RU2324033C1 - Geogrid or mesh structure for soil surface reinforcing - Google Patents

Abstract

FIELD: fixed constructions; reinforcing of the soil surface of road slopes and shore lines, protection of mainline pipelines against soil erosion using geogrids.

SUBSTANCE: geogrid comprises set of flexible tapes made of a woofed structure material that are set on edge and attached one to another with seams to form a meshed structure when the grid in set position. The tapes are made of a material having a woofed structure formed of 150 to 300 polypropylene threads in warp direction and of polypropylene fibrillated or multifilament threads in weft direction, and having a breaking force not less than 100 kN/m. The used seams are shuttle-type seams with bar tacks. The length of the geogrid in its set position is from 10 to 20 m, the width is up to 10 m, and the height - from 50 to 150 mm. The geogrid mesh sides are from 50 to 500 mm in its set position in longwise and crosswise directions. The thickness of flexible woofed tape is from 1.0 to 2.0 mm. The seams are stitched vertically in relation to the flexible edges with twisted sewing threads, made of polyether or polyamide or other synthetic threads with a breaking load not less than 60 N, ensuring a minimal breaking load of the seam not less than 50% of the tape breaking load of the tapes.

EFFECT: enhancement of the geogrid performance characteristics; ultraviolet rays resistance of the material; biological stability; environmental security; maintaining stable characteristics to allow using the geogrid at all times and at all temperatures.

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Description

The invention relates to the construction, namely, to strengthening the soil surface of slopes of roads and railways, coastlines, protecting pipelines from soil erosion, to increase the bearing capacity of the roadway, etc.

Known geogrid with a cellular structure for strengthening the soil surface, made of flexible strips mounted on the ribs and connected to each other in a checkerboard pattern by seams with the formation of a stretched, working position of the cellular structure (see US patent No. 4797026, CL E02D 17/20, 1989).

Known geogrid with a cellular structure made of flexible strips interconnected by seams in such a way that when tensile they form three-dimensional structures (see RF patent No. 2166625, E02D 17/20, E02B 3/12, E01C 5/00 from 27.04. 2001).

The closest in essence and the achieved result to the invention technical solution is a geogrid with a cellular structure made of a set of flexible strips with a textile structure of the material installed on the ribs and connected by seams to form a cellular structure in the working position (see RF patent No. 2180030, E02D 17/20 dated 09/10/1999).

However, the known technical solutions have the following disadvantages: low lattice strength due to low tensile characteristics of the flexible strips, when laying, they require great efforts due to the hard connection of the strips, which at low temperatures can lead to breakage, insufficient filtration coefficient, which contributes to the soil leaching from cells, a significant ratio of transport volume to working.

The problem to which the present invention is directed, is to increase the operational characteristics of the geogrid by increasing the breaking properties of the flexible strips, the most loaded element - the seam, the resistance of the material to ultraviolet radiation, biological resistance, environmental safety, long-term operation while maintaining stable characteristics of working with the geogrid in any season at any temperature, ensuring good filtration ability. The problem was solved due to the fact that in a geogrid with a cellular structure made of a set of flexible strips with a textile structure of material installed on the ribs and connected by seams to form a cellular structure in the working position, the flexible strips are made of a material with a woven structure formed from 150 to 300 polypropylene warp yarns and polypropylene fibrillated or multifilament weft yarns, and have a tensile strength of at least 100 kN / m, and the seams are located vertically in relation to to the ribs of the flexible strips and shuttle with fastening from twisted sewing synthetic threads with a breaking load of at least 60 N, providing a minimum breaking load of the seam of at least 50% of the breaking load of the flexible bands.

In addition, the length of the geogrid in the working position can be from 10 to 20 m, width up to 10 m, and height from 50 to 150 mm; the dimensions of the geogrid cell in the working position can be in the longitudinal and transverse directions from 50 to 500 mm; the thickness of the flexible woven strip may be from 1.0 to 2.0 mm.

Polypropylene in its structure is an inert material, at normal operating temperatures from -50 to + 50 ° it does not interact with any chemical or biological material, which ensures the ecological safety of the geogrid.

Flexible strips of woven material for geogrid are made on tape weaving machines by threading from 150 to 300 threads, for example polypropylene, and polypropylene fibrillated or multifilament yarn up to 1500 denier is used in the weft. The edges of the flexible strip are strengthened by knitting the weft and the edge thread, which, even with local violation of the integrity of the edge, does not allow the threads of the flexible strip to open further.

The flexible strip made is a woven material of white or any other color, a width of 50 to 150 mm, a thickness of 1 to 2 mm. This provides a flexible strip of material with a woven structure with a breaking load of at least 100 kN / m. These discontinuous characteristics of the geogrid are achieved due to the fact that when refueling a woven material with a flexible strip of a large certain number of threads (from 150 to 300) onto a relatively small width of the flexible strip (from 50 to 150 mm), the effect of the rope is obtained and this also provides sufficient lateral stiffness (elastic modulus) of the flexible strip. These discontinuous characteristics of the geogrid are absolutely necessary in conditions of its use on slopes above 30 ° and a height of more than 5 m, because the weight of bulk soil or other materials that are poured into the cells of the geogrid, especially after moisture saturation, at the contact of the bulk soils and the base, an equilibrium of the shear and holding force must be ensured.

According to the calculations of MGSU for a 5 m high embankment, the required tensile strength of the geogrid as a reinforcing material should be 77 kN / m in tension with a single-layer reinforcement. Soil consolidation time is 1.5 years, i.e. reinforcing geogrid during the specified period should have a constant strength of not less than 77 kN / m (see. Scherbina E.V. Geosynthetic materials in construction. DIA, M., 2004, p. 54).

The tests showed that, in comparison with the known geogrids, only the proposed geogrid due to the woven structure of flexible strips with a certain number of threads satisfies these requirements, providing a breaking load of up to 100 kN / m.

Having a woven fabric structure made of polypropylene filaments, flexible strip geogrid freely pass water with the filtering factor of at least 70 m ³ / day and does not hinder the penetration of the turf root system. The polypropylene filaments of the woven material of the flexible strip of the proposed geogrid due to the glassy surface are not subject to calvation, in contrast to the threads of the flexible strip of nonwoven materials having a fiber structure.

The connection of flexible strips to obtain a geogrid is done by seams located vertically relative to the edges of the flexible strips, on special sewing machines with reverse sewing with twisted sewing threads made of polyester or polyamide or other synthetic threads with a breaking load of at least 60 N, which ensures a minimum breaking load of the seam is not less than 50% of the breaking strength of the flexible strips. Unlike flexible strips of geogrids of non-woven finished material, on the woven material of the strip when stitching, the needle of the sewing machine pushes the threads apart and, since the threads are not tightly connected, weakening of the strip at the piercing site does not occur. In the case of stitching of flexible strips of nonwoven materials, the needle cuts through the material of the strip, which leads to a significant decrease in the breaking properties of the strip at the piercing site. The invention is illustrated by drawings, where:

figure 1 - geogrid in the folded state,

figure 2 - geogrid in the working stretched position,

figure 3 - cell geogrid with designations of sizes,

figure 4 is a view 1 in figure 3 (a diagram of the seam at the junction of flexible strips and threads of the woven structure of the material of the strips of the geogrid).

The geogrid 1 consists of a set connected by cross-linking with a shuttle seam with a fastener 2, flexible strips 3 of material with a woven structure formed by warp threads 4 and weft threads 5, and having longitudinal ribs 6. Cells 7 of the geogrid in the stretched state in FIG. 3 have the shape of a hexagon with a size F in the transverse and longitudinal direction of 50 - 500 mm and a size L of the section between the joints up to 200 mm.

The geogrid in the stretched state in figure 2 has the following dimensions:

And - the length of the geogrid from 10 to 20 m;

B - geogrid width up to 10 m;

N - geogrid height from 0.05 to 0.15 m.

The geogrid in the stretched state (with dimensions: length 10 m and width 8.7 m) has an area of 87 m ² and weight up to 35 kg.

When folded, the geogrid is a rectangular module that is convenient for transportation.

The ratio of the volume of the transport position of the geogrid in the form of a module to the extended (working) position is 1: 130, which is very advantageous when transporting the geogrid to the place of use.

The characteristics of the proposed geogrid in comparison with the characteristics of similar produced geogrids obtained as a result of the tests are shown in the table.

Table Geogrid Characteristics Geogrid with polymer stripes Nonwoven Strip Geogrid Geogrid with woven stripes made of polypropylene yarns Breaking load of strips, kN / m 40 twenty one hundred Chemical and biological resistance, year not limited 2 g not limited Filtration ability, m ³ / day 0 40 70 Module area, m ² 14.8 83 87 Flexibility on a beam with a radius of 5 mm at t minus 40 ° С can't stand violation of the structure of the material no violation of the structure of the material no The ratio of the volume of the module in the folded and stretched state 1/54 1/55 1/130

Tests of the proposed geogrid showed the advantages of its characteristics over the known ones, which allows it to be used as a reliable reinforcing means for strengthening slopes, road bases, protecting the surface of slopes over pipeline systems, plugging slag dumps of the mining industry and other geotechnical objects.

The geogrid has low material consumption, the strength of the tapes is 100 kN per 1 m and the strength of the joints is at least 50 kN / m, and provides reliable protection of the soil from erosion and filtering water down the slope.

Using the proposed geogrid can increase the bearing capacity of the roadway, if it is laid in the base of the road or in asphalt concrete due to the redistribution of loads from the vehicle evenly over the entire base of the road.

The increased stability of the soil filling the geogrid to the action of wind and water erosion is due to the implementation of flexible strips with a woven structure of a material obtained from polypropylene yarns. Which also contributes to the natural germination of the roots of the grass cover for additional soil fixation in the geogrid cell.

Claims (4)

1. A geogrid with a cellular structure for strengthening the soil surface, containing a set of flexible strips with a textile structure of the material installed on the ribs and interconnected by seams to form a cellular structure in the working position, characterized in that the flexible strips are made of a material with a woven structure formed from 150 to 300 polypropylene warp yarns and polypropylene fibrillated or multifilament weft yarns, and have a tensile strength of at least 100 kN / m, and the seams are vertically with respect to the ribs of the flexible strips and shuttle with fastening of twisted sewing synthetic threads with a breaking load of at least 60 N, providing a minimum breaking load of the seam of at least 50% of the breaking strength of the flexible bands. 2. The geogrid of claim 1, characterized in that the length of the geogrid in the working position is from 10 to 20 m, a width of 10 m, and a height of 50 to 150 mm. 3. The geogrid according to claim 1, characterized in that the cell dimensions of the geogrid in the working position are in the longitudinal and transverse directions from 50 to 500 mm. 4. The geogrid according to claim 1, characterized in that the thickness of the flexible strip is from 1 to 2 mm.

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