Foundation for a house on reinforced concrete piles. Foundation on reinforced concrete piles for a private house. Types of pile foundations

Modern industrial construction technology has long found a way to build the heaviest and tallest buildings on problematic unstable soils. Foundations on piles have been used in house building since time immemorial, but the star of pile construction truly rose with the invention of stressed reinforced concrete - the most durable and mass-produced material for constructing foundations on reinforced concrete (RC) piles.

What is the difference between a foundation installed on reinforced concrete piles and conventional supports?

Unlike bored or screw pile supports, foundations on driven reinforced concrete piles have a whole bunch of very attractive characteristics:

• Thanks to the reinforced structure, the reinforced concrete body of the pile is much stronger than the bored one. The design of reinforced concrete pile supports has been developed and optimized for high static and dynamic loads;
• Reinforced concrete pile is produced industrially using high-strength concrete and calibrated reinforcement. Unlike home-made bored piles, the production technology of reinforced concrete piles allows you to control the quality and geometry of the support;
• The fundamental difference from other types of supporting foundations is that piles are driven with a pile driver or driven into the ground to a given depth using a vibrating hammer.

For your information! Due to the large length and relatively smooth surface of reinforced concrete piles, they can be easily installed in the coastal zone, on steep slopes, in marshy peat bogs, in frozen conditions, in places where a screw pile and, especially, a bored pile cannot work normally.

In industrial construction, reinforced concrete supports are used to build foundations, which do not require additional preparation before installation. What does it mean? This means that for the construction of the foundation, a reinforced concrete product is used that has passed quality control, static load tests and, most importantly, high-strength concrete grades have fully achieved the calculated strength value. Whereas bored castings, cast at the installation site, are difficult to control for defects.

Design of driven reinforced concrete piles for foundations of private housing construction

The shape and design of reinforced concrete piles are determined by GOST 19804.4-78. In industrial construction, pile supports ranging from three to eleven meters in length are used. For foundations of private housing construction, the most popular pile is the STs 3-30 model. This is a relatively small three-meter square pile support weighing 700 kg.

The driven support is made of high-strength cement grades and has steel reinforcement with hot-rolled reinforcement. One end has a pyramidal point, the dynamic safety factor is 1.5, which allows it to be successfully immersed in dense clay, rocky and frozen soils. The exception is rock and crushed stone embankments.

Construction of a foundation based on driven piles

The intensive development of industrial and private construction has led to the fact that the most comfortable and convenient sites for the construction of buildings in large cities and suburbs have been successfully “eaten up” traditional forms developments. Steep slopes, ravines, and water-saturated soils with quicksand remained undeveloped. All this led to a situation where the use of foundations on piles exceeded the volume of construction on traditional strip foundations and MZLF by several times.

The main advantage of a foundation on reinforced concrete piles is its very high rigidity and stability, but before installation you need to pay attention to certain features:

1. When the support is hammered into the ground, the tip spreads and compacts the soil around the tetrahedral body of the support. Thanks to this, lateral pressure on the walls of the concrete body ensures high rigidity of the foundation even on relatively weak watery soils;
2. With the correct calculation of immersion conditions on a specific type of soil and selection of the power of a diesel pile driver, the number of supports required to form the foundation of one house - 50-60 pieces - can be driven in during one work shift;
3. The standard design of the pile support head allows concrete to be poured within a few hours after immersion to form a monolithic grillage. When using metal frames, fastening rolled metal to concrete supports can be done using standard anchor bolts.

For your information! To prevent heaving and possible pushing out of the pile, it is necessary to insulate the upper part of the reinforced concrete structure with expanded polystyrene, as well as the soil around it with a backfill of expanded clay and sand.

In addition to the obvious positive qualities, reinforced concrete foundation piles also have their disadvantages. After installing the pile support, the deformed and compressed masses of soil continue to put pressure on the lower part and on the side surface of the pillar. Even if the installation depth exceeds the freezing level, high lateral pressure often pushes the pile out of the ground. Most often, northern regions suffer from such a problem, which combine great depth freezing and high groundwater levels. In such conditions, it is necessary to use piles of at least six meters in length for the foundation.

Features of installing reinforced concrete piles under the foundation of a brick house

Despite the obvious simplicity of driving reinforced concrete piles under the foundation, the installation of driven reinforced concrete structures requires preliminary detailed soil exploration for future construction. You can’t just come to the area and try to hammer a reinforced concrete support into the thickness of the soil with a powerful diesel hammer. Therefore, such work should be carried out by companies specializing in the construction of foundations on reinforced concrete piles.

The cost of driving one meter of pile with a cross section of 150x150 will be 500-550 rubles. If the nature of the soil requires the use of special methods of stimulating the supports, the cost of installation may double. Today, the cost of the smallest pile STs 3-30 is from five thousand rubles with delivery to the area and installation. If we compare the cost of installing a reinforced concrete pile under the foundation and a bored one, the cost of the latter will be 2-2.5 times less. If you calculate the number of reinforced concrete supports for arranging the foundation and compare it with the required number of bored ones, then they will be required approximately 2-2.5 times less.

With approximately the same labor costs, a foundation installed on reinforced concrete piles will be much stronger and more durable. The average lifespan of a building built on such a foundation, according to experts, can reach 100 years. In addition, a self-propelled hammer is capable of lifting and driving a pile within 5-10 minutes. When building a bored support, even using a drill press, it will take at least two hours of work to complete.

To build a foundation on reinforced concrete piles, you will need to build a so-called pile field. This is a certain number of supports installed in accordance with the design of the future building in the locations of load-bearing and main walls. For small pile supports, small diesel hammers and pile drivers can be used. For longer ones, six meters or more, you will need a crane and an impact machine with a guide mast and a double-action hammer.

The installation of reinforced concrete piles must be accurately calculated by a specialized specialist. With the correct selection of parameters, the installation process is quite simple. The pile is hung in a vertical position on a driving mast, installed on the ground, and driven into the soil by blows from the head of a diesel hammer.

As the depth deepens with each blow, the rate of settlement first increases and then begins to decrease. As the design depth is approached, the movement of the support slows down until failure occurs. In construction slang, this is the name for the submerged state of a reinforced concrete pillar, in which after 10 hammer blows the head of the pile support remains motionless. This means that the soil around the concrete body is so compacted that it is able to provide the bearing capacity of the support with a calculated stability margin.

In case of an error or incorrect assessment of the geology, the support element may fall to a depth exceeding the calculated one, or, conversely, stop half a meter to a meter before the calculated point. Most often this occurs due to the tip of the pile getting into deposits of fine dry sand. In this case, the construction of the foundation is stopped for ten to twelve days and work continues after the “rest” of the pile support.

If foundation construction is carried out on heavy soils or at very low temperatures, leader drilling may be used before installing supports. To facilitate the immersion of the pile, a well with a diameter of 50-60 mm less than the cross-section of the pile support is drilled at the place of its installation, to a depth of 90% of its immersion level. In addition, the well can be filled with clay emulsions, solutions that facilitate friction between concrete walls and rock layers.

Final operations on the foundation

When forming a pile field, special attention is paid to removing the horizontal plane from the driven supports. Most companies use laser levels and horizon level sensors for these purposes. This makes it possible to obtain a plane from the pile heads with a surface height fluctuation of 3-5 mm on a 10-meter plan. It is almost impossible to achieve such precision manually using stretched cords and threads. Further arrangement of the foundation, as a rule, involves the installation of a pile-grillage frame made of wooden beams, rolled metal, or casting into formwork.

Conclusion

The negative aspects of installing a foundation on piles include the operation of a pile driver or vibrator. Frequent shocks or vibrations that occur during the operation of construction equipment not only cause dissatisfaction among local residents, but also often lead to damage to the foundations of nearby buildings.

Nowadays, when building a house, many people prefer to install the foundation on. They give the building greater strength and stability, and are completely inexpensive for builders. Let's look at what this type of foundation is, and is it possible to build a concrete pile with your own hands?

Advantages and disadvantages

Pile foundations have advantages and disadvantages. Among the positive characteristics are the following:

• Foundations with concrete piles can always be installed with your own hands, regardless of the time of year, climate, or weather conditions.
• Concrete piles are installed in any terrain, be it a plain, a hilly area or even a steep slope.
• One of the advantages of a pile foundation is also quick installation. It is possible to carry out the installation of piles in a couple of days, or even less.
• Another advantage of such foundations is their low cost, since they do not require a lot of various additional materials.

The disadvantages of a pile foundation include the following:

• A house on stilts cannot have a basement.
• Such a base is not suitable for installation under multi-storey buildings, as well as other massive structures. She simply can't stand them. Moreover, when constructing any objects with pile foundations, it is extremely necessary to calculate the entire load on the foundation of the house.

What grades of concrete are used?

Often, when pouring a pile foundation under a house, they prefer to use heavy concrete grade m 500. The types of solutions used in this foundation also depend on what type of piles is planned:

• Non-standardized driven reinforced concrete, bored supports are made from B15 concrete mixture.
• A driven reinforced concrete pile with inserted reinforcement must contain B22.5 concrete mortar.
• When constructing hydraulic structures, it is preferable to use concrete a class higher than the mortar used to connect prefabricated parts.

Types of piles

The following types of house are distinguished:

Based on the method of deepening into the soil

Based on interaction with soil

• Rack piles that are supported by rocky soils.
• Hanging supports - supported by compressible soil.

Let's take a closer look at some types of pile foundations for a house.

Driven piles

• Conventional padded structures. Inventory pipes with a closed bottom hole are installed in the soil by hammering, pressing or screwing. Then the solution is gradually placed inside the wells with pipes, and the pipes themselves are slowly removed.
• Vibro-stamped piles. They are mounted inside pre-punched wells using a device with a vibrating hammer at the end.
• Stuffed inside a stamped well. Before their installation, pyramidal or cone-shaped wells are dug and filled with concrete mortar.

Drilled piles

Reinforced concrete piles

This type of foundation for a house is found cast, as well as prefabricated.

• Cast reinforced concrete supports are produced with a square or rectangular cross-section. Square ones meet with a rounded recess. A steel rod is placed inside the monolithic supports, the length corresponding to the pile itself. If the reinforcement is carried out across the support, low-carbon wire or wire rod with a five-millimeter diameter is used.
• Prefabricated reinforced concrete supports, as a rule, have a tubular shape and are assembled from several parts. Such a pile is installed already assembled.

Installation of reinforced concrete supports is carried out using auxiliary equipment: mobile cranes with hammers for supports, vibrators, and pile drivers.

Installation of concrete supports for the foundation

Before installing piles, it is necessary to study the characteristics of the soil and find out whether underground flows are present here. Then the required number of supports and future load are calculated.

Next comes marking the plan and drilling the soil. If necessary, a small ball of sand is poured into the well and a frame sheet is mounted. When the reinforcing mesh has been installed, you can pour concrete mortar inside. The work will completely harden in 20 days. Only then can construction continue.

Based on all this, we can conclude that building piles with your own hands, without outside help and tips, is not an easy task. However, long efforts, practice, and the availability of the necessary equipment do their job. Watch master classes and video lessons from other builders. After all, they also studied once. And now they are masterfully able to lay any foundation with their own hands in a short time. With great desire and patience, you will also learn how to install a pile foundation with your own hands.

Reinforced concrete piles for a private house

A foundation on stilts for a private house is one of the popular ways of arranging the foundation. In some geological conditions, this type of construction is optimal and recommended. At the project development stage, pre-design surveys are analyzed. Complex engineering work allows you to get a complete picture of the development site, which in turn contributes to a detailed calculation of the future structure.

A pile-driven foundation for a private house requires some atypical work, but in the end it allows you to get an excellent result. If the calculated technical indicators are observed and the established materials are used, the foundation for the house is built quickly and is highly durable.

Foundation on driven reinforced concrete piles

Reinforced concrete piles are foundations that represent one of the most durable types of foundations. It is characterized by high load-bearing capacity. The stability of the structure is ensured by the passage of moving layers and emphasis on hard rock. Basis for division pile foundations The types are determined by the material from which the supports are made. According to this, they distinguish:

1. Reinforced concrete piles of industrial production.
2. Bored supports.

To install driven piles to the point of its vertical location and subsequent immersion, it is necessary to use special construction equipment called a pile driver. are created exactly at the laying point, by pouring solution into the created well.

The main situation in which one should resort to a pile-rammed foundation is one in which there are unstable soils on the building site. , in this case, cannot provide the necessary stability of the future structure, since the soil layers do not have sufficient strength. There is a need to reach a solid foundation, which is why pile foundations are used.

The design of a pile foundation consists of supports driven into the ground, which are buried to a certain depth or until the pile fails when driven. In addition, a special tape structure called a grillage is created around each support. It encircles the contour and performs the task of linking all the supports into a single element. By equipping the grillage, additional resistance to horizontal ground movements is created, as well as uniform distribution of the load created by the building.

And the specific type is determined depending on the parameters of the structure and the type of piles. For bored supports, it is permissible to use prepared timber or rolled metal channel, as well as an I-beam. In rare cases, a monolithic grillage can be created - in a situation where the future structure has a large mass and a complex configuration. For driven piles, exclusively monolithic grillage options are used.

Pile foundations are among the universal foundations that can be used for the construction of buildings and structures of any type and complexity. For a specific object, a set of calculations is performed in order to establish exact parameters for construction. When designing, detailed data on the geological structure of the site is required.

Construction of a foundation on driven piles for a private house step by step

Driven piles for a private house are a reliable and durable option for constructing a foundation. With the help of pile drivers, installation is carried out in a short time and with high quality of work.

Pile-driven foundations can have several options for project implementation:

1. The foundation is in the form of single piles, which are driven in as separate supports for the building.
2. The foundation is in the form of a stretched strip of piles, which is installed under the walls.
3. different scale for base plate equipment.

The preparatory stage, from which the implementation of the project begins, is a complex of construction and organizational work, the ultimate goal of which is to optimize construction and strictly comply with project standards. With competent and accurate implementation of all preparatory activities, it is possible to achieve full compliance with the project.

The construction of a pile foundation includes the following steps:

1. Preparing the building site. At this stage, it is necessary to clear the construction area of ​​debris and, possibly, remove the fertile horizon.
2. Realization of the design position of the supports. Depending on the complexity of the situation and the configuration of the foundation, this can be done either on your own using simple measuring instruments (tape tape), or with the involvement of surveyors who will mark the site using precision instruments and in a short time. It is important to accurately fix the position on the ground. To do this, it is convenient to move the design axes beyond the building site and secure them to the cast-off. After this, it is enough to pull the cord between the points and get the axis of the side of the foundation.
3. Test driving of piles. In the places established by the project, it is necessary to drive a test pile to assess the physical properties of the soil.
4. Driving piles. Using special equipment, it is necessary to install the pile at the designated point. After the support is brought into a strictly vertical position, the top of the support is fixed in the mechanism and the process of immersing the support to depth begins. Pile hammers are installed on various types of machines and ensure rapid immersion of the support into the ground.
5. After all the piles are driven, you can proceed to trimming them. The heads of the supports should be on the same mark, which is easy to make using a level. With the help of pile cutters, jackhammers and other impact and cutting construction tools, only the head required for the project is carried out and remains.
6. Formwork is installed around the supports in accordance with the parameters of the base (width and height).
7. A skeleton made of reinforcement is knitted and secured inside the formwork. It is recommended to use solid rods with a diameter of 10-12 mm. The elements are fastened with knitting wire.
8. Upon completion of the formwork equipment, they proceed to pouring concrete.

A house on a pile foundation is able to withstand high loads and maintain structural integrity. Therefore, a foundation on reinforced concrete piles for a private house is used not only if it is geologically justified, but also on stable soils. Specifications This foundation ensures the reliability of the entire structure.

How to achieve a vertical position of the pile

When constructing a pile field and driving each support, it is important to maintain strict verticality of the structure. This ensures full realization of the practical value of the piles.

After securing the pile in the mechanism of the pile driver, it rises to a nearly vertical position. After one end of the support is installed at the driving point, it is necessary to adjust the verticality of the support. If the pile hits at an angle, then there is a high risk of its destruction, and the quality of immersion will be significantly reduced. If the deviation is not large, the strength characteristics of the foundation will decrease, which is critical for massive buildings and structures.

Depending on the dimensions of the pile, there are several options for controlling verticality:

1. If the pile is small, then you can use a regular hydraulic level, which is applied to all sides of the structure and allows you to bring it into the required position.
2. For large supports, special geodetic instruments, such as an electronic total station, should be used. With its help, an experienced surveyor will install the pile with an accuracy of fractions of millimeters and with minimal deviations from the vertical.

Driven piles are used throughout the world. Their practical value and efficiency have ensured widespread use for solving problems in the construction of private houses and large structures.

A pile foundation is nothing more than a complex of piles connected into a single structure that transfers the load from the building to the foundation. Due to their design, pile foundations are widely used for the construction of a wide variety of houses and buildings.

To perform specific construction tasks for the construction of pile foundations, piles of different types are selected. In this article we will look at what types of piles there are, the material they are made of and methods of immersion at a construction site.

Methods for constructing a pile foundation

Houses on wooden stilts

A pile is a vertical or inclined structure , immersed in the ground or made directly in the ground. The function of piles is to transfer loads from a house or building to the foundation (soil).

When designing and constructing a pile foundation, the type of piles is selected according to the following parameters:

• method of penetration into the ground (installation method);
• method of interaction with the ground;
• pile structure and cross-sectional shape;
• material type.

The following types of piles exist:

Depending on the method of penetration into the ground:

Depending on interaction with the ground:

• rack piles - all types of piles resting on rocky soils, and driven piles, in addition, on low-compressible soils;
• hanging (friction piles) - all types of piles that rest on compressible soils. They transmit the load to the foundation soils by their lower end and side surface.

Installation of various types of piles

Driven reinforced concrete piles (cross section up to 0.8 m inclusive) and shell piles (diameter from 1 m) can be arranged as follows:

• method - with non-tensioned longitudinal reinforcement with transverse reinforcement; prestressed with rod or wire longitudinal reinforcement with and without transverse reinforcement;
• cross-sectional shape - square, rectangular, T-shaped and I-beam, square with a round cavity, hollow with a round section;
• longitudinal section shape - prism, cylinder, with inclined side faces (pyramid, trapezoid);
• design features - integral or composed of individual sections;
• Bottom end design - pointed or flat bottom end; volumetric widening at the end (club-shaped piles); hollow piles with an open or closed lower end or with a camouflage heel.

Concrete piles

Installation of cast-in-place piles:

• cast-in-place piles - arranged by immersing inventory pipes, the lower end of which is closed with a shoe or concrete plug left in the ground. Pipes are immersed by driving, screwing or pressing. As the wells are filled with concrete mixture, these pipes are removed;
• Vibro-stamped driven piles are installed in drilled holes. The wells are filled with a rigid concrete mixture. The mixture is compacted using a vibrating stamp (this is a pipe with a pointed lower end on which a vibrating hammer is attached);
• driven in a stamped bed - for this, pyramidal or conical holes are drilled into the ground, which are subsequently filled with concrete mixture.

Drilling piles:

• bored solid section - to install them, wells are drilled in the ground (both with and without widening); if the soil is clayey, then the wells are drilled above the groundwater level, and the walls of the well are not secured. In other soils, wells are drilled below the groundwater level, and the walls of the wells are secured with clay or inventory casing pipes, which are subsequently removed. Next, the wells are concreted;
• barrettes - drilled piles. Manufactured using a grab or ground cutter;
• bored with a camouflage heel - for their construction, wells are drilled with the subsequent formation of widening by an explosion (for example, electrochemical). The resulting wells are filled with concrete mixture;
• drilling injection machines with a diameter of 0.15-0.35 m - are installed in drilled wells into which a fine-grained concrete mixture is injected (injected). And also arranged with a hollow screw;
• boring injection with a diameter of 0.15-0.35 m with compaction of the surrounding soil - for this, the wells are treated with a series of discharges of high voltage current pulses;
• pillar piles - wells are drilled for their construction (with or without widening). A monolithic cement-sand mortar is placed in the wells and solid elements of a cylindrical or prismatic shape with sides or a diameter of 0.8 m or more are lowered;
• bored piles with a camouflage heel - differ from bored piles with a camouflage heel in that after the formation and filling of the camouflage widening, a reinforced concrete pile is lowered into the hole.

Material for piles

Metal piles

Depending on the material of manufacture, piles are distinguished:

• metal;
• wooden;
• reinforced concrete;
• concrete (rammed)..

Metal piles

They are made from seamless steel pipes with a diameter of 25 to 100 cm (and even more). Steel tongues, I-beams, and other rolled profiles are also used in production. Box-section piles are made from them by welding.

Typically the end of the pipe is equipped with a conical tip. If the pipe is immersed without a tip, then the function of the tip in this case is performed by an earthen cone that forms under the pile during immersion as the pipe begins to fill with compacted soil.

To increase strength indicators, after immersion, hollow metal piles are filled. If after installation they experience light loads, then you don’t have to fill them with concrete.

Screw piles

– a type of metal piles, made in the form of a metal rod with a screw blade at the end. The products have fairly high strength characteristics, so they are often used in construction. The diameter of the screw blade of the pile can reach up to 2.4 m, and the depth of immersion in the ground can be more than 20 m.

Application:

the number, diameter and length of screw piles depend on the load on them and the ground conditions at the construction site. Foundations on screw piles can be installed on terrain of any complexity, without spending time and money on excavation work. Also, the advantages of screw piles include the fact that during their installation there are no dynamic effects on the ground, so they can be used for the construction of extensions to existing structures. An important fact for individual construction is that a pile field like this can be completed within one day.

Screw piles are also used for the construction of high-rise mast structures and power line supports, which are subject to significant wind influences. In addition, the tip with the blade allows the structure to withstand large pulling loads, so they can be used in heaving soils, but they will not be able to “squeeze out” screw pile to the surface.

Screw piles are also used to strengthen emergency foundations. In this case, they are mounted around the perimeter of the emergency foundation and secured to it using brackets.

To prevent corrosion and increase the service life of metal piles, they are treated with anti-corrosion agents before installation.

Wooden piles

Wooden piles

Made from spruce, pine, cedar, larch, fir, oak. To make wooden piles, logs with a diameter of 22-34 cm and a length of 6.5 and 8.5 m are taken, while maintaining the natural slope of the logs (reducing the diameter of the trunk from the butt to the top). The bark is removed from the prepared logs, and then they are trimmed in the right places.

Depending on the design of the pile foundation, wooden piles can be either solid, i.e. made from one log, or spliced ​​along the length. Accordingly, the length of a solid product can vary from 4.5 to 16 meters, and a spliced ​​one - from 20 to 25 meters. To splice the logs, they are joined end to end using overlays. If necessary, logs are spliced ​​not only in length, but also in thickness. Wooden piles obtained in this way are called stack piles.

The length of the pointed part of the wooden pile is 1.5-2 times their diameter. If there are obstacles in the ground, protect the pointed part with a shoe. The upper part of the wooden pile is protected with a yoke or cap.

Wooden piles are installed in the ground by driving, pressing or vibrating.

Application:

The price of wooden piles is usually lower than the price of metal or reinforced concrete analogues, but wooden products can withstand less load. Therefore, wooden piles are not used in high-rise construction, but they are used in low-rise construction in the construction of houses and cottages. They are also used for the construction of temporary structures, small bridges, etc.

Reinforced concrete piles

They can be monolithic or prefabricated.

Reinforced concrete piles

Monolithic reinforced concrete piles often have a rectangular or square cross-section ranging in size from 20×20 to 40×40 cm. Square piles with a cylindrical cavity are also produced with a section size of 25×25 and 30×30 cm and a wall thickness at the narrowest point of at least 4 cm.

Longitudinal reinforcement of monolithic products is carried out with steel rod reinforcement (prestressed or non-prestressed). In the transverse direction, the products are reinforced with low-carbon wire or wire rod with a thickness of 5 mm.

During installation, the impact load is absorbed by the head of the pile, so it is reinforced with three reinforcing meshes arranged horizontally in increments of 5 cm. The point at the bottom is made in the shape of a tetrahedral pyramid, and when installed in hard soil it is protected with a steel shoe.

Prefabricated reinforced concrete piles of a tubular structure are made from separate sections that can be assembled in advance, after which installation (driving) can be carried out.

Installation of reinforced concrete piles is carried out using pile drivers, mobile cranes with pile hammers, etc. Vibration immersion is also used. It is less labor-intensive and costly.

Advantages:

• dense immersion in the soil - when driven with a hammer, the soil around the pile is compacted, and its design resistance increases significantly;
• reinforced concrete driven piles can be used on weak and moving soils, as well as in variable conditions;
• such a foundation is characterized by high strength and durability;
• The pile foundation can have any shape and size.

Flaws:

• When building in a built-up area, it must be borne in mind that driving piles may lead to changes in soil masses. Ground movements are especially insidious in conditions of cramped, spot-filled development, which can negatively affect the integrity of the foundations of adjacent buildings;
• difficulties of driving reinforced concrete products - mainly this increased level noise both from the operation of the equipment itself for driving them, and from hammer blows on the pile;
• reinforced concrete products are more fragile than piles made of other materials, and therefore require appropriate storage conditions. They are laid in horizontal rows, ensuring the same orientation of the ends. Between the horizontal rows in stacks, wooden spacers are laid at the gripping points or near the mounting loops. Storage of round piles is carried out using special bars that prevent rolling;
• the large sizes of reinforced concrete products also cause some difficulties when transporting them to the construction site.

Cast-in-place (concrete) piles

Reinforcement cage for bored piles

Also widely used in construction. Their distinctive feature is that they are manufactured directly on the construction site. The basic technological scheme for their production: a well is made in the ground using some method and filled with concrete, and if, before filling the wells with concrete, a steel reinforcing frame is placed in them, then reinforced concrete cast-in-place piles are obtained. After the concrete mixture has hardened, the resulting pile is trimmed.

The ease of installation makes this foundation very popular. Its advantages include the absence of the need to transport piles.

The disadvantages include the following:

• it is impossible to control the quality;
• cast-in-place piles should not be installed in soils prone to heaving or horizontal movements due to their poor resistance to overturning.

What concrete should I use?

Reinforced concrete and concrete piles are made of heavy concrete. Wherein:

• for non-standardized driven reinforced concrete, as well as cast-in-place and drilled piles, concrete of class B15 or higher is used;
• for driven reinforced concrete with prestressed reinforcement - concrete not lower than B22.5;
• for reinforced concrete grillages of pile foundations - heavy concrete class: for monolithic ones - not lower than B15, for prefabricated ones - not lower than B20;
• for embedding reinforced concrete columns in pile grillage cups - concrete not lower than B15;
• for pile heads with prefabricated strip grillages - concrete not lower than B15;
• the class of concrete used for supports of bridges and hydraulic structures for embedding prefabricated elements of pile foundations must be one step higher than the class of concrete of the prefabricated elements being connected.

Areas of application or how to choose piles

As can be seen from the above material, there is a wide variety different types piles, therefore it is impossible to limit ourselves to describing any one design of a pile foundation. Below are some recommendations that will help you choose the most suitable types of piles for the construction of pile foundations on specific construction sites.

House on screw stilts

When choosing, it is necessary to take into account a set of characteristics:

• house design;
• required strength and stability indicators;
• geology and hydrogeological conditions of the land plot;
• construction timeframes and budget;
• availability of necessary equipment, etc.

It is impossible to determine the exact criteria for choosing a pile foundation based on the totality of the listed parameters. Below are the factors for choosing pile foundations in relation to the values ​​of some of these parameters.

• If the construction site is formed by weak soils (silt, silty loam, peat, clay, fluid loam), then when choosing the type of foundation, several options can be considered:

In the case of silt and fluid loam, it is possible to construct a continuous foundation slab under the entire house or to pre-compress the silt with a load;

In the case of peat and peaty soils - partial or complete removal of peat + subsequent alluvium or backfilling and installation of a foundation on a natural foundation;

It is necessary to take into account that when installing a foundation slab on soft soil, precipitation occurs: general - up to 50-60 cm and uneven - up to 25-35 cm. After work on loading silt, precipitation decreases, but the time costs for carrying out such work do not less than a year;

With a significant peat capacity, peat extraction work also requires a lot of time, labor and material costs. Most often, a technical and economic comparison of pile and slab foundations on soft soils shows the advantage of pile foundations, which provide lower settlements (within acceptable limits) + economic benefits by reducing the volume of excavation work, as well as the consumption of concrete and reinforcement;

• In the case of site planning with fill, a foundation made of driven piles is preferable to foundations on a natural foundation, even when dense soils are located close to the natural soil surface, because in this case, it is designed deep, cutting through the entire thickness of the bedding;
• on sites formed by thick household embankments that cannot be used as a load-bearing layer, columnar foundations are made deep. Instead, it is more advisable to use driven piles that pass through the entire embankment and are buried in dense soils lying below the base of the embankment. If there are solid inclusions in the embankment that cannot be broken through, then bored piles are used;
• when building a house close to beams, ravines, etc., foundations are made from driven piles, and on dry clay soil - from bored piles;
• on subsiding and swelling soils up to 12 m thick, driven piles are used, and with a thickness of 13-30 m, bored piles with widening are used. In this case, the entire subsidence layer must be cut through, and the lower ends of the piles must be buried in non-subsidence soil;
• on heaving soils, pile foundations have an advantage over foundations on a natural foundation, because By leaving a gap between the base of the grillage and the ground surface, the influence of normal forces of frost heaving can be eliminated. However, it is necessary to take into account the tangential forces of frost heaving, the greater the value of which, the longer the piles;
• if there is a significant change in the roof of the load-bearing layer from coarse and rocky soils, it is preferable to use foundations of 2 types: in the area where the roof of the load-bearing layer is close to the surface (up to 2.5-3 m), a columnar foundation is laid on a natural foundation, and in an area where where the roof of the rocky ground drops sharply - piles;
• in permafrost areas, foundations are used on frozen piles, which are immersed in wells filled with soil solution;
• on land plots near reservoirs with a high groundwater level, the construction of a foundation on a natural foundation requires water drawdown for the construction period, and during further operation drainage devices will be required, and pile foundations without deepening the grillage are exempt from construction water drawdown;
• If there is a high probability of landslides, it is effective to strengthen the slopes of areas with large-diameter bored piles (from 1 m) without widening, leaving casing pipes and reinforcement. In case of an active landslide, shell piles with rigid reinforcement are used. After strengthening landslide slopes, the type of foundation is chosen without taking into account the influence of landslide processes.

The video describes the features and advantages of foundations on screw piles:

In modern construction, many different reinforced concrete products are used. These are slabs, beams and panels, etc. In this article we will talk about reinforced concrete pile structures, which are now very often used in the construction of foundations.

What are piles?

These are proven building products that make it possible to build reliable foundations.

These products are now produced from a variety of materials: metal, asbestos, concrete, etc.

Because pile shafts are designed to withstand the loads that are placed on the base of the structure.

They must be extremely reliable, durable and able to cope with any negative factors.

Varieties of assortment

The following types of support trunks are made from reinforced concrete materials:

• monolithic inside, which are immersed in the ground without drilling wells or digging ditches;
• hollow inside, which are immersed in a pre-drilled well;
• stuffed, poured into formwork with a drilled hole.

Technical characteristics of reinforced concrete piles

Most of the parameters of pile shafts are determined by the grade of concrete used in their manufacture.

For example, the grade of concrete characterizes the strength of the trunk. The concrete grade numbers indicate the ultimate compressive strength.

Concrete B7.5 and higher class is used in the production of reinforced concrete piles. The lowest compressive strength is determined by this type of concrete.

Indicators of frost resistance and moisture strength of piles are determined using the same method. They appear on the identification plate after the letters “F” and “W”. For example, for concrete grade B7.5, these parameters are equal to more than 50 cyclic freezing/thawing (F50) and a pressure limit of 2 MPa of water (W2).

The mass of reinforced concrete trunks is determined primarily by their volumes. And the larger they are, the greater the weight indicators.

The positive qualities of reinforced concrete piles of any type include:

• service life (If the foundation was erected without violating the technology, the piles will last more than 100 years without repair);
• high strength (Reinforced concrete piles can withstand the weight of even multi-story panel buildings);
• stability (the trunk is driven to a depth, which allows it to rest on the ground with great bearing capacity);
• the possibility of using supports for construction on difficult terrain (The piled part of the foundation base can be constructed from supports of different lengths.)

The only disadvantage of piles is the heaviness of the product. This indicator often makes delivery and installation inaccessible.

Foundations on reinforced concrete piles are made in areas where the soil is problematic and a building needs to be built. In areas with such soil, only reinforced concrete piles will ensure the stability of the building by transferring the load to stable layers.

A reinforced concrete pile foundation for a block building has many advantages over other types of foundations.

If we compare the construction columnar foundation with others, then the construction of such a foundation for a house made of blocks is much more technologically advanced.

A pile foundation involves drilling wells of a given size, installing reinforcing bars in them, and filling them with concrete.

The big advantage of this method is the ability to drill wells with a hand drill.

How to make piles for a foundation

It is not difficult to make a foundation made of reinforced concrete piles yourself. It is only important to maintain basic calculations:

• trunk sizes;
• gaps between trunks;
• reinforcement parameters;
• brand of concrete;
• laying frequency.

Concrete mix

Pile foundations are often installed in aggressive environments. For this reason, they need concrete that is durable and resistant to “chemicals”. This property of concrete affects the durability of the pile.

You should consult with specialists about the brand of concrete, who, after studying the soil, will recommend appropriate additives to increase stability.

Possible concrete composition:

• cement grade 7001 parts;
• sand 1.5 hours;
• crushed stone 2.5 hours;
• water 0.5 tsp.

It would be better to order industrial concrete for the pile foundation. If it is impossible to buy or deliver concrete to a construction site, they prepare it themselves.

Preparing the site for the foundation

Before starting the installation of piles, prepare the site:

• remove tree roots and topsoil;
• mark the location of the foundation using cords;
• determine the levels of trunks above the surface;
• mark the axes of the piles.

Concreting and reinforcement of piles

After preparing the holes for the piles, “pipes” are rolled out of roofing material, which should correspond to the wells in coverage, and the length is 20-30 cm greater than their depth.

The “pipe” at the top needs to be made stronger, from 2-3 layers of roofing material, and tied together with strong wire. This end will be the top formwork. Then the “pipe” is carefully driven into the well.

If there is a little water at the bottom, it's okay. But when water fills a quarter of the well, it needs to be pumped out.

If such a “pipe” is not made, negative consequences can't be avoided.

Formwork

Concrete hardening occurs within the first day from the moment the mixture is prepared. And in order for the strength to be maximum, it is extremely important to preserve the “cement laitance” in the concrete mass. It should not flow into the ground, because then the specified strength of concrete will not be achieved.

If the ground surface freezes, heaving forces will affect the rough surface of the pile more strongly if it was formed without a “pipe”.

When the wells are prepared, a frame made of reinforcement will be needed. For this purpose, you can take 3 reinforcement rods of six millimeter diameter for each pile shaft. They are fastened with transverse bars at intervals of 50-60 cm.

Vertical rods are installed above the piles below the height of the grillage by 2-3 cm.

After the frame is formed in the well, concrete begins to be supplied in 4-centimeter layers and compacted using vibrators.

Grillage arrangement

To install a grillage for a light home, it is recommended to observe the following parameters:

• height – from 30 cm;
• the width is equal to the width of the base, and if there is none, the width is equal to the thickness of the walls of the 1st floor, but not less than 40 cm.

Cutting the grillage with pipes is unacceptable. The deviation of the pile from the vertical is determined by a plumb line. It should not be more than 5 cm.

When assembling the grillage, you need to carefully secure the elements to the pile heads. If the grillage beam is replaced with load-bearing reinforced concrete lintels, they are secured to each other by welding with reinforcing bars.

After assembling the grillage, all seams and joints are filled with cement mortar or concrete.

Limitations in the use of pile foundations

This type of foundation also has disadvantages, or rather restrictions, that prevent their use.

Reinforced concrete foundations should not be used in horizontally unstable soils, because the building will not be resistant to overturning.

When constructing such a foundation, problems arise with the base.

You have to fill the space between the piles, as in a columnar foundation.

This requires additional costs.

The video demonstrates the driving of reinforced concrete piles IZH-3-38-S1 (S2) S-08 without formwork molding