U.S. patent application number 10/997578 was filed with the patent office on 2005-05-26 for compressible mechanically stabilized earth retaining wall system and method for installation thereof.
This patent application is currently assigned to T & B Structural Systems Inc.. Invention is credited to Bagwell, James Scott, Taylor, Thomas P..
Application Number | 20050111921 10/997578 |
Document ID | / |
Family ID | 34595306 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050111921 |
Kind Code |
A1 |
Taylor, Thomas P. ; et
al. |
May 26, 2005 |
Compressible mechanically stabilized earth retaining wall system
and method for installation thereof
Abstract
A compressible mechanically stabilized earth retaining wall
system and installation thereof is described.
Inventors: |
Taylor, Thomas P.; (Euless,
TX) ; Bagwell, James Scott; (Arlington, TX) |
Correspondence
Address: |
HAYNES AND BOONE, LLP
901 MAIN STREET, SUITE 3100
DALLAS
TX
75202
US
|
Assignee: |
T & B Structural Systems
Inc.
Hurst
TX
|
Family ID: |
34595306 |
Appl. No.: |
10/997578 |
Filed: |
November 24, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60525521 |
Nov 26, 2003 |
|
|
|
Current U.S.
Class: |
405/262 ;
405/284; 405/285; 405/302.4 |
Current CPC
Class: |
E02D 29/0241
20130101 |
Class at
Publication: |
405/262 ;
405/284; 405/285; 405/302.4 |
International
Class: |
E02D 017/00; E02D
005/00 |
Claims
What is claimed is:
1. A system using wire mesh elements formed of vertical and
horizontal wires for reinforcing soil, the system comprising: a
first wire mesh element having a first bend formed therein at a
first angle to form first and second panels, wherein the second
panel is oriented substantially horizontally and the first panel
extends upwards from the second panel at the first angle, and
wherein a top-most horizontal wire of the first panel is at least a
distance D+X from the top of the vertical wires of the first panel;
and a second wire mesh element having a second bend formed therein
at a second angle to form third and fourth panels, wherein the
fourth panel is oriented substantially horizontally and the third
panel extends upward from the fourth panel at the second angle,
wherein the second element is positioned above the first element so
that at least a portion of the vertical wires of the first panel
penetrate the fourth panel to at least the distance D when the
second panel is covered with a material to a height of X above the
top-most horizontal wire of the first panel, wherein X represents a
maximum distance separating the top-most horizontal wire of the
first panel from the fourth panel, and wherein the first and second
elements are not fastened together but move relative to one another
as the value of X decreases due to compression of the material.
2. The system of claim 1 wherein the vertical wires of the first
panel penetrate the fourth panel proximate to the second bend.
3. The system of claim 1 wherein a value of X is determined based
on properties of the material.
4. The system of claim 1 wherein the vertical and horizontal wires
of the first panel are uniformly spaced to create a grid that has
an apparent opening of uniform dimensions.
5. The system of claim 1 further comprising a backing mat attached
to the first panel, wherein the backing mat includes a plurality of
substantially uniformly spaced vertical and horizontal wires that
create a grid with openings smaller than the openings formed by the
vertical and horizontal wires of the first panel.
6. The system of claim 1 further comprising a substantially planar
cap mat placed horizontally over the second L-shaped element,
wherein the cap map comprises a mesh formed of a plurality of
vertical and horizontal wires.
7. The system of claim 1 wherein the first and second angles are
identical.
8. The system of claim 1 wherein the first and second angles are
different.
9. The system of claim 1 wherein the second and fourth panels are
substantially parallel.
10. A method for constructing a mechanically stabilized earth
welded wire soil-reinforcing system using a plurality of wire mesh
L-shaped elements each having a substantially horizontal wire mesh
soil reinforcing (SR) portion and a face panel extending upwards
from the SR portion at an angle .alpha., wherein each face panel
includes horizontal wires and vertical wires having distal ends
that extend a distance D beyond the top-most horizontal wire, the
method comprising: placing material on at least part of a first SR
portion of a first L-shaped element, wherein a void is left between
the material and a first face panel of the first L-shaped element;
positioning a second L-shaped element above the first L-shaped
element, wherein the positioning of the second L-shaped element
includes: resting at least a part of a second SR portion of the
second L-shaped element on the material; placing at least some of
the distal ends of the vertical wires of the first face panel
through the wire mesh of the second SR portion and proximate to a
back face of a second face panel of the second SR portion, wherein
the second SR portion is supported by the material at a distance X
from the top-most horizontal wire of the first face panel and does
not bear on the first face panel, and wherein the first and second
L-shaped elements are not fastened together.
11. The method of claim 10 further comprising: placing material on
at least part of the second SR portion, wherein a void is left
between the material and the second face panel of the second
L-shaped element; and filling the void between the material and the
first face panel of the first L-shaped element using the
material.
12. The method of claim 11 further comprising monitoring the
filling of the void to ensure that the second SR portion remains
substantially horizontal.
13. The method of claim 11 further comprising monitoring the
filling of the void to ensure that the second SR portion remains
substantially parallel to the first SR portion.
14. The method of claim 10 further comprising calculating the
distance X based on a compressibility of the material.
15. The method of claim 10 further comprising attaching a backing
mat to the first face panel, wherein the backing mat includes a
plurality of substantially uniformly spaced vertical and horizontal
wires that create a grid with openings smaller than the openings
formed by the vertical and horizontal wires of the first face
panel.
16. The method of claim 10 further comprising placing a
substantially planar cap mat horizontally over the second L-shaped
element, wherein the cap map comprises a mesh formed of a plurality
of vertical and horizontal wires.
17. The method of claim 10 further comprising calculating the angle
.alpha. for each of the first and second L-shaped elements, wherein
each angle .alpha. is calculated based on a desired shape of the
soil-reinforcing system.
18. The method of claim 17 wherein the calculated angles are
identical.
19. The system of claim 17 wherein the calculated angles are
different.
Description
CROSS REFERENCE
[0001] This application claims priority from U.S. Provisional
Patent Application Ser. No. 60/525,521, filed on Nov. 26, 2003, and
hereby incorporated by reference in its entirety.
BACKGROUND
[0002] Current earth reinforcing systems are used during the
creation of roadways and other projects to stabilize, for example,
soil and other materials. However, many current systems use modular
elements that are fastened together to form a reinforcing
structure. The modular elements may shift with respect to one
another, which creates binding and may damage the integrity of the
reinforcing structure. In addition, such structures often create an
axial force on the underling elements when the material being
reinforced is compressed.
[0003] Accordingly, what is needed is a system and method for
addressing these and similar issues.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a side view of one embodiment of a retaining
element that may be used in a retaining wall system.
[0005] FIG. 2 is a side view of the retaining element of FIG. 1
with a portion of the element covered by backfill.
[0006] FIG. 3 is a side view of the retaining element of FIG. 1
with another retaining element positioned above it.
[0007] FIG. 4 is a side view of the elements of FIG. 3 with the
lower element completely covered and the upper element partially
covered.
WRITTEN DESCRIPTION
[0008] The present disclosure is directed to a system and method
for reinforcing earth walls and, more specifically, to a system and
method of constructing a mechanically stabilized earth welded wire
wall with a series of soil reinforcing elements and facing panels
that do not bear on the facing panel of the lower elements, but
bear on the reinforced backfill zone while allowing the facing
panels to be integrated with the soil reinforcing elements
above.
[0009] It is understood that the following disclosure provides many
different embodiments, or examples, for implementing different
features of the disclosure. Specific examples of components and
arrangements are described below to simplify the present
disclosure. These are, of course, merely examples and are not
intended to be limiting. In addition, the present disclosure may
repeat reference numerals and/or letters in the various examples.
This repetition is for the purpose of simplicity and clarity and
does not in itself dictate a relationship between the various
embodiments and/or configurations discussed.
[0010] For purposes of illustration, the mechanically stabilized
earth wall structures in the following examples comprise elements
of welded wire mesh. The welded wire mesh is formed into an
L-shaped element that has a horizontal welded wire mesh section
(e.g., the bottom of the L) that is buried in the soil and a
vertical welded wire mesh section (e.g., the leg of the L) that is
placed against the soil to prevent raveling of the soil between
successive rows of soil reinforcing. In one embodiment, the
L-shaped element is fabricated by folding a portion of a
substantially planar element approximately ninety degrees.
[0011] The vertical welded wire mesh section defines the face of
the earthen formation. The welded wire mesh is fabricated with a
series of vertical wires that have a series of cross wires (e.g.,
horizontal wires) attached thereto. The top-most cross wire is
positioned below the ends of the vertical wires so that vertical
wires have distal ends that extend above the top-most cross wire.
The overall length from the fold line (where the mesh is bent) to
the distal ends is larger than the distance of the center-to-center
spacing of the soil reinforcing within the mechanically stabilized
earth mass, as will be described below. The top-most cross wire is
positioned a distance "X" below the required elevation of the next
row of soil reinforcing. The distance X may be defined as the
distance of allowable consolidation, compression, or settlement of
the earthen mass between the horizontal portions of the soil
reinforcing elements.
[0012] As will be described later in greater detail with respect to
a particular embodiment, the retaining structure may be constructed
as follows. First, an L-shaped element is placed on a prepared
foundation and backfill is placed on the horizontal section of the
element and compacted to an elevation that provides a desired
vertical spacing of the elements. A wedge shaped void is left at
the back face of the face panel of the L-shaped element. Another
L-shaped element is placed over the distal ends of the face panel
of the lower, previously positioned L-shaped element. The distal
ends of the lower L-shaped element's face panel are placed behind
the face panel and through the mesh of the horizontal section of
the top L-shaped element. The horizontal portion of the higher
L-shaped element is completely supported by the backfill and is not
in contact with any cross element of the soil reinforcing face
panel below. The backfill supports the soil-reinforcing element
above and prevents the top L-shaped element from bearing on the
face panel below. This step is repeated until the elevation desired
for the retaining structure is reached. A cap mat comprising planar
welded wire mesh elements may then be placed horizontally over the
top L-shaped element. The cap mat is placed over the distal ends of
the vertical section of the top L-shaped element, and may or may
not be in contact with the cross wire of the upper most vertical
face panel.
[0013] Referring to FIG. 1, in one embodiment, an L-shaped welded
wire grid element 100 (e.g., a wire mesh panel) is illustrated. The
L-shaped element 100 includes a substantially horizontal
soil-reinforcing element (SR) and a substantially vertical face
panel (FP). It is understood that the use of the terms "horizontal"
and "vertical" are for purposes of illustration only, and that the
soil-reinforcing element and the face panel may be oriented in many
different ways. Furthermore, while the face panel is illustrated as
being at an angle .alpha. of approximately ninety degrees from the
soil-reinforcing panel, it is understood that the angle .alpha. may
be any angle between approximately 1 and 180 degrees. Accordingly,
the term "L-shaped" should not be interpreted to limit the shape of
the element 100.
[0014] Attached to the vertical face panel are cross wires (CW)
(e.g., the horizontal wires of the mesh panel). The
center-to-center vertical spacing of the L-shaped element 100 with
respect to other L-shaped elements (FIG. 3) is set at dimension Y.
The top-most cross wire, CW.sub.top, of the vertical face panel is
set a distance "X" below the center-to-center spacing of the
L-shaped element. The distance X may be defined as the
compressibility range of the center-to-center spacing of the
L-shaped element, as will be described later in greater detail. The
distal ends, PR, of the vertical wires of the vertical face panel
are a distance equal to X+D from CW.sub.top, where D is defined as
the distance that the distal ends extend above the vertical
center-to-center (Y) spacing of an L-shaped element that is
positioned above the element 100.
[0015] FIGS. 2-4 illustrate various stages of one embodiment of the
construction of a mechanically stabilized earth structure (e.g., a
retaining wall). The construction may be described in three basic
steps: a beginning step, an intermediate step, and an ending step,
each of which is described below in greater detail with respect to
a particular figure. These steps may be repeated as needed until
the desired structure has been created.
[0016] Referring to FIG. 2, the beginning step of constructing the
retaining wall involves placing the L-shaped element 100 on a
prepared foundation. More specifically, the horizontal
soil-reinforcing element, SR, is placed on the prepared foundation.
The backfill (BF) is then placed and compacted to the required
thickness, Y, which is equal to the center-to-center spacing of the
L-shaped element. This compacted backfill forms a reinforced
support at the proper height at which another L-shaped element may
be placed without directly contacting the L-shaped element 100. It
is noted that the distal end, PR, is above the center-to-center
spacing of the L-shaped element, Y. The backfill is placed and
compacted so as to create a wedge-shaped void at the face of the
L-shaped element 100.
[0017] Referring to FIG. 3, the intermediate step of constructing
the retaining wall comprises placing an L-shaped element 200 onto
the backfill (FIG. 2) to form the next layer of the retaining wall.
The L-shaped element 200 is placed so that it is supported by the
compacted backfill, BF, at a distance X from CW.sub.top of the
vertical facing panel of the L-shaped element 100. The L-shaped
element 200 is positioned so that the distal ends, PR, of the
L-shaped element 100 penetrate the mesh forming the horizontal
soil-reinforcing element SR of the L-shaped element 200. In the
present example, the distal ends PR of the L-shaped element 100 are
positioned behind the facing panel, FP, of the L-shaped element
200. Accordingly, the horizontal soil-reinforcing element SR of the
L-shaped element 200 is supported by the backfill below it and is
not in contact with any cross element of the L-shaped element 100.
The backfill supports the horizontal soil-reinforcing element SR of
the L-shaped element 200 and does not bear on the vertical face
panel of the L-shaped element 100 below. The L-shaped elements 100
and 200 are not fastened together, which enables them to move
relative to one another without binding as the backfill is
compressed. However, their relative movement is constrained by the
positioning of the distal ends, PR, of the L-shaped element 100
through the mesh forming the horizontal soil-reinforcing element SR
of the L-shaped element 200. It is understood that the backfill may
compress various distances between X (no compression) and
CW.sub.top (full compression). However, in the present embodiment,
it is desirable that the backfill remain at least slightly above
CW.sub.top so that the L-shaped element 200 does not rest on
CW.sub.top of the L-shaped element 100.
[0018] Referring now to FIG. 4, once the L-shaped element 200 is
placed on the backfill and pulled into the desired horizontal
alignment, backfill is placed on the tail of the horizontal
soil-reinforcing element SR of the L-shaped element 200, which
anchors the L-shaped element 200 and keeps it from moving. In
addition, backfill is placed into the void of the L-shaped element
100 to fill in the wedge. During the filling of the void, the
elevation of the horizontal soil-reinforcing element SR of the
L-shaped element 200 may be monitored to maintain a substantially
horizontal relationship and to keep the distance X substantially
uniform.
[0019] This process may be repeated (e.g., the processes of FIGS.
2-4 may be repeated sequentially or the process illustrated by a
single figure may be repeated) until the elevation of the desired
structure is achieved and a cap mat may be installed, which is the
ending step of the construction process in the present example. The
cap mat comprises one or more horizontally oriented welded wire
mesh elements that are placed over the distal ends PR of the
vertical face panels of the uppermost L-shaped elements (e.g., the
L-shaped element 200 in FIG. 4). The cap mat may or may not be in
contact with CW.sub.top of the vertical face panel of the L-shaped
element 200.
[0020] It is understood that the L-shaped elements 100 and 200 may
not be directly vertical to one another, but may be staggered. For
example, the L-shaped element 200 may be placed with only half of
its horizontal soil-reinforcing element SR is above the L-shaped
element 100, while the other half is above another L-shaped element
(not shown). Multiple L-shaped elements may therefore be combined
into various configurations as needed.
[0021] In another embodiment, an improved method of constructing a
compressible mechanically stabilized earth welded wire retaining
wall may include the following. The method includes providing a
substantially L-shaped welded wire mesh element with a horizontal
portion defining a soil reinforcing section and a vertical portion
defining a face panel. The face panel contains a series of vertical
wires that are interconnected by a series of horizontal cross
wires, where the top-most cross wire is a distance "X" below the
elevation of the center-to-center spacing of the soil reinforcing
elements. The distance X may be defined as the compressibility
distance. The vertical wires of the face panel include distal ends
that extend above the top-most cross wire farther than the
compressibility distance "X." The horizontal wires are vertically
spaced within the reinforced mass.
[0022] The method includes placing backfill on the soil reinforcing
section of an L-shaped element and compacting the backfill to an
elevation equal to a desired center-to-center spacing of the
L-shaped elements. Another layer is then added by placing another
L-shaped welded wire mesh element onto the lower L-shaped element.
The top L-shaped element is placed so that the horizontal section
defining the soil reinforcing portion and the face panel are placed
on and are supported by the backfill. The distal ends of the face
panel below are placed through the welded wire mesh horizontal
openings of the overlaying horizontal section near the back face of
the vertical face panel of the L-shaped element above. Furthermore,
the horizontal section is placed on and supported by the backfill
at the distance X from the top-most cross wire of the vertical face
panel of the L-shaped element below and does not bear on the face
panel below.
[0023] In one embodiment, the facing panel contains uniformly
spaced vertical wires and uniformly spaced cross wires that create
a grid as viewed from the front face of the structure that has an
apparent opening of uniform dimensions.
[0024] In another embodiment, the facing panel contains uniformly
spaced vertical wires and uniformly spaced cross wires. Attached to
the back face of the face panel is a backing mat containing
uniformly spaced vertical wires and uniformly spaced cross wires
that span the center-to-center spacing of the face panel's vertical
and cross wires to create a grid as viewed from the front face of
the structure that has an apparent opening of uniform dimensions
that are equal to one half the size of the apparent opening of the
facing panel. In some embodiments, a mesh of smaller apparent
openings may be used to prevent fine material from passing through
the face of the structure.
[0025] In yet another embodiment, the backing mat contains distal
ends of the same length as those of the face panel. In another
embodiment, the backing mat spans more than one L-shaped element.
In still another embodiment, the backing mat's top-most cross wire
is at the same elevation as the top-most cross wire of the face
panel.
[0026] While the preceding description shows and describes one or
more embodiments, it will be understood by those skilled in the art
that various changes in form and detail may be made therein without
departing from the spirit and scope of the present disclosure. For
example, various steps of the described methods may be executed
repetitively, combined, further divided, replaced with alternate
steps, or removed entirely. In addition, different shapes and sizes
of elements may be combined in different configurations to achieve
desired earth retaining structures. Therefore, the claims should be
interpreted in a broad manner, consistent with the present
disclosure.
* * * * *