RU2322543C1 - Geocomposite interlayer for roadbed of motor road - Google Patents

Abstract

FIELD: road building.

SUBSTANCE: proposed geocomposite interlayer for roadbed of motor road features stable draining and capillary breaking properties and watertightness over lower plane. It provides nonwettability of soil and reliable removal of water to slopes of road-bed at provision of designed cross gradient in interlayer. Invention makes it possible to use proposed geocomposite interlayer instead of sand draining layer, thickness up to 40 cm, and provide required optimum moisture content in working layer of roadbed. Novelty is that geogrid is provided with geocloth from top and bottom and additional watertight film is placed between lower plane of geogrid and lower layer of geocloth. Geogrid has three-level structure of arrangement of component members forming cells in geogrid of size preventing coupling of upper and lower layers of geocloth. Members of middle level of structure of geogrid have section height exceeding section height of members of lower and upper levels of geogrid.

EFFECT: improved quality of roadbed.

2 cl, 3 dwg

Description

The present invention relates to structural elements of a transport structure and, in particular, to interlayers in the subgrade of roads and railways. It can also find application in the construction of airfields and in the construction of industrial and civil facilities.

Known geocomposite layer having reinforcing and capillary-breaking properties and used in the construction of roads. This well-known geocomposite interlayer is formed of a geogrid and one layer of geotissue attached to one of the surfaces of the geogrid. At the same time, the geogrid itself has a two-level structure of the arrangement of elements (bands, strings, fibers) that form rectangular cells in the geogrid with dimensions of the order of 30 × 30 mm.

Such a geocomposite layer for the roadbed subgrade has a significant drawback: it does not have high drainage properties and does not provide regulation of the moisture conditions of the roadbed, which limits its scope in road construction.

Known geocomposite layer for the subgrade of the road in the form of a drainage mat "Slavros". This layer has both capillary interrupting and draining properties. It is formed from a geogrid and two layers of geo-fabric fixed on its upper and lower planes. In this layer, the geogrid is made of synthetic strips, strings or fibers placed at certain distances from each other, with longitudinal and transverse orientations relative to the axis of the road. At all intersection points, these strips, strings or fibers are located at two levels and are bonded to each other with the formation of one-piece nodes. The bands, strings or fibers of the geogrid are made of the same material, have equal cross-sectional sizes and form rectangular cells in the geocomposite structure with dimensions in the order of 30 × 30 mm. The upper and lower layers of the geotissue are given a high filtering ability, as a result of which the geocomposite layer is called “drainage mat”. At the same time, this design also has the ability to interrupt the capillaries formed in the soil of the subgrade, which reduces the degree of moisture in the soil of the working layer of the subgrade with a high groundwater horizon.

This well-known technical solution is selected as a prototype, as it is aimed at solving the problem that the claimed invention solves, and has the greatest number of common essential features with it.

The prototype has significant disadvantages. Firstly, during operation, under the influence of vertical loads, the layers of the geotissue bend, close together within the cells, and the cells of the geogrid are silted up, as a result of which the geocomposite layer quickly loses its drainage properties, which in turn does not provide the necessary stability of the earth roadway blades. Secondly, the layer passes the water collected into it to the surface of the subgrade, which is unacceptable in the conditions of the spread of loess, subsidence or saline soils.

The objective of the present invention is to improve the known geocomposite interlayer by both increasing its filtering properties by eliminating the possibility of closing layers of geo-fabric in the cells of the interlayer, and making the interlayer waterproof at its lower plane.

The problem is solved as follows.

In the known geocomposite interlayer for the roadbed, containing a geogrid and two layers of geo-fabric, one of which is located on the upper plane of the geo-grid, and the other is on the lower, according to the present invention, additionally waterproof film is placed on the lower plane of the geo-grid between the geo-grid and the lower layer of geo-fabric and the geogrid is given a three-level structure for the placement of its constituent elements (bands, strings, fibers, etc.). At the same time, the elements of the average level of the structure of the geogrid are given a section height exceeding the height of the section of the elements of its lower and upper levels, which forms cells in the geogrid with dimensions that impede the closure of the upper layer of the geo-fabric with a waterproof film and the lower layer of the geo-fabric. The upper layer of geotissue is made draining, and the lower one is protective, to eliminate mechanical damage to the film in contact with soil particles. The entire geocomposite layer is made in the form of a single non-separable roll construction.

Such a technical solution, with its whole new set of essential features, allows you to create a geocomposite layer for the subgrade of the road with stable drainage, capillary and water-resistant properties along its lower plane, which ensures non-wetting of soils and reliable drainage of water into the slopes of the subgrade while ensuring the design transverse slope in the interlayer. Such a solution allows the use of a geocomposite interlayer instead of a sandy drainage layer up to 40 cm thick and to create the optimum moisture regime for soils in the working layer of the subgrade.

The resulting new set of essential features is provided by changing the structure of the geogrid, giving it a three-level location, placing a waterproof film on the lower plane of the geogrid, and also using two different types of geo-fabric in the geocomposite layer with different functional purpose and, accordingly, different physical and mechanical properties.

Compared with the prototype of the claimed invention has significant differences, which are as follows:

- a geogrid with a three-level structure of the arrangement of its elements was used, which allows to reduce the deflection of the layers of geotissue in the cells of the geogrid;

- the cells in the structure of the geogrid are given dimensions that prevent the closure of layers of geo-fabric, which in turn eliminates the overlapping of channels that divert water to the slopes of the subgrade and reduces the degree of siltation of the interlayer; wherein the elements of the average level of the structure of the geogrid have a section height exceeding the section height of the elements of its lower and upper levels;

- a waterproof film was applied to prevent water from penetrating from the interlayer into the soil of the working layer of the subgrade;

- two different layers of geo-fabric were used, of which one is located on the upper plane of the geo-grid and serves as a filter material, and the other on the lower plane of the geo-grid and under a waterproof film, which provides the film with protection against damage and a stable position on the ground.

The patent information search carried out by the applicant showed that the proposed combination of essential features was not found. Therefore, the claimed invention can be recognized as new.

The present technical solution has an inventive step, since it logically does not follow from the prior art for a specialist of average qualification.

However, certain significant features are known by the claimed solution, but in other combinations other than the claimed combinations. For example, a waterproof film is known, which can be made in the form of a waterproofing material placed on vertical and horizontal elements of building structures.

It is known and the use in road construction of the invention "Subgrade road" (see A.S. 1645377, publ. 30.04.91). According to this invention, the subgrade layer is made of a non-woven synthetic fabric, the longitudinal edges of which are folded in the form of pipes, and between the pipes this material is located on the soil surface. In this invention, the non-woven synthetic material acts as a single structural element and performs one supporting function.

It is known to use an impermeable polymer film to create obstacles to the vertical filtration of air into the soil layer on a sports field (see A.C. 734373, publ. 15.05.80). To do this, the mentioned film is placed on top of the filter plates, under the coating. The film is placed on the plates selectively, which allows one section of the sports field to provide greater permeability than the other. In our case, a waterproof film is not used on top of filter plates, but under a geogrid, which, together with the top layer of geo-fabric, also serves as a filter plate.

It is known to use a waterproofing roll layer in which a waterproof film is used. This well-known layer is a development of Ewald Doerken AG and is a combined version of waterproofing roll material and a drainage system - a drainage cloth that is perforated and has a filter cloth. The waterproofing web material has spikes with which it interacts through the filter material with the drainage web. However, this design is used for the formation of vertical wall drainage during the construction of walls, for example, buildings or walls of tunnels, which differs sharply from the conditions of almost horizontal operation of the proposed design of the geocomposite layer for the subgrade of the road.

In our case, the design of the geocomposite layer is multi-element and performs a set of functions predetermined by the requirements for the subgrade of the road: to provide drainage, capillary interruption, directed drainage and to prevent water from entering the subgrade surface, and these functions should be provided at the same time.

Thus, in the claimed invention used known structural elements, but in a different and different from known cases combination.

The essence and practical applicability of the claimed invention is illustrated by the following description and drawings, where

Figure 1 - cross section of the subgrade of the road;

Figure 2 is a fragment of a longitudinal section of the proposed geocomposite layer for the subgrade of the road;

Figure 3 is a variant of the layout of the elements of the geogrid in the proposed geocomposite layer for the subgrade of the road.

The proposed geocomposite layer 1 for the roadbed 2 of the road (Fig. 1) has a geogrid 3, filtering geotextile 4, waterproof film 5, protective geotextile 6, which protects the film 5 from damage from structural particles of soil 7 and ensures a stable position of the geocomposite layer on subgrade surface. The geogrid consists of elements 8, 9, 10 (Figs. 2, 3) with a three-level structure of their placement. The average level of the structure is formed from elements 9 having a section height exceeding the section height of the upper and lower levels elements 8 and 10 (FIG. 2). Elements 8, 9, 10 can be made in the form of strips, strings, fibers and made of metal or polymeric materials. Elements 8 and 10 are oriented parallel to the longitudinal axis of the road, and elements 9 are perpendicular to it. Other orientations are possible, which are not fundamental for this technical solution. The step of placing the elements 8, 9, 10 in the structure of the geogrid 3 is selected taking into account the need to give the cells 11 of the geogrid sizes that impede the closure of the geotissue 4 with a waterproof film 5 when they are loaded vertically (Figs. 2, 3). A set of elements of the inventive geocomposite layer provides the formation in it of volumetric cavities 11 (Figure 2), intended for the reception and removal of water.

The proposed geocomposite layer for the subgrade of the road is made in the form of a single non-separable roll construction. It can be manufactured in the factory and transported in roll packaging with its subsequent deployment when laying on a subgrade with a layer of design transverse slope.

The proposed geocomposite layer for the subgrade of the road operates as follows. Under vertical loads, the layers of geo-fabric and films bend inside cells 11 of the geo-grid 3. Their closure is prevented by elements 9 of the average level of geo-grids 3, mesh sizes 11 and properties of the protective geo-fabric 6, whose strength is assigned higher than the strength of the filter geo-fabric 4. In the structure of the proposed geocomposite layer, free cavity 11 for receiving water from above and its discharge, which significantly reduces the siltation of the design of the geocomposite layer, and the presence of a waterproof film in it ensures readability of the subgrade surface, proper soil moisture conditions and extend the warranty period of the road.

Claims (2)

1. The geocomposite layer of the subgrade of the road containing a geogrid and two layers of geo-fabric located on the upper and lower planes of the geo-grid, characterized in that a waterproof film is additionally placed between the lower plane of the geo-grid and the lower layer of the geo-fabric, while the geo-grid has a three-level structure of its components elements that form cells in the geogrid with sizes that prevent the upper and lower layers of the geo-fabric from closing, and elements of an average level of structure oreshetki have a section height greater than the height of the sectional elements of the upper and lower its levels. 2. The geocomposite layer according to claim 1, characterized in that the upper and lower layers of geo-fabric are made with different physical and mechanical properties, and the geogrid, layers of geo-fabric and waterproof film are made in the form of a single, non-separable roll construction.

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