The phenomenon of heaving occurs in soils that increase volume in frosty weather. Moisture absorbed into the earth layer freezes and expands. Ice pushes the soil masses out. The second type of swelling occurs due to the capillarity of moisture redistributed in the ground layers. According to the characteristics of the increase in volume, the soil is classified as weakly heaving, medium heaving and strongly heaving. Clay lands and loams are most susceptible to uplift.
The type of structure depends on the characteristics of the soil, because. some are deformed by 17-25 cm. Wooden buildings withstand swelling up to 5 cm, and brick buildings up to 3 cm. For arranging the foundation in areas of heaving, moisture-saturated soils, it is necessary to follow regulatory methods.

Measures against heaving

The heaving force is so great that it can lift a large building. Therefore, on heaving soils, special measures are taken to reduce and prevent heaving. We can distinguish the following measures taken against heaving of soils:

All clay types of soils are subject to heaving.

1. Replacing the soil with non-rocky coarse or gravel sand. This will require a large pit, having a depth exceeding the depth of freezing of the soil. A heaving layer of soil is removed from the dug pit, which allows sand to be poured into it and thoroughly compacted. A material such as sand is very suitable for installation as it has a very high bearing capacity. This method is expensive because it requires a large amount of work.
2. You can also achieve stability by laying it on heaving soils at a level lower than the freezing depth. In this case, the heaving forces will act only on its lateral surfaces, and not on the base. Freezing to the side surface of the base of the house, the soil will move it up and down. As a result of the load, the heaving force per 1 sq.m of the side surface of the base of the house can reach 5 tons. If the house built on has a base equal to 6x6 meters, then the area of ​​\u200b\u200bits side surface will be 36 square meters. meters. The calculation of the tangential heaving force when laying to a depth of 1.5 meters will result in 180 tons. This is enough for the wooden house to rise, as the tree will not be able to resist the heaving force. That's why this way used for the construction of heavy houses made of brick or reinforced concrete blocks. They are based on tape types.
3. To reduce the influence of the tangential heaving force of the soil, a layer of insulation is used, which is laid on the soil layer. This method is suitable for light structures and shallow ones. The thickness of the insulation used is taken into account depending on the climatic conditions of the place where the house is being built.
4. Measures can be taken to divert water to prevent heaving. For this purpose, a drainage system is being arranged along the perimeter of the site. To do this, at a distance of half a meter from the foundation to the depth of its laying, a ditch of the same depth is laid. A perforated pipe is laid in it, which must be laid in a filter cloth with a slight slope. A ditch with a pipe wrapped in cloth must be covered with gravel or coarse sand. The water flowing from the ground must then flow through the drainage pipe into the drainage well through the hole. To ensure natural drainage of water, a sufficiently low area for drainage of water is required. This requires a blind area and storm sewer.

Building a deep foundation

Work here is with finished products: metal or asbestos-cement pipes. The foundation can be obtained with the presence of reinforcement or a metal rod.

Foundation scheme in the first scenario (with reinforcement).

1. A sand cushion is being organized. Layer: 10-15 cm.
2. A block is laid on it (for example, FL 6-12- with parameters 118 x 60 x 30 cm).
3. An asbestos-cement pipe is being introduced. Its minimum diameter is 20 cm.
4. She's attached to the block. concrete mix. The same mixture fills it inside.

Inside the pipe, a reinforcing bush is arranged in advance. It is also filled with concrete. The fittings go beyond the edges of the pipe by about 10-15 cm. So it will be more convenient to weld it to the grillage fittings.

Place of attachment of the pipe to the block: its base, in contact with it. Here, at an angle of 45 degrees, a cement screed is created.

When it dries completely, and the post is firmly fixed on the block, you can do backfill. Here, previously excavated soil or soil of high characteristics regarding heaving is needed.

Scheme in the second scenario:

1. The same sand cushion.
2. A slab (reinforced concrete - monolith) with parameters 60 (width) x 40 (height) is laid on it.
3. The same pipe is introduced, only with a diameter of 20-30 cm.

The introduction of the pipe occurs when the slab is still drying. Installation is obtained in a fresh slab mix.

It is necessary that the pipe touches the plate a little. The metal core should go deep by 10-15 cm. Further work follows the same algorithm as in the first scenario.

It was previously said that only columnar foundations should be placed in heaving soils. And this is justified by the following arguments:

• financial benefit
• the possibility of using reinforced concrete slabs, so labor volumes are reduced by 2-3 times,
• under each pillar, the efficiency of the soil is higher than under the foundation strip.

Expert opinion

If soils with heaving properties lie at the base of the building, you should be especially careful in choosing the type of foundation. After many years of practice, the MzLF design has proven to be very effective - we describe in detail the device, reinforcement and calculation of which in the article “Shallow strip foundation: depth calculation, foundation preparation, do-it-yourself reinforcement and calculation calculator.

GOST 25100-95 “Soils. Classification".

SNiP 2.02.01-83* "Foundations of buildings and structures".

Manual for the design of foundations for buildings and structures (to SNiP 2.02.01-83).

VSN 29-85 Design of shallow foundations of low-rise rural buildings on heaving soils.

Methods for eliminating the effect of heaving

To make a base applicable for heaving soils, use the following techniques:

• creating a wide trapezoidal structure. It reduces the influence of touch forces on the structure.
• lining the walls of the trench channel with waterproofing. The technique is shown for wall insulation in conditions of deepening of the foundation.
• an increase in the width of the tape or monolith, which leads to the leveling of swelling.
• replacement of intumescent soil with sand or gravel raw materials.
• laying a heat-insulating layer on the outside of the building. The method is needed to prevent the rise of the earth during the frosty period.

Degree of heaving of soils

Degree of heaving of soils

• The main indicator is the relative deformation of heaving Efh, which is determined by the ratio of the magnitude of the rise of the surface of the heaving base to the thickness of the frozen layer.
• The Z index is the difference between the groundwater level and the depth of seasonal freezing, the value of which is 1.2 m for heated buildings, and 1.5 m for unheated buildings.

If the degree of heaving in terms of Z and Jl (fluidity) differ, then a larger value is taken.

Since heaving bases show their negative properties when saturated with water, there is another classification method that takes into account the conditions for moistening the base of buildings according to the nature of the terrain.

Type of ground conditions

Moisture conditions of the soil base according to the nature of the terrain.

Elevated and hilly places, watershed plateaus, where soils can be moistened only from atmospheric precipitation.

Plains, slightly hilly places, gentle slopes with long slopes, where soil bases are moistened by atmospheric precipitation and perched water, only partially by groundwater.

Lowlands, hollows, wetlands, in which the ground bases are moistened and saturated with atmospheric precipitation, perched water and groundwater.

That is, if in terms of Z and Jl the base is classified as weakly heaving, but the construction site is located in a lowland or depression, then it should be considered that the soils are strongly heaving.

Thus, heaving soil is sandy or clayey soil, subject to moisture and seasonal freezing.

Ground freezing stages

Russia is a northern country, therefore, in winter, there is always a low temperature on its territory. Depending on the region, the soil can be in a frozen state from 2 to 9 months. When autumn-winter cooling is observed, the deep layers of the soil pass into the following states:

• Stage 1 - preliminary. During it, the soil is cooled to a temperature that does not contribute to the crystallization of water;
• Stage 2 - founded. Here, the water already passes into another state of aggregation, its volumetric expansion occurs, as a result of which it becomes ice;
• Stage 3 - hypothermia. In the course of it, the soil is compressed in frost, which subsequently leads to a sharp decrease in its temperature.

Soil freezing scheme.

It should be noted that all these stages are conditional, since the process of transition from one to another proceeds very slowly. In this case, one more stage can also be distinguished, during which the thawing of the soil occurs. This leads to his drawdown.

Due to the fact that it is in winter that soil heaving is observed, it is strongly not recommended to build houses during this period, because this poses an obvious danger. After construction, there is a high risk of destruction of the finished structure

It is especially important not to carry out the construction of foundations and facilities in the cities of the Far North, where there is a strong freezing of the lower layers of the soil.

Calculation of the intensity of heaving on the site

To calculate the degree of heaving of the soil at the construction site with your own hands, you need use the formula: E = (H - h) / h. wherein:

• E - corresponds to the degree of heaving of the soil;
• h is the height of the soil mass before freezing;
• H is the height of the soil massif after freezing.

To make a calculation of the degree, it is necessary to make appropriate measurements in summer and winter. Soil can be considered heaving, whose height has changed by 1 cm when freezing at 1 m. In this case, "E" will be equal to the coefficient 0.01.

Heaving processes are more susceptible to soils in which there is a high moisture content. When it freezes, it expands to the state of ice and thereby raises the level of the soil. Heaving are considered: clay soils, loam and sandy loam. Clay, due to the presence of a large number of pores, retains water well.

What is heaving soil and why is it dangerous? (video)

How to remove the effect of heaving on the ground?

Exist simple ways remove heaving around the foundation with your own hands:

1. Replacing the layer of soil under and around the base with a non-rocky layer.
2. Laying the foundation on a soil massif below the freezing layer.
3. Insulation of the structure to prevent freezing of the soil.
4. Drainage.

The first method is the most laborious. To do this, you need to dig a foundation pit. depth below the level of freezing of the earth, take out the heaving soil, and fill in its place with heavily compacted sand.

It shows high bearing capacity and does not retain moisture. The large amount of ground work makes it the least popular, although it is an effective way to overcome heaving. This technique is effective for laying low-rise buildings, shallow penetration, such as a barn.

A feature of the second method is the removal of the effect of heaving on the base of the foundation, but its preservation when exposed to the walls of the base. On average, the lateral pressure on the walls is 5 t / 1 m 2. It can be used to build brick houses.

The third method allows you to make an unburied foundation under a private house with your own hands in heaving conditions. The essence of the method is to lay a heater around the perimeter of the foundation to its entire depth. The calculation of the material is done as follows: if its height is 1 m, then the width of the insulation should be 1 m.

To make water drainage around the house or barn, you need to build a drainage. It is a ditch at a distance of 50 cm from the building, the depth of which is the same as the level of the structure. A perforated pipe is laid in a drainage trench under a technical slope and wrapped in geotextile, and then filled with gravel and coarse sand.

Below - consider the types of bases that can be used on soil prone to heaving.

Pile and columnar buried foundations

Foundations with laying to the freezing depth for a private house can be recommended in a pile design or in the form of columnar foundations - with a grillage on which the walls rest. As piles for low-rise buildings, bored piles or their variety are most often used - the foundation of TISE, as well as screw piles.

Such foundations have, in comparison with strip foundations, a smaller side surface area and material consumption. But the supporting surface of the sole of such foundations is also small, which limits their use to relatively light buildings on solid ground.

The design of pile foundations involves the construction of a house with a cold - space between the ground and the lower floor. The floor of the first floor has to be done along the basement. The device of a hard floor above the basement, instead of floors on the ground, increases the cost of construction.

In addition, the arrangement of a powerful monolithic reinforced concrete grillage makes pile foundations more difficult to construct and more expensive than shallowly buried strip foundations.

Take a look at the photo of the foundation with the grillage. After all, this is the same shallowly buried foundation with the legs of piles sticking out from below, and for some reason raised above the ground.

Most often the choice of such a foundation is not justified, except for the fears of "thrifty" developers who do not use the services of professional designers, and the propaganda of TISE drill manufacturers and their followers on forums and neighboring sites.

Pile foundations in private housing construction advantageous to use only for those structures, where an expensive grillage is not required (for example, for wooden or frame buildings with a cold base), or in the presence of particularly difficult soil conditions.

Expert opinion

If soils with heaving properties lie at the base of the building, you should be especially careful when choosing the type of foundation. After many years of practice, the MzLF design has proved to be very effective - we describe in detail the device, reinforcement and calculation of which in the article “Shallow-depth strip foundation: depth calculation, foundation preparation, do-it-yourself reinforcement and calculation calculator”.

In addition to choosing the most suitable type of foundation for construction on heaving foundations, it is necessary to provide for additional measures aimed at preventing soaking and freezing: drainage, blind area insulation, filling the sinuses with compacted bulk material.

Any construction begins with a study of the soil. In an already built-up area, you can skip this step and use the results of studies carried out for other buildings. But often the development of the site begins with a garage. A good example is a frame garage house, which was built by us as a warehouse for building materials and temporary housing for builders.

You need to have a good idea on what kind of soil you are building a garage. Based on its properties, the type is selected and the parameters of the foundation are calculated. An improperly designed foundation can, at best, cost more than it needs to, and at worst, collapse.

Soil heaving is one of the most serious dangers that await foundations built without proper research. However, you should not forget about improper shrinkage either.

Table for determining the degree of soil heaving. Z - a value showing how many meters the groundwater level is below the freezing depth

If you do not want to use the services of specialists, first you have to dig a hole two meters deep with neat vertical walls at the site of the future construction. So you can visually determine the type of soil. In addition, you can conduct a simple experiment that will help dispel your doubts, if you have any.

Take a handful of soil and add water to it

You roll up the “sausage” and, attention, the most crucial moment, roll a bagel out of it. Depending on what happened to the "sausage", we draw conclusions:

• It turned out an excellent bagel - this is clay;
• "Sausage" fell apart into several parts - loam;
• "Sausage" crumbled into small pieces - sandy loam;
• It didn’t even work out to make a “sausage” - sand.

If it is autumn outside, along with the type of soil, you can determine the level groundwater. Worst of all, if water appeared at the bottom of the pit. If it’s dry, it’s best to use a hand drill, and increase the depth of your knowledge about the level of groundwater by another one and a half to two meters. Water is not visible - it is far enough to groundwater and you can even make a basement or cellar.

This table will help determine how deep a garage foundation is required.

But we are not interested in the absolute value of the groundwater level, but in how far it is below the freezing depth. The freezing depth is a standard value, and is determined from the table. Here it is worth considering that winters have recently become milder than before, but every few years it falls on the contrary, more severe. So if you provide an additional margin in the calculations, you will not be mistaken.

Do not forget that it will be much easier to make a foundation on heaving soil if you can reduce the impact on the soil of the factors that cause heaving. For example, make drainage and insulate the blind area.

When the soil freezes, moisture from the frozen layers is squeezed out. And if she does not have time to squeeze out, just swelling occurs.

How does swelling happen

Since the density of water is greater than that of ice, in the process of freezing its volume changes upwards. Based on this, the moisture in the soil becomes the cause of the expansion of its mass. Hence, such a concept as the forces of frost heaving appeared, that is, the forces that affect the process of soil expansion. The soil itself in this case is called heaving.

Healthy! The soil expansion level is typically 0.01. This means that if the top layer of the earth freezes to a depth of 1 m, then the soil volume will increase by 1 cm or more.

Frost heaving itself occurs for several reasons:

• Due to the depth of the upper aquifer. If the water is located close to the surface, then even if the clay is replaced with gravelly sand, it will be ineffective.
• Based on the depth of freezing of the earth during the cold period in a particular region.
• Depending on the type of soil. Most water is found in clay and loam.

Based on the composition of the soil and climatic conditions, heaving and non-heaving soils are distinguished.

Soil heaving features and methods of struggle

To get an answer to the question of how to properly make a foundation on heaving soil, you need to understand the nature of the process provided and its specifics.

In areas with a high level of groundwater, the earth is in a very wet state and, thus, closer to cold weather, it begins to increase in size.

When constructing a foundation on heaving soil, you need to monitor the depth of the soil.

If deepened slightly below the freezing point, fragile layers will exert pressure directed tangentially to the surface of the earth. She will start to rise.

An equally important component is the area of ​​interaction with the ground: the larger, the worse. .

In the future, the soil under the influence of constantly changing vertical loads will sag. And thus, this process is observed non-rhythmically.

As a result, the house begins to buckle, and the foundation cracks and, of course, fails.

A special SNiP of foundations has been created, which are built on heaving surfaces under the number 50-101-2004, the law was adopted back in 2005. Before starting work, it is recommended that everyone familiarize themselves with it.

Regardless of the type, it is desirable to make the foundation device on heaving soils as an expanded monolith at the bottom.

In order to reduce swelling, ground floor create a special heating system, and, of course, insulate the very foundation of the house.

Another way to deal with heaving of the earth is to replace the soil.

As a rule, unstable soils under the upcoming construction are removed, and crushed stone is poured in their place along with sand. An important drawback is the high price of the work provided.

The most common is a shallow base on heaving soils.

The small depth of the bookmark provides an opportunity to remove shear pressure by reducing the size of the interaction.

Nevertheless, in order for the chosen method to be effective, it is necessary to create a special cushion from the mixture, which, in turn, is not subject to heaving (sand, crushed stone of a standard fraction).

It is important that the mixture is poured from the outside of the foundation over the entire area.

If you lay the foundation well below the freezing point, there is a chance that you will compensate for the heaving.

However, it is not profitable to equip the tape with this method, since construction will require rather high costs. Increasingly, they are building columnar foundation on heaving soil.

But it is necessary to carry out difficult calculations in order to evenly divide the pressure. It is necessary to use a bud of different brands and, preferably, a reinforced reinforcing cage.

It is difficult to say which of all the existing foundations is the best foundation for heaving soils themselves - each one has its own characteristics and positive aspects.

In addition, the level of heaving in different areas can vary significantly, which affects the decision to choose the type of foundation.

Soil heaving - what is it

Heaving Important: From a scientific point of view, the tendency for soil to heave is explained by the fact that in the liquid state the density of water is 1 ton per m3, while when it passes into a frozen state, its density decreases to 0.917 t/m3.
Rice. 1.1: Ground heaving

1.2: Consequences of heaving

• Vertical loads - are transferred to the base of the foundation from the soil layer located under it;
• Tangential loads - are transferred to the side walls of the foundation from the contacting soil.

Important: vertical loads have the greatest destructive effect on the base, their force significantly exceeds the effects of lateral heaving.
Rice. 1.3: Directions of action of heaving forces on the foundation

Special properties of heaving soils

A special property of bases that can swell is a significant increase in volume as a result of winter freezing.

How to identify heaving soils? The bases with the property of swelling during freezing include only clay (including loam) and sandy soils (silty, fine and medium size). Gravelous and coarse sands do not belong to heaving.

Sandy, clay soils and their varieties have a finely porous structure, that is, they consist of small mineral particles, between which there are many small cavities. These cavities or pores may contain moisture. When the temperature drops below zero, the moisture in the soil freezes, turning into ice, which, as you know, always increases in volume compared to the initial volume of water. As a result of freezing of water in the pores, an increase in the entire volume of the base occurs, called frost heaving.

The bases are divided according to the degree of heaving, which depends on the level or depth at which groundwater occurs. For clay bases, the fluidity index is also important. We give the following table with a gradation according to the degree of heaving of different types of soils.

Ribbon buried foundation on heaving soils with laying to the freezing depth

buried foundation

Such a foundation is often practiced in the construction of small buildings, because it immediately has a number of key disadvantages:

• Too large a side surface contributes to an increase in the load on the walls of the structure;
• Too high installation cost, because you need to dig deep trenches and protect the walls from collapse;
• Expensive building materials;
• It is necessary to carry out complex calculations of balancing the heaving forces and the mass of the building itself.

These are material-intensive and labor-intensive bases, which are not able to provide optimal protection of the building from soil exposure. But at the same time, they are practiced in relatively cold regions, where the freezing boundary is located high, and under it there is a solid ball of rock. When correct use technology, the sole of the trapezoidal concrete base is installed directly inside the hard rock, which is no longer subject to heaving.

Protection against lateral movements is eliminated by the method of corner reinforcement using intermediate concrete beams. Also, strip buried foundations are often used when you need to build a building with basements.

Construction of a columnar and pile foundation on heaving soil

Such foundations are usually built on the abyss. In addition, they are logical when:

• construction of light buildings: frame construction or a small bath. garage. shed,
• if necessary, lay the foundation at a great depth.
• if necessary, save (columnar foundation is obtained more economical than tape by 1.5-2 times).

Column bases can be made of: stone, concrete, brick, rubble concrete, reinforced concrete. Types of concrete are often referred to as monolithic.

When working on this foundation on heaving soils, it is important to adhere to the following criteria for the positions of the pillars:

1. At the corners of the building.
2. At the intersection of the walls.
3. On straight wall areas. The minimum distance between them is 3 m.

To reduce the impact on the ground, the lower part of the pillars expands. If the pillar is brick, it expands by at least 2 rows.

In soils with strong heaving, the optimal materials for creating a columnar base are as follows:

• asbestos or metal pipes,
• finished reinforced concrete products (slabs, pillars).

The foundation here needs to be arranged deeper than the maximum mark of soil freezing. If it is below one meter, and there is no water at the bottom, then the option with a concrete product is suitable. Heaving has an extremely weak effect on such species, since their cross section is extremely small.

In soils with other heaving (medium and weak), it is possible to create pillars from all of the indicated materials. Very often the pillars here are built of brick.

Column base scheme:

All pillars must be connected into a single structure. To do this, they are connected from above with strapping beams. If there is no way to get a distance of 3 m between them, even less than 2.5 m, then wooden beams are arranged. When the distance goes more than m, reinforced concrete beams are used. They create a grillage.

It is important to determine the parameters of the pillars. It all depends on their material. Above ground level at 40 cm, views are made of concrete, reinforced concrete and rubble concrete. At 38 cm - brick types. At 25 cm - brick types with a pick-up.

To strengthen the columnar foundation, an anchor plate is laid at the base of each column. It also reduces the level of torsion resulting from the impact on the foundation from the side. Such a plate slightly exceeds the width of the column and firmly adheres to the ground. It serves as a powerful protection against heaving.

The column also needs protection from a potential fracture. Therefore, it is reinforced. If the pillar is a monolith, a plasticizer is introduced into the cement composition. If the post is not reinforced, then it should taper towards the top.

Principles for creating a brick pillar:

1. A sand cushion is laid. Layer - at least 50 cm. Coarse-grained or gravelly sand is used.
2. Ruberoid is laid.
3. The column format is a rectangular cone.
4. The top side of the column is pasted over with waterproofing.
5. To create a grillage, prefabricated reinforced concrete slabs are used.
6. From the outside of the column, soil is poured and compacted.
7. This soil is covered with a cement screed.

Principles of creating a concrete pillar

1. The concrete base has the shape of a cone. It slightly exceeds the ground level, about 10-15 cm.
2. A reinforcing cage is made, poured with concrete.
3. A reinforced concrete belt is created from the frame.
4. An overlapping slab is created from the belt.
5. She warms up.

A grillage is being prepared for a bunch of pillars. It evenly distributes the load on all pillars. This guarantees static positions of the posts in the horizontal plane.

When a brick, concrete or foam block building is erected, a reinforced concrete grillage is made. The reinforced post is firmly connected to the grillage reinforcement.

During construction wooden house grillage format - log strapping.

The internal voids between the pillars must be protected from dirt and precipitation. To do this, they arrange a pickup between them.

Foundation work on the deep must be completed within one season. If the foundation is left without the expected load, it may deform.

Foundation specifics for heaving soil

One of the key ones is the strip foundation, however, it is necessary to dig a special pit under it with a depth of about 0.7 m. Having prepared the pit, the side walls are reinforced with waterproofing material, in particular, polyethylene.

After that, a dry mixture is added in 2-3 layers with a width of approximately 15 cm, then it is all qualitatively compacted. At the next stage, formwork is needed for the base.

On top of the pillow, waterproofing is again equipped and a reinforcing cage is created.

It comes out an unburied foundation on heaving ground, can easily withstand a lot of pressure.

After that, the concrete mixture is added to the formwork. Since she did not have time to freeze, large reinforcement bars are installed.

Another small feature - it is desirable to knit reinforcement. Welded reinforcement can be too brittle and brittle.

Less common is the pile foundation on heaving soils, since its construction requires the involvement of special equipment and high labor costs.

The choice is stopped on it only in cases where the freezing point of the earth exceeds 1.5 m.

Piles should be deepened by at least 3-4 m, as a result, products are often made of concrete or reinforced concrete of all varieties, in particular driven, stuffed or screw.

A drainage system is created throughout the site of the house and the base is waterproofed.

An excellent solution can be a columnar foundation, which is built for frame buildings or low-rise buildings.

It, like the pile foundation, is created below the freezing level.

The main material for the construction of pillars is reinforced concrete of high grades, which can withstand a variety of loads and pressure from outside.

In this case, the anchor pad is attached to the support frame, and will act as a support for the building.

With your own hands, you can build a columnar foundation using asbestos pipes with a large reinforcing cage.

Outside, a layer of epoxy resin is created, as a rule, the reinforcing cage is made from a wire about 10 mm thick.

A floating slab base on heaving soils is created together with unstable layers.

With this, the walls of the house do not experience various deformations from the side and, thus, do not collapse, even small cracks are excluded.

Foundation construction on heaving soil as monolithic slab can be created in two ways: slightly buried (when there is no need for a basement or basement) or as a deep slab.

A pit of the required depth is dug under the foundation, the bottom of which is covered with ordinary rubble.

Our services

We provide the following services: pile driving and leader drilling. We have our own fleet of drilling and pile driving equipment and we are ready to supply piles to the site with their further immersion at the construction site. Prices for driving piles are presented on the page: prices for driving piles. To order work on driving reinforced concrete piles, leave an application:

Useful materials

Wall in the ground

This is a method used in the construction of various underground structures near operated residential and non-residential facilities.

Soil testing

Soil testing is a construction phase prior to foundation design.

Types and scope of driven reinforced concrete piles

When designing pile foundations for buildings and engineering structures, the choice of the type of reinforced concrete structures used must be made as carefully as possible.

Soil replacement way out

Since the foundation and the structure as a whole are deformed due to heaving of the soil, many simply replace it, but is it really effective? As mentioned above, the lower layers of the soil, which are represented by sand, do not freeze through so much that this negatively affects the state of the building and its foundation. Therefore, soil replacement is an excellent way out. Accordingly, it will be necessary to use sand during such work. You can mix a little crushed stone into it.

At the same time, experts recommend using gravel sand to create a pillow. With it, soil replacement will be much more efficient, respectively. negative impact from heaving will be reduced many times over. This type of sand is represented by large fractions. Therefore, this material is highly resistant to compression. This means that the shrinkage of the sand cushion will be minimal. It is advisable to purchase gravel material of river origin, because it has higher performance characteristics.

To make a sand cushion you will need the following:

Scheme of the foundation with a drainage system on a gravel-sand cushion.

• gravel;
• water;
• geotextile;
• building level;
• shovel;
• tamper;
• sand;
• waterproofing material.

You need to start work by creating a trench or foundation pit, everything here depends on what type of foundation you decide to choose for your home. The depth of the pit should depend on the amount of soil freezing. When it is created, it will need to be carefully leveled. Then the geotextile is laid out. It is necessary in order to protect the bulk material from the penetration of moisture from the lower layers of the soil. It is advisable to line the geofabric in several layers. Then you can fill in the sand.

This must be done in small layers. Having created the first one, it is moistened and rammed, after which crushed stone is laid out, and then again sand - and so on until a pillow of the required height is created. In the course of this, it is imperative to ensure that the layers are as even as possible. Tampering must be done in such a way that there are no marks from the sole of the shoe on the surface of the pillow. As for its optimal thickness, construction experts recommend making it 10-20 cm high.

When the sand cushion is created, it will be possible to line the waterproofing material, such as roofing material. Then bricks are laid on it, reinforcement is carried out, formwork is mounted and concrete is poured.

Column foundation for heaving soils

Scheme of the columnar foundation.

For low-rise private construction, carried out in conditions of heaving soils, it can be considered optimal. A well-built columnar foundation in these conditions should be below the freezing level of the soil.

This method is one of the most economical. Reinforced concrete posts are best, as they effectively help avoid shear stress.

from reinforced concrete structures can be the best solution for this type of soil. The technology of their manufacture is very convenient and highly adaptable. These foundations are suitable for wetlands, damp areas and soils where there is a high level of groundwater.

On such soils, columnar foundations can have structures in which the anchor platform, which is the support of the entire structure, is rigidly tied to the supporting frame.

Bearing pillars for such a foundation can serve as:

Scheme of a columnar foundation made of blocks.

• asbestos-cement pipes filled with concrete and having reinforced inner walls;
• reinforced concrete pillars;
• pipes made of metal, which are protected from the inside by a cement-sand composition, and from the outside - by epoxy or metal.

Instead of reinforcement, in this case, wire with a diameter of 7 to 11 mm and metal rods are used. Sometimes various metal waste is used: corners, gas pipes or parts of a water supply system.

Concrete for such a foundation is produced exclusively from high-grade cement. Granite crushed stone or sand can be used as a filler.

It is important to know that the admixture of clay, the use of fine sand, broken bricks or crushed limestone can significantly reduce the frost resistance of concrete. The optimal composition of concrete for a columnar foundation is 1 part of cement, 3 parts of sand and 4 parts of crushed stone

The amount of water is determined separately for each specific case: the concrete must be plastic enough to be easy to lay, but the mortar must not pour. This solution is placed in a pre-prepared formwork and compacted a little.

Foundation principles on heaving soils

As a result, it may turn out that the building will be highly susceptible to heaving forces, and the amount spent on the construction of such an unusable foundation will be quite large. However, if it is decided to build a brick building, then foundations buried below the GPG will be appropriate.

Let's give a few examples and try to determine the type of foundation that is suitable in such conditions:

• heavy house. A building made of foam concrete, brick or other similar materials, 3-5 floors high. In this case, it is advisable to use foundations that will be deepened. The decisive condition is the UGV. With a very low groundwater level, it is possible to build a buried foundation below the level to which the soil freezes through. These are the following types of foundations: strip, pile, slab. If geologists detect a high level of freezing and the drainage of the base of the building cannot allow lowering the groundwater level, then a shallow foundation option is possible, that is, a reinforced concrete slab is poured.
• light house. These are mainly timber buildings. In this case, foundations that are buried to a shallow depth are suitable. It is permissible to pour a reinforced slab or a shallow strip foundation. The second option will be less expensive. Important point is to create a rigid structure that will perceive local deformations and distribute them evenly over the building.

Do not lose sight of the possibility of replacing heaving soil with soil with better characteristics. Quite often, the conditions under which heaving soils stop showing their shortcomings are easier to create than to build on such soil. These conditions can be achieved by changing the depth of freezing of the earth to a smaller side - lay insulation around the perimeter of a house under construction and organize a drainage system.

The conditions for construction on any site are individual and differ greatly from the norms. Be sure to conduct geological exploration, find out the characteristics of the soil on the site you have chosen for construction, and after that, proceed with the construction of the house.

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How to reduce the effect of heaving on the foundation of the house

choice of foundationFig

1.5: Map of soil freezing in Russia
strip foundation Important: the solution to the problem is the arrangement of the foundation on reinforced concrete piles, the total cost of which is much lower, and the bearing characteristics, stability in the ground and durability are superior to similar properties of both strip and slab foundations.
sealing pad made of sand Fig. 1.6: Sand and gravel pad under the foundation

1.7: Replacement of heaving soil with sand and arrangement of the drainage system

Useful materials

Piling device

This publication provides information on the technology of arranging foundations from bored, bored injection, screw and driven piles.

Soil bearing capacity

Such a property of the soil as its bearing capacity is the primary information that needs to be clarified at the preparatory stage of foundation construction.

Construction on heaving soils always requires a special approach to choosing a foundation. The forces of heaving of the soil can have a destructive effect ...

Modern classification of soils by heaving

Today, soils are divided into five groups of varieties according to the degree of frosty heaving. Modern classification of soils by heaving depends on the granulometric composition of the soil, natural moisture, the depth of the groundwater level and the estimated depth of soil freezing.

Modern classification of soils according to the degree of frosty heaving is as follows:

1. Strongly heaving soils
2. Medium heaving soils
3. Slightly heaving soils
4. Conditionally non-rocky soils
5. Non-rocky soils

The most frost-prone, strongly heaving soils are: silty sandy loams, loams and silty clays of plastic consistency when the groundwater level is located in the layer of seasonal freezing or below the standard freezing depth in sandy loams by no more than 0.5 m, and in loams and clays by no more than 1 m.

Medium-heavy soils include: dusty sands, sandy loams, loams and clays with natural moisture, exceeding the consistency index of 0.5, when the groundwater level exceeds the standard freezing depth in silty sands by no more than 0.6 m, in sandy loam - by no more than 1 m, in loam - by no more than 1.5 m and in clays - no more than 2 m, according to the degree of frosty heaving.

The group of weakly heaving soils includes: fine and silty sands, sandy loams, loams and clays of refractory consistency, as well as coarse-block soils with silty-clay aggregates when the groundwater level exceeds the standard freezing depth: in dusty and fine-grained sands by no more than 1 m, in sandy loam - by no more than 1.5 m, in loam (with a plasticity number less than 0.12) - no more than by 2 m, in loams (with a plasticity number of more than 0.12) - no more than 2.5 m and in clays (with a plasticity number of less than 0.28) - no more than 3 m.

Conditionally (practically) non-rocky soils include: coarse-grained soils with silt-clay filler, fine and silty sands and all types of clay soils of solid consistency with natural moisture during the freezing period, less than the humidity at the rolling boundary when the groundwater level is below the standard freezing depth: in coarse, silty and fine-grained sands by more than 1 m, in sandy loam - by more than 1.5 m, in loams (with a plasticity number less than 0.12) - by more than 2 m, in loams (with a plasticity number of more than 0.12) by 2.5 m and in clays with a plasticity number of less than 0.28 - by more than 3 m.

Non-rocky soils include: rocky, coarse soils, containing less than 30% by mass of particles with a diameter of gravel sands of large and medium size, regardless of their natural moisture content and the level of groundwater.

This modern soil classification according to the degree of frosty heaving included in the standard for checking the stability of foundations on the action of forces of frost heaving of foundation soils.

When determining the degree of frost heaving of soils one should mainly focus on their natural humidity and the position of the groundwater level for the period corresponding to the beginning of soil freezing.

Go to the beginning of the section → Foundations on heaving soils

• Frost heaving of soils
• Classification of soils according to the degree of frost heaving
• Factors affecting the process of frost heaving of soils
• Depth and rate of soil freezing
• Literature - books on heaving soils and foundations

To buy foam blocks from a manufacturer in the Moscow region or order the required volume, you must first contact the sales department of foam blocks.

Sales department →

Measures against heaving of the soil

It is possible to qualitatively and reliably insulate the foundation from all sides, this will reduce the percentage negative impact frozen ground on the basis

If the house has already been built and at the same time the foundation needs to be additionally protected, then the following methods and techniques can be applied:

• Around the finished foundation, you can completely replace the soil with a non-fluffy one. To do this, you will have to do a lot of earthwork, but the result is worth it.
• It is possible to qualitatively and reliably insulate the foundation from all sides. This will reduce the percentage of the negative impact of frozen ground on the basis.
• High-quality blind areas and storm sewers coming from the base of the house will help drain water and thereby reduce the amount of liquid in the soil. This means that the heaving of the soil will be reduced.

All these construction methods and technologies make it possible to build durable and strong houses on whimsical soils.

Bloat Control Methods

If it became necessary to build foundations on heaving soils, the following measures can be taken during construction:

Scheme of violation of the structure of the base soil during freezing due to heaving forces and during thawing due to a decrease in strength properties due to abundant water saturation of the base.

• complete change of the soil under the base to non-porous. In this case, crushed stone and sand are poured under the supporting structure. From non-foaming materials, backfilling is performed, which makes it possible to reduce swelling from the sides;
• , wall structures which are characterized by high smoothness. In this case, the problems caused by swelling are solved by waterproofing layers that are laid out on the side walls. These layers reduce the adhesion of soil masses to the foundation of the structure;
• the erection of a base with a lower part that looks like an expanded monolith. This method is suitable for very many types of bearing systems, for example, for strip, column and pile foundations;
• laying horizontal thermal insulation on the ground masses around the entire perimeter of the building. This method works effectively only if there is a heating system and normal. Under a well-heated house, in combination with high-quality thermal insulation, swelling of the earth does not occur much.

Scheme of replacing heaving soil with sand.

It is important to remember that the effect of heaving forces is felt the stronger, the closer to the surface of the earth is moisture. . Excessive moisture in the ground can lead to its erosion

Some fluids may contain substances that adversely affect concrete structures and various reinforcing products. These problems are also solved with the help of a waterproofing layer.

Too much moisture in the ground can cause it to erode. Some liquids may contain substances that adversely affect concrete structures and various reinforcing products. These problems are also solved with the help of a waterproofing layer.

During the development of the project, it is necessary to take into account seasonal changes in the occurrence of groundwater. In different regions, the liquid can rise to different heights. Ground moisture can be successfully dealt with by creating drainage systems that reduce swelling at the location of the foundation.

Ribbon buried foundation with laying to the freezing depth

Laying the sole of the strip foundation to the freezing depth does not always protect light low-rise buildings from deformation. Such foundations have a developed lateral surface, along which large tangential heaving forces act. These forces tend to push the foundation and the building up in winter.

Loads from the weight of the building per 1 linear meter of strip foundations in one, two-storey houses do not exceed 40 ... 120 kN. Small loads on the foundations cause their increased sensitivity to the forces of frost heaving.

Tape located in heaving soils the foundations of low-rise buildings are often subject to buckling, if the loads acting on them from the weight of the building do not balance the heaving forces.

Strip foundations to the depth of freezing are material-intensive and expensive foundations, moreover, they do not provide reliable operation of low-rise buildings built on heaving soils.

The cost of building such foundations is too high. specific gravity in total cost building a house.

Strip foundations with soles on recommended apply only to private houses with a basement.

Tape structures construction features on heaving soils

The underground part of the building is able to take the mass of the house and transfer it dense layers soil

When planning which foundation will be relevant in areas with plastic intumescent soils, pay attention to the reliability and durability of the tape. To complete a reinforced concrete strip, you need a maximum of materials, but the costs will be justified

Conditions for the construction of a strip foundation

Shallow-depth tape type of foundation on expanded soils provides for engineering and geological surveys

Heaving soils can lead to cracking of the sole, so it is important to consider: type of soil massif;
the level of freezing of the earth and the amount of water;
load-bearing building;
the presence of underground and underground highways;
period of operation of the building.

• type of soil massif;
• the level of freezing of the earth and the amount of water;
• load-bearing building;
• the presence of underground and underground highways;
• period of operation of the building.

The tape construction is relevant for brick, concrete houses with dense walls, structures with reinforced concrete floors. The walls of the tape can form the walls of the basement or cellar.

Bookmarking tools and materials

The construction of a buried fundamental structure is carried out using the following inventory and consumables:

• level and binding wire;
• shovels - bayonet and shovel;
• cord for marking the territory;
• reinforcement with a ribbed section with a diameter of 10-14 mm;
• wooden boards, an ax, a hammer, nails and a hacksaw;
• cement, crushed stone and sand;
• concrete mixers.

Before starting work, it is important to draw up a project that will indicate the necessary parameters of the product.

Tape bookmark sequence

The construction of the tape base is carried out in several stages:

1. A plan of a building or utility block is created, the depth of the structure is determined.
2. The foundation scheme is transferred from the finished drawing to the ground.
3. A cast-off is mounted at a distance of 1-2 m from the side of the house.
4. A trench 1 m deep is dug, a sand and gravel cushion 12-15 cm high is covered.
5. A layer of waterproofing is laid on the pillow - polyethylene or roofing material. As an alternative to rolled materials, bitumen filling is used.
6. A formwork frame and a reinforcing mesh of rods with a diameter of 8-14 mm are being equipped.
7. Concrete dough from M200 cement, sand and crushed stone is poured into the formwork.

Building experts recommend deepening the foundation below the freezing of the ground and holding it for up to 28 days, and then remove the formwork.

Varieties of fundamental foundations for soils subject to heaving

The construction of the foundation on heaving soils provides for the elimination of soil volume in the winter months. For this purpose, shallow structures of the tape type are performed, which are distinguished by a simple filling algorithm.
Columnar foundations are best built when the supporting elements can be buried below the extreme freezing point of the soil. Pillars are used on loams, areas with high GWL, in damp and wetlands. Supports are made of metal, concrete goods, asbestos-cement pipes.
Piles are problematic to install due to the use of construction equipment. But, if you are ready to invest in the arrangement of summer cottages, this method will be successful.

Factors affecting heaving

Do not assume that the damage from heaving of the soil is somewhat exaggerated. To understand how serious things are, it is necessary to consider such a process in more detail. So, soil heaving occurs inhomogeneously, and this is primarily due to differences in the heights of the earth's surface. They are predominantly observed in the spring, when the south side of the house is heated and also moistened by the spring drop much faster and better. Toward evening, the temperature begins to drop, by which time the ground has already managed to absorb a large amount of melt water, which turns into a layer of ice in it.

Its mass can reach several hundred kg, and this is quite enough to raise part of the foundation to a certain height. This whole process takes place overnight. During the day, when the temperature rises again, the water in the soil begins to thaw. As a result of this, the foundation begins to sag, while a large amount of water again enters the soil, which subsequently crystallizes. And such a process occurs from day to day until the air temperature returns to normal, that is, heat comes.

During the period of spring water level drops, the house can sink a few centimeters, and this is quite enough to cause inevitable destruction in the building. It will be extremely difficult to level them in the future.

The scheme of laying the foundation in freezing soil.

It should be noted that the heaving process can be observed not only in spring, if the waters lie close to the surface of the earth, then a similar phenomenon occurs in winter. As a result, the consequences of it are even more serious.

In addition, the damage from heaving of the soil also depends on the ratio of bound and free water present in it. It is different for every type of soil. So, if it is represented by layers of sand, then the minimum amount of cohesive water will be observed in them. This means that heaving will not have a strong negative effect on the structure. Whereas in such types of soil as sandy loam, loam or clay, the situation is reversed. They contain a large amount of cohesive water. Therefore, there is a strong migration of moisture in them. When such soils freeze, the damage from heaving for buildings is very serious. The deformation can be up to tens of centimeters.

In addition to the ratio of bound and free water, other factors also affect the intensity of heaving, including:

Scheme of installation of the drainage system of the foundation.

• the severity and duration of winter;
• average thickness of snow cover;
• soil composition;
• the amount of seasonal precipitation;
• air humidity;
• terrain;
• the presence of vegetation cover;
• depth of occurrence of waters located underground;
• location relative to the south.

Since heaving can cause serious damage to the structure, it is recommended to build its foundation below the freezing depth of the soil. Its value depends directly on the area where the dwelling will be built. The approximate depth of soil freezing in cities is as follows:

1. Stavropol and Nalchik - 70 cm.
2. Surgut, Nizhnevartovsk, Vorkuta and Salekhard - 240 cm.
3. Petropavlovsk and Tobolsk - 210 cm.
4. Novosibirsk and Omsk - 220 cm.
5. Dnepropetrovsk, Rostov, Minsk and Kyiv - 90 cm.
6. Kustanai and Kurgan - 200 cm.
7. Uralsk and Samara -160 cm.
8. Odessa, Lvov and Sevastopol - 70 cm.
9. Chelyabinsk, Yekaterinburg and Perm - 190 cm.
10. Ufa and Orenburg -180 cm.
11. Nikolaev, Simferopol and Krasnodar - 80 cm.
12. Kazan, Kirov, Izhevsk and Ulyanovsk - 170 cm.
13. Penza, Saratov, Vologda and Kostroma - 150 cm.
14. Tver, St. Petersburg, Voronezh, Tambov, Tula, Novgorod, Moscow, Ryazan and Yaroslavl - 140 cm.
15. Astrakhan and Pskov - 110 cm.
16. Kursk, Volgograd and Smolensk - 120 cm.
17. Kursk, Kharkov, Kaliningrad and Belgorod - 100 cm.

It should be said that the Mediterranean humidity, which is present at the soil, is a decisive factor. She is in more influences the force of heaving. At the same time, the density of the lower layers of the soil also plays a significant role. The higher it is, the less deformation of the structure will be observed, and vice versa, the lower it is, the stronger the heaving of the soil will occur.

Thermally insulated shallow foundation TFMZ

It should be borne in mind that the degree of frost heaving of the soil, the strength of building elements may change over time. This creates a constant risk for buildings built on the foundations described above.

A modern way to solve the problem of frost heaving for a private house is application of heat-insulated shallow foundation (TFMZ).

Any foundation structure can be thermally insulated. To do this, the foundation itself is insulated with a layer of thermal insulation, as well as the soil under and around the foundation.

Thermal insulation of the foundation prevents freezing of the soil near the foundation, which makes it possible not to take into account the effect of frost heaving forces on the building. . The use of modern heat-insulating materials for insulation of the foundation makes this method more cost-effective, allowing to simplify and reduce the cost of the building structure, avoid the risks associated with design and construction errors, with changes in soil properties and building strength during operation.

The use of modern heat-insulating materials for insulation of the foundation makes this method more cost-effective, allowing simplify and reduce the cost of building construction, avoid risks, associated with errors in design and construction, with a change in soil properties and the strength of the building during operation.

Foundation on heaving soils with a high level of groundwater

In winter, some types of soils swell. This phenomenon is called frost heaving. The following types of soils fall under its influence:

1. Clay and loamy.
2. Sandy silty and fine-grained.

They increase their volume under the influence of cold. Because the water accumulated in them freezes in winter. Soil is pushed out. If there is no moisture in the soil, then heaving occurs for this reason - moisture vapor is redistributed in the soil. She goes up.

And in this situation, the soil is considered slightly heaving. In this case, the foundation is additionally protected.

According to this criterion, there are the following categories of soils:

1. With weak heaving.
2. With medium swelling.
3. With strong swelling.

The scale of changes is determined by the type of soil in the working area.

So the foundation is deformed under the influence of frost heaving.

Gradual freezing

If the ground contains a lot of sand and gravel, then frosts are not terrible for it. This is ideal for setting the foundation of any structure. If there are not enough such impurities in the soil, then the foundation is installed above the freezing layer, away from groundwater. If this is not taken into account, then in frosts it will be difficult to avoid heaving of the soil, which can lead to serious consequences: cracks in the frame of the house and even its possible destruction. The consequences depend on the strength of the soil pressure. But this can be completely avoided if everything is foreseen in advance.

Cold weather in our country can last quite a long time - 2-9 months, depending on the region. Therefore, heaving of the soil is quite possible. It does not come immediately, but passes in stages:

1. preliminary stage.
2. Main.
3. Hypothermia.

At the first stage, the soil is only slightly cooled. At this temperature, the liquid in it does not freeze through. But when the second stage comes, the water crystallizes and turns into ice. After this comes the stage of hypothermia. That is, the soil is compressed under the influence of severe cold. Its temperature begins to drop, and if there is a lot of moisture in the soil, it swells. The transition from one stage to another is slow, and it is impossible to calculate this process. After passing through all the stages, the thawing of the frozen ground begins. By the way, this process can cause subsidence at home, which is affected by the strength and frequency of the process.

Given these features, it becomes clear that the installation of the foundation in no case should be carried out in cold, more precisely in frosty, weather. This is especially true for regions such as the far north, for example. If this rule is neglected, the settlement of the house and, possibly, its destruction immediately after construction cannot be avoided. But it is worth considering a number of other reasons, in addition to prolonged cold weather.

Effects of soil freezing on the foundation

Distribution of heaving soils in Russia

Since sandy and clay bases are ubiquitous, it can be assumed that the location of soils with heaving properties covers almost half of the territory of Russia. This includes:

• western regions of the Russian Federation: Kaliningrad, Pskov and Leningrad regions and the Republic of Karelia;
• central zone of the Russian Federation: Vladimir, Kaluga, Ivanovo, Kostroma, Ryazan, Moscow, Smolensk, Tver, Tambov, Tula, Yaroslavl, Belgorod, Bryansk, Vologda, Voronezh, Kirov, Kursk, Lipetsk, Orel, Penza, Samara, Saratov, Ulyanovsk regions , Chuvash Republic;
• the southern parts of the Arkhangelsk and Murmansk regions, the Khabarovsk Territory, the Republic of Yakutia, the Krasnoyarsk Territory, the Irkutsk and Tyumen Regions, the Komi Republic;
• Amur, Chita, Novosibirsk, Omsk, Kemerovo region, Republics of Buryatia, Komi, Tyva, Altai, Sverdlovsk region, Republics of Tatarstan and Bashkortostan, Volgograd region, Rostov region, Republic of Kalmykia;
• northern parts of the Krasnodar and Stavropol Territories.

The permafrost zone is excluded, which covers most of the territories of Yakutia, the Krasnoyarsk Territory, the Tyumen and Arkhangelsk Regions, and the Komi Republic. The permafrost zone is different in that the soil there freezes hundreds of meters deep, so the problem of heaving soils is irrelevant for this zone.

In the same way, the problem of frost swelling is irrelevant for regions where the foundations of buildings are mainly rocky and coarse-grained soils - these are all the North Caucasian republics and the southern part of the Stavropol Territory.

In addition, the problem of heaving does not matter for territories where the bases practically do not freeze through - these are the southern part of the Krasnodar Territory and the Republic of Dagestan.

The depth of freezing, along with the level of groundwater, are the determining factors influencing the amount of possible swelling of the base. For example, in regions close to Lake Baikal, where the freezing depth can reach 2.5 m, the surface rise during swelling can reach 30-40 cm, in the Moscow region, with a freezing depth of 1.5 m, the surface rise is 15-18 cm.

Arrangement of the pile foundation

On problematic soils, a shallow type of support will be optimal. The work consists in twisting the screw piles below the freezing of the soil. The design provides support for the building, regardless of its mass and type of soil (loose, sandy, heaving or waterlogged). The piles have little contact with the swollen earth, excluding its influence on the building.
The design and construction of foundations on piles is subject to SNiP 2.02.03-85, according to which hollow metal, wood and concrete products are used, where cement mortar is poured. According to the bearing load of the building, stands are distinguished that penetrate into soft soils and hanging supports, which are needed for freezing peat bogs or in regions with extreme climates.

The use of piles

Bored products are mounted on swellable soil, concreting them in drilled trenches. The construction algorithm can be represented as follows:

1. Making trenches with a diameter of 30 cm using a hand drill. The depth of the pit (no more than 10 m) is determined according to the increase in the volume of moisture in the soil. The pits are located in increments of 120 cm.
2. Laying a cover made of PVC film, roofing felt or galvanized steel in wells. The event will prevent the elements from being pushed out during the heaving period.
3. Installation of a reinforcing cage in the form of 3 connected rods, which will eliminate the likelihood of a rupture of the base.
4. Concreting rods with heavy concrete. The pouring is carried out continuously, and the dough is compacted by piercing the mixture.

It is permissible to build a house after 30 days - then the concrete composition hardens.

Determination of the degree of heaving of soils

The most reliable data on the degree of heaving of soils can be obtained on the basis of tests at the construction site.

In the absence of experimental data, the degree of heaving of the soil at the construction site it is allowed to determine according to the physical characteristics of soils established during laboratory tests- the type of soil and its variety, the level of groundwater and the plasticity of the soil (fluidity index).

On self-assessment the degree of heaving of the soil, in order to avoid errors in the choice of foundation design, it is recommended to take the most unfavorable soil conditions.

To do this, we use the following evaluation method:

1. In the immediate vicinity of the construction site of the building, we dig one or two pits with a depth of at least 1.5 m. Visually determine the type of soil (sandy or clayey). To determine the type of soil at home, we can recommend such a simple test: a small portion of the soil is abundantly moistened with water, then a tourniquet is rolled up from the resulting mass between the palms of the hands and bent into a ring. It is impossible to roll a tourniquet out of sand. A sandy loam ring crumbles into small fragments, from loam into 2-3 parts, from clay - the ring remains intact.

2. In autumn (not earlier than August), we determine the groundwater level (GWL) in the following ways:

We will find out if there are wells, wells, pits nearby and at what depth the water is in them. How does the location of the well, the well correlate in height with your site, above or below it? How much? Simple calculations may allow you to determine this SPL.

We check with the neighbors if they are nearby - do they have basements, is it dry there, if there is water, then when does it appear and how, again, does this correlate with your site.

For exact definition, you can just dig a hole 1.5-2 deep m. If water does not appear in the pit, then at the bottom of the pit they drill a well with a garden drill for another 1.5 m. If water appears, measure the distance from the soil surface to the level of groundwater. This will be the UPV.

3. We calculate Z - the depth of the groundwater level, counting from the bottom of the layer of seasonal freezing of the soil under the foundation. To do this, we subtract the calculated depth of soil freezing from the obtained value of the WLL.
For example:
At the site of the RPV = 2.4 m.
Estimated depth of soil freezing under the foundation of the house - 0.7 m. (calculation example here).
Then, the value Z=2.4 m. - 0,7 m. = 1,7 m.

3. We determine the conditions for soil moisture according to the type of relief - table 1.

4. According to table 1., knowing the degree of humidity and the value of Z, we determine the degree of heaving of the soil at the construction site.

Table 1. Determination of the degree of soil heaving.

Soil moistening	Z value, m	The degree of soil heaving
Moisture conditions by type of relief	Degree of humidity	Clayey	Sandy
Dry areas - hills, hilly places, watershed plateaus.	Soils are dry - moistened only by precipitation.	> 2	> 1	Weakly heaving
Dry areas - slightly hilly places, plains, gentle slopes with a long slope.	Soils are wet - they are moistened due to atmospheric precipitation and perched water, partly by groundwater.	> 1,5	> 0,5	Medium heaving
Wet areas - low plains, hollows, interslope lowlands, wetlands.	Moisture-saturated soils - are moistened due to precipitation and groundwater, including perched water.	< 1,5	< 0,5	Heavily fluffy

The degree of soil heaving is determined by the worst of the two indicators - the degree of moisture or the Z value.

For example, we have clayey soil on the site, according to the conditions of the relief we determine the degree of humidity - the soils are dry. According to this indicator, the soil seems to be classified as weakly heaving. But the value of Z=1.7 m. (1.7>1.5), and according to this parameter, the soil on the site should be classified as medium-heaving.

Under the same conditions, but at Z=2.5 m. (>2) - the same soil will be slightly heaving.

This soil estimate will be very approximate.- the degree of heaving for some types of soil will be shifted to the unfavorable side.

When occurring under the base of the foundation (within) soils of different consistency, the degree of heaving of these soils as a whole is taken according to the weighted average value.

Where does groundwater come from and what is perched water, read in the article.

How to reduce the heaving of the soil at the base of the foundation

It is often beneficial to strengthen the soil, which will make a simple and reliable foundation. With strongly heaving soils it makes sense focus primarily on improving soil characteristics foundation, and only then on the calculation of the thickness-width of the foundation tape and its reinforcement.

To reduce soil heaving deformations, the following measures are usually performed:

1. A good solution to the problem of stabilizing heaving soils can be embankment of non-rocky soil and the foundation is already on it. In this case, two tasks are solved - the general level of the local area rises (usually this is true for such soils) and the soil parameters improve.

2. Partial or complete replacement of the heaving layer on non-rocky by creating pillows of coarse or medium sand with a high filtration coefficient.

3. Decrease in soil moisture(by using geotextiles to reduce capillary suction, drainage, clay locks and blind areas, lowering the level of groundwater, diverting surface water from the building through a vertical layout, drainage ditches, flumes, trenches, drainage layers, etc.).

4. soil warming, for example, the device of a heat-insulated shallow foundation (TFMZ).

The choice of foundation resistant to frost heaving soil

Soils at the base of the foundation

Choose the type of foundation for your home

Read the article

Choosing a foundation for a private house on heaving soil

Slab foundation is the best option

The earth subject to swelling contributes to the occurrence of cracks in the plinths of buildings. A monolithic slab buried in the ground will be needed to support a wooden or aerated concrete house of a small square. The construction of a monolith has a number of nuances:

• a good way to make a stable base is to use a ribbed plate;
• the solid element is reinforced with jumpers, between which gravel or sand is poured;
• for buildings made of light materials, a platform 25 cm thick is sufficient;
• it is advisable to reinforce the slab with rods with a diameter of 14 mm, observing a step of 20 cm. The reception contributes to the uniform load of houses on soils with a high level of groundwater.

The slab base is assigned the function of a heater. To prevent freezing of soils, a waterproofing coating is applied to the surface of the monolith. The slab can be reinforced with a self-leveling screed, which at the same time will be the start for organizing a warm floor.

Heaving soil what is it and what problems can be with it

Heaving soil is a layer of soil that undergoes frost heaving. This type of soil is unstable. When thawing, or vice versa - freezing, the volume of the soil changes, and thereby affects the foundation of the building, which stands on such land. Of course, this phenomenon is not detrimental to all types of foundations, but soil heaving brings to houses built on tape, columnar and slab types. the largest number problems.

A characteristic feature of heaving soil is its freezing and thawing, and usually these factors are expressed unevenly. For example, on the south side, in spring, the soil will thaw faster, and in winter it will freeze more slowly. Because of this, deformation of the base of the structure will occur, and subsequently will inevitably lead to the gradual destruction of the foundation.

For this reason, many experts in the construction industry support the opinion that the foundation of the house should be sufficiently rigid and effectively contribute to the even distribution of all loads. Therefore, the foundation must be reinforced.

But, of course, the problem cannot be solved by reinforcement alone. Other methods must also be used. Let's consider all this in order.

The negative impact of soil on the foundation and walls of the house

Unfortunately, the heaving type of soil is very common in Russia. These are the so-called loams, clays, sandy loams, and so on, in general, all types of soil that have the ability to retain water.

Therefore, it is important, when building houses, to take into account these points and, most importantly, to choose the appropriate type of building foundation.

Consider the factors that significantly affect this choice. These are two options land plot related to each other:

1. GPG or soil freezing depth. If the soil is wet, then the heaving of the soil will occur to the entire depth to which it freezes;
2. GWL, or groundwater level. This factor affects the degree of soil moisture.

These two parameters have a great influence on how heaving soil behaves during the transitional periods of the calendar year: from winter to spring and from autumn to winter.

Quite often occurs a difficult situation if you need to build a building on a quicksand. In this case, it is imperative to carry out detailed geological exploration, and subsequently carry out work on the insulation of the foundation and make the drainage system of the site where the construction will be carried out.

Soil pressure indicator and its effect on the foundation

This indicator means the pressure of the cobwebbed soil, in particular, on the foundation of the building. Ice in the ground can reach huge masses that are capable of pushing the foundation to the surface. There are two types of type of push-out effect on the base of the house:

• Vertical buoyancy. It occurs due to heaving of the soil layers located under the base of the building.
• Tangent buoyancy, which occurs due to heaving of the soil in contact with the side walls of the foundation.

The vertical force does less damage to the foundation. Deformations are minor and can be prevented in advance. To do this, it is necessary to use only high-quality components for the foundation, and make the base of the structure below the freezing depth.

Under the influence of a tangential force, the soil not only rises, but also stratifies. This can lead to the complete destruction of the building standing on it. This phenomenon is especially dangerous if the house has a small mass.

Schematically, the effect of buoyant forces on the base of the house is presented in the following table:

Shallow foundation of increased rigidity

A more effective way to solve the problem of building low-rise buildings on heaving soils is to use shallow foundations adapted to uneven deformations of the base.

By design, such foundations can be:

• Tape
• In the form of a foundation slab
• And in some cases, columnar with a grillage.

The basic principle of constructing shallow foundations on heaving soils is that, for example, the strip foundations of all the walls of a private house are combined into a single system and form a fairly rigid horizontal frame redistributing uneven deformations of the base.

The use of shallow foundations is based on a fundamentally new approach to their design, which is based on the calculation of foundations by heaving deformations. Wherein foundation deformations are allowed, including uneven, however, they should be less than the limit, which depend on the design features of the building.

When calculating bases for heaving deformations, the pressure transmitted to it, as well as bending stiffness of the foundation and above-foundation structures.

Above-foundation structures (walls, ceilings) are considered not only as a source of loads on foundations, but also as an active element participating in the joint work of the foundation with the foundation.

The use and consideration in calculations of the concepts of rigidity-flexibility of the load-bearing frame of the house allows significantly reduce the depth of the strip foundation for small buildings. The use of shallow strip foundations makes it possible to reduce the cost of foundation construction by 30-80%.

Such foundations require accurate consideration of soil properties, impose increased requirements on the strength of building elements, right choice constructive solutions and quality of construction work.

There are serious theoretical justifications and a large successful practice of building low-rise buildings from any materials on these foundations. At the same time, the existing some negative experience of using shallow foundations, with an expert study, shows that The main reason for such negative situations is errors in the design and construction of buildings.

A necessary condition for the use of this type of foundation in a particular case is readiness and ability of the Customer to carry out high-quality work research, design and construction.

The use of such foundations certainly justified for wooden (log, lumber) or frame buildings, the walls of which are better able to withstand deformations.

Read the article -.

Characteristics of non-rocky soil and features of the construction of the foundation

As mentioned above, the foundation is most optimally erected on safe soils. Non-rocky soil includes rocky and detrital soil. The latter is formed as a result of the destruction of rocks. gravel and rubble can be attributed to it. For the most part, these are coarse-grained materials. Often they are used in the construction industry. This group of soil includes both medium and coarse-grained sand. There is some relationship between and the size of its particles. The larger they are, the safer this layer of soil is and the less impact it has on the foundation.

Scheme of the device of a sand cushion as a support platform.

The foundation is laid with this type of soil according to the following technology. Regardless of the depth of freezing of the soil and its moisture content, it is built shallowly, that is, not deep. This saves time and effort for earthworks. In the presence of rock, the foundation can not be equipped at all. In some European countries, for example, in Montenegro, certain regions of Germany and Finland, houses are built without a foundation due to precisely these terrain features. In the presence of coarse sandy soil, the thickness of the concrete foundation is only about 20 cm.

Undoubtedly, these calculations are relevant only for small houses, and not for multi-storey structures. After pouring the concrete, when it hardens, you can immediately erect the basement of the building or the walls. In other cases, when the nature of the soil is different, a trench 50-70 cm deep breaks out. After that, it is covered with several layers of coarse-grained sand, each 15-20 cm thick

It is important that all layers are thoroughly watered. As for what kind of foundation you can build, there are no restrictions here.

It can be monolithic (slab), columnar or tape. For heaving soil, the most optimal is a columnar foundation or an anchor-type foundation, since in this case the load, including the action of tangential forces, on the foundation will be minimal.

Types of foundations for heaving soils

The reliability of structures erected in places subject to heaving is determined by their resistance to the effects of tangential heaving forces. You can not make a recessed base for a low-rise building with low weight. The load of the house on the base in this case will be less than the action of the tangential heaving forces, which will lead to its destruction. It is allowed to make a deeply buried strip foundation only for houses built from heavy materials.

Since soil freezing in central Russia reaches 1.5 m, the depth of the foundation should be below this level. This will require large material and labor costs.

The way out of this situation was monolithic foundations on piles (or pillars). An indispensable condition for the reliability of the pile structure is the deepening of the pillars to a depth exceeding the level of freezing. The best option for heaving soils is a monolithic reinforced concrete columnar base.

In areas with heaving soils, successfully erected shallow foundations. Most often they are used in the construction of light houses with a small area.

slab foundation, slab foundation

Foundation in the form of a monolithic reinforced concrete slab under the entire area of ​​the house- another option for a shallowly buried foundation.

The large area of ​​support allows to significantly reduce the specific load on the ground. Reinforced reinforcement and high consumption of concrete make slab foundation is the most expensive in private housing construction.

Foundation - a slab for a private house, due to its high cost, it is advisable to use with a weak bearing capacity of the soil on the site. The slab foundation, as well as other types of foundations, can be made with or without thermal insulation to protect against frost heaving of the soil.

should be distinguished slab foundation and shallowly buried monolithic strip foundation with suspended floors on the ground.

In the latter case, a monolithic reinforced concrete strip foundation and a monolithic reinforced concrete floor slab are poured over the ground.

In this option, a monolithic reinforced concrete the floor slab is not involved in transferring the load from the weight of the building to the ground, but plays the role of a floor slab and must be calculated for the standard load of floors, have appropriate strength and reinforcement.

The soil is actually used here only as a temporary formwork when constructing a reinforced concrete floor slab. This design is often referred to as a "suspended floor on the ground."

Strip foundation with monolithic suspended floor slab often mistakenly considered a slab foundation with stiffeners. The structures are really similar, but there is a significant difference in details - reinforcement, dimensions.

In all cases, when constructing foundations, it is necessary to provide for water protection measures aimed at reducing soil heaving deformations - providing decrease in soil moisture, lowering the level of groundwater, diversion of surface water from the house by means of a vertical layout device, drainage facilities, catchment ditches, flumes, trenches, etc.

Lightly buried foundations should be used with caution for houses on steep slopes and slopes. For shallow foundations, the danger of shear (slip) is quite high due to the almost completely absent pinching in the ground

As you can see, the choice of a fundamental design and the calculation of the foundation is a complex and responsible task. The final results primarily depend on a reliable assessment of the soils at the base of the building, which are quite difficult to obtain without surveys. The price of a mistake can be very high. An independent choice of foundation can be recommended for auxiliary, outbuildings and small garden houses.

It is wiser to order the design of the foundation for building a house to specialists.

Additional information on the construction and use of shallow foundations can be obtained from the book of one of the authors of SNiPs V.S. Sazhin "Do not dig deep foundations." Download books in djvu format 389 kb. and in PDF format 4150 kb(follow the link and select "File" > "Upload" in the menu at the top left).

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Calculation of the load, the area of ​​the sole and the thickness of the sand cushion of the shallow foundation

Heaving soils are

Heaving soils- soils that change their volume and properties during freezing - thawing. These include clays, loams, sandy loams, silty and fine sands, as well as coarse soils with the inclusion of the above soils of more than 35% of the volume. When the soil freezes, forces of normal and tangential heaving develop, which, acting on the foundation, can cause it to move and deform the structures above the foundation. Practically non-rocky soils can be: fine and silty sands and clayey soils of a solid consistency with a deep occurrence of the groundwater level, namely, fine sands with z> 0.5 m, silty sands at z> 1.0 m, sandy loam at z> 1.5 m, loam at z> 2.5 m and clay at z > 3.0 m ( z- the depth of the groundwater level, counting from the base of the seasonal freezing layer).

Dictionary-reference book of terms of normative-technical documentation. academic.ru. 2015 .

See what "Heaving Soils" is in other dictionaries:

Heaving soils- - prone to increase in volume when saturated with water and freezing in winter. [Glossary of basic terms required in the design, construction and operation highways. Moscow. 1967] Heading term: Minerals Headings ... ... Encyclopedia of terms, definitions and explanations of building materials

heaving soils- 3.39 heaving soils. The general name of soils, the relative frost heaving of which exceeds 1%.

Most houses are built in regions with a temperate climate, but this does not mean that there are no problems during the construction of buildings. Heaving soils are one of them. The fact is that in conditions of frost heaving, the fundamental foundation of the building can quickly crack, as a result of which its integrity will suffer, and, accordingly, the strength of the foundation.

There are many methods for solving such problems. However, before starting to take any action, it is necessary to take into account the features of the heaving of the earth.

How does swelling happen

Since the density of water is greater than that of ice, in the process of freezing its volume changes upwards. Based on this, the moisture in the soil becomes the cause of the expansion of its mass. Hence, such a concept as the forces of frost heaving appeared, that is, the forces that affect the process of soil expansion. The soil itself in this case is called heaving.

Healthy! The soil expansion level is typically 0.01. This means that if the top layer of the earth freezes to a depth of 1 m, then the soil volume will increase by 1 cm or more.

Frost heaving itself occurs for several reasons:

• Due to the depth of the upper aquifer. If the water is located close to the surface, then even if the clay is replaced with gravelly sand, it will be ineffective.
• Based on the depth of freezing of the earth during the cold period in a particular region.
• Depending on the type of soil. Most water is found in clay and loam.

Based on the composition of the soil and climatic conditions, heaving and non-heaving soils are distinguished.

What is the difference between heaving and non-heaving bases

According to GOST 25100-2011, there are 5 groups of soils that differ in the level of heaving:

• Excessively heaving (the level of soil expansion is more than 12%);
• Strongly foamy - 12%;
• Medium heaving - about 8%;
• Slightly heaving - about 4%;
• Non-porous - less than 4%.

The last category is considered conditional, since there is practically no soil that does not contain water in nature. Only granite and coarse-grained rocks can be attributed to such bases, but in our conditions such soils are extremely rare.

Speaking about what heaving soil is and how to determine it, it is worth considering its composition and groundwater level.

How to independently determine the degree of heaving of the soil

In order to “at home” determine whether there are heaving soils on your site, the easiest way is to dig a pit (vertical working) about 2 m deep and wait a few days. If no water has formed at the bottom of the dug pit, then it is necessary to drill (a garden drill is used for this) a well for another 1.5 m. When water appears in the well, the distance from the groundwater level to the surface is measured using a bar.

To determine the type of soil, it is enough to make a visual inspection of the soil. On the basis of these data, it is possible to draw approximate conclusions about the degree of land expansion in the cold season.

If the soil is slightly heaving, then the GWL will be below the estimated freezing depth. This value directly depends on the type of soil:

• silty sands - 0.5 m;
• sandy loam - no more than 1.0 m;
• loam - 1.5 m;
• clay - 2 m.

If the soil is medium-heavy, then the groundwater level will be below the freezing depth by:

• 0.5 m if sandy loam prevails;
• 1.0 m - loam;
• 1.5 - clay.

If the soil is strongly heaving, then the GWL will be lower by:

• 0.3 m - if the soil mainly consists of sandy loam;
• 0.7 m - loam;
• 1.0 m - clay.

If clay and loam are located quite close to the estimated depth of soil freezing, this is not the best foundation for a shallow foundation. However, this does not mean that it is impossible to build on such soils.

How to solve the problem of heaving soils

There are many ways to reduce the level of soil heaving. Consider the most common.

Soil replacement

Replacing the heaving soil is considered the most labor-intensive and expensive process, since it assumes the complete removal of the soil located at the site of the future construction. After that, new earth or coarse-grained sand and gravel is filled in, and the foundation is laid on non-rocky soil.

Building weight

The lower the weight of the building, the more likely it is that the earth that swells during the cold season will exert pressure on it. To prevent this from happening, it is recommended to build more massive buildings. However, it also leads to serious financial costs.

Construction of a slab foundation

To add additional weight to the building and prevent ground pressure, you can install a slab foundation as the foundation for the house. A solid monolithic slab with a height of more than 20 cm, buried in the ground, will be subjected to frost heaving forces, however, in this case, it will simply rise evenly in winter and take its original position when the air temperature rises.

Technically, it is not difficult to build a slab foundation (difficulties can arise only at the stage), however, such a foundation will also be expensive.

Pile foundation installation

If you want to get by with little bloodshed, then the cheapest way is to install a pile foundation. However, it should be borne in mind that such structures are only suitable for light-weight houses (frame, sip-panel structures, and so on).

As a fundamental basis, fit:

• screw piles that are screwed into the soil just below the freezing level;
• reinforced structures (in this case, it is necessary to prepare wells and install rods wrapped in roofing material and a metal frame in them).

After installing the piles, the elements are connected using load-distributing slabs or beams (grillage), which are laid around the perimeter of the future building and insulated with polystyrene foam or expanded polystyrene.

Some builders erect brick columnar structures up to 60 cm high on heaving soils and deepen them by about 15 cm, but such bases are only suitable for gazebos, summer kitchens and other structures not intended for living.

Permanent home heating

If we compare the temperature of the soil located under a heated and unheated house, then in the first case it will be almost 20% higher. Accordingly, if people live in the building year-round and the building is heated, then the heaving force will be minimized.

Soil drainage

To prevent soil expansion, the water content of the soil can be reduced. To do this, it is necessary to build a drainage well, which will be located at some distance from the building. To build such a system, you need:

• Dig a trench around the house.
• Lay pipes in it with small holes on the sides. In order for water to be drained from the house by gravity, it is necessary to lay pipes at a slight slope towards the drainage well. Accordingly, the closer the pipeline is located to the well, the deeper it is laid.
• Sprinkle pipes with gravel and cover with geotextile.

Ground insulation

To reduce the heaving of the soil, you can build a blind area. Typically, such a structure is made around the perimeter of the building in order to protect the foundation from rainwater. But, if you make more powerful thermal insulation of the blind area, it will be possible to reduce the level of land expansion in the winter.

To make an insulated blind area, you must adhere to the following recommendations:

• The width of the blind area should be 1-1.5 m more than the width of the soil freezing.
• As the basis for the blind area, it is recommended to use sand, which is carefully rammed and spilled with water.
• Expanded polystyrene or any other insulation is laid on the sand with a layer of about 10 cm.
• Waterproofing (roofing material) is laid on top.
• Crushed stone is laid on the waterproofing layer and everything is poured with concrete.
• Before concreting, it is recommended to reinforce with a steel mesh with a diameter of 4 mm and a mesh size of 15 x 15 mm.

In custody

Knowing which soils prevail on the site, you can calculate the level of their heaving, respectively, you can choose the best option for arranging the fundamental foundation or reduce the amount of moisture in the soil. Some builders additionally insulate the foundation, as this also reduces the level of moisture affecting the concrete base of the house.

Heaving soils cause many problems for builders. In winter, they are able to greatly increase in volume, exerting increased pressure on the foundations of the building. At the same time, the structure rises unevenly from the ground, serious cracks appear on the walls. Before you fight the phenomenon, you need to understand what it is.

A difficult issue in self-construction is the determination of what soils are available: heaving or non-heaving. According to GOST 25100-2011, all bases are divided into five groups according to the degree of frosty heaving:

• excessively heaving;
• strongly heaving;
• medium-heavy;
• slightly heaving;
• non-porous.

The last group can be called conditional. There are practically no such types of soils in which frost heaving forces will never arise. The category of safe bases includes only coarse-grained rocks and granite, the occurrence of which on the surface is extremely rare.

Soil type does not affect the likelihood of frost heave forces as much. The factor of occurrence of this phenomenon is not soil, but moisture and negative temperatures. Under certain conditions, negative phenomena can occur in almost any area.

The soil's tendency to heaving is influenced by properties such as:

• capillary activity;
• filtering ability.

According to these indicators, clay soils become the most dangerous types of soil. These include clay, loam and sandy loam. These soils do not filter water well, retain it and do not allow it to pass into the deeper layers. The liquid remains dangerously close to the foundations.

Soil types.

At the same time, clays are characterized by high capillary activity. For comparison, sandy types of soils are capable of pulling water by about 30 cm. The property is relevant when precipitation falls or snow melts. Moisture extends only 30 cm from the source. In this case, the foundations are protected from frost heaving by a blind area of ​​a standard meter width. Clay, on the other hand, can pull moisture up to a distance of 1.5 m; to protect it from atmospheric moisture, it will be necessary to build a very wide blind area to prevent damage.

With a high level of groundwater, even conditionally non-rocky types of soil (coarse and medium sands) can lead to problems. The danger of frost heaving in the sands can also appear under the influence of other factors (for example, the house is located on a site with a slope, even a slight one).

What is dangerous frost heaving

The combined effect of moisture and low temperatures on the soil leads to an increase in its volume. For any building, uneven deformations, which are characteristic of frost heaving, are of particular danger. This is due to the fact that the ground under the outer walls is heated slightly from the building, and in the middle of the house the temperature is above zero.

A crack caused by heaving.

External walls, and especially corners, are able to rise by 15 cm relative to the initial mark. At the same time, deformations under the internal walls do not occur or they are small. Uneven uplift leads to the appearance of inclined cracks in the walls.

Also, frost heaving has a negative effect on the side surface of the foundation.

Ways to fight

So that heaving soils do not cause problems during operation, it is necessary to deal with the causes of frost heaving of clays and other types of soils even at the stage of foundation construction. Methods of struggle depend on the scale of the problem and the type of supporting part of the house. Most often, activities are provided in the complex.

Buried foundations

Every builder knows that in order to effectively combat frost heaving, it is necessary to lay the building's supports below the freezing depth of the soil. This value is found according to special tables and maps or is calculated according to the formula from the Joint Venture "Foundations of buildings and structures". But taking such measures is not always enough. With a deep foundation, it is possible to avoid impacts on the base of the foundation, but there remain tangential forces acting on its lateral surface. They can be decomposed into:

• vertical, which in some cases are able to lift structures;
• horizontal, bending foundations.

Forces of frost heaving depending on the depth of laying.

Methods of struggle depend on the type of structure and foundations. For massive buildings with deep bearings, one or more of the following measures may be recommended:

• coating waterproofing, which not only protects the foundation material from getting wet, but also worsens the adhesion of the soil to them (does not allow the structures to be lifted);
• insulation is performed for the same purpose, extruded polystyrene foam is often used, which also takes on the function of protection against moisture;
• drainage and backfilling of the sinuses with coarse or medium sand allows moisture to be removed from the building;
• the insulated blind area prevents the soil from freezing in the immediate vicinity of the house, which means it eliminates one of the factors necessary for the appearance of heaving;
• competent calculation and execution of reinforcement will allow the elements to withstand horizontal influences.

If the building is made of lightweight materials or has only one floor, it is recommended to use foundations using TISE technology. Such supporting elements are piles, widening towards the bottom. Due to the increase in the cross section, it becomes almost impossible to pull the element out of the soil.

To protect this type of foundation from horizontal influences, you will have to consider the following points:

• competent calculation of the working reinforcement of the pile;
• rigid coupling of the pile with the grillage with the help of reinforcement;
• calculation of the grillage for increased soil pressure on the side surface.

With a large freezing depth, the installation of a deep foundation with insulation, waterproofing, drainage and a warm blind area is not economically viable. It will be easier to build shallow supports. Deepening will become justified only when:

• the need for a basement or basement;
• poor ground strength closer to the surface.

Shallow foundations

Such designs have several advantages. They reduce the cost of building foundations, reduce the time of work. Shallow foundations can be used if the groundwater level is sufficiently high (at least 1.5 m).

The following measures used in the complex will help protect these types of supporting elements of the building:

1. . This design will reduce the depth of freezing of the base. The exact mark for the safe laying of the sole depends on the climate, the thickness of the insulation and the width of the blind area. In most cases, it can be advised to use a protective strip 1 m wide with a heater 5-10 cm thick. The depth of the foundation in this case will be 0.7 - 1 m.
2. . If you forget about the thermal insulation of the basement, the foundation of the house will become an excellent conductor of cold under its own sole. For work it is recommended to use extruded polystyrene foam (penoplex). It is fixed to the entire height of the supporting part of the house: from the sole to the base. The thickness of the insulation above the blind area is on average 100 mm, and below you can use foam plastic 50 mm thick. Additionally, the material protects the foundations from moisture, increasing their service life.
3. . The system allows you to eliminate the second factor in the occurrence of frost heaving: moisture. For drainage to work effectively, it must be properly positioned. The pipe is laid next to the building spot, but not under it. Drainage should be below freezing or in the place where it does not occur (within the action of the insulated blind area). If pipes are laid in freezing ground, they can break in winter. You will also need to comply with the recommended slopes of the drainage pipes, which depend on the diameter of the section.

If there is no possibility of a drainage device (high complexity of work, nowhere to take it out, etc.), you can only get by with a blind area. In this case, the protective strip along the perimeter of the building is made of a large width. It should completely prevent the access of atmospheric moisture to the foundations. For clay, the width should be more than 1.5 m. Landscaping around the building is done so that the slope of the site is in the direction from the house.

The method is applicable under the simultaneous observance of the following conditions:

• good strength characteristics of the base under a layer of chernozem;
• low natural soil moisture;
• deep occurrence of groundwater;
• the absence of slopes in the direction of the building on the site.

With proper selection of the type of foundation and timely adoption of measures to combat frost heaving, serious problems can be avoided during the operation of the house. A careful approach to the issue will allow you to find an effective option that requires the least labor and financial costs.

The problem of building buildings on heaving soils often arises in damp regions located in the temperate climate zone. To date, many different methods of combating frost heaving have been developed and tested in practice.

The main thing is to choose the most suitable one for your construction conditions and then the building will serve you without destruction and deformation for many years. Let us consider in more detail the issue of such construction and practical methods for its solution.

Watch a video about building on heaving soils

What is heaving soil?

As you know, when water freezes, it turns into ice. In this case, its volume changes due to the different densities of ice and water: water has a much higher density than ice. Accordingly, when freezing, water, gradually turning into ice, expands, occupying a larger volume.

If such water freezes while in the ground, then the ground will expand with it. In this case, the forces expanding the soil will be called the forces of frost heaving, and such a water-saturated soil itself will be called heaving.

What is the danger of heaving soil for a building?

Let's see what happens to the heaving soil directly next to the building. In winter, when frost sets in, the water freezes and expands, turning into ice. Along with it, the soil containing it begins to expand. Forces of frost heaving arise.

Forces begin to act on a nearby building, or rather on its foundation, lifting it. In the spring, when the temperature rises, the reverse process occurs: the building sinks due to the fact that the ice melts, turning into water and, accordingly, shrinking, increasing its density and reducing its own occupied volume.

If the foundation is not protected from the action of heaving forces, then the building may shift, which sooner or later will lead to the formation of cracks in the walls of the building and the foundation, and then to the destruction of the building.

Features of heaving soils

Heaving soils can be understood as any soils that can store a sufficiently large amount of water in their volume. The more water is in a unit of soil volume, the more prone this soil is to heaving.

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The most prominent representatives of heaving soils are clay and yellow (quarry) fine sand containing a large amount of clay inclusions. Such soils have a high ability to retain water.

The least heaving in this case will be the following types of soils: all soils that do not contain or contain a minimum amount of clay particles, coarse or medium-grained sand, clastic rocks.

All these soils do not retain, they easily pass water through themselves into the underlying layers of the soil, since they consist of large particles that do not have the ability to stick together with each other like clay.

Factors affecting the strength of heaving

1. Depth of the first aquifer.

The closer to the surface the water is, the obviously more heaving it will be. At the same time, even replacing, for example, clay with gravel sand is ineffective, since there will simply be nowhere for water to go through such soil - there will be an aquifer below.

2. Depth of soil freezing in winter, typical for this region.

At the latitude of Moscow, the soil freezes to 1.5 m. It is obvious that heaving forces can act only in those regions where the temperature drops below 0 degrees in winter. C. The deeper the soil freezes, the stronger the heaving forces will act on the building, all other things being equal.

3. Soil types.

Soils with small particles are most susceptible to heaving, capable of retaining water for a long period due to its poor passage through small particles.

Clay soils also strongly retain water. Water passes through large particles easily, since there is sufficient space between large particles for the passage of water.

Methods for solving the problem of frost heaving during the construction of a building

Currently, there are many methods for reducing heaving, which have proven themselves in practice. Let's consider the most important ones.

1. Complete replacement of soil at the construction site of the building.

This method radically solves the problem of heaving, however, it leads to increased construction costs due to the large amount of excavation required to perform.

The idea of ​​the method is as follows: the soil located at the site of the future construction of the building is completely removed and non-heaving soil, as a rule, coarse-grained sand, is put in its place.

2. The location of the sole of the foundation of the building is below the mark at which the soil usually freezes through.

This method is widespread. In this case, choose a suitable foundation. The most common types of foundations are piled for large, heavy buildings and pile-screw for cottages, summer cottages, and other relatively light, small buildings.

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The pile is deepened to the occurrence of a solid layer of soil and below the level of its freezing. In this case, only the tangential forces of frost heaving will act on the building, more precisely on the walls of the foundation.

The action of the main, vertical forces will be neutralized, since the support of the building will be in non-rocky soil.

3. Year-round heating of the building.

It is well known that the temperature in the foundation area under a heated building is always about 20% higher than the temperature under an unheated building.

Accordingly, the soil under the house with year-round heating will freeze much less and the effect of heaving forces will be weak.

When planning and designing a building, it is important to take this factor into account: it will be more profitable to use the building for year-round use.

4. General weighting of the building.

The forces of frost heaving are capable of lifting a building that has a relatively small mass. If the building is heavy, then such forces will not be able to significantly affect the position of the building.

Hence the conclusion: the heavier the building, the greater its mass, the more successfully such a building, other things being equal, will be able to withstand the action of frost heaving forces in the winter.

Therefore, it is more profitable to build heavy buildings with a large mass on heaving soils, although this naturally leads to large financial and time costs both for the construction of such a building and for its subsequent maintenance during operation.

5. Construction of a slab foundation for a house.

The slab foundation is a single reinforced concrete monolithic slab on which all other elements of the building rest.

The building itself in this case, together with the foundation, is a single structure. The foundation itself is built either directly on the surface of the earth, or at a shallow depth.

In any case, it turns out that the foundation, due to a small depth, will be subject to both tangential and vertical forces of frost heaving: it will simply rise in winter during frosts and fall in spring during thaws.

The peculiarity of this foundation is precisely the single monolithic construction, thanks to which, despite the frequent change in the height of the house, it does not collapse and does not crack.

6. Soil drainage.

The idea of ​​the method is to reduce the water content in the soil by draining it directly from the foundation, after which the heaving abilities are reduced accordingly. this soil. Water from under the house and its location is diverted and the soil in this place becomes less wet. To implement this method, a drainage well is dug at some distance from the house, designed to collect water diverted from the building. A drainage system is being built around the house: a trench is dug and pipes are laid into it, containing holes of small diameter along their entire side surface; the pipes are then connected to the well, thereby forming a single drain system.

Heaving soil is a soil mass that expands in the winter season and exerts strong pressure on the walls of the foundation. It leads to the destruction of the structure, its "pushing" out of the pit.

There are types of structures for erection in such conditions and a list of rules for work: from to reinforcement.

Calculation of the intensity of heaving on the site

To calculate the degree of heaving of the soil at the construction site with your own hands, you need use the formula: E \u003d (H - h) / h, wherein:

• E - corresponds to the degree of heaving of the soil;
• h is the height of the soil mass before freezing;
• H is the height of the soil massif after freezing.

To make a calculation of the degree, it is necessary to make appropriate measurements in summer and winter. Soil can be considered heaving, whose height has changed by 1 cm when freezing at 1 m. In this case, "E" will be equal to the coefficient 0.01.

Heaving processes are more susceptible to soils in which there is a high moisture content. When it freezes, it expands to the state of ice and thereby raises the level of the soil. Heaving are considered: clay soils, loams and sandy loams. Clay, due to the presence of a large number of pores, retains water well.

What is heaving soil and why is it dangerous? (video)

How to remove the effect of heaving on the ground?

There are simple ways to remove heaving around the foundation with your own hands:

1. Replacing the layer of soil under and around the base with a non-rocky layer.
2. Laying the foundation on a soil massif below the freezing layer.
3. Insulation of the structure to prevent freezing of the soil.
4. Drainage.

The first method is the most laborious. To do this, it is necessary, at a depth below the level of freezing of the earth, to take out the heaving soil, and to fill in its place with heavily compacted sand.

It shows high bearing capacity and does not retain moisture. The large amount of ground work makes it the least popular, although it is an effective way to overcome heaving. This technique is effective for laying low-rise buildings, shallow penetration, such as a barn.

A feature of the second method is the removal of the effect of heaving on the base of the foundation, but its preservation when exposed to the walls of the base. On average, the lateral pressure on the walls is 5 t/1 m 2 . With it, you can build brick houses.

The third method allows you to make an unburied foundation for a private house with your own hands in heaving conditions. The essence of the method is to lay a heater around the perimeter of the foundation to its entire depth. The calculation of the material is done as follows: if its height is 1 m, then the width of the insulation should be 1 m.

To make water drainage around the house or barn, you need to build a drainage. It is a ditch at a distance of 50 cm from the building, the depth of which is the same as the level of the structure. A perforated pipe is laid in a drainage trench under a technical slope and wrapped in geotextile, and then filled with gravel and coarse sand.

Below - consider the types of bases that can be used on soil prone to heaving.

Shallow strip foundation on heaving soils

An effective way to make a solid foundation for a house or barn is a shallow (small) strip foundation on heaving soils. This is a concrete tape with reinforcement elements, equipped around the entire perimeter of the building and in places where load-bearing walls lie.. To build a non-buried foundation with your own hands, you must follow these steps:

1. , with a depth of 50-70 cm. The width is calculated based on the width of the base itself in total with the formwork, insulation or waterproofing, as well as decor.
2. Lay the slopes of the open waterproofing trench. For this purpose, only a film is used.
3. Fill the excavation with layers of compacted sand, 20-30 cm each. For compaction, the material is periodically wetted with water.
4. Place formwork from any available material (board,).
5. Lay a hydro-protective barrier on the sand.
6. Make a reinforcing belt with a rod diameter of 12 mm.
7. Pour the non-buried foundation with concrete mortar.
8. Lay the second layer of the reinforcing belt in a non-buried foundation with a grout (a feature that only a shallow-buried foundation type requires)

Welding is not used to connect fittings. To make the non-buried foundation more rigid, a wire 20 cm long is used.

Column foundation on heaving soils

The design can be used for laying a house or a barn on heaving soils, the freezing level of which does not exceed one and a half meters. The columnar foundation took ready-made piles as its basis. Their height reaches 3-4 m.

If you plan to build a small building, then such types of piles as driven from wood or reinforced concrete, as well as screw piles, are effective. Wood is a less durable material for foundation purposes.

The columnar foundation is laid below the freezing level of the soil, so only lateral heaving pressure is maintained. Compared to buried strip structures, it is insignificant, since the pile area is smaller.

Among all types of foundation pillars, screw piles for foundations are the most convenient. To make a columnar foundation with their help, you do not need to drill wells. All the work will be done by screw blades.

The pile structure is available for all watery types of soil: swampy, damp areas. To give the building rigidity, the poles are connected by support-anchor platforms. To do this, the poles are screwed into the ground.

On their surface, you need to make a formwork, lay out a reinforcing cage sewn with metal wire and pour concrete mixture. The calculation of the level of the location of the concrete tape is equal to the surface of the soil or slightly lower.

TISE technology is a new way to counteract heaving

For laying the foundation with your own hands, the most affordable design is TISE. It represents the piles of which are connected by a grillage. Chise can be used for brick, frame or stone construction.

Slab foundation in heaving conditions

There are other ways to make a foundation on heaving soils. In addition to TISE, a shallow and columnar base, a slab foundation is used. This is one that resists heaving due to the large sole area.

It is effective with a simple building structure, when the foundation is a square or rectangle. The calculation of materials shows that this is the most expensive, but no less reliable type of structure. It is made of concrete or reinforced concrete.

A monolithic foundation requires the arrangement of a low base. The calculation of the width of the monolithic slab is done depending on what material is used to build the walls.

The average indicator corresponds to parameters from 15 to 35 cm. 15 cm is suitable, for example, for wooden structures, and 20 cm for brick structures. To lay engineering communications in the slab, holes of the appropriate diameter are made in advance in it.

Which type of foundation to choose - not buried, columnar, slab or TISE - depends on the ability to use the technique, the size of the house, its configuration and the material capabilities of the developer.