RU2716996C1 - Method of producing a polymer geocell lattice and a geocell lattice based thereon - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction, namely to a method of producing a polymer geocell lattice and to a structure of a polymer geocell lattice, intended for reinforcement of soil, and can be used to strengthen weak bases of industrial and civil structures, as well as slopes of coastlines and channels of water bodies, slopes. Method of producing a polymer geocell lattice consists in making measuring strips of modified polyethylene material, in connection of measuring strips with given parameters along length and width in pairs by weld seams, in step shift of welded joints when connecting strip of previous pair with adjacent strip of next formed pair, in formation of geocell array parallel strips. Measuring strips of a modified polyethylene material is made of a polyethylene sheet of thickness 0.8–1.1 mm and density of 0.910–0.965 g/cm³, which modified power 0.7–0.9 MeV electron beam radiation at a radiation current of 45–80 mA and specific processing rate of 0.077–0.1 m/(min·mA).

EFFECT: technical result consists in providing improved physical properties of low-thickness geocell lattice, as well as providing expansion of technological capabilities of using polyethylene sheet with low-thickness dimension range at simultaneous improvement of its operating characteristics to tensile stresses occurring at natural-climatic and force action of filler on walls of lattice cellular structure.

4 cl, 2 dwg, 1 tbl

Description

The invention relates to the field of construction, and in particular, to a method for manufacturing a polymer geocell grid and to a polymer geocell grid design for soil reinforcement and can be used to strengthen weak foundations of industrial and civil structures, as well as slopes of coastlines and channels of water bodies, slopes, road recesses, cones of bridges, reinforcement of foundations and slopes of roads and railways, airfields, industrial and construction sites, as well as coastlines, channels of water bodies etc., where high strength and stable performance and durability of the erected buildings.

Various polymeric geocell gratings are known from the prior art (see patent RU No. 2129189, publ. 04/20/1999, patent RU No. 2358063, publ. 06/10/2009 and patent RU No. 2152480, publ. 10.07.2000, patent US N 4797026, publ. 01.01.89 g) containing a bag of parallel parallel measuring and identical length and width measuring strips based on sheet polyethylene, adjacent strips are stitched together along their length in a checkerboard pattern with welds that are transversely oriented to the longitudinal axis of the strips to form when the bag is stretched in direction normal to the surface of the measuring strips of hollow i eek geosotovoy spatial structure.

The cells of the geocell spatial structure can be filled with both discrete and monolithic material: plant soil with grass sowing, stone material, concrete, in northern conditions - with a peat-sand mixture. The design of the geocell grid with a filler forms a monolithic slab, providing soil reinforcement during road and construction works, strengthens slopes and the banks of water bodies.

For the manufacture of polymer geocell gratings in accordance with the specified level of technology, a technological process is used, according to which measured strips are made from sheet low-pressure polyethylene or a mixture of low-pressure and high-pressure polyethylene, they are fastened in pairs with each other with welds and stepwise welds are shifted when the strip is connected the previous pair with an adjacent strip of the next pair formed with the formation of a packet of parallel measuring strips.

The material for the manufacture of these tapes, as a rule, is polyethylene of various grades.

As the closest analogue of the claimed technical solution in the part related to the polymer geocell grating, the technical solution according to the patent US N 4797026, publ. 01/10/89

However, polyethylene is a thermoplastic material, therefore, when polyethylene is heated under load, for example, under the influence of sunlight under the simultaneous influence of soil pressure, inelastic stretching of the thermoplastic polymer occurs, which leads to deformation of the entire geocell grid and the corresponding movement of the soil layer, which is essential in the manufacture of dimensional strips of sheet polyethylene with a small sheet thickness of less than 1.2 (mm), which is characterized by high flexibility, reducing vertical stability and the rigidity of the lattice cells under the specified operating conditions. These circumstances are especially significant in the manufacture of a geocell grating from measuring strips perforated by drainage holes.

At the same time, low-pressure polyethylene (HDPE - high-density polyethylene) or a mixture of polyethylene of different densities with a sheet thickness of less than 1.2 (mm) in terms of cost, weight characteristics and their transportability are among the most accessible structural materials that are most preferred when used them in construction on significant surface areas and especially in conditions of sloping surfaces.

To improve performance by increasing the strength and stability of the geometrical parameters of the geocell grating, including in the manufacture of measuring strips of small thickness in patent RU No. 2459040, publ. 07/20/2013, a method for manufacturing a geocell grating is proposed, according to which the production of measuring strips is carried out from a modified polyethylene material, the strips are fastened together in pairs with each other, the welds are stepped by shifting the strips of the previous pair with the adjacent stripe of the next pair to form a packet parallel measuring strips.

According to this technical solution, the production of measuring strips is carried out using extrusion technology, in which a polymer material based on low-pressure polyethylene is modified by introducing reinforcing continuous aramid or carbon threads into the first pair of forming rolls before leaving the strip from the extrusion head . The reinforcement step is 1-5 mm, which is set using a metal comb through which the threads were passed before entering the polymer strip.

This technical solution is selected as the closest analogue of the proposed method for the manufacture of a polymer geocell grid.

However, when implementing this technical solution, the material costs for the manufacture of polymer geocell gratings with a standard number of stripes of various widths forming the parameters of the hollow grid cells in height, according to the construction technological requirements of soil reinforcement, are significantly increased. These circumstances are explained by the design features of the extrusion technology designed for the manufacture of modified measuring strips of a specific width.

When implementing this technical solution, the weight characteristics of measuring strips intended for the manufacture of geocell gratings are increased, which complicates the process of their installation during construction work on reinforcing large areas, including when strengthening slopes and shores of water bodies, and limited technological possibilities for using the most affordable industrial the production of rolled polyethylene material based on low-pressure polyethylene sheet or a mixture of low polyethylene th and high pressure when the sheet thickness less than 1.2 (mm).

The technical result of the invention in terms of a method for manufacturing a polymer geocell grid and in part related to a polymer geocell grid is to expand the technological capabilities of using sheet polyethylene with a size range of small thickness while improving its operational characteristics to tensile stresses arising from the natural-climatic and power the effect of aggregate on the walls of the cellular structure of the lattice.

To solve the technical result, a method for manufacturing a polymer geocell grid is proposed, which consists in the production of measuring strips from a modified polyethylene material, in connecting measuring strips with specified parameters along the length and width in pairs between each other with welds, in the step offset of the welds when connecting the strips of the previous pair with in the adjacent strip of the next pair formed, in the formation of a packet of parallel measuring strips of a geocell lattice, according to the invention, is made e dimensional bands of a modified polyethylene material is carried out from a sheet of polyethylene of thickness 0.8-1.1 (mm), 0,910-0.965 density (g / ^cm3), which modified power 0.7-0.9 MeV electron beam radiation at radiation current 45-80 mA, specific processing speed 0.077-0.1 m (min * mA).

According to the invention, the measuring strips are welded using ultrasonic welding at an ultrasound frequency of 18-30 kHz, the welding time is 1.0-3.0 seconds, the pressure retention time is 0.1-2.0 seconds, the delay time is 0, 5-1.5 sec.

To solve the technical result, a polymer geocell grid is proposed, containing a packet of parallel measuring strips identical in length and width based on sheet polyethylene, adjacent strips stitched together along their length in a checkerboard pattern with welds transversely oriented to the longitudinal axis of the strips to form stretching the package in the direction normal to the surface of the measuring strips of the hollow cells of the geocell spatial structure, according to the invention, use radiation but modified by electron beam radiation measuring strips with a thickness of 0.8-1.1 (mm), tensile strength 18-19 kN / m

According to the invention, measuring strips are used with a width of 50-300 (mm).

When implementing this invention, in terms of a method for manufacturing a polymer geocell grid and a polymer geocell grid based on it, the technological possibilities of using sheet polyethylene with a density of 0.910-0.965 g / cm ^{3 are} expanded, which is typical for sheet polyethylene of low pressure or from a mixture of low and high pressure polyethylene , with a standard size series of sheets of small thickness with a simultaneous improvement in this case, the operational characteristics of geocell gratings to tensile stresses, oznikayuschih under natural climatic impact force and aggregate on the mesh of the lattice wall structure.

These circumstances are explained by the fact that in the manufacture of a polymer geocell grating, sheet polyethylene radiation-modified by electron beam radiation is used with the physical parameters specified in the invention according to the radiation power and processing speed, which improves the physical properties of sheet polyethylene and especially sheet polymers of small thickness used in the manufacture of polymer geocell gratings.

It is known from the prior art that improving the physical properties of polymeric materials based on polyolefins, in particular polyethylenes, is achieved by modifying the internal molecular structure of the material. Effective methods for modifying polyolefins is the introduction into their compositions, for example, inorganic fillers (carbon, aerosil, metal oxides and sulfides, see, for example, patent RU No. 2129189), additives of organic compounds, as well as the processing of sheet polymer materials by ionizing radiation, which is the most versatile way to modify performance and manufacturability.

The effect of ionizing radiation on the sheet material based on polyethylene contributes to the emergence of more complex spatial molecular structures in it without changing the chemical composition. The properties of radiation-modified polyethylene depend on the modification conditions (type of exposure, radiation energy, dose, atmosphere, pressure, temperature). The selection of the optimal parameters of the radiation modification of polyethylenes leads to an increase in its heat resistance, wear resistance, impact strength, and to an increase in tensile strength. The process of radiation modification of polymers using electron-beam radiation is in practice based on the radiolytic rupture of less strong chemical bonds between carbon and hydrogen using then the “crosslinking” of the carbon-carbon bond as a stronger compound, while the “crosslinking” process does not damage the polymer chain (see, for example, http://nuclphys.sinp.msu.ru/nuc_techn/el_ac/application.html#1.2. Practical use of electronic accelerators).

Given the prior art relating to the technological processes of modification of polymeric materials, in particular, based on sheet polyethylene, when creating the invention, the technical problem was solved to optimize the parameters of radiation modification by electron beam radiation of industrially produced sheet polyethylene with a thickness of less than 1.2 (mm) , and preferably, based on low-pressure polyethylene or a mixture of low-pressure and high-pressure polyethylene, as the most optimal structural materials in terms of density s, including, for the purposes of their use in the manufacture of geosotovyh lattices.

Optimization of the parameters of the radiation modification of sheet polyethylene at a given thickness and density ensured the creation of a geocell grid according to the invention based on measuring strips of minimum thickness and with parameters of tensile stress comparable to the parameters of the initial sheet polyethylene with a thickness of 1.3-2.0 (mm), traditionally used for the manufacture of geocell gratings.

In the analysis of the prior art, no technical solutions have been identified that have a set of features similar to the claimed technical solution for solving the claimed technical result, which indicates that the technical solution meets the criteria of the invention: "novelty", "inventive step".

When implementing the invention using well-known materials and technological equipment, which indicates compliance with its criterion of "industrial applicability".

The invention is confirmed by the following description and explanatory drawings, where:

fig. 1 - shows a General view of the polymer geocell grid;

fig. 2 - same as in fig. 1 when stretching a packet of measuring strips.

When implementing the invention using rolled sheet low-pressure polyethylene (HDPE - high density polyethylene) with a sheet thickness of 0.8-1.1 (mm) or sheet material based on a mixture of low and high pressure polyethylene at a density of 0.910-0.965 (g / cm ³ ), a roll of which is obtained by the extrusion-calender method with a sheet width of, for example, 1500 (mm). The specified parameters of the rolled sheet polyethylene in thickness are determined from the condition of the tolerance value ± 0.1-0.2 (mm) for this parameter.

Technological equipment for radiation modification of the original rolled sheet polyethylene, which includes:

continuous electron beam accelerator type ELV,

transport trolley for unwinding rolled material with pulling under the outlet window of the accelerator and winding into a roll on another transport trolley.

The high-voltage electron accelerator of continuous operation, type ELV-6M, has adapted parameters of the exhaust foil window for processing a roll of sheet material, in particular, with a sheet width of 1500 (mm). Operating voltage of a high-voltage electron accelerator: 0.7-1.3 MeV; maximum working beam current up to 80 mA;

technological equipment for ultrasonic welding of measured polyethylene sheets to form a packet (see Fig. 1) of parallel strips. The welding method is press. They use a welding machine of the TJ-HJ15 model, power supply - 50 Hz, installation power - 37 kW with a power of each welding machine from 1.7-2.4 kW and an ultrasound frequency - 18-30 kHz, overall installation parameters: 11.5 m ( D) × 3.5 m (W) × 2.2 m (H).

The manufacturing process of the polymer geocell grid is carried out in the following sequence:

1. rolled sheet polyethylene with parameters for a roll thickness of 0.8-1.1 (mm), a roll width of 1500 (mm), a density of 0.910-0.965 (g / cm ³ ) [this parameter preferably corresponds to the trademark HDPE - high-density polyethylene] is wound from a transport trolley and pulled in the direction of a high-voltage accelerator of continuous electrons to the outlet foil window with a specific processing speed of 0.077-0.1 m / (min * mA), at the exit of which the material being treated is subjected to electron beam radiation power 0.7-0.9 MeV p and beam current 45-80 mA radiation, the radiation is carried out modification of the polymer structure of the processed material, the processing depth which corresponds to at least 90% of the thickness of the polyethylene sheet. The specific processing speed depends on the linear velocity of the beam radiation reduced to the current.

The parameters of the radiation modification by electron beam radiation set by the invention are optimal for sheet polyethylene with a thickness of 0.8-1.1 (mm) and a density of 0.910-0.965 (g / cm ³ ). A decrease or increase in these parameters during radiation modification of this type of thermoplastics will result in either:

to the inefficiency of breaking the interatomic bonds of the polymer structure, and therefore to the inefficiency of crosslinking the carbon-carbon polymer chain. As a result, measured strips obtained from this radiation-modified modified sheet of polyethylene of a given thickness will have unstable characteristics in terms of strength to tensile stresses arising from the natural-climatic and forceful effects of the filler on the walls of the mesh structure of the lattice,

or to the manifestation of destructive processes in radiation-modified sheet polyethylene, which appear in the form of cracks and tears.

2. Of the radiation modified by electron beam radiation, rolled sheet polyethylene is made measuring strip identical in width and length. The parameters of the measuring strips in thickness are 0.8-1.1 (mm), in width 50-300 (mm) [specifically, the parameters for the width of the strips are determined by the technological requirements for the manufacture of geocell gratings].

For the manufacture of measuring strips of identical width, the machine tool equipment standard for these purposes is used, which carries out longitudinal pulling of the rolled material through a knife device that is pre-configured for a given cutting width of the measured strips. Then carry out the transverse cutting obtained by the width of the strips to a given technological length. The measured strips obtained after cutting polyethylene sheet are measured with a measuring tool (metal ruler or tape) in width and length in order to determine the identity of the geometric parameters of the obtained strips with a tolerance value of not more than ± 1.0 (mm).

During the implementation of the invention, modified measuring strips with a beam width of 50-300 (mm) and with a thickness of used sheet polyethylene of 1.0 and 1.1 (mm) and a density of 0.940 (g / cm ³ ) were manufactured.

3. Measured stripes of a given width and length obtained from radiation-modified polyethylene sheet are fed to an ultrasonic welding machine.

The method of ultrasonic welding based on materials from polymers is most optimal for one-piece connection of parts from this material using local directivity of energy released in the contact zone of welded parts

When implementing the technological process, the modes of ultrasonic exposure of welding equipment to measuring strips from radiation-modified by electron beam radiation of sheet polyethylene with a density of 0.910-0.965 (g / cm ³ ) with a sheet thickness of 0.8-1.1 (mm), which at ultrasound frequency - 18-30 kHz, have the following parameters:

welding time - 1.0-3.0 seconds, pressure retention time - 0.1-2.0 seconds, delay time - 0.5-1.5 seconds.

With the above parameters of ultrasonic action on the measured strips and given their physical and mechanical parameters, the stability of the formation of linearly oriented welds when connecting the measured strips is ensured, their deformation and splashes of the molten material during thermal exposure to the material used according to the invention are excluded.

Using a welding machine of the above model, packages of geocell gratings were made from the manufactured measuring strips of a given thickness, width and length, the formation of which was carried out according to the traditional technology, which consists in connecting the measuring strips 1 with the given parameters along the length and width in pairs between each other with welds 2 , in the step "b / 2" offset of the welds when connecting the strip of the previous pair with the adjacent strip of the next formed pair, where "b" the distance between the welds 2 of each formed pair n olos.

As a result of the implementation of this technological process, geocell gratings were obtained on the basis of packages of parallel measuring and measuring radiation bands 1, identical in length and width, due to electron beam radiation, with a thickness of 1.0 and 1.1 (mm), based on sheet polyethylene with a density of 0.940 ( g / cm ³⁾ adjacent the package band are interconnected along their length in a staggered transversely oriented to the longitudinal axes of strips of predetermined width weld seams 2 to form a packet when stretching in the direction of holes cial dimensional surface to bands of hollow cells geosotovoy spatial structure (see. Fig. 2). When forming packages of geocell gratings, measuring strips with a width of 50-300 (mm) are used.

The geocell gratings made during the implementation of the invention with a thickness of measuring strips of 1.0 and 1.1 (mm), a band width of 50-300 (mm) and control samples of geocell gratings were evaluated by physicomechanical indicators characterizing their operational reliability.

As control samples used:

sample No. 1 - geocell gratings, the packets of which are formed from measuring strips with a thickness of 1.0 and 1.1 (mm), a width of 50-300 (mm) and which are made of the original non-radiation modified sheet polyethylene with a density of 0.940 (g / cm ³ );

samples No. 2-6 - geocell gratings, the packets of which are formed from measuring strips with a thickness of 1.3-2.0 (mm), a width of 50-300 (mm) and which are made of the original non-radiation modified sheet polyethylene with a density of 0.940 (g / cm ³ ).

Physico-mechanical properties of the investigated control samples of geocell gratings and geocells obtained during the implementation of the invention are shown in the following table 1.

The physical and mechanical indicators presented in Table 1 confirm that the main estimated indicators of the operational reliability of geocell gratings are:

tensile stress of dimensional polymer strips intended for the manufacture of these grids, as well as shear and tensile strength of welds.

The physical and mechanical characteristics of the test samples of geocell gratings and geocells obtained during the implementation of the invention show that the manufacture of geocell gratings from radiation-modified electron beam radiation measuring bands based on sheet polyethylene with a density of 0.910-0.965 (g / cm ³ ) with a thickness of 0.8- 1.1 (mm) their tensile strength on average increases by 30% relative to the initial polyethylene sheet at the specified density and thickness parameters and is practically comparable with the parameters strength to tensile stresses and strength parameters for the welds starting polyethylene sheet of thickness 1.3-2.0 (mm) conventionally used for the manufacture geosotovyh gratings.

Thus, the use of radiation-modified electron-beam radiation of sheet polyethylene of a given density ensured the creation according to the invention of a geocell grating of high operational reliability with a thickness of its measured strips of 0.8-1.1 (mm), which allowed to expand the technological capabilities of industrial sheet polyethylene with standard size near a small thickness and which is especially true for such parameters of their operation as weight and transportability.

Claims (4)

1. A method of manufacturing a polymer geocell grid, which consists in the manufacture of measuring strips from a modified polyethylene material, in connecting measuring strips with specified parameters in length and width in pairs between each other with welds, in the step offset of the welds when connecting the strip of the previous pair with the adjacent strip of the next formed pairs, in the formation of a package of parallel arranged measuring strips of a geocell grating, characterized in that the measuring strips are made of modified polyethylene material vayut polyethylene sheet 0.8-1.1 mm and a density of 0,910-0,965 g / cm ^3, which is modified by electron-beam radiation at a power of 0.7-0.9 MeV emission current 45-80 mA and a specific processing speed 0,077 -0.1 m / (min⋅mA). 2. The method according to p. 1, characterized in that the measuring strips are welded using ultrasonic welding at an ultrasound frequency of 18-30 kHz, the welding time is 1.0-3.0 s, the pressure retention time is 0.1-2, 0 s, delay time - 0.5-1.5 s. 3. A polymer geocell grating containing a packet of parallel measuring strips identical in length and width based on polyethylene sheet, adjacent strips stitched together along their length in a checkerboard pattern with welds transversely oriented to the longitudinal axis of the strips to form welds when stretching the packet in the direction normal to the surface of the measuring strips of the hollow cells of the geocell spatial structure, characterized in that they use measuring strips with a thickness of 0.8-1.1 mm, radiation modified with radiation and having strength at tensile stresses of 18-19 kN / m. 4. The polymer geocell grid according to claim 3, characterized in that the width of the measuring strips is 50-300 mm.

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