Abstract:
A system of composite panels comprised of resin impregnated carbon fiber sheets, on opposing sides of a fiberglass core, having structural values directly related to the thickness of the core and the amount of carbon fiber incorporated, to be used in marine conditions to resist scour or erosion while retaining soil materials behind the panel and resisting hydrostatic loads. Each panel will have high-density polyethylene (HDPE) interlocks on opposite edges allowing the panels to slide together allowing a series of joined panels to form a continuous wall. Additionally the preformed HDPE interlocks may be field-installed and removed allowing the carbon fiber panels to be cut to a specific dimension as necessary.

Description:
FIELD OF THE INVENTION 
   Various embodiments of the invention pertain to the prevention and/or elimination of shoreline erosion and/or scour beneath marine structures. More particularly, at least one embodiment of the invention relates to a bulkhead system of interlocking carbon-reinforced panels with improved strength. 
   DESCRIPTION OF RELATED ART 
   Currently, the most common methods for stabilizing earth materials or earth materials beneath structures in a marine environment are either the placement of rock protection or constructing a bulkhead by the driving of steel, fiberglass, aluminum or vinyl sheet pile adjacent to the material to be protected. Though these methods can be adequate, each has inherent disadvantages. 
   Placement of rock may require encroachment into properties owned by others or areas sensitive with environmental constraints. Conventional steel sheet or aluminum pile may also experience the same encroachment problems and the metallic pile, in a marine condition, is highly subject to corrosion. Additionally, placement of steel sheet pile or rock protection requires the use of heavy equipment along with adequate access. Vinyl and fiberglass sheet pile have very little structural value and are generally utilized in conjunction with rock protection. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1 and 2  illustrate a reinforced retention panel according to one embodiment of one aspect of the invention. 
       FIG. 3  illustrates a method of manufacturing fiber-reinforced panels according to one aspect of one embodiment of the invention. 
       FIG. 4  illustrates how a plurality of fiber-reinforced panels, according to one embodiment of the invention, may be joined using various interlocks, according to various embodiments of the invention, in one implementation of the invention. 
       FIG. 5  illustrates how seawall support pilings may be protected according to one implementation of the fiber-reinforced panels and interlocking system of one embodiment of the present invention. 
       FIG. 6  illustrates a top view of two fiber-reinforced panels joined by an interlock according to one embodiment of the invention. 
       FIG. 7  illustrates yet another embodiment of the invention where each fiber-reinforced panel has a lug along each longitudinal side of the panel. 
       FIG. 8  illustrates a perspective view of an interlock according to one embodiment of the invention. 
       FIG. 9  illustrates a method of assembling an erosion control barrier according to one embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description numerous specific details are set forth in order to provide a thorough understanding of the invention. However, one skilled in the art would recognize that the invention may be practiced without these specific details. In other instances, well known methods, procedures, and/or components have not been described in detail so as not to unnecessarily obscure aspects of the invention. 
   Various aspects of the invention provide a novel bulkhead wall including an interlocking system of reinforced panels that may be employed, for example, to stabilize or protect structures along a shoreline. A bulkhead wall of fiber-reinforced panels, having structural values directly related to the thickness of the panel core and the amount of reinforcing fiber incorporated therein may be use in marine conditions to resist scour or erosion while retaining soil materials behind the panel and resisting hydrostatic loads. 
     FIGS. 1 and 2  illustrate a reinforced retention panel  100  according to one embodiment of one aspect of the invention. The panel  100  includes a core  102  reinforced by one or more layers of reinforcing fiber  104 . The reinforcing fiber  104  may be carbon fiber or any other material which serves to reinforce and/or strengthen the panel  100 . In one implementation, the layers of reinforcing carbon fiber  104  may be arranged near the faces of the panel  100 . 
   According to one embodiment of the invention, the reinforcing layers of carbon fiber  104  include unidirectional fiber  106  running substantially parallel to the longitudinal axis of the panel  100 . The longitudinal axis of the panel  100  being substantially parallel to direction in which the panels are to be driven into the ground. In another embodiment, the reinforcing carbon fiber may be weaved or arranged in various other configurations are directions, relative to the longitudinal axis of the panel, (e.g., perpendicular, diagonal, etc.) to strengthen the panel  100 . 
   According to one embodiment of the invention, the core  102  may be a fiberglass core. In other embodiments, other materials may be used which provide stiffness and strength to the panel  100 . 
   In one embodiment of the invention, the panel  100  includes a lug or blockhead  108  on one edge of the panel  100  along the longitudinal axis of the panel  100 . As described below, this lug or blockhead  108  permits longitudinal movement of a panel while interlocked to other panels. For example, the panel  100  may be driven to a specified depth without affecting other interlocked panels. In another embodiment of the invention, the panel  100  may include lugs or blockheads  108 , along the longitudinal sides of the panel  100 . The lug or blockhead  108  may be attached to the panel using epoxy, or any other conventional method. In another embodiment, the lug or blockhead  108  is manufactured as an integral part of the panel  100 . 
     FIG. 3  illustrates a method of manufacturing fiber-reinforced panels according to one aspect of one embodiment of the invention. One or more layers of resin-impregnated carbon fiber sheets  300  are coupled to one or both sides of a fiberglass core  302 . The structural strength of the panel having structural values directly related to the thickness of the fiberglass core, the amount of carbon fiber incorporated therein, and/or the type of resin used to bind the carbon fiber sheet(s) to the fiberglass core. 
   In one embodiment of the invention, the carbon fiber sheet(s) is impregnated with polyester resin. In another embodiment of the invention, a vinyl ester resin is employed to impregnate and bind the carbon fiber sheet(s) to the fiberglass core. In one implementation, each layer of carbon-fiber and resin may total approximately {fraction (1/16)} of an inch in thickness to the reinforced panel. 
   A lug is attached or created along the length and edge of the panel  304 . Thus, the panels have increased strength, are relatively lightweight, and are inert to environmental conditions, such as corrosion. 
   The carbon fiber reinforced panels disclosed by this invention are unexpectedly strong in comparison to mere fiberglass panels. Tables 1, below, illustrates the result of load tests performed on polyester resin-impregnated carbon fiber panels with a fiberglass core. The overall thickness of the panels are about ⅝ of an inch, including the fiberglass core. The testing involved samples approximately 2 inches by 9 inches long with the carbon fibers positioned perpendicular to the load. As seen from the Maximum Load results, the carbon fiber reinforced panel samples were able to withstand maximum loads in the 3600 pound range representing an average modulus of rupture of 41162 pounds per square inch. 
   
     
       
             
           
             
             
             
             
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               Carbon Fiber-Reinforced Fiberglass Panels Polyester Resin 
             
           
        
         
             
                 
               Max. Load 
               Thickness 
               Width 
               Span 
               Modulus of 
             
             
               Sample # 
               (lbs) 
               (in.) 
               (in.) 
               (in.) 
               Rupture(p.s.i.) 
             
             
                 
             
             
               1 
               3744 
               0.6395 
               2.0515 
               9.00 
               40163 
             
             
               2 
               3606 
               0.6115 
               2.1535 
               9.00 
               40302 
             
             
               3 
               3658 
               0.6015 
               2.1390 
               9.00 
               42541 
             
             
               4 
               3478 
               0.5915 
               2.1485 
               9.00 
               41642 
             
             
                 
             
           
        
       
     
   
   Table 2, below, illustrates the result of load tests performed on reinforced fiberglass panels similar to those show in Table 1, above, but reinforced with carbon fiber impregnated with vinyl ester resin. The testing involved samples approximately 2 inches by 9 inches long with the carbon fibers positioned perpendicular to the load. As seen from the Maximum Load results, the carbon fiber reinforced panel samples were able to withstand maximum loads in the 3900 pound range representing an average modulus of rupture of 47747 pounds per square inch. These tests show that for panel samples of similar dimensions, the use of vinyl ester resin to impregnate or bond the carbon fiber to the panels increases the strength of the panels more than the use of polyester resin for the same purpose. 
   The panels in Samples #2-12, in Table 2, were submerged in saturated salt water over several months prior to the test to determine if the marine environment degrades the panels&#39; structural properties. As the results indicate, the salt water conditions did not affect the strength of the reinforced panels. 
   
     
       
             
           
             
             
             
             
             
             
           
         
             
               TABLE 2 
             
           
           
             
                 
             
             
               Carbon Fiber-Reinforced Fiberglass Panels Vinyl Ester Resin 
             
           
        
         
             
                 
               Max. Load 
               Thickness 
               Width 
               Span 
               Modulus of 
             
             
               Sample # 
               (lbs) 
               (in.) 
               (in.) 
               (in.) 
               Rupture(p.s.i.) 
             
             
                 
             
             
                1 (Dry) 
               4100 
               0.6285 
               2.0084 
               9.00 
               46512 
             
             
                2 (Wet) 
               4006 
               0.6250 
               2.0004 
               9.00 
               46140 
             
             
                3 (Wet) 
               3960 
               0.6265 
               2.0083 
               9.00 
               45210 
             
             
                4 (Wet) 
               4456 
               0.6205 
               1.9954 
               9.00 
               52201 
             
             
                5 (Wet) 
               4310 
               0.6265 
               2.0015 
               9.00 
               49376 
             
             
                6 (Wet) 
               4092 
               0.6225 
               1.9874 
               9.00 
               47821 
             
             
                7 (Wet) 
               3928 
               0.6125 
               1.9874 
               9.00 
               47414 
             
             
                8 (Wet) 
               3930 
               0.6115 
               1.9818 
               9.00 
               47730 
             
             
                9 (Wet) 
               3830 
               0.6050 
               1.9764 
               9.00 
               47645 
             
             
               10 (Wet) 
               3870 
               0.6045 
               1.9957 
               9.00 
               47760 
             
             
               11 (Wet) 
               3910 
               0.6095 
               1.9915 
               9.00 
               47566 
             
             
               12 (Wet) 
               3795 
               0.6025 
               1.9730 
               9.00 
               47588 
             
             
                 
             
           
        
       
     
   
   Table 3, below, illustrates the same load test illustrated above, with respect to Tables 1 and 2, but performed on a fiberglass samples ranging from {fraction (7/16)} to nearly ½ inch thick. As with the above test, fiberglass samples are approximately 2 inches by 9 inches. As can be seen from these tests, the unreinforced fiberglass has much lower maximum loads, in the 600 to 718 lbs. range representing an average modulus of rupture of 14400 pounds per square inch. Although the fiberglass cores used in the two tests were of slightly different thicknesses, the fiberglass cores in Table 1 and 2 were approximately ½ inch thick while the core in Table 3 was {fraction (7/16)} to ½ inch thick, the increased maximum load strength exhibited by the carbon fiber reinforced panels was still significantly greater than would have been expected. 
   
     
       
             
           
             
             
             
             
             
             
           
         
             
               TABLE 3 
             
           
           
             
                 
             
             
               Fiberglass Panels 
             
           
        
         
             
                 
               Max. Load 
               Thickness 
               Width 
               Span 
               Modulus of 
             
             
               Sample # 
               (lbs) 
               (in.) 
               (in.) 
               (in.) 
               Rupture(p.s.i.) 
             
             
                 
             
             
               1 
               660 
               0.4355 
               2.0050 
               9.00 
               15621 
             
             
               2 
               714 
               0.4930 
               2.0000 
               9.00 
               13220 
             
             
               3 
               608 
               0.4380 
               1.9950 
               9.00 
               14297 
             
             
               4 
               718 
               0.4715 
               2.0100 
               9.00 
               14461 
             
             
                 
             
           
        
       
     
   
     FIG. 4  illustrates how a plurality of carbon fiber-reinforced panels  401 - 405 , according to one embodiment of the invention, may be joined using various interlocks  410 - 413 , according to various embodiments of the invention, to create a continuous bulkhead wall in one implementation of the invention. The plurality of carbon fiber-reinforced panels  401 - 405  are joined with sliding interlocks  410 - 413  along their edges. Each individual panel  401 - 405  may be driven into the ground  416  to a specified vertical depth along the outboard face of the structure or material whose sub-grade  420  is to be stabilized or protected. The panels  401  may include one or more lugs to permit the panels to slide up and down, with relation to the interlocks  410 - 413 , while preventing the panels from separating from the interlock and/or an adjoining panel. The tops of the panels may be anchored with bolts, tieback anchors, or a wailer system as necessary to provide support to resist all lateral loads. 
   Because the carbon fiber-reinforced panels are relatively strong and are lightweight, the bulkhead or reinforcing wall is easy to assemble, capable of withstanding heavier loads, and provides for flexible field modifications. 
   As illustrated in  FIG. 4 , various types of interlock arrangements may be used depending on the implementation. In one embodiment of the invention, a single interlock  410  may be used to join to fiber-reinforced panels  401 - 402  while filling any gaps between the panels  401 - 402 . The interlock  410  may run from, approximately, the surface of the ground to, approximately, the top of the panels  401 - 402 . In another implementation, the interlocks  411  may be of sectioned into multiple interlocks  411  that can be stacked to join or couple the panels  402 - 403  while filling any gaps between the panels  402 - 403 . 
   In yet other implementations, the interlocks  412  and  413  need not run continuously from the ground to the top of the fiber-reinforced panels  403 - 405 . Instead, the interlocks may be arranged to create a gap between interlocks. This gap may be as large or small as the implementation requires. For example, a small gap or gaps  418  may be created to permit water to drain out while still preventing erosion of the sub-grade  420  being protected. 
   In yet other implementations, the interlock  422  may run below the ground  420  level to provide greater protection against erosion. 
     FIG. 5  illustrates how seawall support pilings  500  may be protected according to one implementation of the fiber-reinforced panels and interlocking system of one embodiment of the present invention. The timber piling  500  that support the seawall  502  are subject to attack by marine borers when the sea bottom  508  scours below the footing  504  and exposes these piles  500 . A carbon fiber-reinforced panel  504  may be driven into the sea bottom  508  and then secured to the seawall footing  504  with stainless steel bolts  510 . 
   In one implementation of the invention, if voids  512  exist beneath the structure being stabilized or protected, these voids  512  can be filled with pressurized grout utilizing holes drilled through the panel  506 . Sealing of these holes is unnecessary since they are completely filled when the grouting operation is completed. 
     FIG. 6  illustrates a top view of two fiber-reinforced panels joined by an interlock according to one embodiment of the invention. In one embodiment of the invention, the interlock system  602  may be composed of high-density polyethylene (HDPE). The interlock  602  serves to join two fiber-reinforced panels  604  and  606 . 
   A first panel  604  is secured to the interlock  602  with one or more fasteners or bolts  608 . In one implementation, the one or more bolts may be stainless steel bolts or fasteners. In other implementation, the bolts or fasteners may be of other materials which are resistant to corrosion or which have characteristics desirable for a particular implementation. 
   A second panel  606  has a continuous lug  610 , along one edge of the panel  606 . In various implementations of the invention, the lug  610  may be integral with the panel  606  or a separate component which is attached to the panel  606 . In one embodiment of the invention, the lug  610  is made of fiberglass and integral with the panel  606 . The lug  610  slides longitudinally along a groove in the interlock  602 . This interlocking groove allows longitudinal movement of the panel to accommodate driving of each individual panel into the ground while restraining from undesired movement along the other two axes. That is, the interlocking grooves permit the panels to slide up or down but prevents two panels from separating. 
   In one implementation of the invention, every panel has a lug  610  along one side in the longitudinal direction. The fiber-reinforced panels  604  and  606  may be cut to size in the field or during installation as conditions dictate. When using panels with a single lug along one longitudinal side or edge, the panels may be cut to the desired width along the non-lug side or edge. The cut panel (e.g.,  604 ) can still be joined to other panels by using interlock  602 . 
   In one implementation of the invention, the thickness  612  of the fiber-reinforced panels  604  and  606  is uniform, except for the lug portion  610 . For example, in one implementation the panels are half an inch thick. Other fiber-reinforced panels may be manufactured thicker or thinner according to the desired strength for a given implementation. 
     FIG. 7  illustrates yet another embodiment of the invention where each fiber-reinforced panel  702 - 703  has a lug  705  along each longitudinal side of the panel. The interlocks  706 - 708  each have interlocking grooves  710  which join the panels  702 - 703  while permitting the panels to slide in the longitudinal direction so that they may be driven into the ground. According to one implementation of the invention the interlocks may be designed to provide for some clearance (e.g., one-sixteenth of an inch) with the panels. 
   The system of interlocks illustrated in  FIG. 7  may also be interconnected with a panel  704  which has been cut to size, thereby removing one of the lugs along one edge of the panel  704 . The edge without a lug can still be inserted into the groove or channel and, once it has been driven into the ground, may be secured to interlock  708  by bolts or fasteners. In other embodiments of the invention, interlock  708  may be replaced by an interlock  602  as shown in FIG.  6 . 
     FIG. 8  illustrates a perspective view of an interlock  802  according to one embodiment of the invention. The interlock  802  includes two channels  804  and  806  for joining two panels. A first channel  804  permits a panel to slide in and out and up and down. When conditions dictate, a panel may be cut to a desired width, along a longitudinal side, and inserted into the first channel  804 . A second channel  806  includes an interlocking groove  808  that permits a panel to slide up and down but not in and out. 
     FIG. 9  illustrates a method of assembling an erosion control barrier according to one embodiment of the invention. A first fiber-reinforced panel is partially driven into the ground  902 . An interlock (e.g.,  802 ) is joined or coupled along one longitudinal side of the first panel  904 . For example, in one implementation the interlock channel  804  ( FIG. 8 ) is joined to the non-lug side of the first panel and attached to the first panel using bolts or other fasteners. In a second implementation the interlock channel  806  ( FIG. 8 ) may be slid over the lug side of the first panel and held in place by the interlocking groove  808 . A second fiber-reinforced panel is joined to the interlock  806 ,  906 , either in channel  804  or  806 , and partially driven into the ground  808 ,  907 . If joined to channel  804  of the interlock, then it is secured to the interlock  908  after the second fiber-reinforced panel has been driven into the ground. In one implementation, the top portion of one or more panels may be attached to the structure being protected  910 . 
   While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications are possible. Those skilled, in the art will appreciate that various adaptations and modifications of the just described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.