RU162645U1 - BRIDGE SOIL SUPPORT FOR PERMANENTLY FROZEN SOILS - Google Patents

Abstract

A bridge soil-metal support for permafrost soils, consisting of two connected rigidly corrugated shells installed on a soil pillow and filled with a compacted drainage soil, at the top of which support blocks are laid, characterized in that it consists of a continuous shadow-forming snow-covering canopy placed around a soil cover around the soil around the soil pillow, while the area of the canopy exceeds the area of the pillow, and along the entire perimeter of the canopy are installed on the ground and attached to the ends of the canopy side shields, closed vayuschie space between the canopy and the surface of the soil beneath it.

Description

The utility model (hereinafter referred to as the PM) relates to the field of construction of temporary road bridges.

In particular, it can be used for temporary road bridges arranged on permafrost soils (VMG), used as bases on principle I, in which it should be maintained in a frozen state for the entire life of the bridge [1].

Known design of bridge metal support (hereinafter GMO) on a stone pillow [2 p. 183]. It is adopted as a prototype PM.

The main disadvantage of this support is the openness of the soil cushion itself and the soil surface around it, which does not guarantee that the VMG is frozen in the base of the support [as required by SNiP2.02.04-88].

The technical task of the PM is to ensure the frozen state of the VMG used according to principle I in the foundation of GMOs for the entire life of the temporary bridge.

The indicated technical problem was solved due to the fact that the bridge GMO for the VMG consists of two connected rigidly corrugated shells mounted on an earth cushion and filled with compacted drainage soil, on top of which the supporting blocks are laid. The support is characterized in that it consists of a continuous shade-forming snow-holding canopy located around the shells on the soil cushion, while the area of the canopy exceeds the area of the soil around the cushion, and side shields are installed on the ground along the entire perimeter of the canopy and attached to the ends of the canopy, covering the space between the canopy and the ground surface beneath it.

The proposed PM design is shown in the figure, where it is indicated:

pos. 1 - supporting blocks; pos. 2 - corrugated shells; pos. 3 - soil filling shells; pos. 4 - a canopy; pos. 5 - side shields; pos. 6 - supporting the canopy; pos. 7 - soil cushion; pos. 8 - geotextile or geogrid; pos. 9 - top of the thickness of the VMG; pos. 10 - snow.

The GMO device is produced in the following sequence.

Initially, geotextile or geogrid-8 panels lay on a mossy cover. A soil cushion - 7 is arranged on them. After that, the casing 2 assembled in the side of the casing 2 is installed on the cushion 7. Shells 2 are filled (for example, with a grab) in layers (0.3-0.5 m) with compaction with drainage soil 3. Then on top of the soil 3 support blocks 1 are laid (with a crane). At the same time, the bottom of the blocks must constantly be 10 cm or more higher than the edges of the shells (taking into account soil subsidence under load).

After that, supporting beds (bars) 6 are laid on the soil cushion 7. On them are laid and pins attached to them with pins 4 of the canopy 4, made in advance.

Canopy 4 should be designed for snow load.

The canopy from above should be covered with waterproof material (tarpaulin, roofing felt, a durable film, etc.) to drain water from the canopy from rains and melting snow.

The final operation is the installation of side shields 5 around the perimeter of the canopy to protect the space under the canopy from the warm wind in summer and in winter from snow. Outside the canopy, from the top side, arrange rollers from compacted soil (preferably clay) or bags of soil to drain rain and melt water.

The effectiveness of the use of a shade-forming snow canopy is as follows.

In summer, under canopy due to shading, the air temperature is lower (usually 3-5 degrees). Due to this, the depth of thawing of the VMG under it decreases. In winter, when it is not covered with snow, the soil under a canopy freezes to a greater depth than the soil, the surface of which is covered with snow, which, as you know, is a heater.

As a result, the depth of the active layer decreases and the upper boundary of the VMG under the support increases, the carrying capacity of the VMG increases.

Thus, due to the use of a shadow-forming snow-holding canopy, not only the frozen state of the VMG used as the base according to principle I is ensured, but its bearing capacity is increased due to the gradual decrease in the temperature of the VMG under the canopy and the raising of its upper boundary.

Bibliography

1. SNiP 2.02.04-88 Foundations and foundations on permafrost soils. M., 1989.

2. V.I. Telov et al. Road wooden bridges. Tomsk, 1998.

3. Recommendations for the design of supports of military bridges on permafrost soils St. Petersburg WATT, 2010.

Claims (1)

A bridge soil-metal support for permafrost soils, consisting of two connected rigidly corrugated shells installed on a soil pillow and filled with a compacted drainage soil, at the top of which support blocks are laid, characterized in that it consists of a continuous shadow-forming snow-covering canopy placed around a soil cover around the soil around the soil pillow, while the area of the canopy exceeds the area of the pillow, and along the entire perimeter of the canopy are installed on the ground and attached to the ends of the canopy side shields, closed vayuschie space between the canopy and the surface of the soil beneath it.

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