Patent Application
20210017731
The presently disclosed subject matter relates generally to the retention of earthen formations and the field of retaining walls and more particularly to a geosynthetic reinforced wall panels comprising soil reinforcing hoop members and retaining wall system formed therewith.
Retaining walls are commonly used for architectural and site development applications. Retaining walls have historically been constructed from mass concrete. More recently, retaining walls are often constructed using systems of modular facades connected to soil reinforcing elements. Such soil reinforced earthen works are often called “Mechanically Stabilized Earth” structures and have now become a recognized civil engineering structure useful in the retention of hillsides, right of way embankments, and the like. The wall facing elements, which typically consist of masonry blocks, concrete blocks, concrete panels, and/or welded wire forms, are designed to withstand lateral pressures exerted by backfill soils. Reinforcement and stabilization of the soil backfill in mechanically stabilized earth applications is commonly provided using metallic or geosynthetic materials, such as geogrids or geotextiles, that are placed horizontally in the soil fill behind the wall face. The reinforcing elements are connected to the wall face elements and interact with the soil to create a stable reinforced soil mass.
Wall facing elements most often consist of concrete masonry blocks and/or concrete panels. The use of both full height as well as segmental variable height pre-cast concrete wall panels for wall-facing elements in a retaining wall is known such as is disclosed in U.S. Pat. No. 5,568,998, entitled “Precast wall panel and grid connection device” and U.S. Pat. No. 5,580,191, entitled “Marine wall.”
Metallic reinforcing elements comprised of steel and the like have the benefit of exhibiting a high tensile strength and are relatively easy to connect to the wall facing units. Because of their inherently high tensile strength, steel reinforcements often are comprised of discrete strips that are individually bolted to the facing panels. However, a drawback of metallic elements is that they are corrodible and are thus not optimal in backfill materials that are aggressive to metals.
Geosynthetic reinforcing elements, typically comprised of polyethylene terephthalate (PET) or high-density polyethylene (HDPE), are also used for current mechanically stabilized earth retaining structures. Polyester materials, which are high in allowable tensile strength, are not easily connected to wall facing panels and typically require a gravity “pinch” connection to the wall facing element. However, PET reinforcing elements that are mechanically connected to the wall facing panels are typically inefficient due to low connection strength or requiring weaving or wrapping of the PET reinforcing element through an expensive high strength mechanical connector connected to the wall facing panels.
HDPE materials typically have high junction strength to form a robust connection to wall facing panels. However, HDPE is subject to creep deformations whereby this limitation results in a lower allowable tensile strength. Further, the connections between the panel face and reinforcement must be made along the entire panel width. This connection is not simple to employ in the field and results in connection “slack” that exists because the connections may be difficult to seat prior to loading the wall with the backfill soil. The combination of the applied soil pressure and the connection slack results in panel walls that may displace laterally during construction, sometimes resulting in un-plumb and unsightly facades. Accordingly, new approaches are needed with respect to methods and/or techniques of reinforcing retaining walls. For example, improvements are needed with respect to increasing the efficiency in the connection system strength and thereby improving the stability of the retaining wall and the retained soil mass.
The presently disclosed subject matter is summarized as a geosynthetic panel wall system including one or more each of a concrete facing panel element, a stabilizing hoop element coupled to one side of the concrete facing panel element, and a soil reinforcing element coupled to the stabilizing hoop element.
In one example, the concrete facing panel is multiple concrete facing panels, and the stabilizing hoop is multiple stabilizing hoops. The multiple concrete facing panels may be arranged end-to-end, and each of the multiple concrete facing panels may be coupled to the multiple stabilizing hoops.
In another example, the plurality of stabilizing hoops may be arranged vertically on the concrete facing panel. The plurality of stabilizing hoops can also be arranged side-by-side on the concrete facing panel.
In still another example, the stabilizing hoop may be semi-circular in shape having a height H, a length L, and a depth D. The stabilizing hoop may be filled with soil fill.
The soil reinforcing element may be a strip having a width. In one example, the strip may be a continuous wrap from the bottom of the stabilizing hoop to the top of the stabilizing hoop and adapted to be splayed. The strip is made of PET, HDPE, or other flexible material. In another example, the strip may be a geogrid made of geotextiles.
The geosynthetic panel wall system may be free standing. In one such example, the concrete facing panel may be coupled atop a leveling pad to form a free standing gravity geosynthetic panel wall system.
The present subject matter may also include a method of reinforcing a wall. One example of such method may include the steps of: providing a geosynthetic panel wall system having one or more each of a concrete facing panel, a stabilizing hoop, and a soil reinforcing element; casting one or more of the stabilizing hoops onto one or more of the concrete facing panels, wherein each concrete facing panel is coupled to at least one stabilizing hoop on one side of the concrete facing panel; forming a leveling pad; propping the concrete facing panel atop the leveling pad; placing and compacting soil backfill against the one side of the concrete facing panel up to the bottom of the coupled stabilizing hoop; cutting the soil reinforcing element into a strip; placing the strip through the stabilizing hoop against and over the concrete facing panel; filling the stabilizing hoop with soil fill; placing and compacting backfill up to the top of the stabilizing hoop; and folding down the strip into the backfill.
Having thus described the presently disclosed subject matter in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The presently disclosed subject matter now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the presently disclosed subject matter are shown. Like numbers refer to like elements throughout. The presently disclosed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.
In some embodiments, the presently disclosed subject matter provides a geosynthetic reinforced wall panel comprising soil reinforcing hoop members and retaining wall system formed therewith. Namely, a geosynthetic panel wall system is provided that includes at least one concrete facing panel that has at least one stabilizing hoop coupled thereto and wherein a soil reinforcing element or strip may be coupled to the stabilizing hoop.
In some embodiments, the presently disclosed subject matter provides a stabilized concrete facing panel, a connection system, a soil reinforcing system, and methods related thereto. For example, the stabilized concrete facing panel with stabilizing hoops can be used for constructing retaining walls. The stabilized concrete panel can be fabricated through a wet-cast process. The stabilized concrete panel using stabilizing hoops provides increased panel stability during construction as compared with convention methods.
In some embodiments, the presently disclosed geosynthetic panel wall system that includes stabilizing hoops provides a simple connection system with few components for ease of installation, improved connection performance, and improved facing panel alignment.
In some embodiments, the presently disclosed geosynthetic panel wall system that includes stabilizing hoops provides discrete soil reinforcing elements, such as PET strips, HDPE strips, and/or other flexible soil reinforcing elements, that can all use a common connection method. The discrete soil reinforcing elements (e.g., geogrid strips) are wrapped through the stabilizing hoop, which allows the splaying of the soil reinforcing elements to avoid vertical obstructions, and therefore provide quick installation and a means to mitigate challenges around vertical obstructions.
Accordingly, the presently disclosed geosynthetic panel wall system includes stabilizing hoops for panel stability during construction and provides a high strength reinforcing element that is not subject to corrosion. Further, the geosynthetic panel wall system has a simple and effective connection system that does not rely on the type of reinforcement.
Referring now to
Each of the stabilizing hoops 102 has a height H, a length L and a depth D, and can be made of wide range of materials, including but not limited to, polymer, steel or composite materials, and in the preferred embodiment, HDPE material. The stabilizing hoop 102 can be shaped in various forms. In one example, the stabilizing hoop 102 has a circular shape. The height H of the stabilizing hoop 102 can be from about 6 inches (15.24 cm) to about 30 inches (76.2 cm) in one example, or is about 8 inches (20.32 cm) in another example. The length L and the depth D of the stabilizing hoop 102 can from about 24 inches (60.96 cm) to about 96 inches (243.84 cm) in one example, or is about 36 inches (91.44 cm) in another example.
While the geosynthetic panel wall system 100 shown in
Referring now to
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A “geogrid” is a grid structure whose primary purpose is to strengthen or reinforce soil and has open meshes into which soil particles can lock. A preferred form of geosynthetic reinforcement is made by the process disclosed in U.S. Pat. No. 4,374,798 (“the '798 patent”) using HDPE. The reinforcements are known as “integral geogrids”. Integral geogrid material may be uniaxially oriented according to the '798 patent to provide grid-like sheets including a plurality of elongated, parallel, molecularly oriented strands with transversely extending bars integrally connected thereto by less oriented or unoriented junctions, the strands, bars and junctions together defining a multiplicity of elongated openings. HDPE materials are not susceptible to chemical attack and the high junction strength of the processed materials results in robust connections. Accordingly, this type of geogrid is an example of the soil reinforcing elements 104 of the panel wall system 100 and wherein the geogrid is provided in strip form.
Referring now to
Referring now to
At a step 210, at a precast concrete facility, one or more concrete facing panels 101 are provided wherein at least one stabilizing hoop 102 is cast onto each panel.
At a step 212, a level pad, such as the leveling pad 105 shown in
At a step 214, the first row of the concrete facing panels 101 to be propped up is braced at the front and clamped on the sides.
At a step 216, the soil backfill is placed and compacted against the concrete facing panels 101 up to the bottom of the first row of the stabilizing hoops 102.
At a step 218, the soil reinforcing elements 104 are cut and then each placed through its respective stabilizing hoop 102 in a manner that is against and over its concrete facing panel 101. For example, strips of geogrid are cut and then each placed through its respective stabilizing hoop 102 in a manner that is against and over its concrete facing panel 101. The soil reinforcing elements 104 should have sufficient length to form a continuous wrap and then back into the backfill zone.
At a step 220, each of the stabilizing hoops 102 is filled with soil (e.g., soil fill 103) and compacted to engage the stabilizing hoops 102 to the concrete facing panel 101.
At a step 222, backfill is placed on top of the soil reinforcing elements 104 (e.g., strips of geogrid) and also surrounding the confined soil fill 103 to the top of the stabilizing hoop 102. Then, the backfill is compacted.
At a step 224, the soil reinforcing elements 104 (e.g., strips of geogrid) are folded down and pulled back into the backfill zone. The soil reinforcing elements 104 are tensioned by hand and held down with small piles of backfill.
At a step 226, more soil backfill is placed and compacted against the concrete facing panels 101 up to the bottom of the next row of the stabilizing hoops 102.
Full-scale field tests were conducted to demonstrate the panel stability using stabilizing hoops 102 with stone and sand infill, and various connection concepts using soil reinforcing strips (i.e., soil reinforcing elements 104). Two separate test walls (Wall A and Wall B) were installed in back-to-back configuration with 3 columns of 5 feet (1.52 m) tall×5 feet (1.52 m) wide precast concrete panels on each side. Each column is identified by the wall name and a number to represent column number such as Column A-1, A-2 and A-3 for Wall A and Column B-1, B-2 and B-3 for Wall B. The total wall height was 15 feet (4.57 m). The stabilizing hoops 102 were 8 inches (20.32 cm) high, 4 feet (1.22 m) wide across the panel, and 3 feet (0.91 m) deep into the backfill. The backfill was placed and compacted in 10 inches (25.4 cm) lift maximum with typical equipment 15,000 lbs single-drum vibratory roller. The backfill within 3 feet (0.91 m) of concrete facing panel was compacted with hand-held plate tamper simulating construction technique for mechanically stabilized earth wall. The following combination of HDPE and PET soil reinforcing strips, connection and hoop infill were tested at the test walls:
Horizontal wall profile data of the completed test walls was collected using a laser distance measuring tool during construction, right after construction, 40 days, 84 days, 140 days, and 272 days after construction. The test walls were subjected to over 70 inches (1.78 m) of precipitation after construction.
The horizontal wall profiles for each column of the completed walls are shown in
Based on the panel alignment data, all panels were plumb or with positive batter except panels with geogrid loop through two stabilizing hoops 102 on a panel (
In another example of the present subject matter, a large-scale connection test program was carried out to evaluate the effectiveness and quantify the connection strength of the hoop connection system with HDPE and PET soil reinforcing strips (i.e., soil reinforcing elements 104) without a mechanical connector. PET soil reinforcement is high in allowable tensile strength but is not easily connected to wall facing panels. Mechanically connecting PET reinforcing element to the wall facing panels are typically inefficient due to low junction strength or requiring weaving or wrapping of the PET reinforcement through an expensive high strength mechanical connector connected to the wall facing panels. HDPE soil reinforcement typically has high junction strength to form strong connection to wall facing panels but requires a robust mechanical connector.
In an example of a large-scale connection test set up, an 8-inch (20.32-cm) high Tensar® UX1900 geogrid strip was cast 2.5 inches (6.35 cm) into the concrete and 4 inches (10.16 cm) away from the edges of the concrete panel to form an approximately 2 feet (0.61 m) deep hoop. The concrete panel was 16 inches (0.41 m) high x 32 inches (0.81 m) wide×5.5 inches (13.97 cm) thick with a 4000-psi minimum concrete compressive strength. The connection tests were performed using No. 57 stone and concrete sand for the hoop infill with HDPE and PET geogrid strips (hereafter called “geostrips”) as soil reinforcing elements 104. The tests were performed with 200-psf and 1000-psf overburden pressures to simulate loading conditions close to top and at 9 feet (2.74 m) deep into the wall respectively. The connection strength, displacement, and failure mode test results were recorded and summarized in Table 900 shown in
The following observations and conclusions were made based on the connection test results and failure mode:
Following long-standing patent law convention, the terms “a,” “an,” and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to “a subject” includes a plurality of subjects, unless the context clearly is to the contrary (e.g., a plurality of subjects), and so forth.
Throughout this specification and the claims, the terms “comprise,” “comprises,” and “comprising” are used in a non-exclusive sense, except where the context requires otherwise. Likewise, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing amounts, sizes, dimensions, proportions, shapes, formulations, parameters, percentages, quantities, characteristics, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are not and need not be exact, but may be approximate and/or larger or smaller as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art depending on the desired properties sought to be obtained by the presently disclosed subject matter. For example, the term “about,” when referring to a value can be meant to encompass variations of, in some embodiments ±100%, in some embodiments ±50%, in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions.
Further, the term “about” when used in connection with one or more numbers or numerical ranges, should be understood to refer to all such numbers, including all numbers in a range and modifies that range by extending the boundaries above and below the numerical values set forth. The recitation of numerical ranges by endpoints includes all numbers, e.g., whole integers, including fractions thereof, subsumed within that range (for example, the recitation of 1 to 5 includes 1, 2, 3, 4, and 5, as well as fractions thereof, e.g., 1.5, 2.25, 3.75, 4.1, and the like) and any range within that range.
Although the foregoing subject matter has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be understood by those skilled in the art that certain changes and modifications can be practiced within the scope of the appended claims.
The presently disclosed subject matter is related and claims priority to U.S. Provisional Patent App. No. 62/649,079, entitled “Geosynthetic Reinforced Wall Panels Comprising Soil Reinforcing Hoop Members and Retaining Wall System Formed Therewith,” filed on Mar. 28, 2018; the entire disclosure of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/024607 | 3/28/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62649079 | Mar 2018 | US |
