RU2652411C1 - Geogrid for pavement reinforcement - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the field of transport construction, namely, reinforcing interlayers in the form of geogrids, designed to improve the durability of pavement. Geogrids for reinforcement of pavement is a configuration of cells formed by crossing the edges. Configuration of the cells forms a regular hexagon, a triangle or a square with an edge of triangular shape and is located at the base of the pavement, in asphalt concrete pavement or on the boundary of the base layer and asphalt pavement.

EFFECT: technical result consists in greater shear stability and area of contact with the particles of the reinforced layer provision, increasing in the strength parameters of the geogrid.

1 cl, 16 dwg

Description

The invention relates to the field of transport construction, namely to reinforcing layers in the form of geogrids, designed to increase the durability of pavement.

The invention can be used as a reinforcing layer in the construction of pavement in the construction, reconstruction and repair of roads, airfields, sites for various purposes, subjected to high and intense traffic loads.

The prior art analogues are known for strengthening structural layers of pavement in the form of a flat mesh structure made of fiberglass or polymeric materials (RU 2166019, 04/27/2001, RU 134952, 03.03.2013, RU 2124089, 12/27/1998).

The flat design of the analogues leads to insufficient reinforcing function of the structural layers at the location of the geogrid. Analogs themselves do not work well in bending. Geogrids made of fiberglass are characterized by high damage in the process of distribution and compaction of mineral aggregate. Decrease in adhesion properties between coating layers. Due to the flat structure when placing the geogrid on the border of dense heterogeneous materials, in particular between the layers of asphalt concrete, the spell occurs only in the irregularities of the underlying layer, in the rest of the mixture lies on the grid and is held back from being displaced mainly by the adhesion force to the underlying layer.

The patent (RU 2581176, 04.17.2015) describes an extruded geogrid used as a reinforcing and separating layer in the subgrade structures of linear transport and geotechnical structures. The disadvantage of this technical solution is the high damage to the ribs due to their small thickness. The triangular cell has sharp angles, getting large mineral particles into them is difficult, which leads to the formation of voids.

The closest technical solution is the grill RU 102015, 11/25/2009 with the possibility of layout in a roll containing orthogonally intersecting strands of extruded oriented polyolefin material with the formation of windows and nodes with thickenings at the intersection of the strands.

A disadvantage of the known technical solution is the weak nodal connection, which is destroyed in the process of compaction of the reinforced layer as a result of falling into the node of an acute-angled peak of mineral aggregate.

When using this type of geogrid in asphalt concrete, nodal thickenings and loose fit of the ribs to the surface will prevent the cells from completely filling the mixture, which will lead to the formation of voids in the thickness of the asphalt concrete pavement and a decrease in the strength of the road structure.

The objective of the invention is to improve the properties of the lattice for use as a reinforcing layer in the base of pavement and as a reinforcing and cracking in an asphalt concrete coating by reducing surface damage, increasing its strength characteristics, shear resistance, maximally preserving the initial geometric shape of the geogrid (cell shape and ribs) by giving the rib a triangular shape and selecting the thickness of the rib, the shape and size of the cell, depending on the specific conditions.

The technical result of the invention is achieved due to the following distinctive features: the ribs of the lattice of a triangular cross section, with the vertex directed into the reinforced layer, when crossing at the nodes of the ribs form a triangular pyramid.

Due to the hexagonal shape of the cell and the triangular shape of the cross section of the rib, the most complete occupancy of the cells is achieved, which contributes to the formation of a denser layer and a decrease in the number of voids.

When used in asphalt concrete pavement, the large hexagonal shape of the cell provides a large contact area between the lower and reinforced layers, thereby increasing the adhesion between them. The geogrid itself can be coated with a substance having a chemical affinity for bitumen to ensure the best adhesion of the geogrid to the asphalt mix.

The shape of the cell can also be square and triangular.

Due to the volumetric structure and the triangular cross section of the rib, the lattice has greater shear stability and contact area with particles of the reinforced layer than the flat cross section of the rib, the geogrid and the reinforced layer form a single system. As a result, tensile stresses arising in asphalt concrete are perceived by the reinforcing grating and are evenly distributed on the underlying layers.

The triangular cross section of the ribs reduces their damage, contributes to the best distribution of aggregate particles. Ribs with a triangular cross-section are less flexible in comparison with rectangular or flat ribs. In addition, in the zone of occurrence of maximum tensile stress in the grating, the rib has the greatest thickness. The volumetric structure of the geogrid ensures its implementation in the reinforced layer, due to which the joint work of the structure is achieved.

This shape of the cross section of the rib provides free movement of construction equipment, since the contact area of the geogrid with the wheels of vehicles is minimal, which eliminates the possibility of creases, and when laying in asphalt concrete pavement, creases and adhesion to the wheels. The ribs have quite sharp edges, so gloves must be used to avoid injury when working with the grill.

The connection of the three edges in the node forms a triangular pyramid (quadrangular, in the case of a square cell), which protects the lattice node from being split by mineral aggregate particles. Particles, falling into the node with an acute angle, slide along inclined faces into the cell.

Geogrids with insufficient rigidity do not provide the required strength of the reinforcing layer. The cross section of the geogrid rib can be made of different thicknesses, but its thickness must be proportional to the size of the cell to ensure its rigidity.

The essence of the utility model is illustrated by illustrations.

In FIG. 1 shows a general view of a geogrid in a roll.

In FIG. 2 is a general view of a geogrid map.

In FIG. 3 is a view A of a fragment of the geogrid of FIG. one.

In FIG. 4 is a section through the ribs of FIG. 3.

In FIG. 5 is a view B of a fragment of the geogrid of FIG. 2.

In FIG. 6 is a view G of a fragment of the geogrid of FIG. 2.

In FIG. 7 is a section through the ribs of FIG. 5.

In FIG. 8 is a section through the ribs of FIG. 6.

In FIG. 9 is a fragment of a geogrid with a square cell.

In FIG. 10, FIG. 11 is a general view of the connection elements for cards with a square cell.

In FIG. 12 is a fragment of a geogrid with a triangular cell.

In FIG. 13, FIG. 14 is a general view of the connection elements for cards with a triangular cell.

In FIG. 15 is a general diagram of an example of using a grill in a road surface.

In FIG. 16 is a general diagram of an example of using a grill in a road base.

The reinforcing lattice is twisted into rolls 2 (Fig. 1) or is made in the form of cards 3 (Fig. 2). Recommended sizes of geogrid twisted into rolls: length L up to 100 meters, width B up to 7.5 meters. Recommended card sizes: length L1 is 4 meters, width B1 is 7.5 meters.

The intersecting edges 4 (Fig. 3) form cells 5 in the shape of a regular hexagon and nodes 6 in the shape of a triangular pyramid. The cross section of the ribs (Fig. 4) is made in the form of an equilateral or isosceles triangle and is characterized by the height of the cross section of the ribs h, equal to 3 ... 35 mm, while the side of the equilateral triangle a will be 1.155h.

To provide the necessary rigidity of the lattice and a contact spot between the layers sufficient for good adhesion, the cell size b is recommended to be taken in the range from 10 to 100 times the height of the cross section of the rib h. For a hexagonal cell, b is the radius of the inscribed circle (Fig. 3).

The intersecting edges 4 (Fig. 9) form cells 5 in the form of a square and nodes 6 in the form of a square pyramid. The cross section of the ribs (Fig. 4) is made in the form of an equilateral or isosceles triangle and is characterized by the height of the cross section of the ribs h, equal to 3 ... 35 mm, while the side of the equilateral triangle a will be 1.155h.

To provide the necessary rigidity of the lattice and a contact spot between the layers sufficient for good adhesion, the cell size b is recommended to be taken in the range from 10 to 100 times the height of the cross section of the rib h. For a square cell, b is the distance between the inner edges of the ribs (Fig. 9).

The intersecting ribs 4 (FIG. 12) form cells 5 in the shape of a triangle and nodes 6 in the shape of a hexagonal pyramid. The cross section of the ribs (Fig. 4) is made in the form of an equilateral or isosceles triangle and is characterized by the height of the cross section of the ribs h, equal to 3 ... 35 mm, while the side of the equilateral triangle a will be 1.155h.

To provide the necessary rigidity of the lattice and a contact spot between the layers sufficient for good adhesion, the cell size b is recommended to be taken in the range from 10 to 100 times the height of the cross section of the rib h. For a triangular cell, b is the radius of the inscribed circle (Fig. 12).

The height of the cross section of the rib h, equal to 3 ... 5 mm, allows you to twist the lattice into rolls, without stretching and deformation of its elements. When the height of the cross section of the ribs h is equal to 6 ... 35 mm, the geogrid is made in the form of separate cards, interconnected by overlaying the edges of the extreme cells on top of each other.

To connect the cards to each other, the cross section of the edges of the extreme cells is half made on one side in the form of 1 / 3h of the lower part of the triangle (Fig. 5, Fig. 10, Fig. 13) with through holes 7 in the middle of each rib, on the opposite side in 2 / 3h view of the upper part of the triangle (Fig. 6, Fig. 11, Fig. 14) with a spike 8 in the middle of each rib. The diameters of the hole and the spike d should provide strong adhesion and at the same time not reduce the strength of the ribs, their diameter is recommended to be taken equal to d = 2/9 a = 0.257h (Fig. 7, Fig. 8). The length of the spike corresponds to the height of the lower part and is 1 / 3h.

As a result of the coupling of two cards at the junction, the ribs form a cross section in the form of a whole triangle.

If it is impossible to connect during the work due to the mismatch of the holes with the spikes, breaking of the spikes, etc., as well as with poor adhesion, the cards can be connected using clamps or wire.

The grill can be used as a reinforcing layer and a crack-breaking layer in the road surface. In FIG. Figure 15 shows an example of the use of a grill as a reinforcing and crack-breaking layer in asphalt concrete pavement during the construction of a highway of the highest technical category.

A base layer of sand 10, a base layer of crushed stone 11 are laid on a soil foundation 9. A reinforcing geogrid is laid on a rubble layer 1. The geogrid is fixed to the crushed stone base with anchors and the upper or lower and upper or lower, middle and upper layers of asphalt concrete are laid on it (12, 13).

When reinforcing asphalt concrete pavement, the lattice can also be placed between the layers of asphalt concrete pavement, but the maximum reinforcing effect will be achieved when it is placed on the boundary of the layers of crushed stone or asphalt concrete - in the place of concentration of the highest tensile stresses.

When laying the geogrid at the border of the layers of crushed stone and asphalt concrete, preparatory work is being done on laying the crushed stone base. To begin work on laying the geogrid, the crushed stone base must be smooth, dense, and have good shear stability. Lattice delivery to the site is carried out after preparatory work.

The geogrid is laid in the longitudinal direction, exactly, without distortions, by a link of two-person workers (the number of workers can be increased if necessary). When laying, the formation of distortions, waves, etc.

In FIG. 16 shows an example of the use of the grill as a reinforcing layer in the base during the construction of a highway of higher technical categories.

A base layer of sand 10 is laid on the soil base 9. A reinforcing geogrid is laid on the sand layer 1. The geogrid is fixed on the sand base with anchors and a base layer of crushed stone is laid on it 11. Upper or lower and upper or lower, middle and upper layers of asphalt concrete (12, 13).

The reinforcing effect of the lattice in the structure is achieved by increasing the thickness of the cross section of the ribs, as a result of which the stiffness of the cells and the entire lattice as a whole increases, which reduces damage, increases its service life and perceived stresses. In the case of using a hexagonal shape of cells with a triangular cross-sectional shape of the rib, a more uniform distribution of the aggregate occurs and the most complete cell interlock is ensured, which leads to a decrease in the number of voids. Due to the volumetric structure, the lattice penetrates into the reinforced layer, providing good adhesion and reliably holding the aggregate from displacement at the boundary of the layers, thereby slowing the rutting process. A large contact patch provides good adhesion of the reinforced layer to the underlying layer.

Thus, the reinforcing grating is part of a single system, while it perceives all tensile stresses and evenly distributes them to the underlying layers, thereby preventing the propagation of cracks and extending the service life of the asphalt concrete pavement.

It should be noted that the claimed invention is not limited to the implementation options described in the description. Any further refinements of the invention are also possible without departing from the scope of the proposed combination of essential features.

Claims (2)

1. A geogrid for reinforcing pavement, which is a configuration of cells formed by the intersection of ribs, characterized in that the configuration of the cells forms a regular hexagon, triangle or square with a triangular rib and is located at the base of the pavement, in asphalt concrete pavement or on the border of the base layer and asphalt concrete pavement. 2. The geogrid according to claim 1, characterized in that it can be coated with a substance that enhances adhesion.

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