RU51044U1 - UNDERGROUND PEDESTRIAN CROSSING UNDER THE ROAD ON PERMANENT FROZEN - Google Patents

Abstract

The utility model relates to the field of construction, namely the construction of underground structures in areas of permafrost. An underground pedestrian crossing under the permafrost road contains a roadbed, a roadway, an underground tunnel section located under a roadbed and entrance structures located along the edges of the road connecting the underground tunnel section with the surface. What is new in the proposed utility model is that the junction contains hydroprotection and thermal protection, while thermal protection is made in the form of a thermal insulation layer with thermal resistance "R", laid at a depth of 20-60 cm from the surface and representing a ring-shaped figure of a closed shape of constant width "with », The inner contour of which in plan coincides with the outer contour of the underground tunnel section along with the entrance structures. Hydroprotection is made in the form of a canopy over the entrance structures and a waterproofing layer, laid directly above the underground pedestrian crossing and the adjacent territory within the thermal insulation layer. The thermal resistance power “R” and the width “c” of the thermal insulation layer are determined by thermophysical calculation. The technical result of the proposed utility model is to improve the performance of a pedestrian crossing under the road in areas of permafrost soils by eliminating the ingress of groundwater into the underground passage during summer thawing.

Description

The utility model relates to the field of construction, namely the construction of underground structures in areas of permafrost distribution.

A pedestrian crossing over the road is known, which is a pedestrian bridge with side walls located above the carriageway. (Guidelines for the design of city streets and roads. M., Stroyizdat, 1980, p.90-97).

The disadvantages of this passage are that it should have a sufficiently large space between the road surface and the lower structural elements of the pedestrian bridge, which necessitates pedestrians to overcome stairs of great height, and also reduces visibility, which is quite important in cramped city conditions.

The closest in technical essence and the achieved result to the claimed one is the underground pedestrian crossing under the road, containing the roadbed, roadway, underground tunnel section located under the roadbed and located at the edges of the road entrance structures connecting the underground tunnel section of the transition with surface. (P.M. Salamakhin, O.V. Volya, N.P. Lukin and others. Bridges and structures on the roads. Textbook for universities, part 2, M., Transport, 1981, p. 378-379).

This crossing is devoid of the above disadvantages of the pedestrian crossing over the road. However, when operating in permafrost with closed or low-drainage surfaces, a layer of thawed soil that forms in the summer from the natural surface of the soil contributes to the entry of groundwater into the underground part of the pedestrian crossing, which is difficult to protect from and to discharge under these conditions.

The proposed utility model solves the problem of improving the performance of a pedestrian crossing in areas of permafrost distribution by eliminating the ingress of groundwater into the underground passage during summer thawing.

To achieve the technical result, an underground pedestrian crossing under the permafrost road containing the roadbed, the roadway, the underground tunnel section located under the roadbed and the entrance structures located on both sides of the road connecting the underground tunnel section with the surface, contains hydroprotection and thermal protection, while thermal protection is made in the form of a thermal insulation layer laid at a depth of "δ" from the surface and representing the ring-shaped figure of a closed shape of constant width "c", the inner contour of which in plan coincides with the outer contour of the underground tunnel section along with the entrance structures, and

water protection is made in the form of a canopy over the entrance structures and a waterproofing layer, laid directly above the underground pedestrian crossing and the adjacent territory within the thermal insulation layer. In addition, the depth “δ” of the thermal insulation layer may be 20-60 cm.

And the width “c” of the thermal insulation layer can be determined by the formula c = 4d, m, where d is the depth of seasonal thawing of the soil without taking into account thermal insulation.

The essence of the presented utility model is illustrated by drawings,

where figure 1 shows the underground pedestrian crossing in plan (section aa in figure 2);

figure 2 shows a section in a vertical plane along the longitudinal axis of the road (section BB in figure 1;

figure 3 shows a section along the longitudinal axis of the underground pedestrian crossing (section bb in figure 1).

The underground pedestrian crossing under the permafrost road contains a subgrade 1, a roadway 2, an underground tunnel section 3, entrance structures 4. In the adjacent section, a thermal protection is made, which is a thermal insulation layer 5 laid at a depth of 20-60 cm from the surface. For mechanical protection of thermal insulation, filling it with soil is necessary. In terms of physical nature (from the point of view of work efficiency), backfill should tend to zero, but for technological reasons, it cannot be less than a certain value. For manual laying of the soil, the depth of filling is 20-30 cm, and for mechanical laying, the soil layer must be at least 60 cm. The thermal insulation layer in the plan is an annular figure of a closed shape of constant width "c", the inner contour 6 of which in plan coincides with the external the contour of the underground tunnel section along with the entrance structures. Thus, the external insulation loop is limited by line 7. The specified layer

thermal insulation 5 is placed within the road in a subgrade 1, and at the edges of the road, a platform 8 is dumped for this, although there may be other solutions. To prevent rainwater from entering the underpass, a waterproofing is provided, containing a canopy 9 above the entrance structures 4 and a waterproofing layer 10, laid directly above the underground pedestrian crossing and within the territory of the thermal insulation layer 5. The surface of the waterproofing layer 10 and the surface of the site 8 should be biased into the external side. To reduce the depth of summer thawing of the soil under the underground tunnel section 3 can be provided with thermal insulation 11, installed by calculation. The position of the upper boundary of permafrost at the end of the warm season is shown at 12. Entrance and descent to the transition are shown at 13 and 14, respectively. Thermal insulation can be made in the form of a foam layer or expanded clay layer, or in some other way.

The underground pedestrian crossing under the road on permafrost works as follows. One of the main problems arising in conditions of drainless or low drainage surfaces is that the active soil layer in summer is a good conductor of water. Waterproofing in the presence of hydraulic pressures is far from always reliable, as a result of which water enters the underpass and its performance is sharply reduced. In this technical solution, the heat-insulating layer 5 allows you to provide a jumper from frozen soil, which protects against the entry of groundwater into the underpass from the outside.

To obtain a generalized solution, you can use the patterns derived in the work “Recommendations for the design and construction of supports for road and rail bridges on permafrost soils”, M., VNIITS, 1988, p. 37-43 and reflected in

normative and recommendation document “Design and installation of foundations of bridge supports in areas of permafrost distribution”, SP-32-101-95, M., Transstroy Corporation, 1996, pp. 37-54. The essence of the law is that in the zone of permafrost distribution the temperature of the soil at a depth of "d" at some point A is determined by the boundary conditions on the surface in a circle with a diameter of 4d and whose center is located at point A. It follows that the width is "c" rings should be equal to 4d:

c = 4d, m (one)

where d is the height of the active layer without thermal insulation.

Thus, to determine the value of "c" it is necessary to perform two one-dimensional calculations for specific climatic conditions:

1) determine the depth "d" of seasonal thawing of the soil;

2) determine the required value of thermal insulation "R".

Next, the size of "c" is determined by the formula (1).

Claims (3)

1. An underground pedestrian crossing under the permafrost road containing the roadbed, roadway, an underground tunnel section located under the roadbed, and entrance structures located along the edges of the road connecting the underground tunnel section with a surface, characterized in that it contains hydraulic and thermal protection, while thermal protection is made in the form of a layer of thermal insulation, laid at a depth of "δ" from the surface and representing a ring-shaped figure closed about the outline of a constant width "c", the inner contour of which in plan coincides with the outer contour of the underground tunnel section along with the entrance structures, and the hydraulic protection is made in the form of a canopy over the entrance structures and a waterproofing layer laid directly above the underground pedestrian crossing and adjacent territory within thermal insulation layer. 2. An underground pedestrian crossing under the permafrost road according to claim 1, characterized in that the depth "δ" of the thermal insulation layer is 20-60 cm. 3. The underground pedestrian crossing under the road on permafrost according to claim 1, characterized in that the width "c" of the insulating layer is determined by the formula: c = 4d, m where d is the height of the active layer without thermal insulation.