Patent Application
20220064895
The invention relates to the configuration, use, and manufacturing of an improved metal strip soil reinforcing element for ground improvement in a mechanically stabilized earth (MSE) structure using the method of cold forming.
Earth retaining structures that are constructed using soil inclusions are positioned substantially horizontal in compacted backfill and 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.
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-planer. 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 attempts to resist 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, embankment, or earth retaining structure. 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.
The embodiments and methods described in this patent pertains to soil reinforcing that is fabricated with metal strips. Conventionally, metal 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 metal strips are also known to be fabricated with a sinusoidal profile such that the strip extends as a force is applied.
Unfortunately, for metal strip soil reinforcing that utilizes a modified surface, such as a protrusion or raised cross rib, the surface protrusion or raised cross rib is always formed during the final phase of the manufacturing process from raw heated stock in what 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 particular material that may be between 850° C. to 1200° C. based upon the metallic alloy involved. During the hot rolling metalworking process the grains of the material deform and recrystallize during cooling. The hot rolling metalworking process is designed to 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 for hot rolling typically consists of large pieces of metal that may be classified as slabs, blooms, and billets which are then squeezed and modified under high temperature and pressures. In instances where the initial casting-to-forming operation is continuous the cast material is fed directly into hot rolling mills at the predefined temperature. The metal material, typically proximate its glass transition temperature (tg), is processed back-and-forth with a series of high pressure (and hot) rollers to produce the end product shape such as strips, rounds, angles, channels, and the likes thereof which are then cooled in specially constructed cooling arrangements. The surface of the hot rolled element can be configured with raised ribs such as the ribs on conventionally known concrete reinforcing bars (formed by hot rolling). These raised ribs are placed on the element as a final rolling process while the material is still at or near the original billet temperature and so that the microstructure is easily manipulated.
In hot rolling the placement of the raised ribs requires sets of special hydraulic rollers to produce different sizes of elements in different positions. Because special hot rollers are required the thickness, width, and configuration of the conventional element is limited by the hot roller and thus limited in sizes that where hot rollers can be purchased by the consumer. Because special hot rollers are required the number of fabricators, and the types of fabrication facilities capable of handling large thermal masses is also limited.
A conventional metalworking process that can manipulate the surface of metal is called die forming. Metal die forming is a process that uses pressure and dies to manipulate metallic shapes at a cool temperature (e.g., room temperature) that is far below a glass transition (tg) of any initial metallic alloy material.
The die forming process is typically made by means of matched male and female dies. In one process the metal is passed between male and female dies that contain complementary impressions of the desired end pattern. The pattern is formed in the metal when it is cold under pressure. 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.
Unfortunately, current structures in soil reinforcing including soil reinforcing structures formed by hot rolling are not as effective in resisting tensile forces as desired proving difficult to calculate and quantify, are costly and dangerous to produce and expensive to transport to the thermal requirements for hot rolling and the specific requirements for hot rolling.
The present invention provides at least one aspect not appreciated in the conventional arts and provides an improved strip soil reinforcing element and enhanced method of manufacturing as well as providing for a resultant improved mechanically stabilized earth (MSE) structures containing an improved strip soil reinforcing element provided by the present invention.
According to one alternative aspect of the present invention, there is provided a soil reinforcing element and method of manufacturing for use in a mechanically stabilized earth (MSE) structure. A smooth metal strip is fabricated into a soil reinforcing element that is manufactured from stock pulled from a coil, the surface of the strip surface is manipulated using the technique of cold forming. Where the manipulated surface is optimized to consist of a peak and a valley to increase the pullout resistance when embedded in an earthen formation involving a mechanically stabilized earth (MSE) structure.
In a further alternative aspect of the present invention, it is recognized that the invention provides 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.
According to another aspect of the present invention it was discovered that pullout resistance of soil reinforcing elements is a function of frictional resistance that develops along the interface of the soil reinforcing element and the soil and by passive resistance that develops at the location of a profile that is generally perpendicular to the direction of the applied force. It was determined that the configuration and orientation of the passive profile is therefore important to optimize pullout resistance without adding cost to the element.
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 resist pullout from the earth mass. Conventionally, the resistance to rupture of a conventional soil reinforcing element is a function of the metal properties and the cross-sectional area and is easily calculated. 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. Unfortunately, the present Applicant discovered that the pullout resistance of a soil reinforcing element is more complicated to calculate and is a function of the surface area and shape of the element. As a result, according to another aspect of the present invention, it was determined to calculate the predicted pullout resistance of soil reinforcing through laboratory testing and as a result to resolve that the pullout resistance of metal soil reinforcing the ASTM D6706 test was required as modified herein.
It is therefore an advantageous aspect of the present invention 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 passive projections or peaks and valleys, and/or edge relief or projections applied to it that increases the pullout capacity of the soil reinforcing element that has been maximized and verified through laboratory pullout testing and can be assembled into a mechanically stabilized earth (MSE) structure, having a facing element to secure a panel anker and one end of the improved strip soil reinforcement.
According to an alternative aspect of the present invention there is provided an improved strip soil reinforcing element that is fabricated from stock consisting of a strip where all surfaces are smooth, where the surface of the strip is manipulated using a cold forming process by passing it through opposing surfaces of two profile dies, where the profile dies position is adjustable so the strip is passed between the profile dies under pressure, whereas the profile die surface configuration combined with pressure cold forms the profile along the surface of the strip that optimizes pullout resistance.
According to another alternative aspect of the present invention, there is provided a method for manufacturing a metal soil reinforcing element wherein the metal is one of a carbon steel alloy, aluminum, stainless steel, copper alloy, and bronze alloy.
According to another alternative aspect of the present invention there is provided an improved strip soil reinforcing element and method of manufacturer wherein a proximal end of the strip has a through bore and has passive surface profiles spacing, and geometry optimized and verified by pullout testing that resists pulling out under tension.
According to another alternative aspect of the present invention, there is provided an improved strip soil reinforcing element that is fabricated from stock consisting of a generally flat strip where the top, bottom and side surfaces are smooth, where the top surface of the strip is formed with a combination of at least one set of transverse ribs consisting of a peak and valley where the peak and valley are spaced between generally flat surfaces.
According to another alternative aspect of the present invention, there is provided an improved strip soil reinforcing element wherein the peaks and valleys are uniformly spaced based apart along the surface of the strip, and where the peak and valley are uniformly spaced apart and the distance between a next set of peaks and valleys is variable.
According to another aspect of the present invention there is provided a method of manufacturing an improved soil reinforcing element using coiled metal comprising the steps of placing the coil on an unwinding pedestal; passing the strip through a straightening station; passing the strip through a punch station; passing the strip through a profiling station; passing the strip through a guillotine; placing the finished strip in a stack; banding the finished stack of strips and where the order of the process is adaptive and in part interchangeable.
According to another aspect of the present invention there is provide a mechanically stabilized earth (MSE) system and a method for constructing a mechanically stabilized earth system, comprising: a soil reinforcing element consisting of a metal strip fabricated with cold formed profiled peaks and valleys 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: and wherein the combined connection element and soil reinforcing element is capable of swiveling in a horizontal plane.
According to another alternative aspect of the present invention there is presented a strip soil reinforcing element, for use in a mechanically stabilized earth (MSE) structure, comprising: a stock member consisting of a strip wherein all surfaces on the strip are smooth, where the surface of the strip is manipulated using a cold forming process by passing the strip through opposing surfaces of two profile dies imparting a resistance profile on the strip; the resistance profile includes at least one first peak member on a first side of the strip having the first side and an opposite second side, and extending between respective at least a first flat section and a second flat section of the strip; each of the first and the second flat sections extending along a common plane; a first flat side and a second flat side on opposing sides of the at least one peak member having equal lengths and defining an obtuse medial angle therebetween; a first obtuse angle defined from the first flat side of the at least one first peak relative to the first flat section and a second obtuse angle defined from the second flat side of the at least one first peak relative to the second flat section; and the first obtuse angle and the second obtuse angle being between 160-140 degrees and the obtuse medial angle between the first and the second flat sides is between 120-100 degrees; whereby the resistance profile optimizes a pullout resistance of the strip soil reinforcing member from the mechanically stabilized earth (MSE) structure during a use thereof.
According to another alternative aspect of the present invention there is presented a strip soil reinforcing element, further comprising: at least a second peak member on the strip; and the first peak member and the second peak member spaced on the strip by at least one of the first and the second flat sections therebetween.
According to another alternative aspect of the present invention there is presented a strip soil reinforcing element, wherein: the at least first and second peak members being either both on the first side of the strip or on opposite sides of the strip relative to the common plane.
According to another alternative aspect of the present invention there is presented a strip soil reinforcing element, wherein: a length of the first and the second flat sections is one of uniform and nonuniform between respective the first and the second peak members.
According to another alternative aspect of the present invention there is presented a strip soil reinforcing element, wherein: the stock member being manipulated using the cold forming process is at least one of carbon steel, stainless steel, an iron alloy, an aluminum alloy, a copper alloy, and a bronze alloy.
According to another alternative aspect of the present invention there is presented a strip soil reinforcing element, wherein: a proximal end of the strip has a through bore.
According to another alternative aspect of the present invention, there is a system, for constructing a mechanically stabilized earth (MSE) structure, comprising: a strip soil reinforcing element consisting of a metal strip fabricated with cold formed profiled resistance profile having at least a plurality of peaks along a flat surface and a through bore at a proximal end; a facing panel element having a facing panel anker with a coupling device extending from a back face of a facing panel element and adjustably accepting the proximal end of the strip soil reinforcing element and the strip soil reinforcing element; a coupling device extending through the proximal end and the facing panel anker to secure the strip soil reinforcing member to the facing panel anker wherein the combined coupling device and the strip soil reinforcing element capable of swiveling along a common plane.
According to another alternative aspect of the present invention, there is a system, for constructing a mechanically stabilized earth (MSE) structure, further comprising: a plurality of the strip soil reinforcing elements each containing a plurality of the cold formed profiles along respective flat surfaces; each of the strip soil reinforcing elements consisting of a strip wherein all surfaces on the strip are smooth, where the surface of the strip is manipulated forming the cold formed profile using a cold forming process by passing the strip through opposing surfaces of two profile dies imparting the resistance profile on the strip; the resistance profile includes the plurality of peaks on a first side of the strip and each the peak having the first flat side and an opposite second flat side, and extending between respective at least a first flat section and a second flat section of the strip; each of the first and the second flat sections extending along the common plane; a first flat side and a second flat side on opposing sides of the at least one peak member having equal lengths and defining an obtuse medial angle therebetween; a first obtuse angle defined from the first flat side of each the peak relative to the first flat section and a second obtuse angle defined from the corresponding second flat side of each the peak relative to the second flat section; and the first obtuse angle and the second obtuse angle being between 160-140 degrees and the obtuse medial angle between the first and the second flat sides is between 120-100 degrees; whereby the resistance profile optimizes a pullout resistance of the strip soil reinforcing member from the mechanically stabilized earth (MSE) structure during a use thereof.
According to another alternative aspect of the present invention, there is a system, for constructing a mechanically stabilized earth (MSE) structure, comprising a plurality of facing panel elements each having a plurality of facing panel ankers each with a corresponding coupling device extending from a respective back face of each the facing panel element and adjustably accepting respective the proximal ends of the plurality of strip soil reinforcing elements and securing respective the strip soil reinforcing element; and a plurality of soil lifts along the plurality of facing panel elements relative to a base level and a finished grade; and each the plurality of soil lifts is secured in the mechanically stabilized earth (MSE) structure with a corresponding series of the strip soil reinforcing elements.
According to another alternative aspect of the present invention, there is a system, for constructing a mechanically stabilized earth (MSE) structure, wherein: each the strip soil reinforcing elements includes, in the plurality of peaks at least a first peak ember and a second peak member; and the at least first and the second peak members being either both on the first side of the strip or on opposed sides of the strip relative to the common plane; or wherein: a length of the first and the second flat sections of each the strip of the plurality of strips is one of uniform and nonuniform between respective the first and the second peak members; or wherein: the strip soil reinforcing elements are each selected from one of a carbon steel, stainless steel, an iron alloy, an aluminum alloy, a copper alloy, and a bronze alloy.
According to another alternative aspect of the present invention, there is a method manufacturing a strip soil reinforcing element using coiled metal comprising the steps of: a. placing the coiled metal on an unwinding pedestal and unwinding the coiled metal as a strip; b. passing the strip through a first straightening station forming an initially straightened strip; c. passing the initially straightened strip through a cold pressing profiling station and imparting a resistance profile consisting of at least a plurality of cold formed peaks along a surface of the strip; wherein the cold pressing profiling station contains a fixed dye and a movable dye each having complementary profiles so that during the step of imparting the resistance profile a final straightened portion is formed between respective the peaks and valleys along the surface of the strip; d. passing the strip through a punch station; e. passing the strip through a guillotine and cutting the strip to a predetermined length; f. placing the finished strip in a stack; and g. banding the finished stack of strips.
According to another alternative aspect of the present invention, there is a method manufacturing a strip soil reinforcing element using coiled metal wherein: the resistance profile includes the plurality of the cold formed peaks on the strip and each the peak having the first flat side and an opposite second flat side, and extending between respective at least a first flat section and a second flat section of the strip; each of the first and the second flat sections extending along a common plane on the final straightened portions; a first flat side and a second flat side on opposing sides of the peak members having equal lengths and defining an obtuse medial angle therebetween; a first obtuse angle defined from the first flat side of each the peak relative to the first flat section and a second obtuse angle defined from the corresponding second flat side of each the peak relative to the second flat section; and the first obtuse angle and the second obtuse angle being between 160-140 degrees and the obtuse medial angle between the first and the second flat sides is between 120-100 degrees; whereby the resistance profile optimizes a pullout resistance of the strip soil reinforcing member from the mechanically stabilized earth (MSE) structure during a use thereof.
The above and other aspects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
Reference will now be made in detail to embodiments of the invention. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale. The word ‘couple’ and similar terms do not necessarily denote direct and immediate connections, but also include connections through intermediate elements or devices. For purposes of convenience and clarity only, directional (up/down, etc.) or motional (forward/back, etc.) terms may be used with respect to the drawings. These and similar directional terms should not be construed to limit the scope in any manner. It will also be understood that other embodiments may be utilized without departing from the scope of the present invention, and that the detailed description is not to be taken in a limiting sense, and that elements may be differently positioned, or otherwise noted as in the appended claims without requirements of the written description being required thereto.
Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent.
Referring now to
As noted in
When an element contained in soil is loaded so it is pushed into the soil the soil will fail along a surface. The surface, also known as a failure surface, is a function of the friction angle of the soil. The failure surface propagates at an angel of 45+ϕ2. Where ϕ (phi) is the internal friction angle of the soil. An element that is placed in soil and loaded can only move when force exceeds the strength of the soil. When soil failure occurs the passive element punches into the soil in the direction of failure as shown in
The wedge of soil in front of the element defined by Zone-I (ABC) (I) must move the surrounding soil defined by Zone-II (II) out of the way. The angle alpha (α) is a function of the internal friction angle of the soil. The angle beta (β) is a function of the applied force and the compacted density of the surrounding soil as well as the dilatancy characteristics of the soil. The angles alpha (α) and beta (β) are correlated to the angle of 45 degrees plus one-half the internal friction angle of the soil. Zone-II (II) is above zone AD (as shown). During tension, the more that Zones-II and Zones-III (III) are allowed to propagate unobstructed the higher the pullout resistance of the soil reinforcing element. The failure surface follows the outer profile of Zones II, III, and provides substantial resistance to movement when suitably positioned and assembled in a mechanically stabilized earth (MSE) structure.
The preferred embodiment passive profile is shown in
Referring further specifically to
Referring additionally further to
It will be recognized that the noted peaks and valleys are optimized and are intermittently spaced along the metal strips by the method of cold forming and are essentially mirror images of each other when viewing the surface. As a result, it will be recognized that the present concept may be adapted to the present alternative embodiments without departing from the scope and spirit of the Applicant's invention.
Referring now additionally to
Additionally, referring to
Referring additionally now to
As noted in
Although only a few embodiments have been disclosed in detail above, other embodiments are possible, and the inventors intend these to be encompassed within this specification. The specification describes certain technological solutions to solve the technical problems that are described expressly and inherently in this application. This disclosure describes embodiments, and the claims are intended to cover any modification or alternative or generalization of these embodiments which might be predictable to a person having ordinary skill in the art.
Also, the inventor intends that only those claims which may use the word ‘means’ or use the words ‘means for’ to be interpreted under 35 USC 112. Moreover, no limitations from the specification are intended to be read into any claims, unless those limitations are expressly included in the claims.
Where a specific numerical value is mentioned herein, it should be considered that the value may be increased or decreased by 20% (e.g., an angle of X degrees+/−20% is understood as within the disclosure and still staying within the teachings of the present application, unless some different range is specifically mentioned. Where a specified logical sense is used, the opposite logical sense is also intended to be encompassed.
Having described at least one of the preferred embodiments of the present invention with reference to the accompanying drawings, it will be apparent to those skills that the invention is not limited to those precise embodiments, and that various modifications and variations can be made in the presently disclosed system without departing from the scope or spirit of the invention. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.
This application relates to, and claims priority from U.S. Prov. Ser. No. 63/074,127 filed Sep. 3, 2020, the entire contents of which are incorporated herein fully by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63074127 | Sep 2020 | US |
