Patent Publication Number: US-7210877-B2

Title: Erosion control device and matrix

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to a erosion control device for stabilizing soils and remedying beach and land erosion, a number of which can be assembled into a matrix for laying on or just below the surface of the ground or beach. 
   2. Background Information 
   Beach erosion and shore building are natural processes caused by the impact over time of waves on the shore. Waves breaking on the beach carry sedimentary material, also called littoral drift, onshore as the waves ascend the beach, and offshore as the waves retreat back. Waves arrive at an angle to the shore and retreat generally perpendicularly to the shore, resulting in a long shore current. This carries the littoral drift in a series of zigzags along the shoreline. The amount of littoral drift is dependent upon the speed of the waves; faster wave action translates to a higher amount of littoral drift. Littoral drift is deposited when the current (i.e., speed of the waves) slows. Thus, waves “steal” from one part of the beach to “feed” another part of the beach. During high tides, waves deposit sediment on higher areas of the beach while current close to the shoreline wears away at lower-lying areas of the beach. In the unusual event of an earthquake, enormous waves can be created that displace large amounts of sedimentary material. 
   The coast has some natural defenses against erosion. Gently sloping shores dissipate the energy of breaking waves, which decreases their speed as well as the amount of littoral drift. Dunes are natural seawalls, especially when they are covered with vegetation, which binds the sand. Inlets and bays are less subject to severe wave action and turbulence. 
   However, beach erosion and shore building are frequently accelerated by human activities. Heavy use and over development in shore areas, for example, hastens the erosion process. Damaging activities include dredging for marinas, bulldozing dunes, and pedestrian and vehicular traffic. Bulldozing dunes removes an important coastal defense, since dunes are natural seawalls. Pedestrian and vehicular traffic destroys vegetation and weakens bluffs and banks making them more susceptible to erosion. Obviously, removing large quantities of sand and sediment from a shore area without replacing it accelerates erosion. 
   Billions of dollars are spent each year on beach re-nourishment projects all along the coasts of the United States. Sand is brought in and spread on existing beaches in an effort to re-nourish them. Wide, attractive beaches in tourist-drawing seaside communities bring in more tourist dollars. Also, wide beaches are said to protect adjacent developed coastal areas from hurricane damage. In some areas where erosion is causing building structures to be washed away, re-nourishment is preventing loss of real estate every year. Beach re-nourishment, or replenishment, projects are controversial, though, because they are said to disrupt natural rhythms and cause more harm in the long run. Imported sand or sand pumped in from off shore dredges usually erodes away from the replenished beach at a faster rate. 
   Many man-made defenses against erosion, such as breakwaters, jetties, groins, seawalls, sand trapping devices, grass planting, and sand fences, also exist. However, such defenses have disadvantages. For example, breakwaters prevent wave erosion, but not longshore drifts, and are expensive. Seawalls deflect wave energy, but are very expensive and often utilized as a last resort because inevitably the sea slowly destroys sea walls. In fact, poorly designed or improperly installed erosion devices can actually accelerate erosion. 
   In sum, erosion is generally unstoppable. Yet people still flock to the seashore to build homes, hotels, and other structures directly in the path of erosion. Coastal residents continue to pay a high price, as erosion incessantly damages and claims their property. Thus, there is a need for an inexpensive erosion control device that works. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention is an erosion control device for stabilizing soil and remedying beach and soil erosion, which includes:
         (a) an elongated beam portion comprising a first wall and a first base;   (b) a cross-beam portion having a length that is less than half the length of the elongated beam portion, the cross-beam portion comprising a second wall and a second base; and   (c) a mechanism for connecting the erosion control device to a second erosion control device;   wherein the cross-beam portion extends transversely through the elongated beam portion at about a mid-point of the elongated beam portion. Also included herein is an erosion control matrix comprising at least two erosion control devices, each erosion control device comprising:   (a) an elongated beam portion comprising a first wall and a first base; and   (b) a cross-beam portion having a length that is less than half the length of the elongated beam portion, the cross-beam portion extending transversely through the elongated beam portion at about a mid-point of the elongated beam portion, the cross-beam portion comprising a second wall and a second base;   wherein the cross beam portion and the elongated beam portion each comprise opposite end walls, each end wall comprising a semi-circular channel; and wherein the two erosion control devices are detachably connectable end to end, side by side, or end to side.       

   The interconnectable devices of the present invention both prevent erosion and ameliorate the adverse effects of erosion that has already occurred. They are useful for protecting replenished beaches. They can also be used for stabilizing the ground under or on roadbeds, highway shoulders, embankments, dikes, and roadside ditches and drainage ditches. 
   Beaches also support a variety of wildlife, whose niches are destroyed as beaches erode over time. Sea turtle populations, for example, are adversely affected by erosion and detrimental human activities as their nesting sites are compromised. For example, all of the species of sea turtles indigenous to Florida, such as loggerhead ( Caretta caretta ) and green sea turtles ( Chelonia mydas ), are considered threatened or endangered. The decline of leatherbacks ( Dermochelys coriacea ), which nest along the Pacific coasts of Mexico, Costa Rica, etc., has also been dramatic. Matrices of larger size erosion control devices according to the present invention help ameliorate this decline in that they help to remedy and prevent erosion, which benefit sea turtle populations. Also, the spaces within the erosion control matrices of the present invention provide nesting sites for nesting sea turtle, with the erosion control devices surrounding the nesting sea turtle providing protection for it. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     A more complete understanding of the invention and its advantages will be apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein examples of the invention are shown, and wherein: 
       FIG. 1  is a perspective view of an erosion control device according to the present invention; 
       FIG. 2  is a front elevational view of the erosion control device according to  FIG. 1 ; 
       FIG. 3  is a side elevational view of the erosion control device according to  FIG. 1 ; 
       FIG. 4  is a top plan view of an erosion control device according to the present invention, shown with attached eye rings; 
       FIG. 5  is a front elevational view of the erosion control device according to  FIG. 4 ; 
       FIG. 6  is a perspective view of an erosion control matrix according to the present invention; 
       FIG. 7  is a top plan view of the erosion control matrix according to  FIG. 6 ; 
       FIG. 8  is an isometric view of two erosion control devices according to the present invention, shown connected end to end; 
       FIG. 9  is a side elevational view of two erosion control devices according to  FIG. 8 , shown connected end to end; 
       FIG. 10  is a perspective view of an erosion control device according to the present invention; 
       FIG. 11  is a front elevational view of two erosion control devices according to  FIG. 10 , laid end to end; 
       FIG. 12  is a front elevational view of two erosion control devices according to  FIG. 10 , one being on a slope; 
       FIG. 13  is a top plan view of an erosion control matrix according to the present invention; 
       FIG. 14  is a front elevational view of a number of erosion control devices according to the present invention; and 
       FIG. 15  is a perspective view of a rotatable connector of an erosion control device according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In the following description, like reference characters designate like or corresponding parts throughout the several views. Also, in the following description, it is to be understood that such terms as “front,” “back,” “within,” and the like are words of convenience and are not to be construed as limiting terms. Referring in more detail to the drawings, the invention will now be described. 
   Turning first to  FIG. 1 , a generally I-beam-shaped erosion control device according to the present invention, referred to herein as  10 , is comprised of an elongated beam portion  11  and a cross-beam portion  12  that extends transverse to the elongated beam portion. The length of the cross-beam portion  12  is less than half the length of the elongated beam portion  11 . 
   The elongated beam portion  11  is comprised of a first wall  14  supported on a first base  13  (see  FIG. 1 ). The first wall  14  has a generally planar wall top face  15  opposite the first base  13  and substantially perpendicular to two opposed, mirror image, generally planar wall side faces  16 . Preferably, the side faces  16  gradually angle outward toward generally planar base side faces  19 , making the first wall  14  generally trapezoidal in shape. The first wall  14  sits on the first base  13 , which also comprises a generally planar base top face  31  and a generally planar base bottom face (not shown). The base top face  31  and the base bottom face are spaced apart by the base side faces  19  and are substantially parallel to each other. The base side faces  19  are spaced apart by the base top face  31  and the base bottom face and are also substantially parallel to each other. Thus, the first base  13  is generally rectangular in shape. The first base  13  is wider than the first wall  14  so as to impart stability to the erosion control device  10 . 
   With continued attention to  FIG. 1 , the cross-beam portion  12  is substantially equal in height and width to the elongated beam portion  11 . The cross-beam portion  12  extends transversely through the elongated beam portion  11  at approximately the mid-point of the elongated beam portion. The cross-beam portion  12  also includes a second wall  25 , which lies on and is supported by a second base  26 . The second base  26  is substantially wider than the second wall  25 . The second wall  25  has a generally planar second wall top face  27  opposite the second base  26  and substantially perpendicular to two opposed, mirror image, generally planar, second wall side faces  28 . Preferably, the second wall side faces  28  gradually angle outward toward planar second base side faces  29 , making the second wall  25  generally trapezoidal in shape. The second wall  25  sits on the second base  26 , which also comprises a generally planar second base top face  30  and a generally planar second base bottom face (not shown). The second base top face  30  and the second base bottom face are spaced by the second base side faces  29 , and are substantially parallel to each other. The second base side faces  29  are spaced apart by the second base top face  30  and the second base bottom face and are also substantially parallel to each other. Thus, the second base  26  is generally rectangular in shape. Again, the second base  26  is wider than the second wall  25  in order to impart stability to the erosion control device  10 . 
   Turning to  FIG. 2 , a pair of similarly sized, cross apertures  20  extend transversely through the elongated beam portion  11 . The cross apertures  20  are preferably generally circular in shape. In use, each cross aperture  20  receives a cable or chain, which allows tightening of the grid and provides extra strength to the matrix formed by a number of interconnected erosion control devices. 
   Referring to  FIGS. 3 ,  4 , and  5 , the erosion control device  10  includes first end walls  17  at opposite ends of the elongated beam portion  11 . Each one includes a first channel  18  that extends from the wall top face  15  to the base bottom face (see  FIG. 3 ). In use, the first channels  18  accommodate attachment pins  34  (see  FIG. 8 ). As shown in  FIGS. 4 and 5 , pairs of spaced apart, similarly sized end loops  21   a ,  21   b  project from the first end walls  17  and into the first channels  18 . Most preferably, the first channels  18  are generally semi-circular in shape, the end loops  21   a ,  21   b  are generally circular in shape, and the radii of the first channels  18  are approximately equal to the outer radii of the end loops  21   a ,  21   b . The pair of end loops  21   a  is vertically displaced from the pair of end loops  21   b , so they do not knock into each other when two erosion control devices are joined. The end loops  21   a ,  21   b  are most preferably heavy duty, galvanized I-bolts or U-rings. In use, the end loops  21   a ,  21   b  and the first channels  18  secure a number of erosion devices  10  together end to end, as shown in  FIGS. 8 and 9 . 
   Referring again to  FIG. 2 , second end walls  32  at opposite ends of the cross-beam portion  12  similarly each include a second channel  33 , which extends from the second wall top face  27  to the second base bottom face. These second end walls  32  are substantially perpendicularly oriented to the first end walls  17  of the elongated beam portion  11 . In use, the second channels  33  also accommodate attachment pins. As shown in  FIGS. 4 and 5 , pairs of spaced apart, similarly sized end loops  21   c ,  21   d  project from the second end walls  32  into the second channels  33 . Most preferably, the second channels  33  are generally semi-circular in shape, the end loops  21   c ,  21   d  are generally circular in shape, and the radii of the second channels  33  are approximately equal to the outer radii of the end loops  21   c ,  21   d . The pairs of end loops  21   c ,  21   d  are vertically displaced from the pairs of end loops  21   a ,  21   b  in order to facilitate perpendicular connection of erosion control devices  10 , as shown in  FIGS. 5 ,  6 , and  7 . The end loops  21   a–d  are most preferably heavy duty, galvanized eye bolts or U-rings. An alternate embodiment, though, does not include first or second channels, as the erosion control devices need not about one another to be effective. 
   Rebar  36  extends longitudinally through both the elongated beam portion  11  and the cross-beam portion  12 , where the erosion control device is made of a concrete-type material. The end loops  21   a–d  are mounted on opposite ends of the rebar  36  by any suitable means, such as by welding. Alternatively, only one end loop  21   a–d  is employed instead of a pair of end loops. Other suitable means of reinforcement may be employed in place of rebar. 
     FIGS. 8 and 9  illustrate a first erosion control device  10   i  attached end to end to a second, identical erosion control device  10   j  with their longitudinal axes aligned. This linear formation can be used, for example, on the perimeter of an area to be protected, or as a series of relatively parallel underwater groins (sand-trapping structures built generally perpendicular to a beach). To connect two erosion control devices  10   i ,  10   j  end to end, a user brings a first end wall  17  of the first erosion control device  10   i , which end wall comprises end loop  21   a  or  21   b , into contact and alignment with a first end wall  17  of the second erosion control device  10   j , which end wall comprises corresponding end loop  21   a  or  21   b.    
   As seen in  FIG. 9 , the right end wall  17  of the first erosion control device  10   a  is in contact with the left end wall  17  of the second erosion control device  10   b , with end loop  21   b  of the first erosion control device  10   a  corresponding to end loop  21   a  of the second erosion control device  10   b . Consequently, the end loops  21   b  of the erosion control device  10   a  project into the first channel  18  of the second erosion control device  10   b , and the end loops  21   a  of the second erosion control device  10   b  project into the first channel  18  of the first erosion control device  10   a . The end loops  21   a  are then vertically displaced from the end loops  21   b , but they are horizontally aligned. To complete the end to end connection, the user inserts an attachment pin  34  into a pin hole  24  formed by the adjacent, semi-circular first channels  18 . Of course, it is appreciated that the erosion control devices  10   a ,  10   b  may each be rotated 180 degrees so that the left end wall  17  of the first erosion control device  10   a  may contact the right end wall  17  of the second erosion control device  10   b , with end loops  21   a  of the first erosion control device  10   a  corresponding to end loops  21   b  of the second erosion control device  10   b.    
   As shown in  FIGS. 6 and 7 , a number of erosion control devices  10   a–h  are interconnected end to end and side by side in an erosion control matrix  40 . The erosion control devices  10   a–h  are substantially perpendicularly attached, and some are parallel to one another. The first erosion control device  10   a  is substantially perpendicularly connected to fifth and seventh erosion control devices  10   e  and  10   g , a fourth erosion control device  10   d  is substantially perpendicularly connected to sixth and eighth erosion control devices  10   f  and  10   h , and so on. To perpendicularly attach two erosion control devices, using the fourth and sixth erosion control devices  10   d ,  10   f  as an example, the user brings a first end wall  17  of the fourth erosion control device  10   d , which comprises end loop  21   a  or  21   b , into contact and alignment with a second end wall  32  of the sixth erosion control device  10   f , which comprises corresponding end loop  21   c  or  21   d . Consequently, the end loops  21   a  or  21   b  of the fourth erosion control device  10   d  project into the second channel  33  of the sixth erosion control device  10   f , and the end loops  21   c  or  21   d  of the sixth erosion control device  10   f  project into the first channel  18  of the fourth erosion control device  10   d . The end loops  21   a  or  21   b  are then vertically displaced from the end loops  21   c  or  21   d , but they are horizontally aligned. To complete the substantially perpendicular connection, the user inserts an attachment pin  34  into a pin hole  24  (also see  FIGS. 8 and 9 ) formed by the adjacent, semi-circular first and second channels  18 ,  33 . 
   Thus, the erosion control devices  10  are attachable end to end, or side by side, or end to side perpendicularly to one another, and may be oriented in a variety of patterns. The erosion control devices  10  may even form a matrix  40 . The matrix  40  may be further reinforced by cables or chains extending through the cross apertures  20  in the elongated beam portion  11  and between the erosion control devices  10 . 
   The channels  18 ,  33  are preferably shaped alike, so that one end of the elongated beam portion  11  of a first erosion control device  10   a  is detachably connected (perpendicularly) to an end wall of the cross beam portion  12  of the second erosion control device  10   b . An attachment pin  34  is thus preferably insertable in any set of two channels  18 ,  33 , the channels forming a pin hole  24  for closely accommodating the attachment pin  34 . Optionally, an end wall fo an elongated beam portion  11  of a third erosion control device  10   c  is detachably connected to an opposite end wall of the cross beam portion  12  of the second erosion control device  10   b , forming a large cross-shaped matrix (see  FIGS. 6 and 7 . Alternatively, an end wall of a cross beam portion of a third erosion control device  10   c  is connected to the opposite end wall of the elongated beam portion  11  of the first erosion control device  10   a , forming a large I-shaped matrix. Any other suitable mechanism for attachment may be used in place of attachment pins, such as bolts, anchors, chains, or cables. 
   According to the preferred embodiment of the erosion control device  10 , the cross beam portion  12  resembles the elongated beam portion  11 , except that the length of the cross-beam portion  12  is less than about a third of the length of the elongated beam portion  11 . In the preferred embodiment, the side walls  16  curve into the second side walls  28 , the base top face  31 , and the second base top face  30 , which creates radii of curvature R 1 , R 2 , and R 3 , respectively. The base side walls  19  also curvedly merge into the second base side walls  29 , creating radii of curvature R 4 . The radii of curvature R 1  are indicated in  FIGS. 2 and 3 , the radii of curvature R 2  are shown in  FIG. 2 , the radii of curvature R 3  are depicted in  FIG. 3 , and the radii of curvature R 4  are seen in  FIGS. 2 and 3 . This curvature is advantageous in that it reduces stress on concrete devices  10  in contrast with sharp, angled concrete edges. 
   The erosion control devices  10  herein are dual purpose. First, they are used for preventing and/or slowing land and beach erosion. The erosion control devices  10  are particularly useful in restoring beach and dune areas lost from natural erosive forces, such as tides, waves, storms, and hurricanes and also erosion caused by human activities (e.g., pedestrian and vehicular traffic, heavy use of beach and dune areas, and overuse of beach and dune areas). Consequently, the erosion control devices  10  provide protection for coastal structures (e.g., homes, breakwaters, sea walls, and channels) from damage due to beach erosion, particularly during tropical storms and hurricanes. Secondly, the erosion control devices  10  are utilized to rebuild land and beach areas damaged by erosion. 
   To use the erosion control devices  10 , the user lays a first erosion control device  10   a  on the sand or earth, and then connects a second erosion control device  10   b  end to end or side by side with the first erosion control device. The user then connects a third erosion control device  10   c  end to end or side by side with the first or second erosion control device  10   a  or  10   b , and so forth. The same process may be undertaken anywhere erosion exists or may occur, such as on a hillside, embankment, dike, or highway shoulder, at the bottom of a ditch, under a roadbed as it is being built, etc. 
   The erosion control matrix  40  is left on the beach or ground surface. It is preferably buried under a few inches or more of sand (e.g., in a beach re-nourishment project) or earth. If desired, the matrix may be placed on large pieces of fabric for holding the earth in areas subject to heavy erosion. When it is used on a beach, it is preferably placed on top of the existing sand at the dune line at low tide level, and then a few inches of new sand is dumped on top. Like a suit of armor, the matrix protects the beach. 
   The spaces  35  (usually squares; see  FIG. 7 ) of earth between the erosion control devices  10  are convenient locations for planting trees, shrubs, native grasses, etc. The erosion control devices serve to protect the growing plants, which beautify the landscape. Also, the roots of the plants also help to prevent erosion. 
   Furthermore, the erosion devices  10  may be used in highway construction. Exemplary applications in highway construction include: stabilization of soils under roadbeds, erosion control of embankments, ditch linings, highway shoulders, and highway undersurfaces. 
   Matrices  40  of larger size erosion control devices according to the present invention (without cables  41 ) would help ameliorate the decline of sea turtles, in that the devices help prevent and remedy erosion problems, and in that the spaces  35  in the matrices  40  (see  FIG. 7 ) provide a nesting site for a nesting sea turtle with the surrounding devices providing protection for the turtle. For this use, the erosion control matrix  40  should be buried just under the surface of the beach. 
   The erosion control devices  10  are preferably constructed entirely from concrete. Concrete is desirable because it is not subject to corrosion or biodegradation. Concrete is also a preferred construction material because the erosion control devices  10  are easily and relatively inexpensively manufactured by a concrete molding process. To construct concrete erosion control devices  10 , the user simply inserts pre-fabricated rebar  36  into a pre-fabricated form of the erosion control device  10 . Next, the user pours concrete into the form and allows it to harden around the rebar  36  and assume the shape of the form. Upon removal of the concrete containing rebar from the form, the erosion control device  10  is ready for use. Other suitable materials of construction include plastics, metals, composites, and fiberglass. 
   The erosion control devices  10  range in size, depending on the intended use. Relatively small devices  10  about four to five feet in length are used, for example, on embankments, while relatively large devices  10  about 12 feet in length and weighing several tons can be used off-shore. In a preferred embodiment of the erosion control device  10  for remedying beach erosion, the distance between the side walls  19  is approximately 12 feet, and the distance between the base bottom face (not shown) and the wall top face  15  is approximately ⅙ the distance between the side walls  19 . In an alternate embodiment for preventing and controlling ground erosion, the distance between the side walls  19  is approximately three feet, the distance between the base bottom face (not shown) and the wall top face  15  is slightly less than that, and the distance between the second end walls  32  is approximately three feet. 
   Preferably, the cross apertures  20  are between about one and two, more preferably about 1.5, inches in diameter (inner diameter) and about one foot below the wall top face  15 . The end loops are preferably between about one and two, more preferably about 1.5, inches in diameter (inner diameter). 
   Turning to  FIG. 10 , an erosion control device  10   k  comprises an elongated beam portion  11  and a cross-beam portion  12  that extends transverse to the elongated beam portion, with the length of the cross-beam portion  12  being less than half the length of the elongated beam portion  11 . The elongated beam portion  11  is comprised of a first wall  14  supported on a first base  13  (see  FIG. 1 ). The first wall  14  has a generally planar wall top face  15  opposite the first base  13  and substantially perpendicular to two opposed, mirror image, generally planar wall side faces  16 . The first wall  14  is on the first base  13 , which also comprises a generally planar base top face  21  and a generally planar base bottom face. The base top face  31  and the base bottom face are spaced apart by the base side faces  19  and are substantially parallel to each other. The generally rectangular-shaped first base  13  is wider than the first wall  14  so as to impart stability to the erosion control device  10   k . However, this embodiment includes a pair of rotatable connectors  42 , rather than first and second channels and end loops. The rotatable connectors  42  project from the first end walls and/or the second end walls (middle section) of each erosion control device  10   k.    
   As shown in  FIGS. 10 through 15 , the universal rotatable connectors  42  each comprise a connector tail  43  embedded in the erosion control device, and a cylindrical-shaped connector head  44  with a hole extending along a rear portion of the longitudinal axis of the head. The connector tail  43  has a smaller diameter than the diameter of the connector head  44 . As shown in  FIGS. 11 and 15 , a front, threaded end of the connector tail  43  is connectable to the correspondingly threaded hole in the rear end of the connector head  44 . For example, a twist tie, or a screw  46  and nut as shown in  FIG. 15  can be inserted through the holes in the loops  45  of two opposite connectors  42 . The opposite end of the connector tail  43  is preferably connected to rebar  36  embedded in the erosion control device  10 . This opposite end of the connector tail  43  is preferably pointed (see  FIG. 15 ) in order to facilitate connection in the erosion control device. The connector head  44  is rotatable on the connector tail  43 . At the opposite end of the connector head  44  is a loop  45  or other type of connector that allows two head ends to be connected to one another, as shown in  FIGS. 12 and 14 . The connectors  42  allow flexibility in the ways the erosion control devices  10  can be connected to one another. They also allow connection of two erosion control devices  10   k  at any angle. 
   With the connectors  42 , one erosion control device need not be on the same plane as the neighboring erosion control device. For example, an erosion control device  10   k  on a sloped side of an embankment or sand dune can be connected to a second device  10   k  lying relatively horizontal on top of the embankment, as shown in  FIG. 12 . It is only necessary to connect the bottommost rotatable connectors  42  to one another. If desired, a third erosion control device  10   k  on the down slope of the embankment can similarly be connected on the other end of the second device. This positioning on a steep slope can also be done with the loops and pins embodiment described hereinabove. Other mechanisms for connecting two or more erosion devices to one another can be employed in place of rotatable connectors, such as a metal plate with a hole in it, or an I-bolt welded to the rebar  36 . 
   In the second erosion control matrix  50  depicted in  FIG. 13 , a number of erosion control devices  10   l–dd  are fastened together end to middle. For example, device  10   u  is connected to device  10   n  and device  10   aa  on its end walls  17 , and to device  10   t  and device  10   v  on its middle walls  25 . One or more rotatable connectors  42 , or another mechanism of connection, extending from the first end wall  17  of one erosion control device  10   u , are brought into contact and alignment with a corresponding rotatable connector  42  on the second end wall  32  of another erosion control device  10   t . The rotatable connectors  42  are connected to one another, as by a pin or bolt through a hole in the loop  45 . These connections are preferably reversible, so if the set-up is not working for some reason, the devices  10  can be disconnected, moved, and then reconnected. 
   To assemble and use the matrix  50  after trucking a number of erosion control devices  10  to the site where the matrix will be placed, a user lays out the desired number of erosion control devices  10  in the desired pattern and strings them together by passing cables  41  through the two cross-apertures  20  in each device  10  (see  FIG. 13 ). The cables  41  help to prevent the matrix  50  from coming apart in a big storm surge or hurricane, for example. The individual erosion control devices  10  can then be connected to one another by the rotatable connectors  42  or other suitable mechanism for connection. The erosion control matrix  50  can be assembled directly on the site, or it can be assembled nearby, then picked up (by a crane, for example), and dropped onto the site. 
   A matrix may include relatively small erosion control devices or relatively large devices, depending on the application, though a single matrix preferably includes a number of same-sized erosion control devices. A matrix of large erosion control devices  40 ,  50  weighing several tons each can be used off-shore, and may be used to protect one side of a barrier island from erosion, for example. 
   Referring to  FIGS. 14 and 15 , the connector head  44  of a rotatable connector  42  on an end wall  17  of a first erosion control device  10   k  can be connected to a connector head  44  of a corresponding rotatable connector  42  on a middle wall  32  of a device  101  that is laid out perpendicular to the first device  10   k . The same is true on an opposite end of the erosion control device  10   k.    
   From the foregoing it can be realized that the described device of the present invention may be easily and conveniently utilized as an erosion control device and matrix for remedying ground and beach erosion, rebuilding land areas lost to erosion, and various highway applications. It is to be understood that any dimensions given herein are illustrative, and are not meant to be limiting. 
   While preferred embodiments of the invention have been described using specific terms, this description is for illustrative purposes only. It will be apparent to those of ordinary skill in the art that various modifications, substitutions, omissions, and changes may be made without departing from the spirit or scope of the invention, and that such are intended to be within the scope of the present invention as defined by the following claims. It is intended that the doctrine of equivalents be relied upon to determine the fair scope of these claims in connection with any other person&#39;s product which fall outside the literal wording of these claims, but which in reality do not materially depart from this invention. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.