Hydraulic and earth engineering – Earth treatment or control – Shoring – bracing – or cave-in prevention
Reexamination Certificate
2002-01-14
2003-07-22
Shackelford, Heather (Department: 3673)
Hydraulic and earth engineering
Earth treatment or control
Shoring, bracing, or cave-in prevention
C405S262000
Reexamination Certificate
active
06595726
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to geogrid-reinforced retaining walls, the assembly of parts from which such retaining walls are made, and methods of constructing a retaining wall from such elements, and relates more particularly to reinforced earthen retaining walls wherein the face of the retaining wall is formed by a vertically extending section of a wire facing unit having an integral horizontally extending floor to the rear of which a polymer geogrid is secured in a unique manner to reinforce fill material, such as aggregate, including soil or the like, placed behind the wire facing unit and over the geogrid.
2. Description of the Related Art
The use of welded wire facing units in the construction of retaining walls is well known as is the use of polymer geogrids to reinforce such earthen formations. U.S. Pat. No. 4,856,939 (hereinafter referred to as “the '939 patent”), the subject matter of which is incorporated herein in its entirety by reference, discloses the construction of a geogrid-reinforced earthen retaining wall incorporating welded wire facing units wherein the upper portions of the face sections of the wire facing units include kinks or hooks which serve, inter alia, to retain the ends of polymer geogrids, the remainder of the geogrids being designed to extend downwardly and rearwardly into the fill to reinforce the wall.
Polymer geogrids, particularly uniaxially stretched integral polymer geogrids of the type preferred for use in the construction of such retaining walls, may be made by the process disclosed in U.S. Pat. No. 4,374,798 (hereinafter referred to as “the '798 patent”), the subject matter of which is also incorporated herein in its entirety by reference. Such materials are relatively stiff and can be difficult to engage with the hooked formations in the manner proposed in the '939 patent.
Moreover, although the '939 patent shows the geogrid extending downwardly behind the face section of the wire facing unit and then rearwardly along the top of the floor section of the wire facing unit into the fill material, such sharp bends in the geogrid tend to weaken the strands and, in any event, oftentimes the geogrids do not bend so readily and simply extend rearwardly directly from the point where they engage the hook elements at the top of the face section of the wire facing unit, rather than the proposed arrangement where they extend rearwardly from the rear of the floor section of the wire facing unit.
Finally, attaching the geogrid to the top of the face section of the wire facing unit as taught in the '939 patent is inefficient and costly, especially the portion of the geogrid designed to extend downwardly behind the face section of the wire facing unit adding little to the strength of the earthen formation since the geogrid is primarily intended to reinforce the large volume of fill extending behind the wire facing unit.
SUMMARY OF THE INVENTION
A primary object of this invention is to provide a retaining wall system comprising, in combination, an assembly of elements, including a wire facing unit and a geogrid, with a unique interconnection between these elements which overcomes the foregoing and other such disadvantages in prior art systems.
A further object of this invention is the provision of a retaining wall system wherein the rear end portions of the floor section of the wire facing unit are interengaged at or near the forward end portions of a geogrid section in a manner that avoids the need to bend the geogrid, minimizes the amount of geogrid required, and ensures that the geogrid extends into the fill at a level that is most effective in reinforcing the retaining wall.
Yet another object of this invention is the provision of a wire facing unit wherein the wire elements forming the rear end portions of the floor section are bent into generally inverted U-shaped protuberances which define aligned openings extending generally transversely of the floor section of the wire facing unit. The wire elements forming the protuberances are spaced apart by a distance equal to, or a multiple of, the spacing between the apertures defined in the forward end portion of the geogrid so that the geogrid can be laid over the rear end of the floor section of a wire facing unit with the geogrid apertures overlying the upstanding protuberances. A connector rod can then be inserted through the aligned openings formed by the protuberances to secure the geogrid directly to the rear end of the floor section of the wire facing unit.
Another object of this invention is to provide an assembly of elements of the type described wherein the connector rod is somewhat flexible or resilient to facilitate insertion of the rod into the aligned openings in the floor sections of a wire facing unit between the wires forming the protuberances when the sides of the facing unit are not readily accessible as when the facing unit is located intermediate other facing units in the construction of an elongated retaining wall and the facing unit cannot be lifted up for access to the side because of an obstruction or when the geogrid extends over the floor section of more than one wire facing unit.
A still further object of this invention is to provide an assembly of elements, and a method of using the elements to easily and inexpensively form a reinforced retaining wall section, requiring the use of no extraneous materials or tools, and providing a secure engagement between the wire facing unit forming the face section of the wall and the geogrid reinforcing the fill material behind the wall.
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Anderson Robert
Egan Philip D.
Atlantech International Inc.
Jacobson & Holman PLLC
Saldano Lisa M.
Shackelford Heather
LandOfFree
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