RU2459040C9 - Innovative spatially polymer grid (versions) - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: innovative spatially polymer grid (ISPG) is designed to reinforce building structures and to strengthen weak bases of industrial and civil structures, as well as slopes of coastal lines and water reservoir beds. ISPG may find application when erecting aerodromes, road surfaces, strengthening slopes, arranging retaining walls and in other versions of usage in oil and gas, transport, hydraulic engineering sectors of construction, which require high and stable strength and durability indices of erected structures. A spatially polymer grid (SPG) with a cellular structure for stabilisation and reinforcement of soil surface, arranged from flexible strips, preferably from a low pressure polyethylene, arranged in several rows and joined to each other in a staggered order along the length of strips with the possibility to form a cellular structure as strips are stretched in a direction normal to their surface, and such structure will differ by the fact that strips are equipped with drain holes in the form of extended rectangles with semicircumferences on short sides, and besides, the strips are reinforced in a longitudinal direction by aramid or carbon threads at the following ratio of components in wt %: Aramide or carbon thread - 0.2-3, Low pressure polyethylene - balance.

EFFECT: higher bearing capacity and stability of geometric parameters of the structure, no deformation in soil structures reinforced with a ISPG, higher strength and increased service life of erected structures, higher drainage capacity of SPG, reduced cost of a spatially polymer grid, approximately.

18 cl, 6 dwg

Description

The invention relates to the field of construction. The innovative spatial polymer lattice (IPPR) is designed to reinforce building structures and strengthen the weak foundations of industrial and civil structures, as well as slopes of coastlines and channels of water bodies. The claimed innovative spatial polymer lattice can be used in the construction of airfields, pavements, in strengthening slopes, in the construction of retaining walls, and in many other applications in the oil and gas, transport, and hydraulic engineering industries, which require high and stable strength and durability of constructed structures.

Various devices are known from the prior art (see patent RU 2129189, published on 04/20/1999, patent RU 2358063, published on 10.06.2009 and patent RU 2152480, published on 10.07.2000), in which spatial polymer gratings (SPR) are used to fix the surface slope ), in particular the so-called "geogrids". NDPs are made of flexible and durable polymer tapes, cutting the tapes into measuring strips and stitching them together in a checkerboard pattern with transverse seams, obtain cellular structures that can fix and hold soil masses loaded into the cells from displacement. The material for the manufacture of these tapes, as a rule, is polyethylene of various grades. Tapes and strips made of polyethylene are flexible, durable, resistant to adverse environmental factors. However, polyethylene refers to thermoplastic materials, 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 geogrid and the corresponding movement of the soil layer. To address the aforementioned disadvantage of PPR, made mainly of polyethylene, the claimed invention is directed.

The prior art knows a technical solution that partially overcomes this problem. On the website of PRS - Professional Reinforcement Solutions in 2009, information was posted on the NEOLOY geocomposite material for the manufacture of geogrids, such as: NEOWEB. This type of geogrid is made of tapes based on a polymeric material, the matrix of which is made of polyolefins (including polyethylene) and reinforced with nanofibers, in particular discrete fibers made of polyester or polyamide (see http: //www.prs-med. com / content.aspx? page = 5).

Reinforcing the polymer matrix with discrete fibers increases the thermal stability of the material, however, it does not completely solve the above problem, since discrete reinforcing nanofibres strengthen the matrix locally. Individual fibers are interconnected along the length of the material only by the strength of the polymer matrix, which retains thermoplastic properties and remains susceptible to inelastic stretching in the longitudinal direction when changing the temperature conditions of operation under load.

The specified material is selected as the closest analogue of the claimed invention.

The claimed invention is aimed at solving the problem of increasing the strength and stability of the geometric parameters of the design of the PPR during operation under load when changing temperature conditions.

The technical result of the invention is to increase the bearing capacity of the PPR tape, weakened by the implementation of drainage holes, and to exclude deformation of the reinforced soil structures, as well as to increase the strength and increase the service life of the structures being erected.

Another technical result of the invention is to ensure the stability of the geometric parameters of the strip and the design of the PPR as a whole, weakened by the implementation of drainage holes.

An additional technical result of the claimed invention is a significant increase in the drainage ability of the claimed PPR, since the reinforcement allows you to change the shape and increase the size of the perforation of the lattice elements.

In addition, the claimed innovative PPR opens up the possibility of its application in new areas that require increased strength and stability of structures, for example, in the ballast layer of an embankment of railways, in airfield coatings, during the construction of protective military structures, etc.

To achieve the technical result, a spatial polymer lattice (PPR) with a cellular structure for stabilizing and fixing the soil surface is proposed, made of flexible strips, mainly of low pressure polyethylene, arranged in several rows and stitched together in a checkerboard pattern along the length of the strips with the possibility the formation of tensile strips in the direction normal to their surface, a cellular structure, characterized in that the strips are provided with drainage holes in the form of elongated mentioned rectangles with semicircles on the short sides and, moreover, the strips are reinforced in longitudinal direction with aramid or carbon fibers, with the following component ratio, wt.%:

Aramid or carbon thread 0.2-3, Low-pressure polyethylene Rest

In addition, the claimed device suggests the possibility of using strips containing a reinforcing mesh. In this case, the transverse direction does not need reinforcing, and the transverse threads of the mesh perform auxiliary functions to ensure the uniformity of the introduction of longitudinal reinforcing threads into the polymer base. Transverse threads, even if they are in the strip material, are cut during the formation of longitudinal drainage holes, so they do not bear a reinforcing load.

The advantage of the claimed SPR over geogrids reinforced with discrete fibers is that the introduction of continuous fibers in the form of reinforcing threads into the polymer material, namely the polyethylene matrix of the bands, allows the load to be completely transferred from the matrix material to the material of continuous heavy-duty aramid or carbon fibers, having a very high modulus of elasticity, which eliminates the inelastic tension of the obtained SPR under load when changing the temperature conditions of operation.

Longitudinal reinforcement of tapes with continuous aramid or carbon filaments can ultimately reduce the cost of SPR, since it allows to reduce the thickness of the polymer tape and reduce the polymer consumption for its manufacture. The economic result consists in reducing the cost of PPR by approximately 20%.

When forming the SPR, the strips were installed on the ribs and welded and / or stitched together in a checkerboard pattern along the length of the strips with the possibility of forming, when stretched strips in the direction normal to the surface of the strips, a mesh structure. In this case, the welds can be made both at an angle and vertically with respect to the edges of the strips.

In a preferred embodiment, the claimed PPR contains strips based on low-pressure polyethylene, while ultra-high modulus (CBM) fibers, in particular Kevlar fibers, are used as aramid fibers for reinforcing the strips.

In another embodiment, when reinforcing the lattice with carbon fibers, high-strength yarns of the Carbon brand are used as threads for reinforcing strips.

The spatial polymer lattice is characterized in that the flexible strips forming a lattice arranged in several rows are interconnected by welding, in particular by heat welding, while the welds obtained by welding can additionally be reinforced with reinforcement. The simplest option for reinforcing a seam connecting adjacent strips to each other is to reinforce them with a textile seam from any polymer filaments, preferably from high-strength filaments, for example, from aramid filaments. The textile seam can be made of carbon filaments.

The presence of reinforcement so strengthens the polymer base of the geogrid that it allows you to change shape and increase drainage holes.

Reinforcement also allows to reduce the thickness of the tape, which leads to polymer savings and, as a consequence, to reduce the cost of the spatial polymer lattice by approximately 20%, while the strength and other mechanical characteristics of the spatial polymer lattice are preserved.

In accordance with the claimed invention, the drainage holes are made in the form of elongated rectangles with semicircles on the short sides, with a ratio of short and long sides corresponding to the coefficient K, where K = (0.05 ÷ 0.4).

The formula shows the limiting values of K. Thus, at a value of K = 0.05, a section is practically obtained, which causes an undesirable stress concentration at the ends of the section, and the degree of perforation in unstretched form will be less than 1%, which is not enough for drainage functions.

With the value of the coefficient K = 1, the shape of the hole corresponds to a circle and there is no desired effect of deviation of the sides of the rectangles in different directions. The indicated effect can occur only with their large elongation of the drainage hole, i.e. with a value of K less than 0.4.

Empirically it has been established that the ratio of the short and long sides of the drainage hole preferably corresponds to K = (0.13 ÷ 0.23).

The spatial polymer lattice may contain drainage holes arranged in rows, and in one row, the long sides of the rectangles are parallel to the long side of the strip. In this case, the drainage holes of adjacent rows are placed under each other with the formation of columns. Thus, the drainage structure of the lattice is optimally formed when the drainage holes are placed in groups consisting of the same number of rows (rows) and columns.

The claimed SPR is characterized by the fact that in the extended state, when the cells are filled with soil, the long sides of the drainage holes due to the uneven pressure of crushed stone on the walls are able to deviate in different directions from the surface of the strip or tape, thereby increasing the area of the holes and the drainage capacity of the grate to 2 times, while counteracting the movement of the grating in the direction perpendicular to the soil surface.

The spatial polymer lattice corresponding to the claimed invention has an advantage over a geogrid - a prototype made of NEOLOY material, since it is reinforced in the longitudinal direction not by discrete, but by continuous aramid or carbon filaments (the reinforcement step is 1-5 mm).

Tests of an Israeli-made NEOLOY geogrid sample showed the following results. A short-term test of the strength indices was performed on samples of a tape made of NEOLOY material and samples of a geogrid from the specified tape for weld strength. With a tape width of 150 mm, a thickness of 1.33-1.55 mm and perforation with drainage holes with a diameter of 10 mm in increments of 150-167 mm, the average tensile strength of the tape was 2.4 kN (perforation gap). The average tensile strength of the weld for a geogrid of NEOLOY material was 1.79 kN. Short-term tests showed an increased level of strength properties. However, long-term tests of the NEOLOY geogrid showed an unsatisfactory level of weld strength. The tests were carried out by suspending geolattice samples from NEOLOY material under a load of 72 kg for a period of 30 days. During this test, two of the three samples sag under load until less than 1 day was destroyed. Thus, the closest analogue of the claimed invention does not withstand a long-term normative test for the strength of a weld.

In accordance with the claimed invention, reinforcing threads can be introduced into the composition of polymer strips by various methods.

In the event that the reinforcing yarns are introduced into the polyethylene strips of the claimed lattice in the form of a net, reinforcing yarns intended for longitudinal reinforcing of the strip are placed as the basis of the net, and auxiliary threads are set as the weft of the net, setting the reinforcement step.

The invention is illustrated by drawings 1-6 and examples.

The figure 1 shows a fragment of a strip intended for the manufacture of the claimed SPR.

Figure 2 shows a cross-section of the strip shown in figure 1, for a variant with one-sided placement of reinforcing threads.

Figure 3 shows, on an enlarged scale, a fragment of the cross section of the strip shown in Figure 2.

Figure 4 shows a cross-section of a strip for a version with double-sided placement of reinforcing threads.

Figure 5 shows, on an enlarged scale, a fragment of the cross section of the strip shown in Figure 4.

The figure 6 shows the claimed innovative spatial polymer lattice.

The figure 1 shows a preferred embodiment of the manufacture of a polymer strip 1 containing reinforcing and drainage holes, intended for the manufacture of the claimed SPR. A flexible polymer strip 1, intended for the production of SPR, contains in the longitudinal direction reinforcing threads 2, for example aramid threads or threads of carbon fibers. In this case, the polymer strip is made perforated, has a thickness of 1-2 mm, and also has a texture on the outer surface, which is characterized by the presence of protrusions 3 with a height of 0.2-0.4 mm. The polymer strip 1 for the manufacture of the claimed PPR contains a matrix based on polyethylene 4. The specified polyethylene matrix 4 is reinforced in the longitudinal direction, for example, with aramid thread 2 with a reinforcement pitch h, while h = 1 ÷ 5 mm.

When this strip is reinforced in the longitudinal direction by aramid or carbon fibers in the following ratio of components, wt.%:

Aramid or carbon thread 0.2-3, Low-pressure polyethylene Rest

The polymer strip 1 contains through drainage holes 5 (perforation), which are located between the reinforcing threads 2 and are made of elongated shape, elongated along the direction of reinforcement. That is, the drainage holes 5 are made in the form of elongated rectangles with semicircles of radius R on the short sides, while the height of the rectangle is 2R. These holes 5 are oriented by the long sides L parallel to the edges of the strip and the reinforcing threads 2.

As shown in figures 2-3, the reinforcing threads 2 can be located near one side surface of the strip, and preferably placed in the recesses between adjacent texture projections 3. In another embodiment, shown in figures 4-5, the reinforcing threads 2 are located near both side surfaces stripes, and also placed in the recesses between the texture ledges 3.

The figure 6 shows a General view of a stretched SPR in axonometric projection. The strips 1 forming the PPR are placed on the ribs and interconnected by seams 6 of increased strength.

Example 1

A spatial polymer lattice (PPR) was made with a cellular structure designed to stabilize and fix the soil surface, which was made of flexible strips according to the claimed invention. The strip was reinforced in the longitudinal direction with an aramid thread with a diameter of 0.05 mm in the following ratio of components (in wt.%): Aramid CBM thread 0.2 wt.%, Low-pressure polyethylene - the rest. The polymer strip was made 1.27 mm thick. The strip had a texture on the outer surface with a height of protrusions of 0.3 mm. The reinforced strip was made by extrusion technology, while the reinforcing thread was tucked into the molten mass of low-pressure polyethylene immediately after the strip exited the extrusion head and before it entered the first pair of forming rolls. The reinforcement pitch was chosen 5 mm. The reinforcement step was set using a metal comb through which the threads were passed before entering the polymer strip.

The drainage holes were made in the form of elongated rectangles with a length of L = 20 mm (rectangle length) with semicircles on the short sides at R = 1.5 mm, with a ratio of short and long sides corresponding to the coefficient K.

In this case, K = 2 · R / (L + 2 · R) = 2 · 1.5 / (20 + 2 · 1.5) = 0.13, and the degree of perforation is 6%. The resulting tape was cut into measuring strips for the manufacture of PPR of a given size.

When forming the SPR, the strips were mounted on the ribs and welded together using heat welding in a checkerboard pattern along the length of the strips with the possibility of forming, when stretched, the strips in the direction normal to the surface of the strips, a cellular structure. In this case, the welds are made vertically with respect to the edges of the strips.

Test PPR showed an increase in all indicators of strength compared with the prototype. Long-term tests of the declared PPR showed a high level of strength of the weld. The tests were carried out by hanging samples of PPR from the claimed material under a load of 72 kg for a period of 30 days. During this test, all samples sag under load without breaking the specified period of 30 days. Thus, the PPR, corresponding to the claimed invention, withstands the normative long-term test for the strength of the weld.

In addition, the strips from which the PPR was made showed an elastic break, practically without elongation.

The data obtained during the tests confirm that the technical result of the claimed invention is achieved by increasing the strength and stability of the geometric parameters of the PPR design, since the reinforced polymer strips do not deform in the ground under the influence of temperature changes under load.

Example 2

A spatial polymer lattice (PPR) was produced analogously to Example 1. The PPR was made with a cellular structure made of flexible strips reinforced in the longitudinal direction with an aramid thread with a diameter of 0.2 mm in the following ratio of components (in wt.%): Aramid CBM thread 3.0 wt.%, low pressure polyethylene - the rest. The polymer strip is made perforated, while it has a thickness of 1.8 mm, and also has a texture on the outer surface, which is characterized by the presence of protrusions 0.4 mm high. The strip was made by extrusion technology, while the reinforcing thread was tucked into the molten mass of low-pressure polyethylene after exiting the extrusion head before entering the first pair of forming rolls. The reinforcement pitch was selected 2 mm. The reinforcement step was set using a prefabricated mesh, which was introduced into the polymer strip. To do this, the reinforcing aramid yarns were placed as the basis of the mesh, and auxiliary nylon, polyethylene or polyester yarns were used as the weft, only to ensure a given reinforcement step.

The drainage holes were made in the form of elongated rectangles with a length of L = 20 mm (rectangle length) with semicircles on the short sides at R = 3 mm.

In this case, K = 2 · R / (L + 2 · R) = 2 · 3 / (20 + 2 · 3) = 0.23, and the degree of perforation was 12.6%.

Obtained by extrusion, the tape was cut into measuring strips for the manufacture of PPR of a given size. When forming the SPR, the bands were mounted on the ribs and first welded using ultrasonic welding, and then additionally sewn with aramid thread between each other along the lines of the welds (in another embodiment, the welded and textile seams were arranged in parallel at a distance of 5 mm) in a checkerboard pattern with the possibility of stretching the strips in the direction normal to the surface of the strips of the cellular structure. In this case, the seams are made at an angle with respect to the edges of the strips.

Tests conducted, as in example 1, showed that the PPR with reinforced seams has an even higher long-term strength in comparison with the prototype.

Claims (18)

1. Spatial polymer lattice (PPR) with a cellular structure for stabilization and fixing of the soil surface, made of flexible strips, mainly of low-pressure polyethylene, arranged in several rows and stitched together in a checkerboard pattern along the length of the strips with the possibility of formation of stretched strips in the direction normal to their surface, of a cellular structure, characterized in that the strips are provided with drainage holes in the form of elongated rectangles with semicircles on short sides ah and, in addition, the strips are reinforced in the longitudinal direction by aramid or carbon fibers in the following ratio of components, wt.%:
Aramid or carbon thread 0.2-3 Low-pressure polyethylene Rest 2. The spatial polymer lattice according to claim 1, characterized in that the strip for the formation of the lattice is made of low pressure polyethylene. 3. The spatial polymer lattice according to claim 1, characterized in that it is longitudinally reinforced with continuous aramid or carbon filaments with a reinforcement pitch of 1-5 mm. 4. The spatial polymer lattice according to claim 1, characterized in that ultra-high modulus (CBM) filaments, in particular Kevlar brand filaments, are used as aramid filaments for reinforcing strips. 5. The spatial polymer lattice according to claim 1, characterized in that high-strength carbon brand yarns are used as carbon threads for reinforcing strips. 6. The spatial polymer lattice according to claim 1, characterized in that the flexible strips forming the lattice arranged in several rows are connected by welding. 7. The spatial polymer lattice according to claim 6, characterized in that the welds obtained by welding are further strengthened by reinforcement. 8. The spatial polymer lattice according to claim 7, characterized in that the seams obtained by welding are reinforced with a textile seam. 9. The spatial polymer lattice of claim 8, characterized in that the textile seams are made using aramid or carbon threads. 10. The spatial polymer lattice according to claim 1, characterized in that the strips forming the lattice are provided with drainage holes located between the reinforcing threads. 11. The spatial polymer lattice according to claim 10, characterized in that the drainage holes are made in the form of elongated rectangles with semicircles on the short sides, with the ratio of short and long sides corresponding to the coefficient K, where K = (0.05 ÷ 0.4) . 12. The spatial polymer lattice according to claim 11, characterized in that the ratio of short and long sides of the drainage hole mainly corresponds to K = (0.13 ÷ 0.23). 13. The spatial polymer lattice of claim 10, characterized in that the drainage holes are arranged in rows, and in one row the long sides of the rectangles are parallel to the long side of the strip. 14. The spatial polymer lattice of claim 10, characterized in that the drainage holes of adjacent rows are placed under each other with the formation of columns. 15. The spatial polymer lattice of claim 10, characterized in that the drainage holes are placed in groups consisting of the same number of rows (rows) and columns. 16. The spatial polymer lattice of claim 10, characterized in that in the stretched and filled state, the long sides of the drainage holes are configured to deviate in different directions from the surface of the strip, thereby increasing the area of the holes and their drainage ability. 17. The spatial polymer lattice according to claim 1, characterized in that it is longitudinally reinforced with continuous aramid or carbon fibers with a reinforcement step of 1-5 mm. 18. The spatial polymer lattice according to claim 1, characterized in that the reinforcing threads are inserted into polyethylene strips in the form of a grid, in which reinforcing threads for longitudinal reinforcement are located as a base, and auxiliary polymer threads are located as a weft, establishing a reinforcement step .

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