration in order
to establish the predetermined and desired settling rate for liner 1. The
difference here lies in the fact that instead of compressing a material
having a known compression characteristic, the incompressible material is
removed at a predetermined rate (whether it be by auguring, bleeding,
extruding or the like).
FIG. 6 illustrates another embodiment utilizing an incompressible material.
The first and second footer parts are substantially identical to those
illustrated in FIG. 2 and like parts have been given like index numerals.
The primary difference between the embodiment of FIG. 6 and that of FIG. 2
lies in the fact that the embodiment of FIG. 6 utilizes an incompressible
material in the form of a fluid located within a flexible, deformable
container 18, such as a steel container.
A hole 19 is provided in the second footer part 4b to receive a tubular
outlet 20 of the container 18. At its uppermost end, extending beyond
footer part 4b, an appropriate adjustable valve 21 is provided to permit
controlled bleeding of the fluid 17. It will be understood by one skilled
in the art that the outlet for container 18 may extend through a hole in
footer part 4a, rather than footer part 4b. This is illustrated in broken
lines in FIG. 6 wherein the footer part 4a is shown as having a hole 22
extending from the bottom of slot 10. An outlet 23 provided with an
adjustable valve 24 is illustrated as being located within the hole 22.
The container 18 may extend the length of the liner and, if desired, may be
provided with more than one outlet tube 20 and valve 21. Alternatively, a
plurality of shorter containers may be located in slot 10, either in
end-to-end abutting relationship or spaced from each other.
It will be understood by one skilled in the art that the valve or valves 21
will be so adjusted (manually or mechanically) as to release the fluid 17
in a controlled manner to provide the desired controlled settling of liner
1. It will further be understood that if footer part 4b were appropriately
sealed in slot 10, no container 18 would be required, the hole 19 in
footer part 4b or the hole 22 in footer part 4a could be, themselves,
provided with appropriate valve means.
Another embodiment of the present invention is illustrated in FIG. 7. The
initial ground level is shown at 25. In this embodiment, the first footer
part comprises a trench 26, the inside vertical wall of which is lined
with any appropriate material such as the concrete lining 27. The concrete
lining 27 presents a smooth, planar face 27a preferably oriented at an
angle substantially parallel to the edge portion of liner 1 affixed to
channel 11. The face 27a may be covered with a fiber layer, plywood,
polyethylene material or the like, the purpose of which will be described
hereinafter. The remainder of the trench 26 is filled with a known
yieldable material 29 such as silt or the like which would compress at a
rate faster than the surrounding soil. The trench 26 will extend the
length of liner 1.
The second footer part comprises a block 30 of any appropriate material.
The block 30 also extends the length of the liner 1 and may, for example,
comprise a preformed concrete member. The liner 1 is affixed to footer
part 30 in any appropriate way, including the use of L-shaped channel 11
and bolts 14, as described with respect to FIG. 2.
In operation, the compressible material 27 and the size of the trench
portion containing it are chosen in the light of substantially the same
factors outlined with respect to the embodiment of FIG. 2. The same is
true for the size of footer part 30. It will be understood that the
compacted back fill material 2 will tend to urge the second footer part 30
against the face 27a lining wall 27. During the controlled settling
permitted by the compressible material 29, the second footer part 30 will
shift downwardly along the lining wall 27. The fiber or plywood or
synthetic layer 26 will assure proper movement of the second footer part
30 along the lining wall and will prevent bonding or undue friction
therebetween. It will be understood that the layer 28 may be affixed
either to the surface 27a of lining wall 27 or the adjacent surface of
second footer part 30. In either event, the layer 28 preferably covers the
entire surface to which it is affixed. From the above description, it will
be understood that the embodiment of FIG. 7 will provide a predetermined
and controlled settling of liner 1.
In the embodiment of FIG. 7 an incompressible material 29 may also be used,
so long as the material is capable of plastic flow. In such an instance,
as footer part 30 settles, the incompressible material will flow
thereabove.
Another embodiment of the present invention is illustrated in FIG. 8. In
this figure, the first footer part is identical to that of FIG. 2 and like
parts have been given like index numerals. The second footer part 31 is
similar to second footer part 4b of FIG. 2 with the exception that it has
a lateral extension 33, the bottom surface of which is shown at 33a. The
liner 1 may be affixed to the second footer part in any appropriate way.
For purposes of an exemplary showing, it is illustrated as being attached
to the second footer part in the same manner described with respect to
FIG. 2 and like parts have been given like index numerals.
As in the case of the embodiment of FIG. 2, footer part 4a extends the
length of the liner 1, as does the slot 10 therein. Similarly, footer part
31 and its extension 33 run the length of liner 1. In this embodiment, a
block of compressible material of known characteristics is shown at 34
located between the undersurface 33a of extension 33 and the top surface
portion 35 of footer part 4a. The block 34 may be made of any of the
compressible materials listed above and for purposes of an exemplary
showing is illustrated as being a wooden block. The block 34 may run the
length of the extension 33. Alternatively, a series of blocks may be used
in end-to-end relationship. The series of blocks may have their ends
abutting, or they may be spaced from each other. The greater the forces to
be sustained, the more nearly continuous the block or blocks should be. It
will be evident that as the block 34 compresses, the second footer part 31
will shift downwardly witin slot 10, resulting in the settling of liner 1.
The appropriate selection of block 34 with respect to its compression
characteristics, cross-sectional size, and the like will produce the
desired controlled settling.
FIG. 9 illustrates an embodiment wherein the footer comprises a single
footer element 36 and a trench 37, the footer element 36 being intended to
settle in a controlled fashion within trench 37. The trench 37 is formed
at the initial ground level and is of a length equal to the length of the
liner 1. The unitary footer element 36 is adapted to be received within
the trench 37 and extends the length of liner 1. The liner 1 may be
affixed to the footer element 36 in any appropriate manner. Again it is
illustrated as being attached to the footer in the same manner taught with
respect to FIG. 2 and like parts have been given like index numerals.
The cross-sectional configuration and size of footer element 36 will depend
upon the size and nature of the structure being built, the nature of the
fill material 2 and like considerations. The upper surface of the footer
element will be shaped in accordance with the angularity of that portion
of liner 1 affixed to it. While the factor element 36 may have a
rectangular or substantially rectangular cross-section, for purposes of an
exemplary showing it is illustrated as having an inverted U-shaped
cross-section.
Within the trench 37 and beneath footer element 36 there is located an
incompressible material 38. The material 38 may be made up of any of the
incompressible materials listed above and again the amount and nature of
the material 38 will depend upon the settling characteristics desired for
the liner 1 and can readily be determined by one skilled in the art. The
controlled settling is achieved in substantially the same way taught with
respect to FIG. 2 when the material 15 is incompressible. To this end, a
plurality of holes 39 may be provided in footer element 36 to enable
controlled removal of the material 38 by augur means or the like.
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