Pocket mat
lJnied States Patent De Winter Apr. 1, 1975 1 POCKET MAT [75] Inventor: Jan Gerrit De Winter, Enschede, W Lesmes Netherlands Assistant Exammer-S. S. S11verman Attorney, Agent, or FirmStrauch, Nolan, Neale, Nies [73] Assignee: Nicolon B.V., Richtersweg, &amp; Kurz Enschede, Netherlands [22] Filed: June 11, 1973 [21] Appl. No.: 369,063  
 [52] US. Cl 61/38, 161/70, 161/79, 161/145 [51] Int. Cl E02b 3/12 [58] Field of Search 139/384, 410; 61/38, 12, 61/3, 37; 161/88, 89, 49, 90, 70, 79, 145  
 [56] References Cited UNITED STATES PATENTS 503,373 8/1893 Reiwmuth 161/49 2,357,164 8/1944 Berg 139/410 3,090,406 5/1963 Koppelman ct a1 139/410 3,561,219 2/1971 Nishizawa ct a1 61/38 3,565,125 2/1971 Hayes 139/410 3,602,964 9/1971 139/410 3,699,686 10/1972 De Winter 61/38 5 7] ABSTRACT A mat for use in covering a slope or bank of a waterway, and comprising a web of synthetic yarn, said fabric being permeable to water, but impermeable to sand and earth, and a plurality of pockets succeeding one another in the longitudinal direction of the web and each extending over a transverse portion of said web, said pockets having rear walls constituted by said web of fabric, and in use being in contact with the ground, and said pockets being further constituted by a second web of fabric, which is interwoven with the web first-mentioned to form a double cloth, both in transverse narrow strips extending between each adjacent pair of pockets substantially throughout said transverse portion, and in a continuous longitudinal narrow strip interconnecting a marginal portion of said second web with the web first-mentioned.  
 5 Claims, 6 Drawing Figures POCKET MAT This invention relates to a mat for use in covering slopes or banks of waterways, and comprising a web of fabric of synthetic material provided with pockets for receiving ballast material therein, commonly in the form of flat stones or tiles, to keep the mat in position in use.  
  Known mats of this kind are made by sewing together a web of such textile and a second, narrower web of textile along one longitudinal edge and additionally at longitudinally spaced positions breadthwise of the webs to form the pockets. Hereinafter the broader web, to be laid in direct contact with the ground, will be referred to as the filtering web and the narrower web, forming the front walls of the pockets, as the pocket strip. The sewing together of the materials is a cumbersome and time-consuming procedure, and represents a considerable cost item in the manufacture of the product.  
  It is one important object of the present invention to provide a mat of the kind referred to, which avoids the necessity of sewing the two component webs together.  
  According to the invention, there is provided a mat for use in covering a slope or bank of a waterway, and comprising a filtering web of water-resistant fabric of synthetic yarn, said fabric being permeable to water, but impermeable to soil particles, such as sand and earth, and provided with pockets succeeding one another in the longitudinal direction of said web, said pockets having rear walls constituted by said web of fabric, which in use are in contact with the ground, and said pockets being further constituted by a pocket strip consisting of a strip of material narrower than said web, said strip being interwoven with said web as a double cloth in one longitudinal marginal portion of said strip and in narrow transverse strips at positions spaced apart along the length of said strip.  
  The manufacture of such a mat on a loom of the conventional kind, in which the fabric is formed a double cloth over a portion of the webs width only, requires some additional provisions for the loom, it is true, but this is more than off-set by the great advantage that the loom is productive of a ready mat formed with pockets in one pass, i.e. without the necessity of cumbersome sewing work for attaching a separate web of material to the mat.  
  In use, the mat is laid on the slope or bank with the pockets facing upwards and the open ends of the pockets in the upper position.  
  In known mats, in which the pockets are made by sewing, the pocket strip is made longer than the filtering web, and in being sewn to the latter along its one longitudinal edge, is laid in folds extending transversely of the web. As a result the pockets become bulged and can receive ballast material, particularly in the form of flat stones or tiles, without the filtering web, i.e. the rear walls of the pockets, being locally lifted off the ground, so that the mat can lie in substantially flat and taut condition on the ground.  
  In a further elaboration of the principle according to the present invention, this effect, resulting from a pocket strip which is longer than a filtering web, can also be achieved when the pocket strip and the filtering web constitute component parts of a double cloth by having the pocket strip comprise a smaller number of weft threads than the filtering web.  
  Preferably the portion of the mat which is formed as a double cloth is restricted to the width occupied by the pockets, whereas the portion not formed as a double cloth and the web portion forming the rear walls of the pockets is a uniform fabric, referred to as the filtering web of the mat. The advantage of this is that a fabric of uniform construction lies in contact with the ground, except in the connecting zones where the filtering web and the pocket strip are interwoven, resulting in the ground being covered with an equally fine mesh virtually throughout.  
  Accordingly, the advantage of known pocket mats, namely, that ballast material can be easily introduced into the pockets without interfering with the proper bedding of the mat against the ground, is achieved with the present invention in a simple manner without the pocket strip being sewn to the filtering web.  
  According to another advantageous feature of the present invention the filtering web and the pocket strip have a plurality of additional warp threads, preferably of contrasting colour, in the vicinity of the open ends of the pockets, which additional warp threads have longitudinally spaced portions not interwoven with the mat, known in the textile industry as floats or floating portions. These floating portions form tags or loops, through which rope or like material can be inserted to tie up the pockets in a simple and sturdy manner and without the risk of tearing either the filtering web or the pocket strip of the mat, so thatthe ballast material, once placed in position, cannot be washed away by the water, or otherwise displaced or removed without more ado.  
  According to another feature of the invention at the open ends of the pockets, the pocket strip is interwoven with the filtering web over longer portions, longitudinally of the mat, than in the areas between the pockets, thereby to form a restricted entrance or opening to the space provided by the pockets, which will help in retaining ballast material therein, and thus avoid separate provisions for tying up or otherwise closing the pockets.  
  In a particular embodiment of the present invention, in which the pocket portions of the pocket strip have a smaller number of weft threads per unit length of warp than the filtering web, the double-cloth bindings between the pockets are slidable in the longitudinal direction of the mat over some distance in both directions. This creates the possibility of cumulating the greater length obtained by using a lesser number of weft threads into two or more adjacent pockets, thereby to provide more spacious pockets at certain places for receiving thicker and heavier ballast material. In that case the adjacent pocket or pockets would be lost pockets unable to accommodate ballast material.  
  The invention will be described in more detail with reference to the accompanying drawings.  
 In said drawings,  
  FIG. 1 is a diagrammatic plan view of a mat according to the invention;  
  FIG. 2 is a cross-sectional view of the showing of FIG.  
  FIG. 3 shows a mat similar to FIG. 1, but having extended doublecloth binding portions adjacent to the open ends of the pockets;  
  FIG. 4 illustrates a mat with slidable bindings between the pocket strip and the filtering web of the mat and between every otherpair of adjacent pockets;  
  FIGS. 5a and 5b are cross-sectional views of the showing of FIG. 4.  
  Referring to FIG. 1, the mat 1 according to the invention comprises a web of fabric of synthetic yarn, such as nylon, polyethylene or polypropylene, with a mesh width of, for example, 0.15 to 0.4 mm, and a yarn thickness of, say, 0.2-0.7 mm. The water permeability of such fabrics at about cm water column is from 40 to far exceeding 150 l/mlsec.  
  Over a portion b of the overall width B of the mat, the latter is formed as a double cloth, that is to say, over the width b the mat consists of layers which are interwoven into one layer at certain positions. One layer 2, hereinafter referred to as the filtering web, consists of the ter referred to as the pocket strip of the mat, contains a considerably smaller number of weft threads than the remainder of the mat, i.e. the filtering web 2.  
  The pocket strip 3 and the filtering web 2 are interwoven in the areas hatched in FIG. 1. The hatched areas are the so-called binding portions between the pocket strip 3 and the filtering web 2 of the mat, and are constituted by binding strips extending over the width b and spaced longitudinally of the mat, and a narrow binding strip adjacent the lower edge (in FIG. 1) of the pocket strip and the filtering web. Accordingly, in the binding areas the warp and weft threads of both 1 layers 2 and 3 are present in combination, but interwoven, resulting in a particularly intimate connection betweenthe two components parts of the mat. Owing to the fact that the pocket strip 3 is not secured to the filteringweb between successive binding areas 4, pockets 6 are formed between each pair of adjacent binding areas, which are best shown in cross-section in FIG. 2. It also follows from FIG. 2 that the length of the pocket strip, measured longitudinally of the mat, is larger than that of the filtering web of the mat. As described above, this is achieved by using a lesser number of weft threads per unit length for the pocket strip than for the filtering web. As a consequence, the number of times that the warp threads are deformed or deflected by the weft threads is less than in the filtering web, which results in a somewhat greater length of the pocket strip lengthwise of the .warp threads, so that ballast material can be accommodated in pockets 6 without the filtering web being lifted off the ground on which it has been laid.  
  ,In the embodiment shown in FIG. 3, the mat has additional, relatively short and narrow binding areas 7 between the pocket strip and the filtering web at the upper edge (in that figure) of the pocket strip. As a consequence the open ends of the pockets are reduced in size from length a in FIG. 1 to length a&#39; in FIG. 3. This gives the pockets the character of a mouse-trap, that is to say, ballast material, in the form of concrete tiles or other relatively heavy slabs of ballast material, once introduced into the pockets, cannot so easily be removed. 7  
  FIG. 3 further shows, merely diagrammatically, a number of warp threads 8 of a colour contrasting with that of the remainder of the mat 1. These warp threads are woven-in in areas in the vicinity of the upper edge 7 of the pockets, namely, in the filtering web and in the pocket strip of the mat, respectively. In the areas between the binding areas 4, succeeding one another in the longitudinal direction of the mat, the additional, woven-in threads of contrasting colour have a portion 8 in which they are not interwoven with the mat. In combination, the floating thread portions form tags or loops, through which rope or like binding material can be inserted for tying up the pockets. The ballast material contained in the pockets is then confined therein.  
  In the embodiment shown in FIG. 4, finally, normal binding zones 4 between adjacent pockets alternate with binding areas 4 through which the binding warp is slidable longitudinally of the mat. As shown in FIGS. 5a and 5b, this creates the possibility, with pockets 6 of equal basic size, to form enlarged pockets 6 altemating with lost pockets 6&#34;, in which the pocket strip portion lies in substantially flat taut condition upon the filtering web. The enlarged pockets 6&#39; can receive heavier bodies of ballast material, as illustrated in FIG. 5b, and as contrasted with the situation shown in FIG. 5a, in which all of the pockets 6 are of equal size, and consequently relatively flatter ballast material must be used.  
  In a practical case, there was used a fabric having 20 threads/cm of 0.2 mm diameter polyethylene yarn in the warp of the filtering web, the latter being I m wide.  
  In the strip portion the warp may be decreased, for example, to 5 threads/cm of the same thickness, using, instead of polyethylene yarn, for example, polypropylene yarn.  
  The filtering web has a weft of 20 threads/cm and the pocket strip a weft of 16 threads/cm laterally of the pockets, decreasing towards the middle of the pockets to 5 threads/cm.  
  The width of the pocket strip is, for example, 40 cm, which with an interwoven edge connecting the strip portion and the filtering web together, results in pockets of about 40 X 44 cm. Such pockets, with the ratios of weft threads as specified above, provide sufficient space for tiles of 30 X 30 X 4 cm to he slid into the pockets. In the embodiment shown in FIGS. 4 and 5b, under otherwise equal conditions, thicker tiles can he slid into the pockets.  
  It will be understood that the invention is not limited to the embodiments described above and illustrated in the accompanying drawings. Variations and modification will readily occur to those skilled in the art without departing from the scope of the invention as defined in the appended claims.  
 I claim:  
  1. A mat for use in covering a slope or bank of a waterway comprising: a filtering web of woven, waterresistant, synthetic fabric, said fabric being permeable to water but impermeable to soil particles such as sand and earth, and a second web of woven synthetic fabric spanning said filtering web, said second web being narrower than said filtering web whereby one edge of said filtering web lies beyond the corresponding one edge of the second web across the span of the mat, the opposite edge of the second web being interwoven with the filtering web in a strip extending across the span of the mat, said second web also being interwoven with said filtering web in strips spaced across the span of the mat and extending from the first-mentioned strip to said one edge of said second web, thereby forming a series of pockets across the span of the mat which have open.  
 ends facing said one edge of the filtering web, whereby said mat can be disposed on a surface to be covered with the filtering web in contact therewith and with said pockets accessible from the exposed side of said mat and from locations intermediate the edges of said filtering web, and the unit number of those threads extending from edge to edge of the second web being lower than the like oriented threads of the filtering web whereby, with said webs interwoven as aforesaid, said second web will be bulged away from said filtering web to thereby increase the capacity of said pockets.  
  2. A mat according to claim 1 wherein, in locations corresponding to the open ends of said pockets, there are unwoven strips extending lengthwise of and in both said filtering web and said second web and forming looplike means through which closure members for the open ends of said pockets can be introduced.  
  3. A mat according to claim 1 wherein, at the edge of said second web coincident with the open ends of 6 said pockets, the threads extending in the&#39;direction of said edge are of a different color than those employed elsewhere in the mat and thereby visually identify the open ends of the pockets.  
  4. A mat according to claim 1 wherein said second web is interwoven with said filtering web at locations corresponding to the sides of said pockets and at the open ends thereof, thereby inhibiting the removal of material introduced into said pockets.  
  5. A mat according to claim 1 wherein, in alternate ones of the spaced strips in which the filtering web and the second web are interwoven, provision is made for movement of said second web relative to said filtering web, whereby the size of one of the two pockets bounding each said strip can be increased at the expense of the other pocket bounding the strip.