RU2665097C1 - Ground dam in the permafrost zone freezing system and dam with its application - Google Patents

Abstract

FIELD: construction.SUBSTANCE: invention relates to the field of hydraulic engineering construction, namely, to the structures operation under conditions of the northern construction and climatic zone. Ground dam freezing system in the permafrost zone on the permafrost base 1 contains the anti-filtration core 2 with built-in freezing columns 8, configured to pass the liquid cooling medium through the columns. As cooling medium (heat carrier), the natural (genuine) brine is used. Into the freezing system 8 the brines are supplied from the brine storage 15 by means of pump 10 via the brine supply pipeline 11 and the spent brines are taken back to the brine storage 15 via the brine outflow pipeline 12. Brine take-up unit can be designed in the form of telescopic pipe. As minimum, the brine take-up unit 9 can be located at a distance from the brine storage 15 bed bottom, which prevents solids ingress into the brine take-up unit 9. Anti-filtration core 2 of the dam can be backfilled from the soil (for example, loam), moistened with fresh water until the full moisture capacity state. Dam may contain the upper 4 and the lower 5 thrust prisms from the dispersed soil or rock filling, transition zones 6 and 7 from sand, from the upstream side in the transition zone, the anti-filtration geosynthetic salt shield 3 is established, which transits into the blanket. Year-round stability and reliability are achieved by using the natural year-round refrigerating machine, formed in the brine storage, and using the anti-filtration core from the soil moistened with fresh water to the full moisture capacity state, which provides year-round stability of the core. Invention can be applied during the dams in the permafrost zone construction.EFFECT: increase in operation reliability and stability; obtaining the possibility of brines storing in the bounded by a dam water reservoir is provided by the anti-filtration geosynthetic salts protection screen, which transits into the blanket, providing the containing fresh ice dam core insulation.5 cl, 1 dwg

Description

The invention relates to the field of hydraulic engineering, namely to the operation of structures in the northern climatic zone.

During the development of minerals in the permafrost zone, underground waters of increased mineralization (brines) are discovered, which have negative temperatures and interfere with mining operations in pits. To carry out dry work, the brines are pumped to specially created brine storage tanks formed with the help of soil dams.

The problem of ensuring the stability of soil dams in the permafrost zone during operation is still relevant. Practice has shown that frozen dams, where antifiltration and static stability are ensured by frozen soils, are 30% more economical than thawed type dams. In addition, in severe climatic and difficult geocryological conditions (the presence of an ice complex) in most cases it is possible to use only frozen dams.

Waterworks for storing brines in the permafrost zone are specific hydraulic structures. Their specificity is manifested in the fact that the brines during operation acquire in depth the characteristic temperature and hydrochemical regime. It has been established that bottom layers throughout the year have a stable negative temperature ranging from –4.0 ° С to –8.3 ° С [1, 8]. However, due to the fact that brines have a high salt concentration (120-130 g / l), they replace ice in frozen soils and turn it into a brine in the presence of negative temperatures. Having passed into a new cryogenic state, the soil acquires properties close to melt, and sharply lose their filtration and static stability. This is where the problems of the stability of the dams as a whole arise, and this, in turn, is associated with environmental problems, especially hydrological, biological and other systems of entire regions.

The well-known “SOIL DAM ON A PERMANENT FROZEN BASIS” RU 2453655 [7], containing a central part made from the base of the dam to its crest from fine-grained soil, upper and lower side prisms and an anti-filtration diaphragm, and from the lower side to the anti-filter seepage which is made by means of freezing columns and freezing connected to an anti-filter diaphragm. The dam contains a screen turning into a ponur.

The disadvantage is the low reliability of the dam, due to non-year-round operation of freezing devices and the possibility of loss of tightness of the dam. The disadvantage is the low stability of the known dam to salt solutions and the inability to use the reservoir, limited by the dam, for storing natural brine.

Closest to the invention in terms of the problem being solved is a cooling and freezing system for the soil of the body and the base of the dam, containing wells drilled at a certain pitch along the dam in one or two rows [6]. Wells are combined into collector systems through which an artificially prepared solution is pre-cooled in freezing stations. Typically, a salt solution of calcium chloride is used as a brine. The known solution [6] is considered by the authors as a prototype.

A disadvantage of the known system is:

- the need for salts to prepare a cooling solution;

- the need to prepare a brine;

- the presence of special installations for cooling the solution;

- the need to cool the solution to a predetermined temperature.

The objective of the invention is to increase the stability of the dam, the effectiveness of the system through the use of natural cryogenic resources - brines with negative temperatures stored in the brine storage and considered as a natural refrigeration machine to create a frozen antifiltration massif in the body and base, as well as the use of a geosynthetic saline screen with silt, providing additional filtration stability of the structure.

The technical result of the invention is to increase the reliability and year-round stability of the dam, getting the ability to store brines in a reservoir.

The technical result is achieved by the fact that the freezing system of the soil dam in the permafrost zone (on permafrost), containing an anti-filter core with built-in freezing columns made with the possibility of passing through the columns of liquid cooling medium, brine (water solution) is used as a cooling medium (coolant) salts), characterized in that the brine is used natural (natural), brines in the freezing system are fed from the brine using a pump according to giver rassoloprovodu and waste from a recovery brines rassoloprovodu withdrawn back into rassolohranilische. The specified implementation will save the environmental friendliness of the system as a whole.

The brine collection unit can be structurally designed in the form of a telescopic pipe, which provides vertical movement of the brine intake along the entire depth of the brine storage and is able to select the brine from the desired depth.

Minimum brine intake can be located at a distance h from the bottom of the brine storage bed to prevent solids from entering the brine intake.

The anti-filtration core of the dam can be sprinkled from soil (for example, loam) moistened with fresh water to a state of full moisture capacity, which allows freezing to form a continuous frozen waterproof monolith (ice-ground frozen curtain - all pores in the frozen ground mass are filled with ice) and maintain its stable state at relatively small negative temperatures of the coolant provided by year-round pumping of the brine through the freezing columns.

The dam may contain upstream and downstream persistent prisms made of dispersed soil or stone sketches, transition zones made of sand, an anti-filtration geosynthetic salt-shielding screen, turning into a mud, is arranged on the upstream side in the transition zone, which will increase the stability of the dam.

The device is schematically shown in FIG. 1 (section), where:

1 - permafrost base;

2 - frozen anti-filtration core from loam;

3 - geosynthetic salt-protective screen turning into ponur;

4 - riding persistent prism;

5 - bottom persistent prism;

6 - riding transition zone of sand;

7 - lower transition zone of sand;

8 - freezing device;

9 - pickle pickup;

10 - pump;

11 - supply brine line;

12 - discharge brine pipe;

13 - inlet collector;

14 - outlet manifold;

15 - brine storage.

The device operates as follows.

The structure of the hydroelectric complex includes the following structures: soil dam, freezing system, brine storage.

A soil dam is built on a permafrost foundation 1 and contains a frozen anti-filtration core from loam 2; geosynthetic salt shield 3, turning into ponur; top and bottom thrust prisms from dispersed soil or stone sketches 4 and 5; sand transition zones 6 and 7; freezing device 8. The antifiltration core 2 is sprinkled from the soil moistened with fresh water to the state of full moisture capacity. The freezing system contains the following structural elements: freezing device 8; telescopic pickup 9; pump 10; supply 11 and discharge brine pipes 12; inlet 13 and outlet 14 collectors; brine storage of natural brines 15.

On the downstream side, a geosynthetic screen 3 (of HDPE type) is laid along the transition slope of the core and at the base of the upper thrust prism in the form of a dam pond along the transition layer of sand 7. On the downstream side, an ice-ground permafrost curtain, which is created by freezing columns, adjoins the anti-filter screen 3 system 8 and hermetically attached to the screen as a result of freezing.

The use of the invention will improve the reliability of the dam due to the efficiency of the year-round operation of the freezing system, forming a frozen curtain in the body and the base, and the use of a geosynthetic screen with a drop provides additional filtration, including salt-proof, stability of the structure.

The technical result is achieved through the use of brine storage as a natural freezing machine, providing the formation and long-term existence of brines with low negative temperatures, used to maintain the body and foundation of the dam in a frozen state, as well as the use of a geosynthetic screen with sediment, which provides a filtration, including salt-proof, stability of the structure.

What is new is that in the circulation cooling circuit natural solutions are used, low negative temperatures, in which they are formed due to the heat exchange of the brine storage tank with the environment.

Known systems for cooling and freezing soil [2-5]. The working fluid in the devices uses air, liquids (kerosene, specially prepared solutions, etc.), vapor fluids (carbon dioxide, ammonia, freon, etc.). The movement of fluid in cooling and freezing devices can be carried out either due to natural convection or artificial forced convection. In most cases, these plants are seasonal in action (SDA). Work when establishing stable negative values of air temperature.

As analogues, dams of industrial enterprises were considered: a dam on the river. Long, on the river. Miaunge, on the river Sytykan et al. [6], including the brine dam on the brook. Tymtydaah [1].

Field studies have shown, as noted above in the text, that specific temperature and geochemical conditions are formed in the brine storage during operation. In the vertical section, several zones are established during the year, the temperature in which is much lower than constant negative temperatures in the bottom layers of the brine storage [1]. To increase the efficiency of the cooling system, it is advisable to use this phenomenon. This can be achieved constructively by using a telescopic pipe capable of moving the brine intake vertically to pick up the brine. The brine intake drops to a distance h from the bottom, which is assigned from the condition for eliminating erosion of the brine storage bottom during system operation.

The technical result provided by a combination of design features and the use of natural brine with a negative temperature is to increase the efficiency of the system due to the lack of the need to prepare a special cooling solution using a special machine to cool the prepared solution to a predetermined temperature and there is no requirement for a specific freezing configuration wells, and the use of a geosynthetic salt shield and ponura ensure ivayut filtration resistance structures and ecological safety of the environment.

New is that to fill the dam cooling system with a coolant, natural solutions of increased mineralization are used, which, as a result of heat exchange of the brine storage tank with the environment, constantly have negative temperatures in the required amount to maintain the temperature and body of the dam of the cryogenic mode, and the use of a geosynthetic salt shield and ponur provide filtration stability of the structure and environmental safety.

The technical result - improving the reliability and stability of the work - is achieved by using a natural year-round refrigerating machine formed in a brine storage.

The technical result - year-round stability - is achieved by using an anti-filtration core from the soil moistened with fresh water to a state of full moisture capacity, which ensures year-round stability of the core in a frozen state.

An additional technical result - the emergence of the possibility of storing brines in a reservoir limited by a dam, is provided by an anti-filter geosynthetic salt-shielding screen turning into ponur, providing isolation of the core of the dam containing fresh ice.

Industrial application. The invention can be applied in the construction of dams in the permafrost zone.

Information sources

1. Alekseev S.V. Cryohydrogeological systems of the Yakut diamondiferous province. - Novosibirsk: Academic Publishing House "Geo", 2009. - 319 p.

2. Gapeev S.I. Strengthening frozen bases by cooling. L .: Stroyizdat - 1969. - 104 p.

3. Makarov V.I. Thermosiphons in northern construction Novosibirsk: Science. - 1985. - 169 p.

4. Dolgikh G.M., Dolgikh D.G., Okunev S.M. Technical solutions for the freezing of base soils used by the NGO Fundamentstroyarkos // Materials of the international. Conf. "Cryosphere of oil and gas provinces." Tyumen, 2004 .-- p. 56.

5. Sidnyaev N.I., Khrapov P.V., Razgulyaev S.V. Review and analysis of systems for cooling and freezing soils. Materials of the International scientific-practical conference on permafrost engineering dedicated to the 20th anniversary of the foundation of NPO Fundamentstroyarkus LLC. Tyumen: City-Press. - 2011. - p. 156-183 (456 s).

6. Biyanov G.F. Dams on permafrost. M .: Energy. - 1975. - 184 p.

7. RF patent No. 2453655. Soil dam on permafrost. / Yagin V.P., Vaikum V.A., Ogol V.G., Grishin V.A. ЕВВ 7/06, publ. 02/28/2011.

Claims (5)

1. The freezing system of a soil dam in the permafrost zone, containing an anti-filtration core with built-in freezing columns, made with the possibility of passage through the columns of liquid cooling medium, a brine is used as a cooling medium, characterized in that the brine is used natural, brines are fed into the freezing system from brine storage using a pump through the supply brine pipe, and spent brines through the discharge brine pipe are taken back to the brine storage tank. 2. The system according to claim 1, characterized in that the brine assembly is designed in the form of a telescopic pipe, which provides vertical movement of the brine intake over the entire depth of the brine storage. 3. The system according to claim 2, characterized in that the minimum brine intake is located at a distance from the bottom of the brine storage bed, eliminating the ingress of solid particles into the brine intake. 4. A dam with a freezing system according to claim 1, characterized in that the anti-filtration core is sprinkled from the soil moistened with fresh water to a state of full moisture capacity. 5. The dam according to claim 4, characterized in that it contains upstream and downstream thrust prisms made of dispersed soil or stone sketches, transition zones made of sand, an anti-filtration geosynthetic salt-shielding screen turning into ponur is arranged on the upstream side in the transition zone.

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