The invention relates to the configuration, use, and manufacturing of a soil reinforcing element for ground improvement in a mechanically stabilized earth structure using the method of cold forming.
Earth retaining structures that are constructed using soil inclusions that are positioned substantially horizontal in compacted backfill are a form of ground improvement that is classified as mechanically stabilized earth (MSE) structures. MSE structures are known to be used for retaining wall systems, earthen embankments, bridge abutments that support the bridge substructure, dams that retain water, headwalls for structural plate crossings, mining crusher support structures, among others. Some examples of soil reinforcing devices and methods are shown and described in U.S. Pat. No. 8,632,277, which shares inventorship with the present application and is commonly owned, is fully incorporated herein by reference.
Referring to
The earthen formation or backfill 104 may encompass an MSE structure including a plurality of soil reinforcement elements 110 that extend horizontally into the backfill 104 to add tensile capacity thereto. In an exemplary embodiment, the soil reinforcement elements 110 may serve as tensile resisting elements positioned in the backfill 104 in a substantially horizontal alignment at spaced-apart relationships to one another against the compacted soil. Depending on the application, grid-like steel mats or welded wire mesh may be used as soil reinforcement elements 110, but it is not uncommon to employ “geogrids” made of plastic or other materials to accomplish the same end.
The earthen formation or backfill 104 may encompass an MSE structure including a plurality of soil reinforcement elements 110 that extend horizontally into the backfill 104 to add tensile capacity thereto. In an exemplary embodiment, the soil reinforcement elements 110 may serve as tensile resisting elements positioned in the backfill 104 in a substantially horizontal alignment at spaced-apart relationships to one another against the compacted soil. Depending on the application, grid-like steel mats or welded wire mesh may be used as soil reinforcement elements 110, but it is not uncommon to employ “geogrids” made of plastic or other materials to accomplish the same end.
The soil reinforcement element 110 may include a welded wire grid having a pair of longitudinal wires 112 that are substantially parallel to each other. The longitudinal wires 112 may be joined to a plurality of transverse wires 114 in a generally perpendicular fashion by welds at their intersections, thus forming a welded wire gridworks. In exemplary embodiments, the spacing between each longitudinal wire 112 may be about 2 in., while spacing between each transverse wire 114 may be about 6 in. As can be appreciated, however, the spacing and configuration may vary depending on the mixture of tensile force requirements that the reinforcement element 110 must resist.
Lead ends 116 of the longitudinal wires 112 may generally converge toward one another and be welded or otherwise attached to a connection stud 118 of a connector 10 that includes a tab or plate 122 extending from the connection stud 118. The connection stud 118 may include a first end or a stem 120 coupled or otherwise attached to a second end or a tab 122. As will be described below, several variations of the connection stud 118 may be implemented, without departing from the disclosure. In at least one embodiment, the stem 120 may include a cylindrical body having an axial length L. As illustrated, the lead ends 116 may be coupled or otherwise attached to the stem 120 along at least a portion of the axial length L. In one embodiment, the tab 122 may be a substantially planar plate and define at least one centrally-located perforation or hole 124.
The facing anchor 108 may include a pair of horizontally-disposed connection points or plates 126a, 126b cast into and extending from the back face 106 of the facing 102. As can be appreciated, other embodiments include attaching the facing anchor directly to the back face 106, without departing from the disclosure. Furthermore, as can be appreciated, other embodiments of the disclosure contemplate a facing anchor 108 having a single horizontal plate 126 (not shown), where the tab 122 is coupled only to the single plate 126 via appropriate coupling devices.
Each plate 126a, b may include at least one perforation 128 adapted to align with a corresponding perforation 128 on the opposing plate 126a,b. As illustrated in
In this arrangement, the soil reinforcement element 110 (as coupled to the connection stud 118) may be allowed to swivel or rotate about axis Y in a horizontal plane Z (
Moreover, the gap 132 defined between two vertically-offset plates 126a, 126b may also prove significantly advantageous. For example, the gap 132 may compensate or allow for the settling of the MSE structure as the soil reinforcement element 110 settles in the backfill 104. During settling, the tab 122 may be able to shift or slide vertically about the nut and bolt assembly 130 the distance X, thereby compensating for a potential vertical drop of the soil reinforcement element 110 and preventing any buckling of the concrete facing 102. As will be appreciated by those skilled in the art, varying designs of anchors 108 may be used that increase or decrease the distance X to compensate for potential settling or other MSE mechanical phenomena.
Furthermore, it is not uncommon for concrete facings 102 to shift in reaction to MSE settling or thermal expansion/contraction. In instances where such movement occurs, the soil reinforcement elements 110, which include longitudinal longitudinal wires 112, of the disclosure are capable of correspondingly swiveling about axis Y and shifting the vertical distance X to prevent misalignment, buckling, or damage to the concrete facing 102.
The construction of an MSE structure is a repetitive process that consists of placing compacted backfill and soil reinforcing in regular interval thicknesses until a desired height of the structure is achieved. The soil reinforcing elements are generally the same length from top to bottom and are spaced at regular intervals in both the horizontal and vertical direction. It is known that the soil reinforcing elements are fabricated from metal or plastic. The soil reinforcing can consist of strips or continuous sheets. The strips may consist of elements that are fabricated to form a grid. The soil reinforcing elements can be configured so the soil reinforcing profile is planar or bi-planar. The soil reinforcing can be fabricated to contain different surface configurations, patterns, and profiles along their length.
The soil reinforcing elements may be placed in an embankment with or without a facing element. The soil reinforcing elements are generally placed perpendicular to the face of the embankment however they may be placed in other skewed directions to bypass obstructions. For noncontinuous soil reinforcing elements the adjacent elements are spaced apart and are routinely within the same horizontal plane. The soil reinforcing in combination with the compacted backfill forms a composite structure. The compacted backfill resists compressive forces while the soil reinforcing resists tensile forces.
In instances where the soil reinforcing elements are attached to a facing element, the facing can be concrete, timber, steel, welded wire mesh or the likes thereof. The proximal ends of the soil reinforcing elements are attached to the facing in many different ways. The facing element forms the external surface of the MSE structure or embankment. The facing elements can be positioned vertically, or they can be battered into the earthen formation. The facing element prevents erosion of the backfill at the proximal end of the soil reinforcing between successive rows and columns of the soil reinforcing elements. The facing element may also serve as a decorative veneer.
Flat elongated strips as are conventionally known in the art for use in stabilized earth structures are shown and described in U.S. Pat. No. 4,710,062, the contents of which are incorporated herein by reference. For example, as shown in
It should be understood that the background is provided to aid in an understanding of the present disclosure and that nothing in the background section shall be construed as an admission of prior art in relation to the inventions described herein.
In an embodiment, a soil reinforcing element may include: a flat elongated strip of material defining an upper planar surface and a bottom planar surface; and a frictional profile formed on each of the upper planar surface and the bottom planar surface. The frictional profile may include a plurality of protuberances. The plurality of protuberances may be spaced apart from one another by a constant interval. The frictional profile may include a plurality of depressions. The plurality of depressions may be spaced apart from one another by a constant interval. The plurality of protuberances may be grouped into a plurality of groups and each of the groups is spaced apart from one another by a constant interval. The flat elongated strip of material may be twisted at intervals to form a plurality of sections, adjacent ones of the plurality of sections being twisted by 180 degrees with respect to one another. The flat elongated strip of material may be formed from metal, e.g., aluminum, stainless steel, or carbon steel.
In a further embodiment, a method of manufacturing a soil reinforcing element may include: providing a flat elongated strip where all surfaces of the flat elongated strip are smooth; and passing the flat elongated strip through a cold forming embossing roller device to emboss a frictional pattern on opposing surface of the flat elongated strip corresponding to impressions on roller surfaces of the embossing roller. The method may further include twisting the flat elongated strip, about a central axis longitudinally extending along a length of the flat elongated strip, into a plurality of sections, adjacent ones of the sections being twisted 180 degrees relative to one another.
In a still further embodiment, a method of manufacturing a soil reinforcing element using coiled metal may include: placing a coil on an unwinding pedestal to uncoil a strip from the coil; passing the strip through a straightening station to straighten the strip; passing the strip through a punch station to flatten the strip; passing the strip through an embossing station to create a frictional profile on top and bottom surfaces of the strip; passing the strip through a twisting station; passing the strip through a guillotine to cut the strip to a predetermined length; placing the finished strip in a stack; and banding the finished stack of strips. The frictional profile may include a plurality of protuberances. The frictional profile may include a plurality of depressions. The passing the strip through the twisting station may create a plurality of adjacent twisted sections that are twisted 180 degrees relative to one another about an axis extending lengthwise through the strip. The frictional profile may include at least one of a plurality of protuberances and depressions, the plurality of protuberances being grouped into a plurality of groups and each of the groups being spaced apart from one another by a constant interval.
These and other aspects of the present disclosure are described in greater detail below with reference to the accompanying figures.
Various embodiments and aspects of the present disclosure will be described with reference to the accompanying drawings in which like or similar features are labeled with the same reference number. The following description and drawings are illustrative of the present disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.
According to an embodiment of the present disclosure, a soil reinforcing element 150 is described with reference to
As shown best in
Another embodiment of a soil reinforcing element 200 is shown and described with respect to
As shown in
A method of manufacturing the soil reinforcing elements 150 and 200 may include providing a relatively flat elongated strip of metal that has a smooth surface on the top and bottom surfaces 152T, 152B and forming depressions or protuberances (i.e., raised elements) in the top and bottom surfaces 152T, 152B. The manipulation of the surface profile is fabricated by the method of cold form embossing. It is also economically advantageous to fabricate the soil reinforcing using stock metal material that is contained on a coil. Where the cold formed rolled raised and depressed profile is intermittently spaced along the flat elongated strip surface, where the spacing and shape of the raised and depressed profile is optimized and verified by using the method of pullout testing.
A further embodiment of a soil reinforcing element 300 is shown and described with respect to
Each of the reinforcing elements 300 may include a through bore (not shown) to facilitate coupling of the reinforcing element to an MSE.
A method of manufacturing the soil reinforcing element 300 may include providing a flat elongated strip 302 of material, e.g., metal. The flat elongated strip 302 may be substantially similar to the flat elongated strips 150, 200 described above except that the flat elongated strip 302 has been twisted about an axis longitudinally extending along its length by intermittently twisting the flat elongated strip 302 by 180 degrees such each of the sections 306 have their respective top and bottom surfaces remaining substantially planar with respect to the top and bottom surfaces of adjacent ones of the sections 306. As shown in
A particular frictional profile may be formed on respective ones of the top and bottom surfaces of the flat elongated strip of material by passing the flat elongated strip through an embossing station, such that as discussed above with respect to
Where the process method of manufacturing shown in
The embodiments and methods described in this patent pertains to soil reinforcing that is fabricated with flat elongated strips. Flat elongated strip soil reinforcing is known to have surfaces that are fabricated to form a grid, fabricated with a surface that is smooth or that has raised cross ribs. The flat elongated strips are also known to be fabricated with a sinusoidal or other geometric profile in a manner that allows for extension as a force is applied. For flat elongated strip soil reinforcing that utilizes a modified surface, such as a protrusion or raised cross rib, the surface protrusion or raised cross rib is formed during the final phase of the manufacturing process that is known as the hot rolling process.
Hot rolling is a metalworking process that takes place at a temperature above the recrystallization temperature of the material that may be between 850° C. to 1200° C. During the metalworking process the grains of the material deform and recrystallize. The metalworking process is designed so the metal maintains a microstructure where the crystals are approximately the same length and so as to prevent the metal from work hardening. The starting material typically consists of large pieces of metal that may be classified as slabs, blooms, and billets. In instances where the casting operation is continuous the material is fed directly into rolling mills at the predefined temperature. In some operations the material may start at room temperature, then is reheated to the proper temperature. In both cases the material is processed with a series of rollers to produce the end product shape such as strips, rounds, angles, channels, and the likes thereof. The surface of the element can be configured with raised ribs such as the ribs on concrete reinforcing bars. The raised ribs are placed on the element as a final rolling process while the material is still at or near the original billet temperature.
The placement of the raised protuberances (e.g., protuberances 154) requires sets of special rollers, e.g., embossing rollers, to produce elements, e.g., depressions or protuberances on the material that is passed through the rollers. Because special rollers are required the thickness, width, and configuration of the element is limited by the roller and limited in sizes that can be purchased by the consumer. Because special rollers are required the number of fabricators is also limited. It is therefore advantageous to develop a manufacturing process where a metal element can be manipulated into a soil reinforcing element of different widths and thicknesses and with different surface and cross section profiles using a cold rolling process.
A metalworking process that can manipulate the surface of metal is called embossing. Metal embossing is a stamping process that produces raised or sunken reliefs in the metal. The stamping process is typically made by means of matched male and female dies. In one process the metal is passed between male and female rollers that contain impressions of the desired pattern. The pattern is formed in the metal when it is cold. This is advantageous as it allows for the fabrication using different metal stock such as strips, plates, and bars. It also allows for the use of bars with different cross sections such as rectangular, square, round, hexagonal or any desired pattern placed on the surfaces or edges.
Soil reinforcing is designed to resists tension forces that develop in an earth mass. The soil reinforcing must be strong enough to resist rupture and to resists pullout from the earth mass. The resistance to rupture of a soil reinforcing element is a function of the metal properties and the cross-sectional area and is easily calculated. The pullout resistance of a soil reinforcing element is more complicated to calculate and is a function of the surface area and shape. To aid in predicting the pullout resistance of soil reinforcing it is determined through pullout testing. One such pullout test method is governed by the American Society for Testing and Materials (ASTM) specification D6706, Standard Test Method for Measuring Geosynthetic Pullout Resistance in Soil. To determine the pullout resistance of metal soil reinforcing the ASTM D6706 test is modified as required.
When used with soil reinforcing the raised reliefs that are hot-rolled on the surface of flat elongated strip is known to increase the resistance to pullout from the compacted backfill. A flat elongated strip with surface reliefs has a higher pullout capacity than that of a flat elongated strip with no surface relief. It is therefore advantageous to devise an economical method of manufacturing a soil reinforcing element that allows for the use of commonly produced metal shapes, that can have surface reliefs or projections, and, or, edge relief or projections, that increase the pullout capacity of the soil reinforcing element that is verified and optimized through testing.
It is also advantageous to devise an economical method of manufacturing a soil reinforcing element that allows for the use of commonly produced metal shapes where the cross section can manipulated by twisting the element so as to increase the pullout capacity of the soil reinforcing element that is verified and optimized through testing.
A system for constructing a mechanically stabilized earth structure may include a soil reinforcing element, e.g., the reinforcing element 150, 200, or 300, consisting of a flat elongated strip fabricated with cold formed embossed elements along the surface and a through bore at the proximal end; a facing anchor having first and second connection plates extending from the back face of an earth structure and being vertically-offset from each other at predetermined distances that accepts the proximal end of the soil reinforcing, each connection plate defining a horizontally-disposed through bore; and a coupling device extendable through each horizontally-disposed through bore and the central opening of the connection element to secure to the soil reinforcing to the facing anchor, wherein the combination of the through bore, central opening and the coupling device prevent the element from uncoupling. The combined connection element and soil reinforcing element 150, 200, or 300 may be configured to swivel in a horizontal plane. In an embodiment, the soil reinforcing element 150, 200, or 300 may replace the reinforcement elements 110 of the MSE structure that was described above with reference to
The system may include: a soil reinforcing element 150, 200, or 300 consisting of a flat elongated strip fabricated with cold formed embossed elements along the surface and a through bore may be formed in a proximal section of the of the flat elongated strip to facilitate coupling of the soil reinforcing element to a facing element such as those described above with respect to
A system for constructing a mechanically stabilized earth structure may include: a soil reinforcing element a flat elongated strip fabricated with cold formed twists along the central axis and a through bore at the proximal end (e.g., the soil reinforcing element 300); a facing anchor having first and second connection plates extending from the back face of an earth structure and being vertically-offset from each other at predetermined distances that accepts the proximal end of the soil reinforcing, each connection plate defining a horizontally-disposed through bore; and a coupling device extendable through each horizontally-disposed through bore and the central opening of the connection element to secure to the soil reinforcing to the facing anchor, wherein the combination of the through bore, central opening and the coupling device prevent the element from uncoupling. The combined connection element and soil reinforcing element may be configured to swivel in a horizontal plane.
In a further embodiment, a system for constructing a mechanically stabilized earth structure may include: a soil reinforcing element consisting of a flat elongated strip fabricated with cold formed twists along the central axis and a through bore at the proximal end; a facing consisting of welded wire mesh with horizontal and vertical wires, where the vertical wires extend as prongs at the top edge; and connecting the proximal end of the soil reinforcing to the wire facing element by passing the through bore of the proximal end of the soil reinforcing element over the vertical prongs of the facing element.
While the present disclosure may have been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope and spirit of the present disclosure as defined by the appended claims and their equivalents. In other words, the various exemplary embodiments disclosed in the present specification and drawings are merely specific embodiments to facilitate an understanding of the various aspects of the present disclosure and are not intended to limit the scope of the present disclosure. For example, the particular ordering of the steps may be modified or changed without departing from the scope and spirit of the present disclosure. Therefore, the scope of the present disclosure is defined not by the detailed description of the disclosure but by the appended claimed, and all differences in the scope should be construed as being included in the present disclosure.
The present application claims priority to and the benefit of U.S. Prov. Pat. App. Ser. No. 63/014,292, which was filed on Apr. 23, 2020, which to the extent that it is consistent with the present disclosure is hereby incorporated herein by reference in its entirety and to the extent that it is not inconsistent with the present disclosure.
Number | Date | Country | |
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63014292 | Apr 2020 | US |