RU2705656C1 - Road embankment on permafrost - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction, namely, to erection of road embankments on permafrost in areas with snow transfer. Road embankment on permafrost in areas with snow transfer comprises a filling body located on natural surface of base soils, a cooling system for stabilizing temperature conditions of permafrost soils, wherein the embankment body is made in the trapezium cross-section in the form of a trapezoid with the upper (small) base for the arrival of the transport, bounded on the sides by the planks and the lower base, which is equal to the sum of the upper base and two projections with the width "d" of the sloping parts, in which the angle of inclination of the side surfaces is equal to "α_i". In winter period on slope parts of embankment and adjacent sections there formed is snow prism, in cross section representing triangle, one side of which coincides with surface of sloping part of embankment, second one – with natural surface of soil of bases, and third is located to horizontal line at angle "α_sn", at that one of tops of triangle coincides with that of main platform. Cooling system for stabilization of temperature conditions of permafrost soils is made in the form of bases located directly on natural surface of soils parallel to road embankment of soil prism, in cross section which is a trapezoid with upper (small) base width "b_p", height" h_p", at that spacing between opposite planks of main embankment and upper base of soil prism is equal to "c" and is determined from given relationship.

EFFECT: reduced volume of road embankment, reduced total cost of structure.

1 cl, 6 dwg

Description

The invention relates to the field of construction, namely to the construction of road embankments on permafrost in areas with snow transfer.

Known road embankment in permafrost in areas with snow transfer, containing the body of the embankment located on the natural surface of the soil base, and the body of the embankment is made in cross section in the form of a trapezoid (Dydyshko P.I. “VNIIZHT.” - M .: Intekst, 2012. Fig. 2.91 p. 247 and Fig. 2.111, p. 262), The advantage of the design is the presence of a cooling device. The disadvantage of this technical solution is the reduced service life of the cooling device relative to the life of the road embankment.

Known road embankment in permafrost in areas with snow transfer, containing the body of the embankment located on the natural surface of the base soils, a cooling system for stabilizing the temperature regime of permafrost soils, and the body of the embankment is made in cross section in the form of a trapezoid with an upper (small) base for transport bounded on the sides by brows and a lower base equal to the sum of the upper base and two projections with a width of "d" sloping parts, in which the angle of inclination of the side surfaces is equal to "α _n ", while in winter a snow prism is formed on the slope parts of the embankment and adjacent areas, in the cross section a triangle, one side of which coincides with the surface of the slope of the embankment, the second - with the natural surface of the base soils, and the third is horizontal at an angle “α _sn ”, and one of the vertices of the triangle coincides with the edge of the main site (Technical conditions for the design, construction and commissioning of railways on the Yamal Peninsula. STO Gazpromtrans 4-2012, Moscow: 2012, p. 5.23, p. 12), The advantage of this technical solution is the equalization of the life of the cooling device with the life of the road embankment.

The disadvantage of this technical solution is the excessively large volume of soil slopes of the embankment.

The purpose of the proposed technical solution is to reduce the volume of soil of the embankment and, accordingly, reduce the total cost of the structure.

This goal is achieved by the fact that the road embankment on permafrost in areas with snow transfer contains the body of the embankment located on the natural surface of the base soils and a cooling system to stabilize the temperature regime of permafrost soils. The body of the embankment is made in cross section in the form of a trapezoid with an upper (small) base for passage of vehicles bounded on the sides by brows and a lower base equal to the sum of the upper base and two projections with a width of "d" sloping parts in which the angle of inclination of the side surfaces is equal to "α _n ". In winter, on the sloping parts of the embankment and related portions formed snow prism in cross section showing a triangle, one side of which coincides with the surface of the sloping portion of the embankment, the second - the natural surface of foundation soils, and the third is the horizontal angle «α _CH ”, And one of the vertices of the triangle coincides with the edge of the main platform. The cooling system for stabilizing the temperature regime of permafrost soils is made in the form of bases located directly on the natural surface of the soil parallel to the embankment of the soil prism, in cross section representing a trapezoid with an upper (small) base of width "b _p ", height "h _p ". The horizontal distance between the opposite edges of the main platform of the embankment and the upper base of the soil prism is “c”, with:

where h _d - the depth of summer thawing in natural conditions, m

In addition, between the body of the road embankment and the soil prism of the cooling system, a layer of thermal insulation with a protective layer of soil is laid directly on the natural surface of the base soils, while:

The essence of the technical solution is illustrated by the drawing, where

in FIG. 1 shows a diagram of the proposed technical solution for stabilizing the temperature regime of permafrost soils.

The proposed technical solution considers the cross-section of the embankment in which, instead of the laid-off slopes, a site is dug out from local unconsolidated soils outside the snow prism. Permafrost road embankment in areas with snow transport contains embankment body 1, soil prism 2, thermal insulation layer 3 with a protective soil layer 4.

The body of the embankment 1, located on the natural surface of the soils of the bases 5, is made in cross section in the form of a trapezoid with an upper (small) base b _o for the passage of vehicles, bounded on the sides by brows and a lower base equal to the sum of the upper base and two projections with a width of "d" slope parts in which the angle of inclination of the side surfaces is “α _n ”, and in winter, a snow prism 6 is formed on the slope parts of the embankment and adjacent areas, in the cross section representing a triangle, one side of which is falls with the surface of the sloping part of the body of embankment 1, the second - with the natural surface of the soils of the bases 5, and the third is located horizontally at an angle “α _sn ", and one of the vertices of the triangle coincides with the edge of the upper (small) base of the body of embankment 1. The system is linked by the relations :

where: c is the distance between the opposite edges of the main platform of the embankment and the upper base of the soil prism, m;

h _n - the body height of the embankment, m;

h _p - the height of the soil prism, m;

tgα _sn is the value characterizing the slope of the snow prism;

b _p - the width of the soil prism, m;

b _d - the depth of summer thawing in natural conditions, m;

h _sn - the height of snow deposits in natural conditions, m

In addition, between the body of the road embankment and the soil prism of the cooling system, a thermal insulation layer 3 with a protective soil layer 4 is laid directly on the natural surface of the base soils, while:

where: e is the distance between the body of the road embankment and the soil prism, m;

d is the width of the sloping part of the body of the embankment, m;

tgα _n - a value characterizing the slope of the embankment.

Permafrost road embankment in areas with snow transport works as follows.

In FIG. Figure 1 shows half the cross section of the embankment (due to thermal symmetry) with a height of h _n , with snow deposits in natural conditions h _sn and snow deposition 6 at the slope of the embankment with a slope of 1: 5. At the same time, the main site of the embankment is exposed to snow. Such snow deposits correspond to the Salekhard region. However, the snow deposition scheme itself is characteristic of the whole territory where snow transfer takes place: snow blows off from the main site, and snow deposits accumulate at the slopes, but with a different slope depending on the amount of snow transfer. Snow slopes for the north of the Yamal Peninsula are 1:10 and along the bed. The weakest point is the base soil zone under the base of the embankment slope, the melt zone in depth here exceeds 7 m. A common constructive measure to combat the harmful thermal effects of snow deposits is to adjust the cross section of the embankment, i.e., broadening of the main embankment site. This increases the zone without snow, through which cold enters, which improves the temperature regime, reducing the talik zone at the bottom of the slope of the embankment.

The proposed technical solution contains a cooling system (Fig. 1), made in the form located directly on the natural surface of the soil of the bases 5 parallel to the body of the road embankment 1 of the soil prism 2.

The cooling element of the soil prism from the local soil is its surface, raised to a height relative to the surrounding area, exceeding the maximum snow cover power during the winter period under natural conditions in the area adjacent to the embankment, as shown in FIG. 1, as a result of which the snow is blown away from it and during the whole winter intensive cooling of the underlying soil occurs through this surface.

To increase the cooling efficiency on the inner strip of the surface of the soil of the base between the soles of the opposite slopes of the embankment and the cooling soil prism, thermal insulation 3 can be additionally placed in the form of a foam layer with a protective layer 4 of soil (Fig. 1). Under thermal insulation, the surface of the permafrost soil rises, and the depth of seasonal thawing under the foot of the slope decreases, and the general nature of the temperature field at the base of the embankment improves significantly.

The operation of the cooling system is described in more detail in Appendix 1.

The proposed technical solution provides for the replacement of part of the laid slopes of the embankment with a site from local uncompacted soils outside the snow prism 6 (Fig. 1). We see almost the same effect as slopes, but with lower soil costs. The comparison shows that replacing the laid down slopes by cooling pads can lead to a 10-30% reduction in the volume of soil for the embankment, while for the sites it is possible to effectively use local soils unsuitable for filling the embankment itself.

In the summer, the cooling system stops working, the heat flux into the soil of the base through the surface of the bulk prism exceeds the similar value of the heat flux entering through the natural surface, because There is no vegetation on the site. Nevertheless, the cooling of the soil of the base through the exposed surface of the embankment is sufficient to lead to a gradual decrease in permafrost to a certain limit, guaranteeing stabilization of the temperature regime under the embankment. It is very important that the process of regulating the temperature regime of soils at the base of the embankment becomes controllable. With this technical solution, it becomes possible to control and largely compensate for the warming effect of snow drifts forming at the bottom of the slopes, thereby contributing to increased stability of the subgrade.

Description of essential features.

The first significant feature of the proposed technical solution is the body of the embankment, located on the natural surface of the soil and ensuring the passage of transport.

The second significant feature is a cooling system containing a bulk soil prism from local soil located on the natural surface of the soil parallel to the road embankment, while the surface of the bulk soil prism should be at or exceed the maximum natural level of snow cover in the surrounding area.

The third significant sign is that the bulk soil prism is located outside the zone of formation of maximum snow deposits at the bottom of the slopes of the embankment.

All three essential features are necessary and sufficient to ensure the goal - stabilization of the temperature regime of permafrost soils at the base of the embankment.

The effectiveness of the proposed technical solution is characterized by the fact that for filling the soil prism, 10-30% less soil volume is required, and this can be ordinary (local) soil, while more expensive air-conditioning material that is acceptable according to the Technical Conditions is needed to put down the slopes.

APPENDIX 1

FEATURES OF TAKING INTO ACCOUNT THE THERMAL INFLUENCE OF SNOW SEDIMENTS AT RAILS OF RAILS AND ROADS IN REGIONS WITH PRE-PERFORMANCE OF PERFORMANCE SOILS

The nature and magnitude of snow deposits are one of the main factors determining the temperature regime of body soils and the bases of embankments in the regions of permafrost distribution. Structural and technological measures that compensate for the harmful thermal effects of snow deposits are very expensive. Therefore, the study of the thermal effect of snow deposits and the development of effective measures to compensate for the harmful component of this effect is an important and urgent task.

In fig. Figure 1 shows half the cross section of the embankment (due to thermal symmetry) 3.0 m high, with snow deposits in natural conditions 0.3 m and snow deposition at the slope of the embankment with a slope of 1: 5. At the same time, the main site of the embankment is exposed to snow. Such snow deposits correspond to the Salekhard region. However, the snow deposition scheme itself is characteristic of the whole territory where snow transfer takes place: snow blows off from the main site, and snow deposits accumulate at the slopes, but with a different slope depending on the amount of snow transfer. In fig. Figure 2 shows snow deposits for the north of the Yamal Peninsula (the slopes of the snow slopes there are 1:10 and more).

In fig. Figure 1 shows the temperature field at the end of the warm season, i.e. at the time of maximum thawing. We see that the weakest point is the zone of base soils under the sole of the slope of the embankment. The melt zone in depth here exceeds 7 m.

In the presence of high-icy soils (and this is a characteristic of the Arctic) after thawing, subsidence of soils will occur, which causes the slopes to slip. To avoid deformations, various structural and technological measures are used: they change the cross-sectional configuration of the embankment, use heat-insulating materials, cooling units, etc.

In fig. Figure 3 shows an example of a common constructive measure to combat the harmful thermal effects of snow deposits - adjusting the cross section of the embankment. In fig. 3b shows the broadening of the main site of the embankment. This increases the area without snow, i.e. through which cold comes for a total of one year, which improves the temperature regime, reducing the talik zone at the bottom of the slope of the embankment. The same constructive solutions in essence, but slightly different in form, are shown in Fig. 3c and d - here the increase in the cooling zone is achieved by the provision of slopes.

In fig. 3e, a technical solution is described, characterized by the use of steep slopes - for regions with no snow transfer, which are characterized by bare vertical surfaces from snow.

Adjusting the temperature by additional parts of the cross section requires significant additional soil volumes. In a significant number of regions located in the zone of permafrost distribution, good soils suitable for filling embankments are scarce. Therefore, it is important to find technical solutions that are equal in effect, but requiring less soil costs.

In fig. 4 shows such a solution. The same cross section of the embankment as in Fig. 1, located in the same natural conditions (Salekhard region). But here, instead of the laid-off slopes, a site 1 of local uncompacted soils outside the snow prism 2 is dumped. The temperature field at the same time moment as in Fig. 1. We see almost the same effect as the slopes, but with lower soil costs: the isotherms of 0 ° C and -0.5 ° C in the area of the bottom of the slope of the embankment leveled, and a new frozen zone 3 with a temperature of -1 ° C was formed on the right .

In fig. Figure 5 gives a comparison of the volumes of soil for two different approaches: the creation of laid down slopes and the creation of separate cooling pads.

The comparison shows that replacing the laid down slopes by cooling pads can lead to a 10-30% reduction in the volume of soil for the embankment, while for the sites it is possible to effectively use local soils unsuitable for filling the embankment itself.

Claims (8)

1. Permafrost road embankment in areas with snow transport, containing the embankment body located on the natural surface of the base soils, a cooling system to stabilize the temperature regime of permafrost soils, and the embankment body is made in cross section in the form of a trapezoid with an upper (small) base for arrival transport, bounded on the sides by the brows, and the lower base, equal to the sum of the upper base and two projections with a width of "d" sloping parts, in which the angle of inclination of the side surfaces is equal to "α _n ", in winter, a snow prism is formed on the slope parts of the embankment and adjacent areas, in the cross section a triangle, one side of which coincides with the surface of the slope of the embankment, the second - with the natural surface of the base soils, and the third is horizontal to the angle α _removal ", wherein one of the vertices of the triangle coincides with Brovko primary site, wherein the cooling system for temperature stabilization permafrost situated made in the form n indirectly on the natural surface of foundation soils parallel road embankment dirt prism, a cross section which is a trapezoid with an upper (small) base width «b _n", the height «h _f", the distance between the main platform colliding eyebrows mound and the upper base dirt prisms of horizontally equal to "s", while:

m; b _p ≥3h _d , m; h _p ≥h _sn , m, where h _d - the depth of summer thawing in natural conditions, m 2. A road embankment according to claim 1, characterized in that a layer of thermal insulation with a protective soil layer is laid directly on the natural surface of the base soils at a width “e” between the body of the road embankment and the soil prism of the cooling system: e = c-d, m;

m

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