Multi-panel seawall segment

Abstract

A multi-panel sheet piling segment has been developed. The sheet piling segment includes two lateral end panels with each lateral end panel having a connector for another segment of sheet piling, two lateral middle panels, and three connecting panels that join the lateral end panels and the lateral middle panels together at an angle.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 10/286,564 entitled “Re-enforced Composite Sheet Piling Segments” that was filed on Nov. 1, 2002.

BACKGROUND OF INVENTION

1. Field of the Invention

The invention relates generally to the structure of building materials. More specifically, the invention relates to multi-panel sheet piling segments.

2. Background Art

Sheet piling is a construction material that is commonly used to build walls such as retaining sea-walls. The sheet piling is typically manufactured in individual segments that are attached to other segments to form a continuous wall. Since the segments are usually driven into the ground for stability, the segments may be several meters tall.

Sheet piling was once commonly made with steel or other metals. However, such piling may now be made with fiber re-enforced polymers (FRP). FRPs are formed out of a cured resin that has been re-enforced with fibers made of materials such as glass. The resin typically may be polyester or vinylester. While not as strong as steel, these materials offer better performance due to resistance to corrosion and other effects of chemical environments. Steel is an example of an “isotropic” material in that loads are distributed equally through out the material. In contrast, FRPs are generally considered “anisotropic” in that loads are not distributed equally in the material. For example, a composite material such as fiberglass is stronger along the orientation of the glass fibers than in other areas of the material.

While the FRP materials are resistant to corrosion, they will absorb water when exposed to that environment for long periods of time. This is a particular problem when sheet piling made from FRPs is used to build a seawall. If the sheet piling is exposed long enough and absorbs enough water, the structure may become weakened to the point of failure. Additionally, when FRP sheet piling is used to build a seawall, it also is exposed to active pressure from soil on one side of the wall while being exposed to a passive pressure from the water on the other side. Over time, the panels of material can weaken and the panels may deform or fail catastrophically under this type of pressure alone or combined with any weakening of the material from water absorption.

The potential for such failures are particularly acute at the joints that join the panels together and at any corner or edge of a panel. According to modeling, maximum tension occurs at the corner angles of the panels. Typical solutions involved re-enforcing points of potential failure on a panel of sheet piling with a concave shaped re-enforcement. However, these re-enforcements have proven insufficient to provide the additional strength to a panel made of anisotropic materials (such as FRPs).

SUMMARY OF INVENTION

In some aspects, the invention relates to a sheet piling segment, comprising: two lateral end panels, where each lateral end panel has a connector for another segment of sheet piling; two lateral middle panels; and three connecting panels that join the lateral end panels and the lateral middle panels together at an angle.

Advantages of the present invention include

The sheet piling segment of this embodiment has the advantage of having its two connectors on opposite sides of the segment. This helps create a balanced segment with the neutral axis being located in its geometric center. Additionally, the added panels provide better shear resistance for the entire panel.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

It should be noted that identical features in different drawings are shown with the same reference numeral.

FIG. 1 shows an overhead view of two joined sheet piling segments in accordance with one embodiment of the present invention.

FIG. 2 shows an overhead view of a re-enforced corner of a sheet piling segment in accordance with one embodiment of the present invention.

FIG. 3 shows and overhead view of a joint of two joined sheet piling segments in accordance with one embodiment of the present invention.

FIG. 4 shows an overhead view of a multi-panel sheet piling segment in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 shows an overhead view of two joined sheet piling segments 10a and 10b in accordance with one embodiment of the present invention. The two sheet piling segments or “sheets” shown are typically used in construction of seawalls in either freshwater or saltwater environments. In the present embodiment, each sheet 10a and 10b is made of three distinct panels 12 that are roughly configured in a “Z” shaped arrangement. Each panel fits with adjacent panels to form a corner 14 of the segment. The panels 12 form an angle of approximately 120° at each corner 14. In alternative embodiments, the number of panels in a segment of sheet piling may vary along with their relative angles to each other.

The two segments 10a and 10b are connected at a joint. One panel 10a has a male joint attachment 16, while the other panel 10b has a female joint attachment 18. These two attachments 16 and 18 fit together to form the joint that interlocks the segments 10a and 10b. Multiple segments are fitted together to form a length of wall. In this embodiment, each segment has a male joint attachment 16 and a female joint attachment 18 on alternative ends of the segment. In alternative embodiments, segments may have two male attachments or two female attachments.

If the segments are used to construct a seawall, forces are exerted on the panels 12 and the joint on one side by soil and on the other side by water. In the present embodiment, the segments 10a and 10b are re-enforced along the panels 20 and the corners 22 in order to prevent the segments from bulging at these points and potentially failing catastrophically. The panel re-enforcement 20 has a circular cross-section and is centered on the panel 12. An overhead view of the corner re-enforcement 22 is shown in FIG. 2 in accordance with one embodiment of the present invention. The re-enforcement 22 is centered on the corner 14 of the two panels 12 of the sheet piling segment. Re-enforcing this area of the corner 14 helps prevent the panels 0.12 from bulging outward and compromising the integrity of the corner 14. The re-enforcement 22 has a convex cross-sectional shape that maximizes the re-enforcement strength for the corner while optimizing the use of materials to manufacture the sheet. A re-enforcement with a convex cross-sectional shape is particularly suited for used with anisotropic materials such as FRPs. A convex re-enforcement helps prevent rupturing of a matrix of fibers in the material.

In order to prevent separation of the sheet piling segments 10a and 10b at the joint, the male joint attachment 16 is re-enforced between the attachment 16 and its panel 12. An overhead view of the male joint attachment re-enforcement 24 is shown in FIG. 3 in accordance with one embodiment of the present invention. The re-enforcement 24 is centered between the panel 12 and the male attachment 16. Re-enforcing this area of the attachment 16 helps prevent twisting and buckling of the male attachment 16 that would result in its separation from the female attachment 18. The re-enforcement 24 has a triangular cross-sectional area that maximizes the re-enforcement strength of the attachment 16 while optimizing the use of materials. A triangular shaped re-enforcement 24 is used due to the 90° angle between the panel 12 and the bottom of the male attachment 16.

In some embodiments, the dimensions of the sheet may be 18 inches long (i.e., the linear length from the male attachment to the female attachment of a segment) and 8 inches wide (i.e., the linear distance between the two end panels of the segment). The segment may have a height of several feet or longer. The thickness of a panel of the segment may be 0.25 inches. In alternative embodiments, these dimensions may vary accordingly.

The segment of sheet piling may be made of polyurethane material. Polyurethane is a material with hydrophobic properties of low water absorption, even when the outer skin has been breached (e.g., by drill holes). The material is also highly impact resistant and stable under prolonged exposed to ultra-violet (UV) radiation and saltwater. In typical applications, polyurethane may be “heat cured”. Curing is a chemical process where a liquid material (e.g., a resin) cross-links to form a solid. The curing process may be initiated or accelerated by the application of heat. It is commonly done during the molding process and may take a few seconds to a few hours for completion depending on the materials involved.

Polyurethane elastomers are one member of a large family of elastic polymers called rubber. Polyurethane may be a liquid that can be molded into any shape or size. It is formed by reacting a polyol (an alcohol with more than two reactive hydroxyl groups per molecule) with a diisocyanate or a polymeric isocyanate in the presence of suitable catalysts and additives. The chemical formula for polyurethane is: C₃H₈N₂O. A wide variety of diisocyanates and polyols can be used to produce polyurethane in alternative embodiments. It should be understood that the term “polyurethane” includes a wide variety of thermoplastic polyurethane elastomers that are manufactured differently and may have different performance characteristics.

In an alternative embodiment, polyurethane may be used as a base component of a multi-component mixture. Such a multi-component material includes: a hardening catalyst such as isocyanate and a resin such as polyurethane. The advantage of a multi-component mixture is that it does not require heat during the curing process. In alternative embodiments, alternative materials could be used that are suitable as a hardening catalyst and a resin.

In an alternative embodiment, a polyurethane based material (either alone as a single component material of polyurethane or in a multi-component material) is used with re-enforcing fibers to form the sheet piling segments. The segments are manufactured by a process called “pultrusion”. With the pultrusion process, the fibers are pulled through a wet bath of polyurethane resin. The fibers are wetted with polyurethane by the bath. The wet fibers are then cast into a matrix to increase the structural strength of the segment. The matrix may be a woven pattern whose design may vary to increase the strength of the finished product. The material is then pulled through a die where the segment of sheet piling is formed. The segment is then heat cured to solidify the polyurethane and complete the manufacture of the segment. The fibers used in the process may be made of glass, carbon, or other suitable material that provides strength to the material.

In an alternative embodiment, sheet piling segments may be made of standard FRP materials with a water-resistant gel coating applied to the surface of the piling. The gel-coating will prevent absorption of water by the underlying FRP material and consequently prevent weakening of the integrity of the sheet piling segment. An example of a suitable material for use as a gel coating is a “neopental isothalic acid resin” system. This material protects FRPs from water absorption while it also resists barnacles and other parasites. In other embodiments, other suitable water-resistant materials could be applied to the surface of the FRP to prevent water absorption.

FIG. 4 shows an overhead view of an alternative embodiment of a multi-panel sheet piling segment 40. The segment 40 includes seven separate panels along with a male connector 16 and a female connector 18. The segment also includes panel re-enforcements 20 and corner re-enforcements 22 as previously described. Additionally, each of the connectors 16 and 18 has a re-enforcement 24 as previously described.

The seven panels of the segment 40 are two separate types: lateral panels 42 that run parallel to the direction of the wall; and connecting panels 44 that connect the lateral panels. Each lateral panel 42 is joined with a connecting panel 44 on at least one end. The lateral panels 42 on the ends of the segment are connected to a male 16 or female 18 connector in lieu of a second connecting panel 44. The middle lateral panels 42 are joined with a connecting panel 44 on each end.

In the embodiment shown in FIG. 4, a lateral panel 42 and a connecting panel 44 are joined at a 110° angle. In this embodiment, the thickness of each lateral panel 42 is 0.175 inches and the thickness of each connecting panel 44 is 0.150 inches. The thickness of each corner re-enforcement 22 is 0.327 inches and the thickness of each panel re-enforcement 20 is 0.400 inches. The depth between

• • opposing lateral panels 42 is 5.800 inches and the depth between a lateral panel 42 and a panel re-enforcement 20 on a connecting panel 44 is 2.900 inches. Finally, the lateral length of the entire sheet segment 40 from male connector 16 to female connector 18 is 24.000 inches. It should be understood that these dimensions are given by way of example for this embodiment and other embodiments of the present invention could have some or none of these characteristics.

The sheet piling segment of this embodiment has the advantage of having its two connectors 16 and 18 on opposite sides of the segment. This helps create a balanced segment with the neutral axis being located in its geometric center. Additionally, the added panels provide better shear resistance for the entire panel.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed here. Accordingly, the scope of the invention should be limited only by the attached claims.

Claims

1. A sheet piling segment, comprising:

two lateral end panels, where each lateral end panel has a connector for another segment of sheet piling;

two lateral middle panels; and

three connecting panels that join the lateral end panels and the lateral middle panels together at an angle.

2. The sheet piling segment of claim 1, where the connectors are located on opposite sides of the sheet piling segment.

3. The sheet piling segment of claim 1, where one of the connectors is a male connector and the other connector is a female connector.

4. The sheet piling segment of claim 1, further comprising:

a re-enforcement with a convex cross-sectional area that is located in the angles between the lateral panels and the connecting panels.

5. The sheet piling segment of claim 4, where the thickness of the re-enforcement for the angle is 0.327 inches.

6. The sheet piling segment of claim 1, where the angle is about 110 degrees.

7. The sheet piling segment of claim 1, where the length of the segment is about 24 inches.

8. The sheet piling segment of claim 1, where the depth of the segment is about 5.8 inches.

9. The sheet piling segment of claim 1, where the thickness of the connecting panels is about 0.15 inches.

10. The sheet piling segment of claim 1, where the thickness of the lateral end panels and the lateral middle panels is about 0.175 inches.

11. The sheet piling segment of claim 1, where the connecting panels have a panel re-enforcement.

12. The sheet piling segment of claim 11, where the panel re-enforcement is located at the mid-point of the length of the connecting panel.

13. The sheet piling segment of claim 11, where the panel re-enforcement has a thickness of about 0.400 inches.