Continuity monolithic construction allows you to observe the heating of concrete in winter time. The regulation of work is provided in SNiP 3-03-01-87 (updated joint venture 70.13330.2012). There are prescribed measures that do not allow water freezing in solution, the formation of ice on the reinforcement frame at the average daily temperature below + 5 ° C, the minimum is less than 0. The methods are characterized by equipment, costs of means and energy.

The main requirement for obtaining guaranteed quality structures is to carry out work at a prescribed pace and a clear sequence, without digressive projects. During transportation, the solution should not be cooled below the calculated temperature. It is allowed to increase the mixing time by 25%.

On the perplexed soils, the fill of the structures occurs on SNIP II-18-76. The method is chosen not so much at the cost part, as in high-quality indicators of the product obtained as a result.

During the frost, the warming of concrete is carried out by the following main ways:

1. Thermos. In the solution at the factory add hot water (40-70 ° C) and put it in a warmed formwork. When setting in the process of hydration, about 80 kcal of heat is distinguished, which are added with the existing mixture temperature. The thermal insulation holds the mass from freezing to the set of the desired strength indicator. Exothermic effect is often combined with other methods.

2. Contamination additives. The technology of their use and properties attached to concrete are indicated by the manufacturer in the product passport. The formwork should prevent the fast heat loss. This indicator is envisaged design calculationMaximum value does not exceed 10 ° C / h. Fragments that may cool faster (protrusions, narrowing section) are coated from accelerated evaporation with waterproofing, insulation or organize their heating. Permanent control of the surrounding temperature is underway so that if it is reduced less permitted to take additional measures.

3. Heated by air. In the closed space, heating the convective movement of heated air is organized. From the tarpaulin canvas, it is possible to build warmth over the shaft form and maintain the desired temperature using a heat generator (diesel or electrocalorifer). For the uniform distribution of hot air flow injected with a fan, a special sleeve with perforation is used.

4. Steaming. Given the complexity of equipment and energy consumption, it is massively used in the factory conditions to create elements of prefabricated structures. The technology assumes the fill of concrete into the formwork with double walls, which serves hot steam. It creates a "steam shirt" around the solution providing uniform hydration. It is used in a complex with plasticizing additives.

5. Heating formwork. The method is common in the rapid construction of structures ( monolithic buildings). To do this, the concrete must be at high sprouting. Electrical heating comes from the border of the contact with the formwork in the grinding array. It is the heating cable along the outer surface of the form. In order not to form air becks, it is removed by a vibrator. The method is used to fill in winter thin and medium walls (with or without reinforcement). It is characterized by the requirements for temperature - the mixture and the soil to a depth of 0.3-05 m are pre-heated to + 15 ° C.

The most economical methods include electrical heating technologies that cover the entire volume of the mixture (electrode, transformer, cable collected in a specific scheme).

Electrode heating concrete

The principle is based on heat release during current passage through a liquid solution between the rods to which the voltage from the transformer is supplied. The method does not apply in thick reinforced designs. Well pointed himself when erecting screeching and ribbon foundations in winter.

AC power transformer with voltage from 60 to 127 V. For products with steel reinforcement carcass Need an accurate design calculation of the circuit and parameters of the electrical circuit.

The electrode can be of different types:

• rod, size Ø6-12 mm;
• string (wire Ø6-10 mm);
• surface (plate width 40-80 mm).

Rod electrodes are used on remote fragments of large and complex form constructions. They are installed no closer than 3 cm for formwork. String options are intended for extended areas. This scheme is preferable when contacting concrete with a frozen base. Surface tapes are fixed directly on the formwork, they are packeroid and are not in contact with the solution.

The depth of electrical heating electrodes is 1/2 distances between the rods or stripes. The warm mass of the surface covers the inner layers, where the processes are less intense. Increase the release of energy in concrete can be supplied to electrodes through a transformer different phases.

After soaring the monolith, the immersed electrodes remain inside, the protruding parts are cut off. The main advantage of using the electrodes is the ability to continuously maintain temperature, specific project technology, in the designs of any shape and thickness.

Warming up by transformer

Based on the immersion of the heating cable connected to the downstream transformer. To do this, take the conductor of the PNSV brand from 1.2 to 3 mm. It is placed in increasing at least 15 mm so that it is completely immersed in the solution. The output ends for connecting from the transformer are made from aluminum APV-2.5; APB-4.

The calculation of the scheme is based on the fact that heated 1m³ you need about 1.3 kW of power. The value depends on the air temperature - the colder in winter, the more energy you need.

For heating with a wire PNSV of each 1m³ of concrete, 30-50 m of the cable is needed. The calculation will definitely show, since with the "Star" connection scheme in each piece of wire requires a current of 15 A, "Triangle" (PNSV 1,2) - 18 A.

The selection of the VET cable or KDBS will eliminate the transformer with electrodes from technology. It is resorted to this method if there is no ability to apply the desired number of devices on a remote object or no power supply. The vehicle is connected to the household power grid, the kit includes couplings. For it, they take a connection scheme similar to PNSV.

It is necessary to maintain the temperature using a transformer with a smooth adjustment of the current force. For small individual construction, the usual welding machine. Industrial stations KTPTO-80/86, TSDZ-63, SPb transformers give the heating of the order of 30 m³ of concrete.

The latest methods of warming up

Improving technology made it possible for heating columns, beams of overlappings and others relative thin elements Apply infrared devices. They are made in the form of thermomats that turn out outside the frozen form. Warming occurs evenly, throughout the contact surface. For standard products use solid heaters made in size.

The brand concrete in vivo is gaining strength in 28 days, thanks to infrared effects, the hydration process takes place in 11 hours. The installation and complexity of structures is greatly simplified, the speed of this part of construction during operation in winter increases.

The incidence of a relatively small cross section (columns, piles) was the induction method. The rise in temperature inside the shape occurs under the influence electromagnetic fieldcreated by the cable shoes. Such an induction winding warms the metal of formwork and reinforcement, the heat released turns into a frozen solution. It is characterized by uniformity, the ability to pre-raise the temperature of the formwork and the reinforcing frame before the fill.

The temperature of the heating of the monolith to the set of a given fortress is set depending on the class: B10 is gaining 50%, B25 - almost 30%.

Product quality made in concrete produced in winteris controlled regardless of the warming methods (immersion of the electrode or surface impact) according to SNiP 152-01-2003.

Articles

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The development of the soil associated with the chunks of the trench in winter conditions is complicated by necessity pre-training And heating the frozen soil. The depth of the seasonal freezing of the soil is determined according to meteorological stations.
In urban conditions, if large number Existing cable lines and other underground communications The use of shock instruments (jackhammers, scrap, wedges, etc.) is impossible due to the danger of mechanical damage to the current cable lines and other underground communications.
Therefore, a frozen primer before the start of work on the ridge of the trench in the area of \u200b\u200bthe active cable lines should be pre-warmed so that earthworks will be shovel without the use of shock tools.
Soil heating can be carried out by electric reflector furnaces, electrical horizontal and vertical steel electrodes, electric three-phase heaters, gas burners, steam and water needles, hot sand, cereals, etc. Ways of heating soil, in which heating needles are entered into frozen soil by drilling Wells or their driving, not received applications, since this method is effective and its use can be justified economically with a lean depth of more than 0.8 m, that is, at a depth, which is not used for cable work. Soil heating can also be conducted by high frequency currents, however, this method has not yet received practical application Due to the complexity of equipment and low coefficient useful action Installations. Regardless of the method of the adopted method, the warmed surface is pre-cleaned from snow, ice and upper bases of the base (asphalt, concrete).

Soil Heating Electric Current industrial frequency With the help of steel electrodes laid horizontally on the ice cream ground, is to create an electric current chain, where the frozen soil is used as resistance.
Horizontal electrodes from strip, angular and any other profiles of 2.5-3 m longs are laid horizontally on frozen soil. The distance between the rows of electrodes included in the variance phases should be 400 - 500 mm at a voltage of 220 V and 700-800 mm at a voltage of 380 V. due to the fact that frozen soil does not conduct poorly electricityThe surface of the soil is falling asleep with a layer of sawdust moistened in an aqueous salt solution with a thickness of 150-200 mm. In the initial period of inclusion of the electrodes, the main heat is transferred to the soil from sawdust, in which intensive heating occurs under the influence of electric current. As the soil is heated, increasing its conductivity and passing through the soil of electric current the intensity of the heating of the soil rises.
In order to reduce heat loss from scattering, the sawdust layer is compacted and covered with wooden shields, mats, tale, etc.
Consumption electrical Energy For heating the soil using steel electrodes, the humidity of the soil is largely determined and ranges from 42 to 60 kWh per 1 m 3 of the solar soil with a heat of heating from 24 to 30 hours.
The work on the defrosting of the soil by electric shock should be carried out under the supervision of qualified personnel responsible for compliance with the mode of heating, ensuring the safety of work and serviceability. These requirements and difficulties of their implementation, of course, limit the possibility of using this method. The best and more secure method is the use of voltage up to 12 V.

Fig. 15. Construction of three-phase heaters for soil heating

a - heater; b - inclusion scheme; 1 - rod steel diameter 19 mm, 2-cut steel with a diameter of 25 mm, 3-cutting steel with a diameter of 19-25 mm, 4 - Contacts Copper cross section 200 mm 2, 5 - steel strip 30x6 mm 2.

Electric three-phase heaters Allowed to produce soil at a voltage of 10 V. The heater element consists of three steel rods, each rod is inserted into two steel pipes, the total length of which is 30 mm less than the length of the rod; The ends of the rod are welded with the ends of these pipes.
Space between the rod and internal surface each pipe was covered with quartz sand and for sealing is flooded with liquid glass (Fig. 15) - the ends of the three pipes located in plane aa, interconnected by a strip of steel welded to them, forming a neutral point of the heater star. Three end of pipes located in plane b-bWith the help of the copper clamps fixed on them, they are joined through a special pioneering transformer with a capacity of 15 kV-a to electrical network. The heater is placed directly to the soil and falling asleep with a thickness of 200 mm thick. To reduce heat losses, the warmed plot is additionally covered with fiberglass mats.
The consumption of electrical energy for heating 1 m 3 of the soil with this method is 50-55 kWh, and the heating time is 24 hours.

Electric reflex oven. As the experience of maintaining repair work has shown in the conditions of urban networks, the most convenient, transportable and fast under the same conditions determined by the degree of freezing, the nature of the heated soil and the quality of the coating is the heat of heating with electric reflex crums. As a heater in the furnace, nichrome or fahe-worry wire with a diameter of 3.5 mm, piled by a helix on an insulated asbestos steel pipe (Fig. 16).
The reflector of the furnace is made of bent along the axis in parabola with a distance from the reflective reflector to the spiral (focus) of 60 mm aluminum, duraluminum or steel chrome-plated sheet with a thickness of 1 mm. The reflector reflects the thermal energy of the furnace, directing it to the portion of heated ice cream soil. To protect the reflector from mechanical damage, the furnace closes with steel casing. There is an air interval between the casing and the reflector, which reduces heat loss from dispersion.
The reflex furnace joins the electrical network with a voltage of 380/220/127 V.
When the soil is heated, a set of three single-phase reflector furnaces is collected, which are connected to a star or triangle, respectively, the network voltage. The heating area of \u200b\u200bone furnace is 0.4x1.5 m 2; Power kit 18 kW stoves.


Fig. 16. Reflex furnace for heating soil ice cream.
1 - heating element, 2 - reflector, 3 - casing; four - contact clamps
The consumption of electricity for heating 1 m 3 of the solar soil is approximately 50 kWh with a duration of heating from 6 to 10 hours.
When using the furnace, it is also necessary to ensure safe conditions for the production of work. The heating site should be fenced, the contact clamps for connecting the wire are closed, and the spirals of the leaks should not touch the soil.

Heat of frozen frozen fire.For this purpose, both liquid and gaseous fuel are used. Solar oil is used as liquid fuel. Its consumption is 4-5 kg \u200b\u200bper 1 m 3 of heated soil. The installation consists of boxes and nozzles. With the length of the boxes 20-25 m, the setting per day makes it possible to heat the ground at a depth of 0.7-0.8 m.
The process of heating lasts 15-16 hours. For the rest of times, the daytaking of the soil occurs due to the accumulated heat of its surface layer.
A more efficient and economic fuel for heating the soil is gaseous.
Gas burner used for this purpose is a segment of a steel tube with a diameter of 18 mm with a flattened cone. Hemispherical boxes are made of sheet steel with a thickness of 1.5-2.5 mm. For savings (heat loss boxes are sprinkled heat insulating layer Soil thickness up to 100 mm. The cost of heating soil gas fuel It averages 0.2-0.3 rubles / m 3.
Heated grounds of chipples applied with a minor work (digging of buttons and trenches for insertion). The fire is diluted after clearing the place from snow and ice. For greater efficiency, heating the fire is covered with 1.5-2 mm thick sheets. After the soil is heated to a depth of 200-250 mm, which is installed by a special steel probe, give the fire to burn out, after which they choose the shovels of the soil. Then, at the bottom of the resulting depressions, the fire is again breeding, repeating this operation until the ice creaming ground is selected for the entire depth. In the course of work on the heating of soil, it is necessary to ensure that the water from the melting snow and ice does not pour the fire.
In the process of heating the soil, the active cables may be damaged as a result of the effects of the heat heater. As experience has shown, for proper protection of the acting cables during the heating of the soil, it is necessary that a layer of at least 200 mm with a thickness of the earth is maintained between the heater and cable during the entire heating time.

When inclusable with the help of the cathodes of the ground section into the electrical circuit, the heating current of 120, 220 and 380 V can be missed through it.

The electrical conductivity of the soil depends on its humidity (Fig. 3, a), state and temperature of moisture, concentrations are in the ground solutions of salts and acids (Fig. 3, b), the structure and temperature of the soil (Fig. 3, c), etc. .

The complexity of the structure of the soil occurring physical phenomena and changes related to power processes, significantly complicates the theoretical side of the soil electrical heating, which is still in the study stage.

Fig. 1. Installation of horizontal (stringed) electrodes on frozen soil with filling sawdust
1 - frozen soil; 2 - horizontal (inkjet) electrodes with a diameter of 12-16 mm; 3 - wires, supplying current; 4 - sawdust moistened with salt solution; 5 - upper insulation (only wooden shields, mats, etc.)

Fig. 2. Installation of vertical (rod) electrodes in frozen soil with frighting sawdust
1 - vertical electrodes; 2 - wires supplying current; 3 - sawdust, moistened with salt solution, 4-top insulation (only tol, wooden spits, mats, etc.)

Taning the soil is performed using horizontal (shunt) and vertical (rod and deep) electrodes. When thawing with horizontal electrodes (Fig. 1), the surface of the heated portion of the soil is coated with a 15-25-cm layer moistened with aqueous salt solution (sodium chloride, calcium, copper Kaper et al.) Having assignments only to give the current and warm up the top layer of frozen soil, since the latter even at a voltage of 380 almost does not pass.

With horizontal electrodes, heat is transmitted initially soil only from the heating layer of sawdust. Only the upper minor thickness of the soil layer adjacent to the electrodes is turned on in the electrical panel and is the resistance in which heat is distinguished.

The distance between the rows of electrodes included in different phases is 40-50 cm at a voltage of 220 V and 70-80 cm at a voltage of 380 V. The use of horizontal electrodes is advisable in heating the frozen bases and a small (up to 0.5-0.7 m) of the depth of freezing, as well as in cases where the vertical (rod) electrodes cannot be applied due to the small electrical conductivity of the soil or the impossibility of driving them into the ground.

When thawing with vertical rod electrodes, wet sawdusts first serve as an initial to warming up the upper layer of soil, which, as it turns on to the electrical circuit, after which the sawdust only reduces the heat loss of the thawed soil. Instead, sawdust can serve solutions of salts poured into the grooves in the ground, punched with chisel between all electrodes to a depth of 6 cm.

When shelting the surface of heated soil with a layer of dry sawdust, as practice shows, the device of such groove gives good results.
The use of vertical electrodes is more efficient at a depth of frozen soil more than 0.7 m, as well as if it is impossible to ensure proper contact between horizontal electrodes and soil. In solid (clay and sandy soils with a humidity of more than 15-20%) electrodes are clogged to a depth of 20-25 cm, and then immersed deeper as the soil is thawed (approximately every 4-5 hours).

The distance between the electrodes is prescribed from 40 to 70 cm depending on the voltage, the nature and temperature of the soil. When thawing to a depth of 1.5 m, it is recommended to have two sets of electrodes - short and long; By thawing the soil to the depth of short electrodes, they are replaced with long. Heated soil to a depth of 2 m and more should be made in several techniques, layered with a periodic removal of the outlined layers when the current is turned off. In order to save electricity and the maximum power use, it should be strive to strive to the end of the exhaustion, the temperature of the soil does not exceed + 5 ° and the maximum + 20 °, and the heating should be partitioned by periodically turning off the current.

Fig. 3. Change specific resistance Soil in action
A - from the moisture content of the red clay soil, b - from the contents of NACI in the clay ground with 30% of its humidity (by weight), 8 - from the soil temperature with humidity 18.6%

Installation for thawing the soil consists of shields and sofit (4-5 per each distribution shield) To connect electrodes to the network.

When using deep electrodes, thawing of frozen soil is produced from the bottom up to its daily surface. For this, the round steel electrodes with a diameter of 12-19 mm (depending on their length and soil hardness) are scored through the entire thickness of the frozen layer by 15-20 cm into a telly soil. At the beginning of the thawing, the electric current extending in the soil mob, heats it and pulls the part of the illuminated layer directly directly. Thus, the heat flux, gradually increasing the thickness of the bottom up, sequentially heats the frozen soil, and almost all the heat released heat is used to yield the frozen layer.
This method of thawing, in addition to reducing heat loss, gives a number of other benefits.

As it is known, excavators can develop without preliminary loosening the frozen crust of the soil with a thickness of up to 25-40 cm, which makes it possible to reduce the depth of the soaked soil. Since the upper layers of the soil are usually the most complex and energy-intensive, then developing them in non-taxable state reduces electricity consumption and accelerates the production of work.

The use of higher voltage makes it possible to increase the distance between the electrodes. The latter at a voltage of 220 V is taken in 0.5 m, and at 380 V is already 0.7 m.
The lower end of the electrode is sharpened, and in the top drill through hole with a diameter of 3-4 mm, through which the copper bare wire is passed 25-30 cm; One end of the wire is welded to the electrode, and the other join the electrical network with the subsequent alternation of the phases.

In case of difficulty driving electrodes, wells in diameter, which is 1-2 mm less than the adopted diameter of the electrode.
According to the experimental data of Sukhlinka with a humidity of 18% with a depth of 1.5 m and the voltage of the current 220 V is thawing for about 16 hours.
Heated platform allocate portable fence And multiplied with warning signals with a categorically prohibition of entering it.
When applying any method of heating the soil, it is necessary to strictly follow the rules set forth in the special "instructions for the use of electrical heating in construction.

Towing high frequency currents. Frustrated soil permeate for high frequency currents, and he warming it occurs due to heat allocated in the ground when placed it and variable electric field High frequency.
The high frequency generator consists of an increase in transformer, rectifier, generator lamps, capacitors and an oscillatory circuit. Mobile installation is mounted in the trapper and feeds from a voltage of 220-380 V or from a mobile power station.
The method is possible with a small amount of work, the development of trenches and especially in emergency work, when the deadline for execution is a decisive factor.

Our country is located in northern latitudes. Winter S. negative temperatures takes a lot of time from builders. However, it is possible not to stop capital construction, if you take the heating of the soil. Such a procedure is becoming increasingly popular. In this article we will talk about the basic ways to warm the soil.

Why do you need soil warming in winter?

When construction is carried out within the city, remove frozen soil with the help of jackhaft equipment becomes dangerous. You can easily damage underground communications, which are so many in the city: cable lines, water pipes, gas pipelines. In such places, it is often possible to remove the soil. In winter, the ground with shovels do not get out of the trench. Therefore, the grove is ordered immediately before starting construction work. At the same time, we order the warm-up of concrete after filling the foundation for its hydration and proper hardness set.

What are the ways to warm up soil?

It is possible to warm up the land in place of construction in a multitude of ways. They differ not only by costs, but also efficiency. We list the main of them:

1. Were warm water.Such a method is suitable for defrosting small land plots. By area, labyrinths of flexible sleeves are placed, which are covered with polyethylene or any heat insulator. Sleeves are allowed heated to 70-90 degrees Celsius water. To do this, use a thermal generator or pyrolysis boiler. Defrost speed - no more than 60 cm per day. Disadvantages - high cost of equipment and low speed Warming up
2. Warming steam and steam needles. The plot is drilled well depth from one and a half to two meters for special metal pipes diameter up to 50 mm. These so-called needles have no more than 3 mm at the ends of the hole. Pipes are placed in a checker manner every 1-1.5 meters. The needles serves a saturated water vapor (temperature - more than 100 degrees Celsius, pressure - 7 atmospheres). This method is applied only for deep boobs - more than 1.5 meters. Disadvantages are complex preparatory work, release large volumes of condensate and the need for constant control of the process.
3. Warming up with fans. This method is similar to the steam needles used by the instrument. Also used pipes 1 meter long and a diameter of up to 60 mm. They are installed in bored wells at the same distance. Inside the pipes there is a liquid dielectric with high thermal conductivity. Tanes are connected to the power grid. Electricity consumption per 1 cu. Meter of the Earth - 42 kW * h. Disadvantages - high costs.
4. Heating with electric mats. The method involves the use of infrared mats operating on the principle of similar mats for "warm sex." The electromates heat the soil to a temperature of 70 degrees. The depth of heating is not more than 80 cm in 32 hours. Electricity consumption - 0.5 kW * h per 1 square meter. Disadvantages - fragile material, need for constant control.
5. Warming by ethylene glycol by installing Waker Neuson. The equipment works on diesel fuel. From this point of view, it is autonomous and does not depend on the lodging of communications (electricity). By area, the snake area unfolds the hose on which heated ethylene glycol will circulate. This liquid is characterized by the highest thermal conductivity and greater than that of water, the boiling point. Hoses are covered with mats from thermal insulation. One installation allows you to defrost 400 square meters To the depth of 1.5 meters in 8 days.

Our company offers soil and concrete warming services precisely using the Waker Neuson installation. This method is considered to be the most effective in terms of the cost of the area area and at the time of defrosting.

A significant part of Russia is located in zones with long and harsh winter. However, construction is carried out here round year, in connection with which about 20% of the total earthworks It is necessary to perform with the frozle state of the soil.

For frozen soils, a significant increase in the complexity of their development due to elevated mechanical strength. In addition, the frozen state of the soil complicates the technology, limits the use of some types of earthmoving (excavators) and earthmoving (bulldozers, scrapers, faders) machines, reduces the performance of vehicles, contributes to rapid wear of machine parts, especially their working bodies. At the same time, temporary recesses in frozen soil can be developed without slopes.

Depending on the specific local conditions, the maintenance of the soil in winter conditions are carried out by the following methods: 1) the protection of the soil from the freezing and the subsequent development of ordinary methods, 2) the development of the soil in a murzed state with preliminary loosening, 3) direct development of frozen soil, 4) thawing the pound and Its developing in molding.

Protection of the soil from the freezing is carried out by looping the surface layers, the shelter of the surface by various controllers, impregnating the pound with salt solutions.

Grinding soil with plowing and harrowing is produced on a plot designed to develop in winter conditions. As a result, the upper layer of pound acquires a loose structure with closed emptiness filled with air, which has sufficient thermal insulation properties. Plowing leads factor plows or rippers to a depth of 20 ... 35 cm with subsequent harrowing to a depth of 15 ... 20 cm in one direction (or in cross-directions), which increases the thermal insulation effect by 18 ... 30%.

The shelter of the surface of the soil is performed by thermal insulation materials, it is desirable from cheap local materials: wood leaves, dry moss, peat trifles, straw mats, slag, bucket and sawdust, stacked by a layer of 20 ... 40 cm directly by pound. The superficial insulation of the pound is used mainly for small surroundings.

The loosening of the frozen soil followed by the development of earth racing or earth-moving and fanport machines is carried out by a mechanical or explosive method.

Mechanical loosening is based on cutting, splitting or chip layer of frozen soil with static or dynamic exposure.

Static impact is based on the impact of continuous cutting effort in frozen ground with a special working body - tooth. For this, special equipment is used, in which the continuous cutting force of the tooth is created by tractor-tractor's tractor. Machines of this type are produced by layer-by-layer penetration of frozen soil, ensuring the depth of loosenings of about 0.3 ... 0.4 m. The soil is parallel (approximately 0.5 m) with subsequent transverse penetrations at an angle of 60 ... 90 ° to the previous one. The productivity of the ripper 15 ... 20 m3 / h. As static rippers, hydraulic excavators with a working body - a tooth-ripper are used.

The possibility of layer-by-layer design of an outstanding pound makes static rippers applicable regardless of the depth of the freezing.

Dynamic impact is based on the creation of shock Nafu-Zok on the open surface of the freezed pound. In this way, the pound is destroyed by the hammers of the free fall (loosening with splitting) or by the hammers of the directional action (looping with scolf). The hammer of the free fall may have a shape of a ball or wedge weighing up to 5 tons, suspended on the rope to the excavator arrows and discharged from a height of 5 ... 8 m. Balls are recommended to be used when loosening sand and sampling pounds, and wedges - clay (with a plot of frozen 0 , 5 ... 0.7 m).

Diesel hammers used as a target of aimed action used as hinged equipment To the excavator or tractor. Diesel hammers allow you to destroy the pound to a depth of 1.3 m.

The explosion of the explosion is effective with the depths of the freezing of 0.4 ... 1.5 m and more and with significant volumes of the development of an outstanding pound. It is used primarily in unresolved areas, and on the upticiously built-up - using the shelters and explosion localizers (heavy treadmills). When the depth of 1.5 m is used to the depth and slit methods, and at high depths - a well or slit. The slit at a distance of 0.9 ... 1.2 m One of the other is cut by the milling type with pheleznis machines or bars. One medium, extreme and intermediate gaps are charged from three adjacent cracks to compensate for the shift of the frozen pound during an explosion and to reduce the seismic effect. Charges elongated or focused charges, after which they are clogged with sand. When exploding, a frozen pound is completely crushed, without damaging the walls of the pit or trench.

The direct development of frozen soil (imperative loaning) is conducted by two methods: block and mechanical.

The block method is based on the fact that the monolithic of the frozen soil is broken by cutting it into blocks, which are then removed by an excavator, a construction crane or tractor. Cutting to blocks are performed by mutually perpendicular directions. With a shallow depth of freezing (up to 0.6 m), only longitudinal slits are enough. The depth of the cuts in the frozle layer of the slots should be about 80% of the drainage depth, since the loose layer on the border of the frozen and melt zones is not an obstacle to the separation of the blocks from the array. The distance between the sliced \u200b\u200bslits depends on the size of the edge of the excavator bucket (the dimensions of the blocks should be 10 ... 15% less than the width of the Zea bucket of the excavator). For shipment of blocks, excavators with buckets with a capacity of 0.5 m3 and above, equipped mainly in the reverse shovel, as the unloading of the blocks of the bucket of a direct shovel is very difficult.

The mechanical method is based on the force (sometimes in combination with shock or vibrational) effect on an array of frozen soil. It is implemented by using both ordinary earthmoving and earthmoving machines and machines equipped with special working bodies.

Conventional machines are used with a small depth of freezing pounds: Excavators Direct and reverse shovels with a carpet with a capacity of up to 0.65 m3 - 0.25 m, the same, with a bucket with a capacity up to 1.6 m3 - 0.4 m, Dragwin excavators - up to 0.15 m, bulldozers and scrapers - 0.05 ... 0.1 m.

To expand the scope of application in winter, the use of single-loving excavators special equipment: buckets with vibrational active teeth and buckets with a tester-tesry device. Due to the excessive cutting force, such single-sized excavators may lay aside an array of frozen pound, combining the processes of loosening and excavation into one.

The layer development of the soil is carried out by a specialized earth-milling machine that takes off the "chips" with a thickness of up to 0.3 m and a width of 2.6 m. The movement of the developed frozen soil produce bulldozer equipment included in the machine kit.

The thawing of frozen soil is carried out by thermal methods characterized by considerable complexity and energy intensity. Therefore, thermal methods apply only in cases where others effective methods Unacceptable or unacceptable, namely: near the existing underground communications and cables, if necessary, extinguishing the freezing base, with emergency and repair workIn cramped conditions (especially in the conditions of technical re-equipment and reconstruction of enterprises).

Methods for thawing the marzular soil are classified both in the direction of the propagation of heat in the ground and according to the applied type of heat carrier.

In the direction of the propagation of heat into the ground, the following three methods of thawing soil can be distinguished.

The method of thawing the soil from above is ineffective, since the heat source is placed in the cold air zone, which causes large heat losses. At the same time, this method is fairly easy and easy to implement, as it requires minimal preparatory work.

The method of thawing the soil from the bottom up requires a minimal consumption of energy, since the thawing occurs under the protection of the ice crust and heat loss is practically excluded. The main disadvantage of this method is the need to fulfill labor-intensive preparatory operationsthat limits its scope.

When the soil is thawing along the radial direction of heat applies to the pound radially from the vertically installed finding elements, pocked into the pound. This method in its economic indicators occupies an intermediate position between the two previously described, and for its implementation requires significant preparatory work.

In the form of the coolant distinguish the following main methods for thawing frozen soils.

Fire method used for excerpts in winter small trenches. To do this, it is economically used to use a link unit consisting of row-made-dollar boxes in the form of truncated cones cut along the longitudinal axis, from which the solid gallery is collected. The first of the boxes is a combustion chamber in which solid or liquid fuel is burned. The exhaust pipe of the last box provides a craving, thanks to which combustion products pass along the gallery and warm the ground under it. To reduce heat loss, the gallery is sprinkled with a layer of melting soil or slag. The strip of the fatty soil falls asleep with sawdust, and further depressing deep into the heat of heat accumulated in the soil.

The method of electrical heating is based on the flow of current through a heated material, as a result of which it acquires a positive temperature. The main technical means are horizontal or vertical electrodes.

When the soil is thawing with horizontal electrodes along the surface of the soil, the electrodes from the strip or round steel are placed, whose ends are rejected by 15 ... 20 cm for connecting to wires. The surface of the heated area is covered with a layer of sawdust with a thickness of 15 ... 20 cm, which are wetted saline With a concentration of 0.2 ... 0.5% with such a calculation to ensure that the solution was at least a mass of sawdust. Initially, moistened sawdust is a conductive element, since the frozen soil is not a conductor. Under the influence of heat generated in the sawdust layer, pulls off the top layer of the soil, which turns into the current conductor from the electrode to the electrode. After that, under the influence of warmth, it begins to plunge the following layer of soil, and then the underlying layers. In the future, the saward layer protects the heated area from the heat loss into the atmosphere, for which the sawdust layer is covered with a tale or shields. This method is used with the depth of freezing a pound up to 0.7 m, electricity consumption for heating 1 m3 of the soil ranges from 150 to 300 mJ, the temperature in sawdust does not exceed 8 o ... 9 ° C.

The soil thawing by vertical electrodes is carried out using reinforcement rods with pointed lower ends. At the depth of freezing 0.7 m, they are clogged into a soil in a checker order to a depth of 20 ... 25 cm, and as it is thawing upper layers The soil is immersed on a greater depth. When thawing from top to bottom, it is necessary to systematically remove the snow and arrange a sawmill, moistened with brine. Warm mode with rod electrodes is the same as at strip, and during the power off of the electricity, the electrodes should be demolished as the soil is heated to 1.3 ... 1.5 m. After turning off the electricity for 1 ... 2 days depth The thawing continues to increase due to the heat accumulated in the soil under the protection of the sawing layer. The energy consumption in this method is somewhat lower than with the method of horizontal electrodes.

Using heating from the bottom up, prior to the start of the warming, it is necessary to drill wells located in a checker order, to a depth above 15 ... 20 cm thick of a frozen pound. Energy consumption during pound disposal is reduced significantly, making up 50 ... 150 MJ by 1 m3, and the sawdust layer is not required.

When the stem electrodes are heated into the underlying tel lip and simultaneous device on the daily surface of the sawing, impregnated with salt solution, the thawing occurs both in the direction from top to bottom and bottom up. In this case, the faucet of preparatory work is significantly higher than in the first two versions. Apply this method only in exceptional cases when it is necessary to exfinitely carry out pounds.

Steam thawing is based on a pair inlet in a pound, for which special technical means - Steam needles, which are a metallic function of up to 2 m long, with a diameter of 25 ... 50 mm. The tip with a hole with a diameter of 2 ... 3 mm is imposed on the bottom of the pipe. The needles are connected to steam pipeline flexible rubber hoses with cranes. The needles are plugged into wells, pre-drilled to a depth equal to 70% of the depth of the thawing. The wells are closed with protective caps equipped with glands to skip the steam needle. Steam is fed under a pressure of 0.06 ... 0.07 MPa. After installing the accumulated caps, the warmed surface is coated with a layer of thermally insulating material (for example, sawdust). The needles are in a checker order with the distance between the centers 1 ... 1.5 m. The steam consumption per 1 m3 pound is 50 ... 100 kg. This method requires a heat consumption of approximately 2 times larger than the method of depth electrodes.