Tufted geosynthetic ground cover

Abstract

A backing tufted with yarns in lines of spaced-apart tufts extending as simulated grass blades from an upper surface for a tufted geosynthetic ground cover, in which each line of tufts has a repeating pattern of a first sequence of adjacent tufts tufted on a colinear line and a second sequence of tufts tufted such that a first tuft in the second sequence is tufted with a side shift on a line that is oblique relative to the colinear line, the colinear line extending for a majority of the length of the repeating pattern, and the tufted geosynthetic ground cover, being placed over a ground surface and receiving infill, resists cover movement relative to the ground by frictional interface between the ground surface and the yarns extending across a bottom surface and resists infill migration across the upper surface through interstices between the tufts

Description

[0001] TUFTED GEOSYNTHETIC GROUND COVER

[0002] Technical Field

[0003] The present invention relates to tufted geosynthetic ground covers. More particularly, the present invention relates to tufted geosynthetic ground covers having tufting patterns for increased frictional interface relative to a ground surface to resist movement of the ground cover to shear loading forces while reducing migration of infill material through the tufts.

[0004] Background of the Invention

[0005] Large-area landfills and waste sites typically remain open for a number of years for receiving waste materials, mining spoils or power plant wastes and ash, landfill trash and municipal solids and liquids wastes. Such waste sites typically have elevational slopes rising from a toe or base to an upper elevated apex or peak as the additional deposits of waste materials are placed in the landfill. The elevation of landfills may typically reach several hundred feet above the toe with accumulated deposits of waste fill materials. While steep slopes allow geometrically increased storage volume, slopes and particularly steep slopes experience significantly high shear forces. These shear forces occur in response to the waste fill materials loaded within a vertical portion of the area allocated for the landfill and also arise from dry shear (wind) and hydraulic shear (ambient precipitation and water flow such as from rainfall on the waste site) from high volumes of water flowing downwardly over the ground cover. Steep slopes often experience large hydraulic shear forces from rapid water flow run-off. Portions of a landfill that approach capacity may be covered for short terms (up to about ten years) while other areas of the landfill receive material. The short term cover may use a dirt layer of several feet overlaid as cap. There are drawbacks to such as plant growth requires routine maintenance, and the site remains open to subground infiltration of ambient water such as snow melt and precipitation. In recent years, ground sites have been covered with joined panels of tufted elongated geosynthetic sheet featuring reduced ambient inflow, reduced maintenance, and spaced-apart tufts as simulated grass. Alternatively, an impermeable geomembrane may cover the ground site below the tufted geosynthetic to restrict ambient water inflow below grade and allow water flow from the covered site to down-hill drainage channels and remote water receiving basins for treatment and release to water streams and rivers.

[0006] A synthetic ground cover comprises panels of tufted geosynthetic sheets made of a backing and spaced-apart tufts of yarn extending as simulated blades of grass. The blades shade the backing but often the tufted geosynthetic ground cover includes an infill distribution of sand (or particles) that fill-in the interstices. While the infill helps to an extent in holding the geosynthetic sheet to the ground a primary purpose is to shade the backing from UV light that degrades and damages the backing. The backing typically is made from a woven polypropylene material that has a lower tolerance to UV degradation while the tufts that are typically made from polyethylene yarns. UV light degrades the polypropylene backing and may lead to ground cover failure with tears or rips in the backing. Ground cover design and installation needs to consider cover stability and integrity during the closure period. The geosynthetic ground cover during operational use experiences shear loadings that arise from shear forces (wind and hydraulic flow) as well as daily thermal expansion and contraction. The shear and thermodynamic forces experienced in operational use of the geosynthetic ground cover causes movement relative to the ground, and over time, the geosynthetic ground cover forms wavey portions having ripples, wrinkles, or bunching. As used herein, ripple refers to a waxy portion of the tufted geosynthetic ground cover, for example a height of about Vi inch or less. The term wrinkle refers to an upstanding folding of the tufted geosynthetic ground cover, for example a height of about !4 to 1 inch. The term bunching refers to a compaction of a portion of the tufted geosynthetic ground cover forming tight folds or groups of multiple or enlarged winkles. Portions of the geosynthetic may move downwardly on a slope due to thermal expansion, but lack sufficient retraction to return upwardly. The effect is that the ground cover moves downwardly slowly over time. Further, the dry and hydraulic shear forces cause migration of the covering infill. The particulate such as a sand mixture migrates on flow channels defined by the interstices between adjacent tufts. Migration of the infill develops openings between the tufts that exposes the backing of the ground cover to UV light.

[0007] Manufacturing and raw material component costs also impact the applicability of tufted geosynthetic ground covers in addressing these technical in-field operational cover issues. For example, a smaller gauge, and thus more densely spaced tufts, incur increased material costs, and the resulting smaller interstices still experience infill migration. Also, a significant factor in cover cost is machine ran time. The longer the amount of time required for a tufting machine to tuft a backing increases the per linear foot cost of the tufted geosynthetic. Tufting machines generally are most efficient in straight line tufting. The machine can operate at a faster machine direction rate. However, patterned tufting that assists in reducing infill migration involves multiple side shifts during tufting processing. Such side shift processing is subject to more frequent delay time due to needle breakage or yarn breakage. A slower process rate reduces downtime delays but increases production tune per linear foot.

[0008] Accordingly, there is a need in the technical field of covers for large area ground sites for a readily manufactured ground cover that provides increased interface friction between the ground cover and the ground surface to resist ground cover movement during installed use for covering large area land sites and reduced infill migration, in response to shear loading forces from hydraulic flow and dry flow wind forces. It is to such that the present invention is directed.

[0009] Summary Of The Invention

[0010] The present invention meets the need in the industry for a ground cover readily manufactured yet featuring increased interface friction between the ground cover and the ground surface to resist ground cover movement during installed use for covering large area land sites and reduced infill migration in response to shear loading forces from hydraulic flow and wind. More particularly, the present invention provides a tufted geosynthetic ground cover for overlying a ground surface, comprising a backing tufted with yarns in a plurality of lines of spaced-apart tufts that extend as simulated grass blades from an upper surface of the backing, said tufts formed by yarn bridges across a bottom surface, and in which each line of tufts has a repeating pattern of a first sequence of adjacent tufts tufted on a colinear line and a second sequence of tufts tufted such that a first tuft in the second sequence is tufted with a side shift on a line that is oblique relative to the colinear line, the colinear line extending for a majority of the length of the repeating pattern, and the tufted geosynthetic ground cover, being placed over a ground surface and receiving infill, resists cover movement relative to the ground by frictional interface between the ground surface and the yams extending across a bottom surface and resists infill migration across the upper surface through interstices between the tufts.

[0011] In another aspect, the present invention provides a method of tufting a tufted geosynthetic ground cover, comprising the steps of:

[0012] (a) providing an elongated backing having a bottom surface and an upper surface; and

[0013] (b) tufting a repeating pattern of a first sequence of tufts and a second sequence of tufts, said first sequence and second sequence each formed in a plurality of spaced-apart lines of tufts in a machine-direction with respective portions of the plurality of yams defining bridges on a bottom surface between adjacent spaced-apart tufts and tufted through the elongated backing, said tufts extending from an upper surface of the elongated backing as simulated blades of grass, said spaced-apart tufts defining interstices therebetween for receiving an infill material; said first sequence of adjacent tufts in each of the plurality of lines of tufts tufted on a respective colinear line and said second sequence of adjacent tufts tufted such that a first tuft in the second sequence is tufted on a line that is oblique relative to the colinear line of the first sequence of tufts, wherein said first sequence of tufts extends for a majority of the length of the repeating pattern, whereby the tufted geosynthetic ground cover, being placed over a ground surface and receiving infill, has an increased frictional interface between the bridges and the ground surface and reduced sand migration through the interstices between the tufts.

[0014] Objects, advantages, and features of the present invention will become readily apparent upon a reading of the following detailed description in conjunction with the drawings.

[0015] Brief Description Of The Drawings

[0016] Fig. 1 illustrates a top perspective view of a tufted geosynthetic ground cover overlying a surface of a large area land site.

[0017] Fig. 2 illustrates a bottom plan view of a first embodiment of a tufted geosynthetic ground cover in accordance with the present invention.

[0018] Fig. 3 illustrates a top plan view of the first embodiment of the tufted geosynthetic ground cover illustrated in Fig. 2.

[0019] Fig. 4 illustrates a bottom plan view of a second embodiment of a tufted geosynthetic ground cover in accordance with the present invention.

[0020] Fig. 5 illustrates a bottom plan view of a third embodiment of a tufted geosynthetic ground cover in accordance with the present invention.

[0021] Fig. 6 illustrates a botom plan view of a fourth embodiment of a tufted geosynthetic ground cover in accordance with the present invention.

[0022] Fig. 7 illustrates a bottom plan view of a fifth embodiment of a tufted geosynthetic ground cover in accordance with the present invention. Fig. 8 illustrates a bottom plan view of a sixth embodiment of a tufted geosynthetic ground cover in accordance with the present invention.

[0023] Fig. 9 illustrates a detailed bottom plan view of the sixth embodiment of a tufted geosynthetic ground cover shown in Fig. 8.

[0024] Fig. 10 illustrates a bottom plan view of a seventh embodiment of a tufted geosynthetic ground cover in accordance with the present invention.

[0025] Fig. 11 illustrates in schematic diagram an embodiment of a tufted geosynthetic ground cover in accordance with the present invention.

[0026] Detailed Description

[0027] A tufted geosynthetic ground cove for covering a large area land surface, comprising an elongated backing having an upper surface and a bottom surface and a plurality of spaced-apart tufts formed with respective synthetic yams tufted through the elongated backing in a plurality of spaced-apart lines of tufts in a machine-direction with respective portions of the yams defining bridges on the bottom surface between adjacent tufts, said tufts extending from tire upper surface of the elongated backing as simulated blades of grass, said spaced-apart tufts defining interstices therebetween for receiving an infill. Each of the plurality of lines of tufts has a repeating pattern of a first sequence of adjacent tufts tufted on a colinear line and a second sequence of tufts tufted such that a first tuft in the second sequence is tufted on a line that is oblique relative to the colinear line of the first sequence of tufts. The colinear line of the first sequence extends for a majority of the length of the repeating pattern and the tufted geosynthetic ground cover, being placed ewer a ground surface and receiving infill, has an increased frictional interface between the bridges and the ground surface and reduced migration of infill through the interstices between the tufts.

[0028] In the tufted geosynthetic ground cover, the elongated backing comprises a woven textile or comprises a non-woven textile.

[0029] In the tufted geosynthetic ground cover, the infill material comprises a sand mixture.

[0030] The tufted geosynthetic ground cover, wherein the colinear line of the first sequence extends for between 50% and 95% of the length of the repeating pattern.

[0031] In the tufted geosynthetic ground cover, the second sequence of tufts define a second colinear line parallel to the colinear line.

[0032] In the tufted geosynthetic ground cover, wherein each tuft in the second sequence of tufts is tufted on a line oblique to a line on which a preceding tuft is tufted.

[0033] In the tufted geosynthetic ground cover, wherein the colinear line for a subsequent repeating pattern is coaxial with the colinear line of a preceding repeating pattern.

[0034] In the tufted geosynthetic ground cover, wherein the second sequence comprises a second repeating pattern of a first tuft tufted on a line oblique to the colinear line and subsequent tufts in the second repeating pattern are tufted on a line parallel to the colinear line of the first sequence.

[0035] In the tufted geosynthetic ground cover, wherein the first tuft in the first of the second repeating pattern is tufted lateral of the colinear line in a first direction and the first tuft in a second of the second repeating pattern is tufted lateral of the parallel line in a second direction opposing the first direction. In the tufted geosynthetic ground cover, wherein the first tuft in the first sequence of a subsequent repeating pattern is tufted on a line oblique to the tuft line of the second sequence of tufts in the preceding repeating pattern and the colinear line of the tufts in the first sequence of the subsequent repeating pattern is coaxial with the colinear line of the preceding repeating sequence.

[0036] In the tufted geosynthetic ground cover, wherein the colinear line for a subsequent repeating pattern is parallel to the colinear line of a preceding repeating pattern.

[0037] In the tufted geosynthetic ground cover, wherein the colinear line for a subsequent repeating pattern is parallel to the colinear line of a preceding repeating pattern.

[0038] In the tufted geosynthetic ground cover, wherein said second sequence of tufts comprises a first tuft tufted on a line oblique relative to the colinear line of the first sequence of tufts, said first tuft lateral in a first direction.

[0039] In the tufted geosynthetic ground cover, wherein a subsequent portion of said second sequence comprises the first tuft tufted lateral in a second direction opposing the first direction.

[0040] In another aspect, the present invention provides a method of tufting a tufted geosynthetic ground cover, comprising the steps of:

[0041] (a) providing an elongated backing having a bottom surface and an upper surface; and

[0042] (b) tufting a repeating pattern of a first sequence of tufts and a second sequence of tufts, said first sequence and second sequence each formed in a plurality of spaced-apart lines of tufts in a machine-direction with respective portions of the plurality of yams defining bridges on a bottom surface between adjacent spaced-apart tufts and tufted through the elongated backing, said tufts extending from an upper surface of the elongated backing as simulated blades of grass, said spaced-apart tufts defining interstices therebetween for receiving an infill material. The first sequence of adjacent tufts in each of the plurality of lines of tufts tufted on a respective colinear line and the second sequence of adjacent tufts tufted such that a first tuft in the second sequence is tufted on a line that is oblique relative to the colinear line of the first sequence of tufts. The first sequence of tufts extends for a majority of the length of the repeating pattern. The tufted geosynthetic ground cover, being placed over a ground surface and receiving infill, has an increased frictional interface between the bridges and the ground surface and reduced sand migration through the interstices between the tufts.

[0043] The method of tufting a tufted geosynthetic ground, wherein the tufting of a subsequent repeating pattern of the first sequence of tufts and the second sequence of tufts occurs with a first tuft of the first sequence in the subsequent repeating pattern tufted on a line that is oblique relative to the second sequence of tufts in a preceding adjacent repeating pattern.

[0044] The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein the tufting of the first sequence extends for between 50% and 95% of the length of the repeating pattern.

[0045] The method of tufting a tufted geosynthetic ground cover, wherein the tufting of the second sequence of tufts is on a second colinear line parallel to the colinear line.

[0046] The method of tufting a tufted geosynthetic ground cover, wherein tufting each tuft in the second sequence of tufts is on a line oblique to a line on which a preceding tuft is tufted. The method of tufting a tufted geosynthetic ground cove, wherein the oblique line is in a first direction.

[0047] The method of tufting a tufted geosynthetic ground cover, wherein the oblique line is in a second direction after a predetermined length for the second sequence of tufts is tufted.

[0048] The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein a colinear line for a subsequent repeating pattern is coaxial with the colinear line of a preceding repeating pattern.

[0049] The method of tufting a tufted geosynthetic ground cover, wherein the first tuft in a subsequent repeating pattern is tufted lateral of the colinear line in a first direction and the first tuft in the second sequence in the subsequent repeating pattern is tufted lateral in a second direction opposing the first direction.

[0050] The method of tufting a tufted geosynthetic ground cover, wherein the first tuft in a subsequent repeating pattern is tufted on a line oblique to a tuft line of the second sequence of tufts in the preceding repeating pattern and the colinear- line of the tufts in the first sequence of the subsequent repeating pattern is coaxial with the colinear line of the preceding repeating sequence.

[0051] With reference to the drawings, in which like parts have like identifiers, the present invention provides a tufted geosynthetic ground cover 20 for overlying a large area land site. A bottom surface 22 of the tufted geosynthetic ground cover 20 may directly contact a ground surface 24 or, alternatively, the tufted geosynthetic ground cover 20 may install over a geomembrane 26 (typically water impermeable for restricting inflow of ambient water below the ground surface. The bottom surface 22 in contact with the ground surface 24 or the geomembrane 26 experiences an interface friction. The interface friction resists movement of the tufted geosynthetic ground cover 20 relative to the ground surface (or geomembrane) in response to shear forces on the tufted geosynthetic ground cover 20. These shear forces occur from wind or hydraulic flow over the tufted geosynthetic ground cover 20.

[0052] The tufted geosynthetic ground cover 20 comprises an elongated backing 30 having the bottom surface 22 and opposing top surface 32. The backing 30 includes a plurality of spaced-apart tufts 34 that extend from the top surface 32. The tufts 34 form with synthetic yarns tufted on a needle tufting machine through the elongated backing 30 in a plurality of spaced-apart lines 36 of tufts 34 in a machine-direction. Respective portions of the yams define bridges 38 on the bottom surface 22 between adjacent tufts 34, whereby the tufts extend from the upper surface 32 of the elongated backing 30 as simulated blades of grass.

[0053] Figs. 2 illustrates a bottom plan view of the tufted geosynthetic ground cover 20 in accordance with the present invention and Fig. 3 illustrates the ground cover 20 in top plan view. Fig. 2 illustrates tire bridges 38 as short-length (gauge) box structures in the respective line 36. The leading and the trailing end of the bridge 38 is tire point of entry of the respective tufting needle that carries a respective yarn through the backing 30. The needle withdraws leaving a yarn loop extending from the opposing surface 32. The distal end of the loop is cut to define a pair of separate lengths of yarn extending from the upper surface 32 as simulated blades of grass. Alternatively, tire loops may be uncut for a loop tuft. The bridges 38 and bottom surface 22 of the backing 30 create interface friction with the ground surface or with the geomembrane 26 when the ground cover is installed for ground cover purposes. The interface friction resists movement of the tufted geosynthetic ground cover 20.

[0054] With continuing reference to Fig. 1 , the spaced-apart tufts 34 define interstices 40 between adjacent tufts (in a respective line 36 or an adjacent line). The interstices 40 receive an infill material 42, preferably granular, for filling from the upper surface 32 of the backing 30 to proximate a distal extent of the tufts 34, preferably intermediate the backing 30 and the distal extent of the tufts. The tufts 34 in a respective line 36 are spaced apart a first distance 44, commonly referenced as a gauge. Adjacent lines 36 are spaced apart a second distance 46. The gauge between tufts 34 and between lines 36 may be the same. The interstices 40 define flow paths (arrow 47) across the upper surface 32. The infill material 42 may migrate flowingly on the flow paths 47 between the adjacent lines 36 and around the tufts 34 in response to shear forces applied to the tufted geosynthetic ground cover 20. Migrated infill over time may lead to portions of the tufted geosynthetic ground cover 20 being vacant of infill 42 and thus open to UV exposure from the sun light. UV exposure causes degradation and weakening of the backing 32 and overtime may result in cuts or failure of the tufted geosynthetic ground cover 20.

[0055] The structure of the tufted geosynthetic ground cover 20 however achieves both an increased interface friction to reduce relative movement of the tufted geosynthetic ground cover 20 and a reduction of infill migration across the upper surface 32. The increased interface friction reduces the movement of the tufted geosynthetic ground cover 20 relative to the ground in response to shear forces. The reduction in infill migration in response to shear forces results in increased stability of the installed infill 42. With reference to Figs. 2 and 3, the present invention achieves reduced costs yet with increased frictional interface and reduced infill migration by providing the respective plurality of tufts 34 tufted in the backing 30 with a repeating pattern 50 of a first sequence 52 of adjacent tufts 34 and a second sequence 54 of adjacent tufts 34. (Fig. 1 illustrates a trailing end portion of the first sequence 52 and a leading end portion of the second sequence 54.) The first sequence 52 tufts the tufts 34 on a colinear line 56 for a predetermined length 58 in the backing 30. The second sequence 54 of tufts 34 commences tufting the tufts 34 with a side shift on a line 60 extending at an oblique angle relative to the colinear line 56 of the first sequence 52. Particularly, the second sequence 54 forms the tufts thereof such that a first tuft 62 in the second sequence tufts on tire line 60 that is oblique relative to the colinear line 56 of the first sequence 52 of tufts. This oblique side shift positions the tuft 62 intermediate the adjacent lines 36. Preferably, the side shift is a ' / z gauge for positioning the tuft 62 medial adjacent lines 36. The second sequence 54 of tufts 34 creates blockage 49 in the flow path 47 with the first tuft 62 and subsequent tufts of the second sequence. The flow of ambient water and / or infill 42 must move laterally around the blockage 49 to new flow paths 51. This blockage 49 reduces migration of the infill 42 across the surface 32.

[0056] The second sequence 52 of tufts 34 extends a second predetermined length 64 before the repeating pattern 50 repeats with a subsequent set of the first and second sequences 52, 54 of tufts 34. The repeating pattern 50 thereby has length 65 of the first sequence length 58 plus the second sequence length 64. It is contemplated that the second sequence 52 may have the one first tuft 62, or more tufts 34 tufted on a line. Alternatively, and as illustrated, a second sequence 50 of tufts 34 may tuft on a colinear line parallel to the colinear line 56 of the first sequence 50, or alternatively as illustrated may tuft on other lines that are oblique relative to the colinear line 56 as well as with different gauges.

[0057] In the embodiment illustrated in Figs. 2 and 3, the second sequence 52 of tufts 34 forms on a repeating alternating sequence of the first tuft 62 at a % of the gauge 44 in a first oblique direction for line 60, a second tuft in an second direction opposing the first oblique direction at ½ of the gauge 44, a third tuft in the first oblique direction at Vi of the gauge 44, and a fourth tuft in the second d irection at ¾ of the gauge 44, with oblique angles of 45°. This sequence positions the fourth tuft coaxial with the line 56 of the first sequence. The illustrated embodiment has three alternating sequences to define the second sequence 54 of tufts 34. The final tuft of the second sequence is positioned coaxial with the colinear line 56 and the repeating pattern 50 then repeats with the tufting of the first sequence 52 followed by the second sequence 54 coaxial with the collinear line 56. The tufting of the backing 20 continues with the repeating Pitting pattern 50 of the first sequence 52 and second sequence 54.

[0058] With a uniform gauge 44 of 1 / 4 inch, the embodiment illustrated in Figs. 2 and 3 has a repeating pattern length 65 of 11 inches of which the first sequence length 58 is nine (9) inches and the second sequence length is two (2) inches.

[0059] As noted above, the second sequence 54 may have the one tuft 62 before repeating the first sequence 52. In such embodiment, the first sequence length 58 is nine (9) inches and the second sequence length 64 is one-half (1 / 2) inch.

[0060] The tufting of the first sequence 52 is along the colinear line 56, with the adjacent tufts 34 spaced on the selected gauge 44. Tufting on the colinear line 56 enables the tufting machine to operate in a machine direction without lateral movement (or side shifts). Such continuous machine direction tufting tends to provide a highly efficient production environment with minimal broken threads or needles. Each occurrence of a lateral movement or side shift may require a stoppage for replacement of the needle or knotting the yarn ends together. Stoppages take machine time from production, which increases the cost for tufting the backing 30 for the tufted geosynthetic ground cover 20. However, side shift tufting at higher colinear run speed may experience a greater frequency of down time for correction of breakages during tufting operations. To reduce such downtime, the tufting machines for side shift tufting are preferably set for a run speed slower than can be used for colinear tufting. The tufting process of combined colinear and side shift tufting thus typically runs side-step machine direction slow but colinear line tufting at the slower side shift speed experiences the benefit of less downtime.

[0061] In the present invention, the colinear line 56 of the first sequence 52 extends for a majority of the length 65 of the repeating pattern 50. In various embodiments of the present invention, the length of the colinear line 56 ranges from about 50% to about 95% of the length 65 of the repeating pattern 50. This enables efficient tufting of the backing 30 to save on production costs that arise from side shifts during tufting. The side shift on the line 60 defines the bridge 38 at an angle to machine direction colinear line 56 for each of the lines 36 of tufts. The angled bridges 38 in each of the plurality of lines 36 define respective impediments to movement of the cover 20, such as on the colinear line 56, relative to the ground. The tuft 62 extending from the upper surface 32 (and subsequent tufts in the second sequence 54) defines the impediment or blockage 49 in the flow path 47 intermediate adjacent lines 36 of tufts. The tufts of the second sequence 54 in the adjacent rows define flow paths 51 lateral of the flow path 47. The tufted geosynthetic ground cover 20, being placed over the ground surface 22 (or geomembrane 24) as shown in Fig. 1 , and receiving infill 42, resists relative movement in response to shear forces arising from the increased frictional interface of the tufted geosynthetic ground cover 20 between the angled bridges 38 (and the backing 30) and the ground surface 24, and further, has reduced sand migration on the flow paths 47 through the interstices 40 because the periodic intermediate side shift defined tufts 62 form flow impediments 49.

[0062] Fig. 4 illustrates a bottom plan view of a second embodiment 70 of a tufted geosynthetic ground cover in accordance with the present invention. In this embodiment, the first sequence 52 has a sequence length 58 of 6 inches and a second sequence 54 has a sequence length 64 of 6 inches.

[0063] Fig. 5 illustrates a bottom plan view of a third embodiment 76 of a tufted geosynthetic ground cover in accordance with the present invention. In this embodiment, the first sequence 52 has a sequence length 58 of 17 inches and a second sequence 54 has a sequence length 64 of 5.5 inches.

[0064] Fig. 6 illustrates a bottom plan view of a fourth embodiment 84 of a tufted geosynthetic ground cover in accordance with the present invention. In this embodiment, the first sequence 52 has a sequence length 58 of 6 inches and a second sequence 54 has a sequence length 64 of 6 inches with the first tuft 62 of the second sequence on ¼ side shift in a first direction to offset a colinear line 86 of tufts in the second sequence 52 relative to the line 56 of the first sequence. The second sequence 52 ends with 14 side shift in the second direction to position the tuft coaxial with the line 56 for repeating the repeating pattern 50. Fig. 7 illustrates a bottom plan view of a fifth embodiment 92 of a tufted geosynthetic ground cover in accordance with the present invention. In this embodiment, the first sequence 52 has a sequence length 58 of 18 inches and a second sequence 54 has a sequence length 64 of 6 inches with the first tuft 62 of the second sequence on YA side shift in a first direction to offset a colinear line 86 of tufts in the second sequence 52 relative to the line 56 of the first sequence. The second sequence 52 ends with Fi side shift in the second direction to position the tuft coaxial with the line 56 for repeating the repeating pattern 50.

[0065] Fig. 8 illustrates a bottom plan view of a sixth embodiment 100 of a tufted geosynthetic ground cover in accordance with the present invention. In this embodiment, the first sequence 52 has a sequence length 58 of 6 inches and the second sequence 54 has a sequence length 64 of 3 inches. In this embodiment, the second sequence 54 forms a box stitch pattern 102. The second sequence 52 ends with a side shift in the second direction to position the subsequent tuft coaxial with the line 56 for repeating the repeating pattern 50.

[0066] Fig. 9 illustrates a detailed plan view of the box stitch pattern 102. The box stitch pattern 102 forms by the tufting machine making sequential side shifts. As noted above, each side shift incurs a production cost due to a slower production run speed to minimize breakages that require production stoppages. The box stitch pattern 102 forms by the tufting machine making a first side shift in a first direction for at least one tuft, then returning to linear tufting on a line that is parallel to the line 56, before making a second side shift in a second direction opposite the first direction for at least one tuft, then returning to linear tufting on a line that is coaxially with the line 56. More particularly, the tufting machine tufts linearly on line 56. The box stitch pattern 102 is then formed at the end of the first sequence 52. First, the tufting machine makes a first side shift 112 in a first direction 114 for at least one tuft 116. This defines a first side of the “box” in the box stitch pattern 102. The tufting machine than returns to linear tufting on a line 118 parallel to the line 56. This defines a second side of the “box”. After a predetermined number of tufts are formed, the tufting machine makes a second side shift 120 in a second direction 122 for at least one tuft 124. This defines the third side of the “box”. (The tufting machine tufting the adjacent row and performing the same first and second side shift defines the side 128 of the “box” opposing the second side.) The tufting machine then returns to linear tufting on a line 126 coaxial with the line 56. Tire line 126 may be part of an adjacent box stitch pattern 102 in the second sequence 54 or may be tufts in a first sequence 52 of a subsequent repeating pattern 50. Fig. 9 illustrates a second sequence 54 of three (3) repeating box stitch patterns 102.

[0067] Alternate embodiments of a cost-advantaged ground cover are readily developed. For example, an alternate embodiment of the sequences having the box stitch pattern shown in Fig. 8 has the first sequence length 58 of 14 inches and the second sequence length 64 of 5 inches, for a repeating pattern length 65 of 19 inches. Another alternate embodiment the sequences having the box stitch pattern shown in Fig. 8 has the first sequence length 58 of 36 inches and the second sequence length 64 of 5 inches, for a repeating pattern length 65 of 41 inches.

[0068] Fig. 10 illustrates a bottom plan view of a seventh embodiment 129 of a tufted geosynthetic ground cover having a plurality of sinusoidal sequence tufting patterns 130 providing alternating arcuate lines of tufting 132 and 134. Generally, the tufting lines formed by the tufting machine define the arcuate path 132 by repeated sequential side shifts in a first direction during tufting until reaching a predetermine length at an end tuft of the arc. The tufting machine then forms the opposing arcuate path 134 by repeated sequences of side shifts in a second direction opposing the first direction until reaching the predetermined length at an end tuft of the second arc. As illustrated at 135, a second (or more) linearly aligned tufts may be tufted after the tuft formed by the side shift.

[0069] The illustrated embodiment 129 includes a first linear tufting sequence 131 (52) with a second tufting sequence 133 (54) of the first and second sinusoidal lines 132, 134 of tufts. However, the illustrated embodiment tufts in the second sequence repeating patterns of the first and sec ond arcuate lines 132, 134. The repeated side shifts during such tufting may have a reduced production rate compared with process production tufting extended linear lines (52) of tufts. The tufting pattern 129 balances the cost advantages of linear tufting w ith the increased frictional engagement and reduced migration of infill from the intermediate tufting of the second sequence 54 of the opposing arcuate lines 132, 134 of tufts. The side shifts define sequential blockages 49 in linear flow' paths 47 over the surface 32 of the backing sheet 30 and define arcuate flow' paths in a first direction until the second arcuate sequence 134 blocks and defines an adjacent flow path in a second direction. Each alternating arcuate flow path induced by the respective blockage 49 reduces flow rate of ambient water and of migration of infill 42.

[0070] Fig. 11 illustrates in schematic diagram an embodiment of a tufted geosynthetic ground cover 150 in accordance with the present invention. In this embodiment, the repeating pattern 152 of tufts comprises a first pattern sequence 154, a second pattern sequence 156, a third pattern sequence 158, and a fourth pattern sequence 160. The pattern sequence may be one of the patterns discussed above. The repeating pattern 152 has a tufting length 162 with the first pattern sequence 154 having a tufting length 164, the second pattern sequence 156 having a tufting length 166, the third pattern sequence 158 having a tufting length 168, and the fourth pattern sequence 160 having a tufting length 170.

[0071] For example, the first pattern sequence 154 may be a linear tuft line as illustrated in tufting sequence 52 in Figs. 2 and 3, the second pattern sequence 156 may be the second sequence 54 discussed above in reference to Figs. 2 and 3, the third pattern sequence 158 may be the box pattern 102 (discussed above relative to Figs. 6 and 7), and the fourth pattern sequence 160 may be the sinusoidal sequence 130 (discussed above relative to Fig. 10). The repeating pattern 152 thereafter repeats tufting pattern sequences 154, 156, 158 and 160, and continues repeating the pattern 152 sequentially in the length of the backing 30.

[0072] Other repeating patterns may readily be developed, for reducing production costs with selected respective length of the linear tuft lines while minimizing side shifts to and from second sequence(s) of tufting patterns that define the respective flow path impingements or blockages 49. For example, a repeating pattern may have the linear tufting sequence 52, the offset pattern 54 as shown in Figs. 2 and 3 or Figs. 4 and 5), and a third offset pattern shown in Figs. 6 and 7. The example repeating pattern then repeats in the backing. The relative lengths of the respec tive first, second, and other tufting patterns in the repeating pattern sequences may be selected in accordance with the invention to balance the requirement of frictional interface between the geosynthetic ground cover and the ground surface with the production costs of the tufting production rate for linear tufting and side shifts for the second sequence of tufting.

[0073] The forgoing discloses the tufted geosynthetic ground cover of the present invention providing resistance to shear forces that cause movement of the tufted geosynthetic ground cover relative to the ground while resisting infill migration through interstices between adjacent tufts, in various illustrative embodiments in which each line of tufts has a repeating pattern of a first sequence of adjacent tufts tufted on a colinear line and a second sequence of tufts tufted such that a first tuft in the second sequence is tufted with a side shift on a line that is oblique relative to the colinear line, the colinear line extending for a majority of the length of the repeating pattern. Variations and alternate embodiments will be readily apparent to one of ordinary skill in the art and in keeping with the claims appended hereto.

Claims

CLAIMSWhat is claimed is:1 . A tufted geosynthetic ground cover, comprising: an elongated backing having an upper surface and a bottom surface; a plurality of spaced-apart tufts formed with respective synthetic yarns tufted through the elongated backing in a plurality of spaced-apart lines of tufts in a machine-direction with respective portions of the yams defining bridges on the bottom surface between adjacent tufts, said tufts extending from the upper surface of the elongated backing as simulated blades of grass, said spaced-apart tu fits defining interstices therebetween for receiving an infill; each of the plurality of lines of tufts having a repeating pattern of a first sequence of adjacent tufts tufted on a colinear line and a second sequence of tufts tufted such that a first tuft in the second sequence is tufted on a line that is oblique relative to the colinear line of the first sequence of tufts, wherein said colinear line of the first sequence extends for a majority of the length of the repeating pattern, whereby the tufted geosynthetic ground cover, being placed over a ground surface and receiving infill, has an increased frictional interface between the bridges and the ground surface and reduced migration of infill through the interstices between the tufts.

2. The tufted geosynthetic ground cover as recited in claim 1, wherein the elongated backing comprises a woven textile.

3. The tufted geosynthetic ground cover as recited in claim 1 , wherein the elongated backing comprises a non-woven textile.

4. The tufted geosynthetic ground cover as recited in claim 1, wherein the infill material comprises a sand mixture.

5. The tufted geosynthetic ground cover as recited in claim 1, wherein the colinear line of the first sequence extends for between 50% and 95% of the length of the repeating pattern.

6. The tufted geosynthetic ground cover as recited in claim 1 , wherein the second sequence of tufts define a second colinear line parallel to the colinear line.

7. The tufted geosynthetic ground cover as recited in claim 1 , wherein each tuft in the second sequence of tufts is tufted on a line oblique to a line on which a preceding tuft is tufted.

8. The tufted geosynthetic ground cover as recited in claim 7, wherein the colinear line for a subsequent repeating pattern is coaxial with the colinear line of a preceding repeating pattern.

9. The tufted geosynthetic ground cover as recited in claim 1 , wherein the second sequence comprises a second repeating pattern of a first tuft tufted on a line oblique to the colinear line and subsequent tufts in the second repeating pattern are tufted on a line parallel to the colinear line of the first sequence.

10. The tufted geosynthetic ground cover as recited in claim 9, wherein the first tuft in the first of the second repeating pattern is tufted lateral of tire colinear line in a first direction and the first tuft in a second of the second repeating pattern is tufted lateral of the parallel line in a second direction opposing the first direction.

11. The tufted geosynthetic ground cover as recited in claim 10, wherein the first tuft in the first sequence of a subsequent repeating pattern is tufted on a line oblique to the tuft line of the second sequence of tufts in the preceding repeating pattern and the colinear line of the tufts in the first sequence of the subsequent repeating pattern is coaxial with the colinear line of the preceding repeating sequence.

12. The tufted geosynthetic ground cover as recited in claim 9, wherein the colinear line for a subsequent repeating pattern is parallel to the colinear line of a preceding repeating pattern.

13. The tufted geosynthetic ground cover as recited in claim 9, wherein the colinear line for a subsequent repeating pattern is parallel to the colinear line of a preceding repeating pattern.

14. The tufted geosynthetic ground cover as recited in claim 1, wherein said second sequence of tufts comprises a first tuft tufted on a line oblique relative to the colinear line of the first sequence of tufts, said first tuft lateral in a first direction.

15. The tufted geosynthetic ground cover as recited in claim 14, wherein a subsequent portion of said second sequence comprises the first tuft tufted lateral in a second direction opposing the first direction.

16. A method of tufting a tufted geosynthetic ground cover, comprising the steps of: providing an elongated backing having a bottom surface and an upper surface; tufting a repeating pattern of a first sequence of tufts and a second sequence of tufts, said first sequence and second sequence each formed in a plurality7of spaced-apart lines of tufts in a machine-direction with respective portions of the plurality of yarns defining bridges on a bottom surface between adjacent spaced-apart tufts and tufted through the elongated backing, said tufts extending from an upper surface of the elongated backing as simulated blades of grass, said spaced- apart tufts defining interstices therebetween for receiving an infill material; said first sequence of adjacent tufts in each of the plurality of lines of tufts tufted on a respective colinear line and said second sequence of adjacent tufts tufted such that a first tuft in the second sequence is tufted on a line that is oblique relative to the colinear- line of the first sequence of tufts, wherein said first sequence of tufts extends for a majority of the length of the repeating pattern, whereby the tufted geosynthetic ground cover, being placed over a ground surface and receiving infill, has an increased frictional interface between the bridges and the ground surface and reduced sand migration through the interstices between tire tufts.

17. The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein the tufting of a subsequent repeating pattern of the first sequence of tufts and the second sequence of tufts occurs with a first tuft of the first sequence in the subsequent repeating pattern tufted on a line that is oblique relative to the second sequence of tufts in a preceding adjacent repeating pattern.

18. The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein the tufting of the first sequence extends for between 50% and 95% of the length of the repeating pattern.

19. The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein the second sequence of tufts tuft on a second colinear line parallel to the colinear line.

20. The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein each tuft in the second sequence of tufts is tufted on a line oblique to a line on which a preceding tuft is tufted.

21. The method of tufting a tufted geosynthetic ground cover as recited in claim 20, wherein the oblique line is in a first direction.

22. The method of tufting a tufted geosynthetic ground cover as recited in claim 21, wherein the oblique line is in a second direction after a predetermined length for the second sequence of tufts is tufted.

23. The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein a colinear line for a subsequent repeating pattern is coaxial with the colinear line of a preceding repeating pattern.

24. The method of tufting a tufted geosynthetic ground cover as recited in claim 16, wherein the first tuft in a subsequent repeating pattern is tufted lateral of the colinear line in a first direction and the first tuft in the second sequence in the subsequent repeating pattern is tufted lateral in a second direction opposing the first direction.

25. The method of tufting a tufted geosynthetic ground cover as recited in claim 24, wherein the first tuft in a subsequent repeating pattern is tufted on a line oblique to a tuft line of the second sequence of tufts in the preceding repeating pattern and the colinear line of the tufts in the first sequence of the subsequent repeating pattern is coaxial with the colinear line of the preceding repeating sequence.

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