Reinforced geocell and a method for producing the same

Abstract

A reinforced geocell is made of flexible polymeric strips arranged in rows and interconnected in a staggered order lengthwise to form a three-dimensional cell structure when stretched in the direction normal to surfaces of the strips. The strips are provided with drainage apertures and are reinforced in a longitudinal direction with reinforcing threads having at least two fibrous elements twisted along full lengths thereof. A method for producing a geocell includes extruding a polymeric material for producing a sheet material, laying out twisted reinforcing threads onto the sheet material, calendaring the sheet material when heated to 120 to 200? C. to press reinforcing threads into the sheet material, cutting a reinforced sheet material into sheets, perforating the sheets for producing drainage apertures, cutting the sheets into strips, and interconnecting the strips in a staggered order to form a three-dimensional cell structure.

Claims

1. A reinforced geocell, comprising: flexible polymeric strips being arranged in rows and interconnected in a staggered order lengthwise and being stretched in a direction normal to surfaces of the strips so as to form a three dimensional cell structure; drainage apertures perforated into the strips; and reinforcing threads pressed into the strips in a longitudinal direction of the strips, wherein each reinforcing thread is comprised of at least two fibrous elements twisted along lengths thereof so as to have a twisted length at a depth of at least 0.25 mm from an exposed surface of a corresponding strip, within a corresponding strip.

2. The geocell according to claim 1, wherein each reinforcing thread has 5 to 20 twists per cm.

3. The geocell according to claim 1, wherein each reinforcing thread is comprised of polyester or polyethylene terephthalate.

4. The geocell according to claim 1, wherein the reinforcing threads have thickness of not more than 1 mm and are arranged with a transverse pitch ranging from 1 to 10 mm.

5. The geocell according to claim 1, wherein the strips are comprised of high density polyethylene (HDPE) or a mixture of HDPE and low density polyethylene (LDPE).

6. The geocell according to claim 1, wherein the drainage apertures are shaped as elongated rectangles with rounded corners.

7. A method for producing a three-dimensional reinforced cell structure, comprising the steps of: extruding a melted polymeric material so as to produce a sheet material, laying reinforcing threads onto the sheet material, calendering the sheet material heated to 120 to 200? C and pressing the reinforcing threads into the sheet material so as to form a reinforced sheet material, cutting the reinforced sheet material into sheets, perforating the sheets so as to form drainage apertures through the sheets, cutting the sheets into strips, the reinforcing threads being in a longitudinal direction of a corresponding strip, and connecting the strips in a staggered order so as to form the three-dimensional reinforced cell structure, wherein each reinforcing thread is comprised of at least two fibrous elements twisted along lengths thereof so as to have a twisted length at a depth of at least 0.25 mm from an exposed surface of a respective strip, within a respective strip.

8. The method, according to claim 7, further comprising the step of: impregnating the reinforcing threads with an adhesive composition before the step of laying reinforcing threads onto the sheet material.

9. The method, according to claim 7, wherein the reinforcing threads are comprised of at least one of a group consisting of: polyester and polyethylene terephthalate.

10. The geocell according to claim 1, wherein the two fibrous elements have a transverse pitch ranging from 1 to 10 mm.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention is illustrated by the accompanying drawings.

(2) FIG. 1 shows a structure of the strips used for producing the geocell.

(3) FIG. 2 shows a view of the reinforcing threads.

(4) FIG. 3 shows a view of the geocell, according to the claimed invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) The gas The claimed reinforced geocell (FIG. 3) consists of flexible strips (1) made of a sheet material (FIG. 1), which flexible strips (1) are arranged in rows and interconnected in a staggered order (seams (2)) by, e.g., ultrasonic welding or threads.

(6) The strips (1) are made of a polymeric material, in particular, of HDPE or a mixture of HDPE and LDPE. The strips (1) may have a thickness of 1 to 2 mm.

(7) Further, the strips (1) are reinforced lengthwise with reinforcing threads (3) comprising two or more fibrous elements (fibers) twisted along a full length thereof (FIG. 2). Preferably, the fibrous elements have 5 to 20 twists per 1 centimeter of the lengths thereof. The reinforcing threads (3) may be made of polyester or lavsan and have a diameter up to 1 mm, and the reinforcing threads are pressed into the strip (1) to a depth at least 0.25 mm and arranged with a transverse pitch ranging from 1 to 10 mm.

(8) The strips (1) are also provided with drainage apertures (4) having preferably the shape of elongated rectangles with rounded corners.

(9) The disclosed geocell may be produced as follows.

(10) A melted polymeric material is extruded for producing a polymeric sheet material. The twisted reinforcing threads are laid onto the sheet material produced, and the latter is calendered at a temperature ranging from 120 to 200? C. by using embossed rolls that ensure pressing the reinforcing threads to a depth at least 0.25 mm. In order to improve adhesion, the reinforcing threads may be preliminarily impregnated with an adhesive composition, e.g., with Latacril BM glue (TU (stands for technical regulations) 2385-403-00208947). A reinforced sheet material thus produced is roll-cooled and cut into sheets. Then, the sheets are perforated for producing drainage apertures. After that, the so produced perforated sheets are cut into strips (ribbons). The strips are interconnected in a staggered order by using ultrasonic welding and are sewn together with a thread, thus forming a three-dimensional cell structure. The final structure is stretched for producing a geocell.

EXAMPLE

(11) According to the above disclosed method, a geocell was produced from polyethylene strips having a thickness of 1.5 mm and reinforced with twisted polyester threads having a thickness of 1 mm and consisted of two fibrous elements (threads) having a thickness of 0.5 mm each and 10 twists per cm. The threads were arranged with a transverse pitch of 2 mm. Also, the strips were provided with 20?4 mm rectangular drainage apertures with rounded ends.

(12) For the purpose of comparison, a geocell was produced according to the closest analogue under the same parameters but with the use of non-twisted reinforcing threads.

(13) The results of comparison between the disclosed structure and that known from the closest analogue are shown in Table 1.

(14) TABLE-US-00001 TABLE 1 Characteristics of geocells produced according to the closest analogue and the claimed invention Geocell produced according to the closest analogous Claimed Parameter solution geocell Thickness of the strip, mm 1.5 1.5 Tensile strength of the non-perforated 20.25 25.22 strip at a maximum load, kN/m Tensile strength of the perforated 16.1 17.47 strip at a maximum load, kN/m Unit elongation of the perforated 22.45 21.05 strip at a maximum load, % Unit elongation of the non-perforated 100.42 101.33 strip at a break point, % Seam pull strength of the perforated 18.66 19.07 strip, kN/m Strength of an infilled compacted 2.1 2.4 material reinforced by the geocell at shear loads, kg/cm.sup.2

(15) Thus, the claimed structure ensures reliable holding of the reinforcing elements in the geocell strips as well as improved strength of the geocell at stretching and shear loads.