Patent Grant
6851889
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.
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.
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.
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.
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 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' structural properties. As the results indicate, the salt water conditions did not affect the strength of the reinforced panels.
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.
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
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.
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.
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.
The system of interlocks illustrated in
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.
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