RU2762303C1 - Method for constructing a heat-insulating structure - Google Patents

Abstract

FIELD: building.

SUBSTANCE: invention relates to the field of building, namely, is intended for application in construction of ground structures in the permafrost zone, for heat insulation and simultaneous reinforcement thereof, and can also be applied for building structures for strengthening culverts on permafrost soils. The method for constructing a heat-insulating structure includes the operations of: linking geostrips in a perpendicular plane relative to the plane of the base, linking geostrips with a flexible base - a bottom - and forming a cellular structure - a geoshell, installing and securing a cellular structure at the construction site using a frame, filling cells with an inert material, dismantling the frame, compacting the filler. The flexible bottom is made of a heat-insulating material.

EFFECT: reduction in the depth of thawing, increase in the stability and reduction in the unevenness of setting of the thawed soils.

2 cl, 3 dwg

Description

The invention relates to the field of construction, namely, is intended for use in the construction of soil structures, mainly road embankments, in the permafrost zone, for thermal insulation and simultaneous reinforcement. It can also be used in the construction of structures for strengthening culverts on permafrost soils.

A known method of constructing a heat-insulating structure, including the operation of the device of the underlying layer of sand, the laying of expanded polystyrene plates, the device of a protective layer of sand over the plates [STO NOSTROY 2.25.28-011].

The method has the following disadvantages: polystyrene foam board does not have a bearing capacity; it cannot work in conditions of uneven subsidence of the base.

The use of heat insulators only in some cases (when the thickness of the heat-insulating layer is more than 20 cm, which leads to a significant increase in the cost of construction and is rarely used in practice) can completely exclude thawing of frozen soils. As a rule, the base of expanded polystyrene plates thaws to a certain depth. Due to the thawing of the base, its uneven settlement occurs. The expanded polystyrene plate is deformed, through cracks are formed, the thermal insulation capacity decreases.

A known method of constructing a heat-insulating structure with a bearing capacity, including the installation of a cellular mat at the construction site, filling the cells with foam, which, when solidified, forms a heat-insulating material [US 2013/0170907 A1 Jul. 4, 2013 LIGHTWEIGHT SUPPORT MAT FOR EQUIPMENT AND VEHICLES].

The walls of the cells can have perforations; during the formation of the slab, the foam flows into the holes, due to which the formed substance is retained in the cells.

This method has the following advantages:

- the depth of seasonal thawing of the base of the structure decreases;

- the mat perceives the load, since the walls of the cells have a bearing capacity;

- the mat works in conditions of uneven settlement of the base, since the walls of the cells are flexible.

This method has the following disadvantages:

- complex and costly construction technology. It is difficult and expensive to deliver foam for pouring cells over long distances. The cost of foam exceeds the cost of expanded polystyrene by an order of magnitude;

- the structure does not work in conditions of significant uneven settlement, typical for thawing soils. For example, a flexible cellular mat withstands, without collapsing, uneven settlement in the form of base deflection up to 5 cm per 1 m length, assuming the shape of the base surface. With an increase in the uneven settlement of up to 10 cm per m length, which is typical for thawing bases, the cell filler will be destroyed, since it is fragile and not flexible;

- in the process of filling the cells with foam, it is impossible to create a flat horizontal surface. In the vertical protrusions of the filler (frozen foam) under the action of the load, a stress concentration is created, as a result of which the filler of the cells is destroyed;

- the structure does not have the required reinforcing ability under construction conditions on weak subsidence soils, it cannot hold thawed soils.

In the permafrost zone, it is preferable to build highways with the assumption that the base thaws to a fixed depth, while, as a rule, the maximum thawing of soils occurs under the lower part of the embankment slopes and along the bottom of the embankment. Thawing is accompanied by precipitation, subsidence and erosion of thawed soil. The construction of drainage ditches causes the permafrost to thaw, the thawed soil is eroded, the bottom of the ditch deepens, the rigid structure of strengthening the channel of the ditch is destroyed.

There is a known method of constructing a structure that reinforces the soil, which includes the following operations: stitching geo-strips together in a perpendicular plane relative to the plane of the base, stitching geo-stripes with a flexible base-bottom and forming a cellular structure (geo-shell), installing and fixing a cellular structure at the construction site using a frame, filling the cells with inert material, dismantling the frame, sealing the filler [TU 8329-003-68168870-2011].

When strengthening the channel of the ditches with the help of a structure constructed in this way, the cells with the filler are closed with a special canopy in order to avoid washing out the filler.

The method has the following advantages:

- a geo-envelope with a small cell (30 × 30 cm) distributes the load from vehicles over a large area, prevents the displacement of soils located under it;

- significant volumes of soil can be retained in the cells of the geosheath (the cell size can reach 1.5 × 1.5 m at a height of 0.7 m). A geoenclosure with a large cell serves as a subgrade, which ensures the movement of vehicles on thawed soils with a low bearing capacity;

- a geo-shell with an aggregate reduces the uneven settlement, can operate in conditions of significant uneven base settlement;

- a geo-shell with an aggregate prevents the erosion of thawed soil. When strengthening the bottom of drainage ditches in this way, the geo-shell filled with sand takes the shape of the bottom and holds the soil;

- the tissue walls and the bottom of the cells serve as a drainage layer;

- the construction method is quite simple. The assembled geo-shell is easy to transport.

The method has the following disadvantage: the structure constructed in this way does not have a thermal insulating ability.

The aim of the present invention is to provide a method for constructing a structure having both thermal insulation and reinforcing properties.

This goal is achieved by the fact that in the known method, which includes the operations of stitching together geo-strips in a perpendicular plane relative to the plane of the base, stitching geo-strips with a flexible base-bottom and forming a cellular structure (geo-shell), installing and fixing a cellular structure at the construction site using a frame, filling the cells with inert material, dismantling the frame, sealing the filler, the base-bottom is made of heat-insulating roll material.

Additional heat-insulating material can be placed in the cells, both at the factory and at the construction site (for example, expanded polystyrene granules, expanded polystyrene tiles). A protective layer of inert material is arranged over the heat insulator.

An additional heat-insulating material with a load-bearing capacity without a protective layer can be placed in the cells, for example, aggloporite crushed stone treated with a bitumen emulsion.

The technical result is achieved by reducing the depth of thawing of base soils and simultaneous reinforcement of thawed soils with low bearing capacity.

The essence of the proposed technical solution is illustrated by drawings, which shows:

in fig. 1 - GeoFRAM geo-shell;

in fig. 2 - road embankment with the proposed heat-insulating structure;

in fig. 3 - road embankment without the proposed heat-insulating structure.

In addition, an Appendix was made to clarify the text of the Description.

The invention is carried out as follows. A thermophysical calculation is performed first, on the basis of which the required thickness of the heat insulator is set based on the permissible depth of seasonal thawing. Known programs that allow you to perform such a calculation based on numerical analysis, for example, the certified program TMFLAT (Passek V.V.), etc.

In the factory, geo-strips 1 are sewn from woven geotextile and the bottom 2, protruding beyond the cellular structure, is sewn in from a roll of heat-insulating material, forming a cellular structure (geo-shell) 3. At the construction site of the embankment, on a leveled base, a frame 4 is installed and the geo-shell 3 is stretched on it. If required, additional heat-insulating material 5 is placed in the cells, then the cells are covered with inert material, preferably sand. The frame is dismantled, the soil in the cells is compacted. After the completion of these operations, subsequent work on the construction of embankment 6 and pavement is performed in the usual manner.

After the construction of the embankment, the original permafrost surface 7 rises to the bottom of the embankment, a new permafrost surface 8 is formed.

The proposed method for constructing a heat-insulating structure can be used to strengthen watercourses. The proposed method reduces the depth of thawing of frozen soils of the bottom of the watercourse. Due to the fact that the geosheath is flexible, it sinks together with the bottom of the watercourse, preventing soil erosion. To strengthen watercourses, geosheaths are used that have a canopy, which is fixed with special tapes.

The effectiveness of the claimed method lies in improving the quality of construction by reducing the depth of thawing of the base and strengthening the thawed soil of the base. The bearing capacity of the base soil increases.

An example of the implementation of the method.

In the permafrost zone, on the territory of the Yamalo-Nenets Autonomous Okrug, near the village. Pangody, a V category highway is under construction. The depth of seasonal thawing of the soils of the active layer is 2.3 m. The site is swampy. The quarries are located at a great distance from the road under construction. To exclude thawing of the base, the construction of an embankment with a height of at least 2.4 m is required.

It was decided to use the GeoFRAM geo-shell with a heat-insulating bottom and build an embankment 1.5 m high.Without the use of thermal insulation, the thickness of the compressible layer at the base of the embankment would be about 1 m, the sediment would be 15 cm. the maximum value along the axis of the embankment.

Work on the installation of a heat-insulating structure was carried out in the following order. A frame was installed on the prepared base, and a geo-shell with a height of 0.375 m with a cell size of 0.3 × 0.3 m was stretched on it. The geo-shell was made of woven geotextile with a breaking strength of 89 kN / m. The width of the geosheath exceeded the width of the embankment by 4 m on each side. The bottom of the geosheath was made of polyfas heat-insulating material in 2 layers. Since the maximum thawing occurs at the base of the lower part of the slope, tiles cut from 4 cm thick TECHNONICOL expanded polystyrene plates were placed in the cells of the geosheath under the embankment slope, thus strengthening the thermal insulation. The area of the tiles corresponded to the area of the cells. Thawing of frozen soils along the embankment often leads to subsidence, the formation of ditches, which leads to the destruction of the embankment body.

Then the cells were filled with sand. The compaction was done with a light roller. The embankment was filled up to the design level in the usual manner. A protective layer of sand mixed with vegetation was arranged over the cells of the geosheath that protruded beyond the embankment, and grasses were sown.

A year after the construction of the embankment, a survey of the facility was carried out. The depth of thawing of the embankment base under the roadside was 60 cm. The settlement of the embankment base was within the allowable range and amounted to 5 cm. The surface of the geosheath cells protruding beyond the embankment slightly subsided. The geo-shell strengthened the surface of the thawed soil; no damage or erosion was found.

Claims (2)

1. A method of constructing a heat-insulating structure, including the operations: stitching together geo-strips in a perpendicular plane relative to the plane of the base, stitching geo-strips with a flexible base - the bottom and forming a cellular structure - a geo-shell, installing and fixing a cellular structure at the construction site using a frame, filling the cells with inert material, dismantling the frame, sealing the filler, characterized in that the flexible bottom is made of heat-insulating material. 2. A method of constructing a heat-insulating structure according to claim 1, characterized in that the flexible bottom is made by stitching woven geotextile with heat-insulating material.

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