RU2681893C1 - Tunnel with sub-zero air temperature in winter in its interior part - Google Patents

Abstract

FIELD: construction.SUBSTANCE: invention relates to the field of construction, namely to the construction of underground structures or tunnel. Tunnel with a negative in winter temperature of air in its inner part contains along its length a central section located at the calculated depth, and two transitional open-top sections connecting the central part with the ground surface, all three sections in cross-section contain a tray with a roadway above it and concrete walls and are made continuous without deformation joints. Tunnel contains a thermo-regulating coating, a drainage layer, drainage pipes, and all the concrete elements of the tray, walls and floors contain organized cracks. Drainage layer is located on the surface of the tray and the walls from the inside of the tunnel. Thermostatic coating is located directly on the drainage layer throughout this layer. Drainage pipes are located in the lower part of the tray and are connected by channels to the drainage layer. Organized cracks are located simultaneously over the entire cross-section of concrete, formed at the sites of targeted weakening of the concrete section at design points and injected with a composition having a strength not less than concrete, the distance along the length of the tunnel between the organized cracks is assigned by calculation.EFFECT: technical result consists in increasing the durability of the tunnel, providing a significant improvement in operating conditions.6 cl, 15 dwg

Description

The invention relates to the field of construction, namely the construction of underground structures or a tunnel.

A well-known tunnel with a negative air temperature in winter in its inner part, containing along its length a central section located at the calculated depth, and two transitional sections open at the top connecting the central section with the day surface of the soil, with all three sections in cross section a tray with a roadbed and concrete walls above it (Metro and tunnels, No. 2, 2001, “Construction of a tunnel under the Moscow Canal”).

The disadvantage of the tunnel is the presence of expansion joints located at a calculated distance from each other. As a result, in the winter period, ice form in the zone of expansion joints, which significantly complicate the operation.

A well-known tunnel with a negative air temperature in winter in its inner part, containing along its length a central section located at the calculated depth, and two transitional sections open at the top connecting the central section with the day surface of the soil, with all three sections in cross section a tray with a roadbed and concrete walls beneath it, and made continuous without expansion joints (Metro and tunnels, No. 2, 2001, “Construction of a tunnel under the Moscow Canal”). The text of the article is given in the Appendix to the description of the invention.

The disadvantage of this technical solution is that the absence of expansion joints was achieved by reinforced longitudinal reinforcement. This measure does not eliminate the stress state of concrete, but only distributes large cracks into small ones. Moreover, taking into account the use of waterproofing, the water permeability of concrete turned out to be insignificant, but the durability of concrete sharply decreased.

The aim of the proposed technical solution is to increase the durability of the tunnel.

This goal is achieved in that the tunnel with a negative air temperature in winter in its inner part contains along its length a central section located at the calculated depth, and two transitional sections open from above, connecting the central part with the ground surface. All three sections in cross section contain a tray with a roadbed and concrete walls located above it, and are made continuous without expansion joints. The tunnel contains a thermoregulatory coating, a drainage layer, drainage pipelines, and all concrete elements of the tray, walls and floors contain organized cracks, while the drainage layer is located on the surface of the tray and walls from the side of the inside of the tunnel, the temperature control coating is located directly on the drainage layer throughout of this layer, drainage pipelines are located in the lower part of the tray and are connected by channels to the drainage layer. Organized cracks are located simultaneously over the entire cross-section of concrete, formed in places of deliberate weakening of the concrete section at design points, and are injected with a composition that has no less strength than concrete, and the distance along the tunnel length between organized cracks is calculated.

In addition, the central section has an overlap containing a concrete slab, located on the lower surface of the slab first with a drainage layer and then with a heat-regulating coating, and on the upper surface with a soil layer and then a thermal insulation layer, with the drainage layer, heat-regulating coating, soil layer and layer thermal insulation are located throughout the cross section.

In addition, the tray at a groundwater level above the level of drainage pipelines is made in the form of a slab of reinforced concrete.

In addition, the tunnel contains a layer of insulation located at the level of the surface of the soil outside the section of the tunnel on each side to a width of "C", while

C = 4 h _p , m,

where h _p - the depth of seasonal freezing of the soil when exposed to snow surface.

In addition, the walls above the groundwater level are made of corrugated metal with a vertical orientation of the corrugations.

In addition, the drainage layer is made of porous material with open pores.

The invention is illustrated by drawings, where:

in FIG. 1 presents an analogue of the invention — a tunnel with expansion joints, a section along the longitudinal axis of the tunnel;

in FIG. 2 shows a prototype of the invention — a heavily reinforced tunnel without expansion joints, a section along the longitudinal axis of the tunnel;

in FIG. 3 presents the proposed technical solution of the tunnel without expansion joints, a section along the longitudinal axis of the tunnel;

in FIG. 4 shows a cross section of the central section of the tunnel in the event of overlap, section AA in FIG. 3;

in FIG. 5 shows a cross section of the transition section of the tunnel, section BB in FIG. 3;

in FIG. 6 shows a cross section of the transitional section of the tunnel, section BB in FIG. 3, an option when the groundwater level is below drainage pipelines;

in FIG. 7 shows a cross section of the transition section of the tunnel, section BB in FIG. 3, an option for low groundwater;

in FIG. 8 shows a cross section of the central section of the tunnel in the presence of overlap, section GG in FIG. 3;

in FIG. 9 shows the design scheme for conducting thermophysical calculation of the chute part of the tunnel, section DD in FIG. four;

in FIG. 10 shows a diagram of the temperature distribution in depth in the chute part of the tunnel (see Fig. 9) at the moment of maximum freezing;

in FIG. 11 shows the design scheme for conducting thermophysical calculation of the overlap of the tunnel, section EE in FIG. four;

in FIG. 12 shows a diagram of the temperature distribution over the thickness of the floor (see FIG. 11) at the moment of maximum freezing;

in FIG. 13 shows a design diagram for conducting a thermophysical calculation of a tunnel wall, section MF in FIG. four;

in FIG. 14 shows a diagram of the temperature distribution over the thickness of a wall and adjacent soil (see FIG. 13) at the moment of maximum freezing;

in FIG. 15 shows the required position of the zero isotherm in the area of the upper part of the wall with an open section at the moment of maximum freezing.

In addition, the Appendix with the text of the article that describes the prototype is attached to the description text.

A tunnel with a negative air temperature in winter in its inner part contains along its length two transitional 1 open sections from above and a central 2 section located between them. The temperature in the interior of the tunnel approaches the temperature of the outside air, i.e. air temperature above the ground surface. This is because the end sections are open from above, and the central section is either open, or, if not open, is usually short and blown.

In FIG. 1, an analogue is presented — a tunnel containing concrete lining 3, protected by waterproofing 4, with expansion joints 5 in length. A road lane (railway or automobile) in the underground 6 part goes into the above-ground 7 part. The waterproofness of the seams is difficult to ensure, therefore, in winter, ice forms in the joints, complicating the operation of the tunnel.

In FIG. 2 shows a prototype - a tunnel that does not have expansion joints. This was achieved due to the strong reinforcement of concrete. As a result, large cracks disappeared, but the whole concrete is saturated with microcracks, which dramatically reduce the durability of the material, and therefore the entire tunnel.

The goal - increasing the durability of the tunnel - is achieved by the introduction of new elements: organized cracks 8, thermostatic coating 9, the drainage layer 10 with drainage pipes and the insulation layer 11.

In FIG. 4 (section A - A in FIG. 3) shows a cross section of the central 2 section of the tunnel in the case of overlap. The lining 3 (see Fig. 3) is made of monolithic concrete and contains a trough plate 12, walls 13 and a slab 14. Concrete can be reinforced in accordance with calculations. A drainage layer 10 is located throughout the cross-section. For drainage of water, thickenings 15 are provided in the lower part of the tray plate 12, in which drainage pipes 16 are located, which are connected by channels 17 to the drainage layer 10. The drainage layer 10 is located directly on the inside of the lining (position 12 , 13, 14), and the thermo-regulating coating 9 is in contact with it from the inside (cavity 18) 9. The thermo-regulating coating 9 may consist of passive thermal insulation (for example, polystyrene foam), and may contain elements active heat (e.g. heaters). In each case, this is decided in accordance with local conditions.

In the trough zone, the roadway 6 is located. The lining on the soil side can be protected by waterproofing 4. At the level of the day surface 19 of the soil (U P) there is a thermal insulation 11, which is located directly above the tunnel on the width “c” of the tunnel cross section and has side sections with a width of “c”, sometimes with vertical sections 20. Thermal insulation 11 is protected by a protective layer 21.

In FIG. 5 (section B - B in Fig. 3) shows a cross section of the transitional 1 section of the tunnel. The same cross-section can be in the central section with a small overall depth of the location of the roadway 6. The main elements of the cross section are basically the same as in FIG. 4. But the thermal insulation 11 is located only on the outside of the tunnel and is separated from the thermostatic layer 9 by a seam 22. To enable additional heating, heating elements 23 are equipped. FIG. 6 shows a variant of the cross section shown in FIG. 5. In the event that the groundwater level (groundwater level) 24 is lower than the drainage pipelines 16, then the chute part is located directly on the ground 25, while the stability of the walls is provided by spacers 26.

In FIG. 7 (section BB in FIG. 3), a cross-sectional embodiment of the transition section 1 is shown when the level of 24 groundwater (ground water) is below the level of 19 day surface (UE). In this case, the upper part of the lining is made of corrugated metal 27 with a vertical orientation of the corrugations.

In FIG. 8 (section G-D in FIG. 3) shows a variant of the cross section of the central portion 2, when the soil thickness between the floor and the ground surface 19 of the soil is not enough to provide the required temperature regime of the tunnel lining. In this case, the overlap is carried out by the span 28, which through the supporting parts 29 rests on the walls 13.

A tunnel with a temperature negative in winter in its inner part works as follows.

In winter, cold air enters the cavity of the 18 tunnel and cools the inner surface of the tunnel. In addition, the soil mass is cooled from the day surface 19. From the side of the cavity 18, thermostatic coating 9 prevents unacceptable cooling, and from the side of the day surface 19 the heat insulation 11 prevents the unacceptable cooling.

The formation of the temperature regime of the tunnel in the winter is as follows.

In general, a three-dimensional thermal process is going on in the tunnel zone. However, heat fluxes in the direction of the longitudinal axis of the tunnel can be neglected, with the exception of individual nodes. The remaining two-dimensional process is formed due to the relationship of the characteristic one-dimensional processes.

The one-dimensional heat transfer process in the tray part occurs in the calculation zone, which can be represented by the column in FIG. 9: crushed stone of the roadbed 6 from above, then a thermostatic coating 9, a drainage layer 10, a reinforced concrete slab 12 and a base soil 25. It is necessary that in the cold season always the temperature in the area of the drainage layer 10 is positive. This is achieved by the corresponding power of the thermostatic coating 9, on the one hand, and by the heat flux from the deep layers of the soil (for example, the average annual temperature of the soil at a depth of 10 m and more is + 8 ° С in Moscow). Diagram 30 of the distribution of temperature over depth at the most unfavorable moment is shown in FIG. 10. The point M of the transition from the negative to the positive part of the plot is located within the thermostatic coating 9.

The one-dimensional heat transfer process in the floor (see FIG. 4) occurs in the calculation zone, which can be represented by the column in FIG. 11. Here in the winter, cooling occurs both above and below. The condition here must be ensured the same as in the previous case: a positive temperature must be ensured throughout the drainage layer year-round. This is ensured, on the one hand, by the temperature control layer 9, and on the other hand, by the heat reserve accumulated during the summer in the ceiling, mainly due to the soil layer 25. In connection with the foregoing, this design is possible with a certain minimum thickness of this layer. In FIG. 12 shows the temperature distribution (plot 31) over the thickness of the floor at the most unfavorable time: the point N of the transition of the plot from the positive to the negative zone is located within the thermostatic coating 9.

The one-dimensional heat transfer process in the wall is characterized by figures 13 and 14. It is qualitatively similar to the heat transfer process in the tray part (see Figs. 9 and 10).

It is most difficult to ensure positive temperatures in the drainage layer 10 in the upper part of the wall 13 when the section is open at the top. At the most unfavorable moment of time, the outline of the zero isotherm 33 should be provided in accordance with FIG. 15. An increase in thermal insulation may be irrational. In this case, it is advisable to provide the temperature control coating 10 with a heating cable 23, which can be included at extreme times.

Speaking about the operation of the tunnel, it is necessary to note that the waterproofness of the concrete lining is ensured by the fact that its structure provides for “organized cracks” that form in specially weakened cross-sections along the length of the tunnel and are injected when concrete reaches temperatures close to zero. As a result, the water resistance of organized cracks is ensured.

A tunnel with a temperature negative in winter in its interior is constructed as follows.

It should be noted one important feature of the structure that distinguishes the proposed technical solution: this is the formation of "organized cracks" in the process of concreting the lining, the essence of which will be described in the next section.

Characterization of essential features.

The main goal of this technical solution is to increase the durability of the tunnel. This is achieved by several measures.

The first measure (the first significant sign) is organized cracks in the concrete lining of the tunnel. The fact is that during the hardening of the concrete mixture, a large amount of heat is released, and the concrete monolithic lining during production is heated to 60 ° C and above. When cooling, the lining should be reduced in length, but the surrounding soil does not allow free deformations to appear. Stresses arise that significantly exceed the tensile strength of concrete, which leads to the formation of cracks. Cracks occur randomly and at a short distance from each other, which essentially destroys the structure of concrete and sharply reduces its durability. To prevent this, at a certain distance along the length of the tunnel, the cross section is weakened from the surface, as a result, cracks immediately form in weakened places and increase in size as the concrete cools down. The rest of the concrete remains without cracks. Until the crack is opened, the stresses in the concrete are zero. As soon as we inject a crack with a hardening composition, a further decrease in the temperature of the lining will lead to the appearance and growth of tensile stresses. To prevent stresses from exceeding the permissible strength values and, therefore, to prevent new cracks from forming, injection (i.e., closure of parts adjacent to the crack) of organized cracks should take place at the lowest possible temperature. If you close at the lowest winter temperature, then during further operation, stresses will arise only in the summer period, and they will be compressive. However, the expectation of a winter period and the lowest temperature dramatically increases the construction period, so it is advisable to close the lining at a positive temperature. But then there will be large tensile stresses in the winter (and the appearance of cracks).

To eliminate this drawback, a thermostatic coating 9 (second essential feature) is provided in the cross section of the tunnel. The temperature-controlled coating may consist only of passive thermal insulation, and may additionally contain active heating elements, for example, a heating cable 23 (see Fig. 5). The specified coating is calculated so that the inner surface of the concrete lining has a positive temperature all year round.

Despite the presence of waterproofing 4, water may leak through damage to the waterproofing. Leaks can be lower than the groundwater level, and due to surface water flowing from the surface into the deeper layers, and due to rainwater when the cross section is open. To eliminate leaks between the thermostatic coating 9 and the lining, a drainage layer 10 is arranged, which allows you to collect water from any part of the cross section of the tunnel and transfer it to the drainage pipes 16 through channels 17. Thus, the drainage layer, drainage pipes and channels are, respectively, the third, fourth and fifth essential features.

The essential features are such features, reflected in the restrictive part of the formula. Central and transitional sections (sixth and seventh essential features) - characterize unambiguously the composition of the claimed tunnel and are respectively the sixth and seventh essential features. The eighth and ninth essential features are the tray and the walls of the tunnel, since they also uniquely determine the composition of the claimed tunnel.

All of the nine essential features listed above are necessary to achieve the claimed technical result - to increase the durability of the tunnel. Other essential features are not required, therefore, these features are also sufficient.

In a number of special cases, the claimed technical solution can be improved, which is described in paragraphs. 2. 3, 4, 5, 6 claims. Additional essential features that make it possible to achieve the claimed technical result under more appropriate conditions in a simpler way are: overlapping (Fig. 4) in the central section of the tunnel (the tenth essential feature), a slab (Fig. 4) made of reinforced concrete (eleventh essential feature), thermal insulation ( Fig. 5), laid at the level of the daily surface of the soil outside the section of the tunnel (the twelfth essential feature), part of the wall (Fig. 7) made of corrugated metal (the thirteenth essential feature) and the drainage scheme layer (fourteenth essential feature).

The effectiveness of the proposed technical solution is determined, first of all, by achieving the main goal - increasing the durability of the tunnel. At the same time, another effect was obtained - a significant improvement in operating conditions. All this is achieved by:

- lack of expansion joints;

- lack of cracking in concrete;

- Removing the problem of frost resistance of concrete lining (year-round positive temperature);

- establishing drainage in the winter;

- lack of ice.

application

to the description of the invention

(article from the journal Metro and Tunnels, No. 2, 2001

“Construction of a tunnel under the Moscow Canal”)

Claims (8)

1. A tunnel with a negative air temperature in winter in its inner part, containing along its length a central section located at the calculated depth, and two transitional sections open at the top connecting the central section to the ground surface of the soil, all three sections in cross section contain a tray with a roadbed located above it and concrete walls, and are made continuous without expansion joints, characterized in that it contains a temperature-controlled coating, a drainage layer, a drainage pipe wires, and all concrete elements of the tray, walls and floors contain organized cracks, while the drainage layer is located on the surface of the tray and walls from the inside of the tunnel, the temperature control coating is located directly on the drainage layer throughout this layer, drainage pipelines are located in the lower part tray and connected by channels to the drainage layer, and organized cracks are located simultaneously along the entire transverse concrete section, formed in places of focused weakening of the concrete section at the calculated points and injected with a composition having no less than concrete strength, while the distance along the tunnel length between the organized cracks is assigned by calculation. 2. The tunnel according to claim 1, characterized in that the central section has an overlap containing a concrete floor slab located on the lower surface of the slab first with a drainage layer and then with a thermostatic coating, and on the upper surface with a soil layer and then a thermal insulation layer, with a drainage layer the layer, thermostatic coating, the soil layer and the thermal insulation layer are located throughout the entire cross section. 3. The tunnel according to claim 1, characterized in that the tray at a groundwater level above the level of drainage pipelines is made in the form of a slab of reinforced concrete. 4. The tunnel under item 1, characterized in that it contains a layer of insulation located at the level of the surface of the soil outside the section of the tunnel on each side to a width of "C", while C = 4h _p , m where h _p - the depth of seasonal freezing of the soil when exposed to snow surface. 5. The tunnel under item 1, characterized in that the walls above the groundwater level are made of corrugated metal with a vertical orientation of the corrugations. 6. The tunnel under item 1, characterized in that the drainage layer is made of porous material with open pores.

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