Retaining wall having modular panels
A ground retaining wall includes wall panels formed from steel sheet to provide a flat exterior wall surface on a front side and having side flanges on vertically extending edges for joining panels together. The wall includes reinforcement studs and brackets attached to a back side of the panels and extending between a top cap and a base pan of the panels. Each bracket is located along a panel side flange at a seam where two panels are joined together. The wall also includes support brace assemblies each attached to the panels at one of the seams. The brace assembly includes a base plate attached to a bottom strut and a brace rod. The brace rod extends diagonally between the base plate and wall panel. The wall may include a concrete base covering the wall panel base pans and the brace assembly base plates.
This application claims priority of U.S. provisional patent application No. 60/811,971, filed Jun. 8, 2006.
FIELD OF THE INVENTIONThe invention relates generally to ground retaining walls, and more specifically to using modular steel panels to construct ground retaining walls.
BACKGROUND OF THE INVENTIONRetaining walls used to hold back earth are commonly used in landscaping to create level or gently sloping areas on otherwise steep slopes, and to reduce soil erosion and water runoff. Soils have natural angles of repose, and retaining walls are used to maintain a steeper slope. While holding back the soil, the wall must be able to resist sliding, overturning and settling pressures from the soil and ground water.
There are several basic types of retaining walls, including: gravity, reinforced soil, embedded (cantilever, angled or propped) and bins. A gravity retaining wall has a vertical or nearly vertical face, and its ability to retain the soil depends on the gravitational force of its own weight. Gravity walls are usually made from a large mass of stone, concrete or composite material, since they depend on the size and weight of the wall mass to resist pressures from behind. Gravity walls will often have a slight setback, or batter, to improve wall stability by leaning back into the retained soil. Taller gravity walls may include pre-cast concrete facing reinforced with geosynthetic or steel-reinforced backfill. Other types of gravity walls include those made with gabions (stacked steel wire baskets filled with rocks) and crib walls (cells built up log cabin style from precast concrete or timber and filled with soil). Gravity walls usually must be a minimum of 50 to 60 percent as deep (thick) as the height of the wall, and may have to be larger if there is a slope or surcharge on the wall.
For reinforced soil walls, the soil reinforcement is placed in horizontal layers throughout the height of the wall. Common soil reinforcement materials include steel straps and geogrid, a high-strength polymer mesh, that provide tensile strength to hold soil together. The reinforced soil's mass, along with the precast concrete facing, forms the wall.
Embedded walls are constructed from contiguous or interlocking individual piles or wall-panels to form a continuous structure. Embedded walls may be cantilever, anchored or propped. Cantilever walls derive their equilibrium from the lower embedded depth of the wall and rely on the passive resistance of the soil in front of the lower part of the wall for stability. Anchored or propped walls derive their equilibrium partly from the embedded lower portion of the wall and partly from an anchorage located behind the wall or from a prop system in front of the wall supporting the upper part of the wall. Cantilevered walls are often made from steel-reinforced, cast-in-place concrete shaped like an inverted T. These walls cantilever loads to a large structural footing, such that horizontal pressures from behind the wall are converted to vertical pressures on the footing below. Cantilevered walls are sometimes buttressed on the front by short wing walls oriented at right angles to the main trend of the wall. These walls require rigid concrete footings below seasonal frost depth.
Steel sheet wall panels are typically not used in gravity or cantilever retaining walls. Steel sheet is used in pile walls, however, which are constructed by driving the steel sheets (usually having a corrugated cross sectional profile) into a slope or excavation. Their most common use is within temporary deep excavations. They are economical when retention of soft soils is required. They can be driven to depths below the excavation bottom to control heaving in soft clays or piping in saturated sands.
Steel components are also used in constructing bin-type retaining walls. The bin wall is a gravity-type retaining wall system made from sectional bins of galvanized steel components that can be bolted together to form the bins. The bins are linked to form a series of interconnected open-bottom steel boxes, that are then filled with soil or other granular material to resist overturning and sliding forces by the weight of the filled bin, similar to a gravity wall system.
Thus, various retaining walls have been made from site-formed concrete, preformed concrete panels, masonry, stone, brick, steel or timber. In many installations, a backfill of gravel or stone is provided at the lower level immediately behind the retaining wall to facilitate water drainage along the base of the wall. A drainage pipe may be placed within the gravel or stone backfill to remove water from behind the wall.
An objective of this invention is to provide a retaining wall that does not rely upon its own weight for resistance and has the ability to resist pressure more in the manner of an anchored cantilever wall, without having the ponderous inverted T shape and placement on rigid concrete footings. Another objective is to provide lightweight components that are easy to assemble into a wall. Another objective is to use components that can be scaled in size and shape, thereby making walls easier to design and construct, and in many instances resulting in a more durable and aesthetically pleasing, retaining wall structure. These and other objectives, and the manner in which they are accomplished, will become apparent upon reading the descriptions which follow.
SUMMARY OF THE INVENTIONA retaining wall is constructed from modular wall panels having flat exterior wall surfaces similar to wall panels used to construct in ground swimming pools. The panels are preferably made of steel and are galvanized or otherwise coated to resist corrosion. The individual panels have a generally flat sheet portion with a flange formed on each vertically extending side by bending the side edges at a right angle in the same direction. These side flanges have matching bolt holes allowing another panel to be joined to it on either side to form a vertical wall. The panels are also bent at the top and the base into the same direction to the panel as the side flanges to form a top cap and a base pan, as described more fully in the detailed description. The panels can be either straight or curved to a desired radius. Wall panels of this type used for constructing swimming pools have been available from Cardinal Systems Inc. and are disclosed in published application US 2004/0255544A1.
When these panels are joined together, they create a wall with a forwardly-facing flat surface. The flat surface appearance can be maintained, or various types of decorative facade and other finishes can be applied to it, as described herein. Because the panels are produced in a wide variety of dimensions, and can be straight or curved, many different wall contours can be easily designed, scaled and erected.
The reverse side of the panels (behind the wall) may be reinforced by one or more vertical reinforcement studs placed at spaced intervals, and by vertical reinforcement brackets placed along one or both side edges where the panels are joined together. According to one embodiment, the vertical reinforcement studs are substantially Z-shaped in cross section having one flange secured to the back side of the panel. The studs may have passageways through the web of the stud to accommodate and support wire conduit or plastic plumbing tubing passed along the back side of the wall. The reinforcement brackets are substantially C-shaped channels with bolt holes to match the bolt holes in the side edges of the panels. They may also have passageways like the studs.
The retaining wall also includes support brace assemblies attached to the back side of the panels. The brace assembly including a base structure attached to a side flange adjacent the bottom of the side flange, and a brace rod attached to the base structure away from the panel and attached at its opposite end to an upper section of the side flange of the panel such that the brace rod extends diagonally upward from the base structure to the wall panel. According to one embodiment of such brace assemblies, an A-frame brace assembly includes a base plate with a back flange, a drive stake passing through the base plate to anchor the plate, a bottom strut extending from the base plate to the wall and bolted to a bottom section of a wall panel side flange, and a long diagonal brace. The diagonal brace is bolted at one end to the bottom strut over the base plate and at its other end to an upper section of the wall panel side flange. The diagonal brace is preferably an adjustable-length brace with a threaded rod or a turnbuckle at the top end to adjust the length between the base plate and the wall panel, and thus aid in vertically plumbing the wall. An alternative but similar brace assembly may have a wider angle bar as the bottom structure and have a slot for the drive stake to pass through one side of the angle bar.
In cold climates, the wall is preferably erected over a base trench filled with rock or aggregate stone to reduce dislocation due to frost heave. The wall is erected by assembling and bolting together the appropriate panels and brace assemblies as described herein. After a wall is erected from wall panels and plumbed, it can be anchored by driving short rebar rods through holes in the base pans of the panels. Then long strands of rebar may be laid along the length of the wall, preferably with one strand lying along the junctions of the side flanges and base pans and another strand lying along the junctions of the diagonal brace and the bottom strut. A concrete base is poured around the backside base of the wall of sufficient depth to cover and encapsulate the base pans and the rebar rods and strands, the bottom strut, the base plate and drive stake, and a lower portion of the diagonal brace.
A layer of rock or gravel is then backfilled over the concrete base for collecting and draining ground water from behind the retaining wall. A perforated pipe may be laid in the gravel layer to collect the ground water. The pipe can be vented through the wall at low spot collection points to discharge the water above ground on the front side of the wall or drain to daylight at an end of the wall. A cover of landscaping cloth is placed over the rock drain to keep soil from infiltrating the rock layer and blocking drainage. Then regular soil may be backfilled behind the wall to level the area up to or just below the top of the wall.
When used in a decorative landscaping application, the retaining wall can be finished on the open front side by a variety of paint or other surface coatings. It can also support a stucco finish by fastening a support mesh to the retaining wall panels to receive the stucco base and finish. Other types of decorative facade and veneers can also be applied.
In addition to the single wall design, two or more walls can be used together to create terraces or to make step down pathways. Alternatively, a steel stairwell box may be placed in the wall between adjoining panels. Steel benches or coves, such as a firewood box or a storage bin can be placed in the wall. The panels may also have cutouts for electrical junction boxes for outdoor lighting or utility outlets.
For the purpose of illustrating the invention, the drawings show a form of the invention that is presently preferred. However, it should be understood that this invention is not limited to the precise arrangements and instrumentalities shown.
The modular wall panels 16 are formed from steel sheet to provide a flat exterior wall surface 18. Wall panels of this type are commonly used to construct in-ground swimming pools. As shown in
The wall panel 16 is also bent at the top and base in the same direction to the panel as the side flanges 22. The bending forms a top and bottom surface extending at a right angle to the panel, preferably about five inches wide, then another right angle to make a return flange to form a top cap 26 and a base pan 28 for the panel. The base pan 28 is shown in greater detail in
The panels 16 can be either straight or curved to a desired radius. Panels of this type used for constructing swimming pools have been available from Cardinal Systems Inc. and are disclosed in published application US 2004/0255544A1. An exemplary wall panel may be made of galvanized or other coated 14 gauge steel.
The panel 16 shown in
When the wall panels 16 are joined together, they create walls 12, 14 having forwardly-facing flat surfaces 18 (which may be straight or curved). On the reverse side of the panels 16 (behind the wall), the panels may be reinforced by one or more vertical reinforcement studs 38 at spaced intervals and vertical reinforcement brackets 40 located along one or both side edges where the panels are joined together. The weight of the soil behind a retaining wall, however, creates a bulging pressure on the wall surface and at the seam where two panels are joined together. The studs 38 and brackets 40 are used to stiffen the panels 16 against this pressure. The studs 38 are preferably spaced at regular intervals (e.g., at 16 inch centers on a 48 inch wide panel). The studs 38 are preferably 14 gauge coated steel having a roughly Z-shaped cross section as shown in
The vertical reinforcement brackets 40 are substantially C-shaped in cross section as shown in
The retaining wall assembly 10 also includes support brace assemblies attached to the back side of the panels 16, as shown in more detail in
The wall panels 16 may be curved to any radius. Corners of the wall may be formed of corner pieces. The corner pieces can form a right angle corner or, alternatively, could be curved corners of various radii. The corner pieces have side flanges like the wall panels and have bolt holes aligned with those in the wall panels. The corner pieces also have a top cap and base pan like the wall panels 16.
In a method of constructing a retaining wall such as walls 12, 14 from the steel panels 16, the site is first surveyed to locate and mark the line and elevation of the base for the wall or walls. A soil bank is then cut away as necessary to create a generally flat ledge along the full line of the wall at the elevation of the wall base. Preferably, at least 2½ feet should be cleared behind the line of the wall to accommodate the brace assemblies 60. As shown in
The wall panels 16 are then assembled with the flat side 18 facing outwardly. The vertical support studs 38 can be fastened onto the wall panels 16 at the proper spacing before the panels are connected together. If the optional leveling assemblies 36 are being used, the base plates, rods and nuts, and leveler brackets are installed at slots in the base pans 28 near each bottom corner. The wall panels 16 can then be connected with a C-shaped reinforcement bracket 40 against at least one (or both) of the panel side flanges 22 at each seam between adjoining panels. The bracket 40 is set into the wall panel such that the web is against the side flange 22 and the bolt holes 24 are aligned. Bolts are inserted through the bracket 40 and the flanges 22 of the adjoining panels and nuts are finger tightened to hold the panels in place. The wall can be generally leveled with shims or the optional threaded leveler assemblies 36 before the nuts are tightened with a wrench.
The A-frame brace assemblies 60 are then attached to the back side of the panels. In this embodiment, a brace assembly includes a base plate 62 with a back flange 64 to act as an anchor in the concrete that will be poured over it. A short angle piece is used as a bottom strut 68. An alternative angle piece may be wider and include a notch (not shown) to pass through a drive stake. The strut 68 is attached to the base plate 62 at one end and the other end is bolted to a lower set of holes through the side flanges 22 and C-bracket 40, preferably at each seam between panels. Then the long diagonal brace 70 is bolted to the bottom strut 68 in a position over the base plate 62 and its other end is bolted to an upper set of holes in the bracket 40 and side flanges 22. The adjustable-length brace with a threaded rod or a turnbuckle at the top end is used to adjust the length between the base plate and the wall panel to vertically plumb the wall. Then the wall can be precisely leveled if desired by adjusting the threaded rods of the assembly 36 or by using shims. When the wall is plumb and level, the base of the wall can be anchored by driving short sections of rebar (10-16 inch) into the ground through holes in the base pan 28 and driving an angle drive stake 66 through a cutout (not shown) in the base plate 62 to anchor the plate prior to pouring concrete.
Long strands of rebar can then be placed along the length of the wall. Preferably, two rebar strands 86 are laid, one against an angle formed by the diagonal brace and the short strut of the brace assembly and the other against an angle formed by the short strut and the side flanges 22 of the wall panels.
A concrete encapsulating base 84 should be poured behind the wall to a depth of a least eight inches, filling and covering the base pans 28 of the wall panels 16, the back flange 64 of the brace assembly base plate 62, the rebar strands 86 and drive stake 66, and a lower portion of the diagonal brace 70. With this encapsulation in the concrete, the wall acts as a light weight, upright, retaining wall. The light weight reduces problems from settling. The upright posture and embedded A-frame support assemblies anchor the wall against overturning torque. The concrete base and A-frame support also anchor the wall against being pushed out from the soil bank by pressure from the backfilled dirt. The rock trench under the wall reduces the likelihood of frost heaving dislodging the wall.
As shown in
If more than one wall is going to be installed to create a terraced effect, the lower wall should be filled first. The terracing effect of multiple walls can also be used to create a step down pathway, as shown by the multiple wall assembly 110 in
Alternatively a steel stairwell box may be placed in the wall between adjoining panels. Such stairwells are well known in the swimming pool industry, and are adapted to bolt into the side flanges of the wall panels. Steel benches or coves, such as a firewood box or storage bin can be placed on or in the wall. The wall panels may also have cutouts for electrical junction boxes 96 for outdoor lighting or utility outlets. The wall panel side flanges have cutout sections through which piping or electrical conduit can be run prior to backfilling.
When used in a decorative landscaping application, a retaining wall can be finished on the open front side using paint or other surface coatings. The retaining wall can also support a stucco finish, as shown in
Claims
1. A ground retaining wall comprising:
- a plurality of modular steel wall panels of a type formed from steel sheet to provide a flat exterior wall surface on a front side the panel, and on an opposite back side having a side flange on each vertically extending edge with matching bolt holes to allow panels to be joined together, the back side also having a top and bottom surface extending at a right angle to the panel to form a top cap and a base pan for the panel;
- a plurality of vertical reinforcement studs each attached to the back side of a panel at spaced intervals to stiffen the panel against bulging pressure, the studs extending from the base pan to the top cap;
- a plurality of vertical reinforcement brackets each located along at least one side flange of a panel at a seam where two panels are joined together, the bracket having bolt holes spaced to match the bolt holes in the side flanges of the wall panels;
- a plurality of support brace assemblies each attached to a side flange of a panel at the seam where two panels are joined together, the brace assembly including a base structure attached to the side flange adjacent the bottom of the side flange, and a brace rod attached at one end to the base structure at a location away from the panel and attached at its opposite end to an upper section of the side flange of the panel such that the brace rod extends diagonally upward from the base structure to the wall panel.
2. A ground retaining wall as in claim 1, further comprising a concrete base poured behind the wall covering and encapsulating the base pans of the panels and the base structure of the support brace assemblies.
3. A ground retaining wall as in claim 2, wherein the base structure includes a base plate extending generally horizontally way from the wall panel and a flange on the back edge of the plate extending upwardly from the plate, and a drive stake is received through the base plate to anchor the plate, wherein the concrete layer covers and encapsulates the flange and the drive stake.
4. A ground retaining wall as in claim 1, wherein the brace rod is an adjustable-length rod to adjust a length of the brace rod between the base structure and the wall panel.
5. A ground retaining wall as in claim 4, wherein the brace rod has a threaded rod or a turnbuckle to adjust the length of the brace between the base structure and the wall panel.
6. A ground retaining wall as in claim 1, wherein each vertical reinforcement studs is made of steel sheet formed into an elongated member having a substantially Z-shaped cross section in which a first flange of the stud is fastened against a flat portion of the wall panel, a web of the stud extends inwardly perpendicular to the plane of the panel, and a second flange extends in a direction opposite the first flange.
7. A ground retaining wall as in claim 6, wherein each stud includes at least one cutout through the web to allow passage of electrical conduit or plumbing behind the wall.
8. A ground retaining wall as in claim 1, wherein the reinforcement brackets are made of sheet steel formed into an elongated channel member having substantially C-shaped cross section in which a web portion has the bolt holes spaced to match the bolt holes in the side flanges of the wall panels, and a flange at each end of the web contacts the top cap and the base pan respectively when the bracket is installed.
9. A ground retaining wall as in claim 2, wherein the wall panels have a height adjustment leveler assembly attached to the base pan of the wall panel, and wherein the concrete layer covers and encapsulates the leveler assemblies.
10. A ground retaining wall as in claim 9, wherein the leveler assembly includes a threaded rod passing though the base pan near each bottom corner.
11. A method of constructing a ground retaining wall, comprising the steps of:
- locating and marking the line and elevation of a base for the wall;
- cutting away as much of any existing soil bank to create a generally flat ledge along the line of the wall at the elevation of the wall base and allowing at least 2½ feet of ledge behind the line of the wall to accommodate brace assemblies;
- obtaining a plurality of wall panels of a type formed from steel sheet to provide a flat exterior wall surface on a front side the panel, and on an opposite back side having a side flange on each vertically extending edge with matching bolt holes to allow panels to be joined together, the back side also having a top and bottom surface extending at a right angle to the panel to form a top cap and a base pan for the panel;
- obtaining a plurality of vertical reinforcement studs of sufficient length to extend from the base pan to the top cap of the wall panels;
- attaching one or more studs to the back side of each wall panel at spaced intervals in a vertical orientation such that a stud extends from the base pan to the top cap;
- obtaining a plurality of vertical reinforcement brackets having bolt holes spaced to match the bolt holes in the side flanges of the wall panels;
- assembling the wall panels over the line of the wall by placing adjacent panels side by side with the flat exterior wall surfaces in the same direction such that the bolt holes on the side flanges of adjacent panels are aligned, placing each reinforcing bracket along one side flange of a panel at a seam where two adjacent panels are joined together, inserting bolts though aligned holes in the bracket and the side flanges of adjoining panels, and tightening nuts onto the bolts to secure the panels together;
- obtaining a plurality of support brace assemblies, a brace assembly including a base structure attachable to the side flange of a wall panel, and a brace rod attachable at one end to the base structure at a location away from the panel and attachable at its opposite end to an upper section of the side flange of the panel;
- attaching the support brace assemblies to the wall panels by attaching the base structure of each brace assembly to a side flange of a wall panel adjacent the bottom of the side flange, and attaching the brace rod to an upper section of the side flange such that the rod extends diagonally upward from the base structure to the wall panel;
- pouring a concrete base behind the wall of sufficient height and width to cover and encapsulate the base pans of the panels and the base structure of the support brace assemblies;
- laying a water collection pipe over the concrete base and venting the pipe through or around the wall to drain water collected in the pipe from behind the wall;
- covering the pipe with a layer of rock;
- covering the layer of rock with a landscape cloth; and
- backfilling soil behind the wall up to or just below the top of the wall.
12. A method of constructing a ground retaining wall as in claim 11, wherein the brace rods are adjustable-length rods, comprising the further step of adjusting the length of the brace rods as necessary to vertically plum the wall before tightening nuts onto the bolts to secure the panels together.
13. A method of constructing a ground retaining wall as in claim 12, wherein the base structure of the support assembly includes a base pan having a back flange and a slot for passing through a drive stake, comprising the further step of driving a drive stake through each base plate down into the soil ledge beneath the base plates, and wherein the step of pouring a concrete base behind the wall includes pouring the concrete to a sufficient height and width to cover and encapsulate the back flanges and drive stakes of the base plates.
14. A method of constructing a ground retaining wall as in claim 11, wherein the brace rods of the brace assemblies are adjustable-length rods, comprising the further step of using the adjustable length capability to vertically plumbing the wall prior to pouring the concrete layer.
15. A method of constructing a ground retaining wall as in claim 11, comprising the further step of placing strands of rebar across the bottom struts of the brace assemblies and extending along the length of the wall prior to pouring the concrete base.
16. A method of constructing a ground retaining wall as in claim 11, comprising the further steps of providing the reinforcement studs with cutouts through the webs of the studs to allow passage of electrical conduit or plumbing, and stringing such electrical conduit or piping through the cutouts along the back side of the wall before prior to completing the step of backfilling soil behind the wall.
17. A method of constructing a ground retaining wall as in claim 11, comprising the further steps of building a main retaining wall as the highest elevation wall by the steps of claim 11, and then building one or more retaining walls at lower elevations around the main wall.
18. A method of constructing a ground retaining wall as in claim 17, comprising the further steps of building two or more retaining walls at lower elevations around the main wall and graduating the height and length of the additional walls to form a terraced step down pathway from the main wall.
19. A method of constructing a ground retaining wall as in claim 11, further comprising the step of coating the flat exterior wall surface on a front side the panels with a decorative finish.
Type: Application
Filed: Jun 7, 2007
Publication Date: Dec 13, 2007
Inventor: David A. Bradley (Pottsville, PA)
Application Number: 11/810,870
International Classification: E02D 17/00 (20060101);