IL83239A - Unit comprising mesh combined with geotextile - Google Patents

Description

83239/2 'J3ima 12 ny mmxn ηκη πτ'Π' UNIT COMPRISING MESH COMBINED WITH GEOTEXTILE YEHUDA WELDED MESH LTD. n"y2 πτ^α mnm ΠΊΙΠ' Inventor: Chaim Perach C: 16214 Field of the I nventlon This Invention Is concerned with geotexti les and more particularly with units comprising mesh combined with geotexti les.

Background of the I nvent on Geotexti les are materials that are porous and relatively Immune to the ravages of geological environment. Accordingly geotexti les have found use by construction and soil engineers for preventing and /or repairing slips and landslides. Soli systems are inherently particulate systems that are governed by particulate mechanics as distinguished from liquid or solid mechanics. Stresses on soli give rise to a non-linear, non-reversl ble sliding between particles. Soils are granular (sand, gravel, etc) or cohesive (clays). Cohesive soil particles are plate or rod shaped. Since when under stress, soils tend to slide It Is often necessary to build retaining walls to prevent the sliding or slipping of the soil. Retaining structures are especially necessary when the building or construction Is taking place on slopes or elevated areas. In the past retaining walls were constructed by excavating a section of the slope, a retaining or gravity wall was formed and poured at the front border of the excavated section. After the wal I hardened, the remaining opened excavated area was back filled. The back fills used In the past generally were relatively expensive substitute fill, such as sand or gravel to assure ample drainage and to minimize sliding stresses on the retaining wal I s.

More recently geotexti les have been used to reinforce the fills by laying sheets of the geotexti le In the excavated area to interrupt failure planes. Depending on the specific characteristics of the local soil, this technique enables the reuse of the excavated soli as the fill behind the wall. The geotextlles porosity and surface characteristics provide some friction which minimizes "sliding" of the soil and enables drainage to further enhance the stability of the retaining wal I .

A problem with this use of geotextlles has been that the geotextlles Inherently tend to elongate or stretch notoriously under stress. This stretchable characteristic effectively cancels the capability of the geotextlle sheets to retain the soli and thereby to effectively Interrupt the failure planes. When the geotextlle was fitted to the fill to provjde a face, the stretchable characteristic of the geotextlle caused the face of the geotextlle to bulge.

Another problem encountered with use of the geotextlles as soil reinforcements In the past has been that there Is no effective way to attach the geotextlle sheets to the concrete retaining walls.

Accordingly It Is an object of soil engineers to minimize the stretching that occurs In geotextlles In actual use when under stress.

Another object of the engineers In the field s to attach the geotextlle fill reinforcing material to the retaining wall.

Brief Descri t on of the I n ent Ion According to a broad aspect of the present invention a geotextlle unit Is provided, said unit comprising a rigid mesh combined with geotextl le material .

According to a feature of the present Invention the geotextlle material Is Integral to the rigid mesh.

According to a related feature of this Invention the mesh keeps the geotextlle material from stretching without Inhibiting the porosity or natural friction of the geotextlle material. In fact, a synergistic benefit of the geotextlle unit is that the mesh amplifies the natural friction of the geotextlle. The amplified friction, the rigidity and the porosity of the geotextlle unit effectively enables the conversion of the fill into a unitary block that does not permit internal slides. Accordingly the retaining wail is no longer necessary. A "curtai " structure can be used Instead.

Yet another and related feature of this Invention Is the use of the unique geotextlle unit as a soil reinforcement in repairing or preventing slips and landslides, said reinforcement comprising sheets of geotextlle units having a rigid mesh Integrally covered by geotextlle material, said sheets being used as a component of the fill to separate layers of the fill; thereby, Interrupting failure planes, and said geotextlle material In association with the mesh of the unit assuring Increased friction with the flM while said rigid mesh prevents the stretching of the geotextlle material.

According to yet another feature of this invention, the geotextlle unit is made by setting the mesh between two sheets of geotextlle material and attaching the mesh to both the sheets of geotextl le material .

According to still another feature of the Invention the mesh Is attached to both sheets of geotextlle material along horizontal and vertical metallic rods making up the mesh. ι 83239/2 According †o another feature of the Invention and In a preferred embodiment thereof the geotextlle material Is a plastic material and the sheets are attached to the mesh by a pressurized heat lamination process which heat welds the geotextlle sheets together In the areas between the rods.

According to yet another feature of the Invention the geotextlle unit and variations thereof are used to enhance the construction of highways, dikes, parking lots and stadiums among other projects which entail soil reinforcement.

Brief Description of the drawings The above named and. other features and objects of the present Invention will be best understood when considered In the light of the following description of a broad aspect of the invention made In conjunction with the accompany drawings; wherein,: Fig. 1 Is an exploded pictorial view of the' Inventive geotextlle unit, I Fig. 2 Is a plan view of the assembled geotextlle unit, and Figs. 3-5 are side elevatlonal views of different embodiments showing the geotextlle unit used for soli reinforcement.

Fig. 6 shows a side sectional view of a, part of a stadium constructed using the geotextlle unit, and Fig. 7 is an exploded sectional side view of the geotextlle unit used In road construction. 83239/2 General descr Iptlon < The geotextlle unit 11 In a preferred embodiment as shown In Fig. 1 comprises three layers. The first and third layers 12 and 13; I.e.,the outer layers shown In Fig. 1 are of geotextlle material. In certain embodiments one of the outer layers may be of a smooth or slippery plastic material not a geotextlle material. As Is well known geotextlle material Is extremely porous and therefore enables both radial and axial drainage. The good drainage contributes to the stabl llty of the backfll I. , Some variations of geotextlle material appears to be tufted or fibrous; having what seems like tufts of fibers or curled fibers at the surfaces of the sheets. The fibers provide some friction between I the sheets and any surface juxtaposed to the sheets. The fibrous exterior Is Indicated at 14 on sheet 12 In Figs. 1 and 2. The fibrous tufted area extends over the outer surface of at least one of the sheets, however In the Interest of clarity of the drawings It Is only ! shown at the representati e area 14. Other variations Include material that Is comprised of fine plastic nejtlng or mesh.

While the Invention Is drawn to a geotextlle unit It should be understood that the Invention covers units with any material having radial and axial porosity combined with the frictlonal characteristics of geotextlles, and the ability to resist the natural corrosl veness of soils.

The middle layer 17 Is a rigid mesh. In a preferred embodiment the mesh Is comprised of rows 19 and colums 19 of steel rods welded together at the juctlons, such as Junction 21 of the steel rod of row 18b and the steel rod of column 19(f). The rows are shown as rows I8a-18g. The columns are shown as columns 19a - 19g. 83239/2 As shown in Fig. 2, the steel mesh Is Integrally joined to the sheets 12 and 13 of geotextlle material. According to one method of Integrally joining the sheets of geotextlle material to the steel mesh, the sheets are joined together along both sides of each of the row and column steel rods. However according to a preferred embodiment, the sheets are heat laminated together In the areas between the rods such as shown at area 22 In Fig. 2. The units possess the characteristics of high porosity, high resistance to sliding (friction), high tensile strength and are practically non-stretchabl e.

Fig. 3 shows one mode of using the geotextlle units for soil reinforcement, behind a "curtain" (thin wall). An excavation 31 Is made at the end of raised -sol I site 32. A first geotextlle unit 33 Is laid at the bottpm of the excavation. The backfill material whether clay, sand or gravel which was originally excavated is placed In a layer 34 on top of the geotextlle unit. Note that the mesh enables bending the unit to form different shapes such as the characterized vertical "U" shape 36 at the end of the unit 33.1 The vertical "U" 36 is defined by the end of the horizontal section of unit 33, the vertical section 38 and the oppositely disposed short horizontal section 38. The fill 34 is compacted In one* or more layers and covered by another shaped geotextlle unit 37. The unl† 37 is again 'loaded with fill 41. This process Is repeated Until the excavated section Is loaded with fill. Finally the top most geotextlle unit 42 has a biased section 43 ending In a horizontoal section 44. Fill 47 is loaded on top to complete the filling in of the excavation. The wall Is no longer necessary for retaining purposes but is useful to protect the geotextl le units. 83239/2 I1 Fig. 4 shows another use of the geotextlle units 11 In a soil reinforcing capacity. Here again a section 31 Is excavated at one side of upraised section 32. A geo textile unit 56 which is not bent or shaped Is placed at the bottom of the excavation. Fill 57 Is placed on top of sheet 57 and compacted In one or more layers. The fill preferrably Is the excavated dirt. A second geotextlle unit 58 is placed over the compacted fill. The process Is repeated until the desired height Is reached. If desired, the portion of the geotextlle units abutting the walls have †he geotextlle material cut away to enable attaching the mesh to the curtain or wall 59 as Indicated at 61, for example, where sections of the front portion of the mesh or Just protrubences are attached to the wall. If the wall Is concrete the protrubences are Inserted Into the space Into which the concrete Is poured.

Fig 5 shows the use of the geotextlle unit in conjunction with other building materials; e.g. hollow block such as block 66. The block 66 Is shown lying on Its side in Fig 5a.

■J In Fig 5 proper, the blocks 66 are shown stacked one atop the other to form a wall 67. The wall borders the f 11 led In excavated area 31 Juxtaposed to upraised section 32. The geotextlle untts such as unit 68 are used for soil reinforcement In the manner described with regard to Figs 3 and 4 except that protuberance such as protuberance 69 are bent approximately 90 degrees and Inserted Into the hollow blocks. Subsequently concrete may be poured Into the hollow blocks to finish the retaining wal I and attach the wall and the geotextlle units. Although the drawing shows a geotextlle unit per block It should be understood that the Invention Is not so limited.

Fig 6 shows a variation of the construction method of Fig 5. In Fig 6 the hollows blocks 66 are staggered to provided an inclined structure 71. The inclined structure is suitable for stadium seating for example.

Fig. 7 shows the use of a variation of the geotexti le unit as a sub-base In road construction. The unit 76 is comprised of a geotexti I e upper sheet 77, the mesh 78 and a bottom slippery plastic sheet 79. Preferrabty the sheets are heat laminated to the mesh to form a unit 76. The unit 76 is a sub-base that is placed on the soil 81. It is especially effective when the soil 81 is expansive. The asphalt base 82 is placed on top of the unit 76. The road i completed in the usual manner well known to those skilled in the art.

The unit 76 "insulates" the asphalt base from the stresses normally caused by the expansion of the soil. When the soil expands the unit 76 slides on the soi l and thus the transmission of the stresses of expansion to the asphalt base is interrupted. The cracks In the roads normally caused by the expansion are minimized If not el Imlnated entirely.

In summary, among other benefits, the soli reinforcing of the geotexti le unit enables the excavated dirt to be used again as the fill. The friction and rigidity provided by the geotextile unit acting against the Juxtaposed ground and fill Interrupts the slide planes to strengthen the retention of the upraised section 32. The extent of Improved retention enables using significantly less bulky retaining walls. In fact a "curtain" comprised of plastic can be used. Alternatively no wall or a thin concrete wall 48 can be used.

Means on the geotextile unit are provided for attaching the 83239/2 horizontal units to the vertical walls. More particularly as shown In Fig 3a the mesh unit Is cut at 51 of a column rod such as column rod I9d to enable providing a nipple or protuberance 52 which extends Into the wall 48. In Fig 3 such nipples are shown extending Into the wall from all except the top most geotextl le -unit.

The mesh prevents the geotextlle from stretching and thereby assures that the slide planes are properly Interrupted. The synergistic benefit of the mesh, among other things. Is that the mesh enables forming the geotextlle unit to assume vertical spaced apart horizontal and biased positions.

While distinct forms are shown In the figures other shapes are certainly within the scope of the Invention. The mesh actually amplifies the friction between the geotextlle unit and the spll. The mesh also enables attachment to the walls to help support the walls.

In a preferred emdodlment the rods of the mesh are of construction steel, at least 3 mm In diameter. The space between the rows Is 5 cm or more and the space between the columns Is 5 cm or more. ' The rods are preferably treated to resist rust or are of a rust resl stant ai loy. ' Among the other benefi s of the geotextlle units Is that the units enable both vetlcal and horizontal drainage.

The units have been tested to ascertain their ef ectiveness In causing the fill to act as a unitary block, which Is what Is ultimately required of a soil reinforcing device. Pull out tests were conducted using meshes alone and compared to pull out tests made using geotextlle units. The geotextlle unit Is almost three times as effective as the mesh alone. For exam le, it was found that 8 tons per square meter of pull were required to start moving the mesh In a clay soi l having an internal friction angle of 29 degrees as compared to three tons to start moving the mesh alone. The spacing of the mesh was 10 centimeters by 20 centimeters and comprised of 4 mm diameter rods. The pulling force was applied to the rods that were spaced apart by 10 centimeters. The vertical load was equivalent to 3.5 meter high compacted backfil l. Thus, the unique geotextlle units effectively caused the soli to act as a single block.

For background material on soli reinforcing see the book entitled "Foundations and Earth Structures". Design Manual 7.2 of the Department of the U.S. Navy. Navy Faci lities Command, especial ly applicable are pages 7.2 -116, 117. * The examples show landfills, however many other uses of the unique geotextlle unit are possible. For example, If used In the construction of embankments or dams, steeper slopes can be used to provide worthwhile, significant savings in earth fill volume.

Accordingly the unit provided herein Is a rare and unusual soli reinforcing unit which finds many uses that provide unexpected structural and economical benefits.

While the invention has been described using certain exemplary embodiments t should be understood that the description is by way of example only and not as limitation on the scope of the Invention which s defined by the following claims. 83239/3

Claims (10)

1. A porous geotextile unit comprising a porous geotextile material and means for minimizing the stretching of the porous geotextile material including a rigid mesh of construction steel rods and means for integrally coupling the porous geotextile material to the mesh wherein the porous geotextile material comprises first and second sheets of porous geotextile material disposed on opposite sides of said mesh and the means for integrally coupling the porous geotextile material to the mesh comprises heat welds joining said first and second sheets of porous geotextile material only at the areas between the rods.

2. The geotextile unit of claim 1, wherein the construction steel rods are arranged in rows and columns.

3. The geotextile unit of claim 2 and also comprising means for welding the rods together at intersections of the rows and columns .

4. The geotextile unit of claim 2, wherein the geotextile material is removed from selected areas of the unit and wherein the rods form protuberances.

5. . Arrangement for soil reinforcement for use in repairing or preventing slips and landslides or the construction of steep slopes, said reinforcement arrangement comprising a plurality of porous geotextile units each comprising a porous geotextile material and means for minimizing the stretching of the porous geotextile material including a rigid mesh of construction steel rods and means for integrally coupling the porous geotextile material to the mesh wherein the porous geotextile material 83239/3 comprises first and second sheets of porous geotextile material disposed on opposite sides of said mesh and the means for integrally coupling the porous geotextile material to the mesh comprises heat welds joining said first and second sheets of porous geotextile material only at the areas between the rods, said units used as components of the fill to separate layers of the fill thereby interrupting failure planes, said units assuring friction with the fill, and said rigid mesh comprising means for preventing the stretching of the material while enabling the forming of the geotextile units.

6. The soil reinforcement arrangement of claim 5 and also comprising wall means and means for attaching the geotextile units to the wall means.

7. The soil reinforcement arrangement of claim 5 and also comprising wall means comprised of stacked hollow blocks, and where protuberances of the mesh of the geotextile units are bent to extend into the hollow blocks.

8. The soil reinforcement arrangement of claim 7, wherein the hollow blocks are precast in one unit.

9. The soil reinforcement arrangement of claim 7, wherein the hollow blocks are staggered to provide stadium like seating arrangement . 83239/2 arrangement .

10. The geotextile unit of claim 1 and also comprising a sheet, disposed on one side of the mesh and formed of a material having less friction than the geotextile material. For the Applicants, c: 16214