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Reinforcement piles. Reinforcement of a columnar foundation on piles

Reinforcement piles. Reinforcement of a columnar foundation on piles

Due to the design features and operating conditions, reinforcement of piles is a prerequisite. Heaving forces arising in the layers tend to bend, move, tear or push the reinforced concrete product outward. Concrete can withstand only compressive loads, but not bending ones. Steel rods are introduced into the composition, making it possible to obtain a new material - reinforced concrete, and increase the resistance of the pile foundation to tensile loads.

The depth of the wells into which concrete is placed in individual construction rarely exceeds 2.5 - 4 m. To prevent soil from falling into the face during reinforcement and concreting, formwork is used. The most popular are cylinders made of roofing felt, polyethylene, and asbestos-cement pipes. Reinforcement of bored piles is carried out in permanent formwork, which allows reducing the protective layer of concrete. In addition, polymer pipes solve several problems:

waterproofing of concrete structures;
reduction in pull-out forces (it is difficult for soils to grip smooth material), but at the same time this reduces the load-bearing capacity of the pile, because lateral friction force decreases;
preventing rock from collapsing at the face.

When installing a pile foundation, you must follow the regulatory documents:

SP 24.13330 – pile foundations;
SP 28.13330 – anti-corrosion protection;
SP 45.13330 – foundations, foundations operating in the ground;
Departmental and industry design guidelines;
PPR plans, technological maps (standard) for the execution of work.

Depending on the size of the well, vertical loads, and torque, the percentage of reinforcement is 0.4 - 3%. For example, when choosing B25 concrete for piles with a diameter of 30 cm, you will need:

3% reinforcement at a design moment within 70 tf*m;
2% at 60 tf*m;
1% at 30 tf*m;
0.4% at 15 tf*m.

When the borehole diameter increases to 40 cm (usually the maximum size of a hand tool or motor drill), the same percentage of reinforcement is allowed at moments increased by 1.2 times.

Reinforcement schemes

The magnitude and type of pile foundation loads significantly affect the consumption of reinforcement. For example, if piles with a diameter of 30 cm experience exclusively vertical indentation, resting on a layer with a high load-bearing capacity, the shaft may not be reinforced; the strength of the concrete core is sufficient to ensure the stability of the structure.

The head part is always reinforced so that the vertical rods, bent at right angles, are later connected to the frame of a monolithic grillage or slab (slab grillage). Moreover, the structure is sunk into concrete after the mixture has been laid. The characteristics of the frame for the head part of the pile foundation are as follows:

rod length – 1 – 1.5 m;
number of rods – 4 – 7 pieces;
spiral, clamps – optional;
grillage outlet - 50 cm for piles with a diameter of 30 - 40 cm;

If horizontal loads with inevitable torques appear in the calculation scheme, the frame must be immersed to the entire depth of the well, and the following elements are added to the pile foundation reinforcement scheme:

clamps - square (usually for 30-40 cm in diameter), rings (large diameters);
plastic gaskets - of various shapes, are manufactured by industry.

Clamps give the frames the necessary spatial geometry, and gaskets provide a protective concrete layer to prevent the destruction of the metal from corrosion. The pitch of the clamps is 30 – 70 cm, increases in the middle part, decreases at the bottom and mouth. An example of the simplest calculation of the minimum percentage of reinforcement is as follows:

cross-sectional area of a pile 40 cm in diameter – 3.14 x R2 = 3.14 x 202 cm = 1256 cm2
minimum acceptable percentage – 0.4% x 1256 cm2 = 5 cm2
maximum permissible percentage - 3% x 1256 cm2 = 37.68 cm2
reinforcement cross-section from GOST tables is 2.01 cm2 for 16 mm rod, 1.54 cm2 for 14 mm rod, 1.13 cm2 for 12 mm reinforcement.

At the minimum possible coefficient, each pile will require 4 rods of 14 mm diameter or 5 rods of 15 mm diameter. For the maximum allowable, you will need 18 16 mm rods, 24 14 mm reinforcement or 33 12 mm rods.

In practice, in private housing construction, 4-6 rods are usually used, 4 is the minimum number of rods. The protective layer is provided by attaching special plastic spacers to the reinforcement, separating the metal from the formwork.

Selection of fittings

According to SP 63.13330, reinforcement corresponding to GOST 5781 classes is used for pile foundations:

A3 – marked A400 or A500, has a corrugated surface, increased adhesion to concrete, intended for vertical frame rods;
A1 – smooth, used in clamps, designated A240.

The length of the rods is calculated by adding the depth of the well, the height of the grillage above the ground, 50 cm required for embedding the curved part into the grillage. The length of the clamps is determined based on the configuration (ring, square).

Conventional reinforcement is made from steels 35GS, 25G2S, 32G2Rps, it is not intended for welding, it is tied with wire. Special fittings have the letter C in the designation (for example A400C), they are created from alloy steels that do not change the properties of welding joints.

Each pile foundation structure with a diameter of 40 cm buried in the ground has a specific load-bearing capacity, depending on the resistance of the soil under the base and along its entire length (lateral friction).

Therefore, the developer remains to calculate the prefabricated load of the building (the weight of all elements of the load-bearing frame, snow/wind loads from the SP tables, furniture, other operational loads), divide it by the load-bearing capacity of the pile in order to obtain the required number of wells for the pile foundation.

Considering the minimum length of piles and the diameter of holes in the ground (usually 40 cm) in individual construction, it is recommended to provide a double strength margin. For example, due to the high cost of geological research, a hole in a construction site is dug by the developer himself, and the composition of the soil is determined by eye. To compensate for the error, insufficient length, small diameter (30-40 cm), experts recommend:

multiply the weight of walls and ceilings by 2, this is approximately equal to the weight of snow cover, residents, furniture, equipment, wind loads;
for SIP panels and frame structures it is better to use coefficient 3, since they are very light.

The final figure for prefabricated loads is additionally multiplied by 1.3 to ensure a guaranteed strength margin. In practice, for light one-story buildings, calculations show that one or two 30 cm piles, having a length of 2.5 m, fully support the weight of the cottage, subject to guaranteed achievement of the load-bearing layer.

Making frames

The technology for reinforcing a pile foundation has practically no secrets; you just need to follow the sequence of actions:

bending of clamps - the diameter of the rings or squares should be 4 - 8 cm less than the internal diameter of the formwork in order to provide a protective layer of 2 - 4 cm, respectively;
cut of vertical rods - the length is chosen depending on the height of the grillage, the depth of the face, adding 50 cm to the bend for connection with the grillage frame;
knitting - fastening rods with wire to clamps every 30 - 70 cm.

After that, all that remains is to put several plastic spacers around the perimeter on the clamps, lower the frame the entire length inside the formwork, and lay the concrete.

These recommendations will be useful to individual developers when independently reinforcing bored piles. They will allow you to avoid mistakes and provide a sufficient strength margin for the maximum possible service life of the building.

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Reinforcement of a columnar foundation is a prerequisite for obtaining a strong, reliable foundation for a house. Concrete can withstand compressive loads, but deforms when subjected to bending and tension. There are several types of metal frames for bored piles. They are mounted using different technologies depending on the parameters of the support and its operating conditions.

Types of metal frame

Reinforcement can be of several types:

Flat, made of several layers of metal rods connected to each other by transverse bridges using wire or welding. They are used as a basis for laying bored supports and increasing the strength of reinforced concrete supports of small diameter.
Volumetric in the form of a circle or square, manufactured using automated welding lines. Requires accurate calculations before installation. They are used for structures that bear a significant load from house construction.

According to GOST 10992, reinforcement of piles can be longitudinal and transverse-longitudinal.

The longitudinal method is used to reinforce structures installed in stable soil of medium density: sandy loam, clay, loam. In seismically active areas, such reinforcement is not used due to poor resistance to bending and tension.

The reinforced longitudinal frame consists of corrugated metal rods connected to each other using jumpers. The longitudinal row should have from 4 to 8 rows of rods, with a cross-section from 12 to 15 mm.

During the driving process, the upper and lower parts of the pile experience maximum load. To prevent the structure from deforming, it is reinforced on top with steel mesh installed at a distance of 50 mm from each other. 4-5 pieces of such grids are installed. The lower part is reinforced with a steel cage made in the shape of a cone. It is welded to protruding reinforcement bars bent inward.

The longitudinal-transverse method is more reliable. Due to the high consumption of metal, such supports are much more expensive. But they are able to withstand increased loads. The frame is made from metal rods with a diameter of 11 to 15 mm, class A1 or A2. The transverse jumpers connecting the longitudinal rows are made of metal, with a cross-section from 8 to 12 mm.

When reinforcing round supports, steel mesh assembled into a cylinder is sometimes used.

The distance between the crossbars is selected depending on the density of the soil. In the central part the pitch is 200-300 mm. If the support is more than 12 m, the distance between the jumpers should be no more than 200 mm.

The upper ends of the supports are reinforced with a mesh of reinforcement, and a steel tip is placed on the lower end.

Calculation of frame parameters

Pile foundations are widely used in the construction of small houses made of lightweight materials. The higher the mass of the building, the wider the cross-section of the support should be. The most commonly used are bored piles with a diameter of 30 cm.

When calculating the number of supports, their cross-section and method of reinforcement, it is necessary to take into account the characteristics of the soil on the construction site and the weight of the house, taking into account the materials used for construction, furniture, and people who may be in the house.

It is better to entrust such an important stage to professionals. If the calculations are incorrect, the support may not withstand the load-bearing load from housing construction and may become deformed or collapse. This will entail, at best, the need for major repairs, and in the worst case scenario, it will pose a threat to the lives of people in the house.

On stable soils, when a layer of dense soil is reached, piles with a cross-section of 30 cm and a length of 2.5 mm will be sufficient. To install a foundation for medium-sized housing construction, you will need about 40 pieces of reinforced piles.

Reinforcement of bored piles

Bored supports are manufactured at the construction site, and they are also reinforced with a metal frame there.

A well of the required size is drilled in the ground. The pre-assembled steel frame is then inserted into it using a crane. Then the pipe is installed and filled with concrete.

Sequence of installation of bored piles:

Perform all necessary calculations. The number and diameter of piles are determined.
According to the project, the location of supports on the site is marked.
They drill a well: 150-200 cm of earth is removed using a drill bit, the remaining depth is reached using an auger.
Sand, 250-300 mm thick, is poured into the bottom of the hole; the sand cushion serves to increase the load-bearing properties of the soil.
The casing pipe, which serves as formwork, is lowered.
Reinforcement of bored piles is carried out. A frame made of reinforcement is inserted into the drilled hole using a crane. It is made with horizontal strapping from vertical rods with a diameter of 10-16 mm.
The well is filled with cement-sand mortar prepared in a ratio of 1:3.
The casing pipe is raised as the cavity is filled with solution.
When the well is completely filled with concrete solution, the casing pipe is removed and the head of the support is formed.

To prevent damage to the integrity of the newly poured pile, the supports are poured with concrete solution one at a time. The adjacent pile is mounted after the previous one has gained strength of at least 30%.

Reinforcement of drill-injection supports

The technology for installing drilled injection piles is similar to installing bored supports. Only the sequence when pouring and installing reinforcement changes.

When installing drill-injection supports, first the hole is filled with cement mortar, and immediately before it hardens, a pre-mounted reinforced frame is lowered inside.

Drill injection construction involves the method of injecting fine concrete into a pre-prepared well. In this way, supports with a cross section of up to 25 cm are installed.

Reinforcement of driven supports

Driven-type piles are manufactured in a factory. All production cycles are carried out on special production lines, including installation of the metal frame.

The formwork is a metal pipe; a reinforced frame is inserted into it. After this, the structure is filled with concrete and transported to a special chamber, where the concrete hardens under the influence of a certain temperature. When the strength reaches the required parameters, the pile is transported to a warehouse.

DIY pile reinforcement

You need to prepare everything you need to make a metal frame in advance. To install bored supports you will need the following tools and materials:

grinder for cutting metal rods;
welding machine for installing a reinforced frame;
vibration device for compacting concrete mortar inside the pile;
drilling machine;
concrete mixer;
shovels;
ready-made concrete or its components: sand, cement, crushed stone;
metal rods, corrugated and smooth;
roofing felt;
wire.

Step-by-step instructions for reinforcing piles with your own hands:

Steel rods are cut into pieces of the required length using a grinder.
For transverse jumpers, sections of rods are bent to obtain a rounded shape or 4 pieces are prepared, which are subsequently welded to the sides of the longitudinal frame.
The required number of longitudinal rods are laid parallel to each other, their upper, lower ends and the middle are connected by transverse jumpers.
The second part of the frame is assembled. They are connected to each other with a double weld.
Treated with anti-corrosion compounds.
The reinforced frame is lowered into the prepared hole.
Fill with concrete mortar and compact it with a vibration installation.

After installing the piles and gaining sufficient strength, they begin to install the grillage. They install formwork from boards, which must be set strictly according to the level.

Grillage reinforcement

The grillage serves to uniformly transfer the load from house construction through the pillars to dense layers of soil. It protects the building from excessive shrinkage in areas of greatest load-bearing load. It can be hanging or buried in the ground.

Reinforcement is performed with two rows of metal rods laid along the concrete strip. The upper and lower rows of rods are connected using vertical and horizontal jumpers.

The following are used as jumpers:

Rectangular fittings curved in the form of clamps. It is made from smooth metal rods of class A, with a cross section of 8-10 mm.
The rods are welded to the upper and lower longitudinal rows. All elements must be made of the same material.

In longitudinal rows, the rods are mounted in increments of 10 centimeters, 3-4 rows of rods in each belt. Jumpers are installed at a distance of 200-300 mm. Vertical rods are attached in increments of at least 40 cm from each other.

The reinforcement must be hidden in concrete. When interacting with air and precipitation, it will begin to collapse over time.

After cutting the piles to the required size, reinforcement will protrude from them. It will be used as a connecting element between the grillage and the pillars.

Before starting reinforcement, loads are calculated and a drawing of the location of the reinforcement cage is made.

Step-by-step instructions for reinforcing the grillage:

Install the formwork, making sure that its side walls are strictly level.
Metal rods are fastened together, 3-4 pieces each, with wire and lowered into the formwork. The jumpers are installed at a distance of 200-400 mm from each other.
The corners are connected using bent L- and U-shaped profiles.
The reinforcement should retreat from the formwork by 50 mm on each side and below, so that later it does not turn out that its edges protrude from the concrete strip.

The steel frame must be positioned strictly horizontally and vertically. The quality of the grillage and the reliability of the house depend on this.

The diameter of the piles used must be at least 30 cm, the number of steel rods in the longitudinal belt must be 3 or more pieces, and the reinforcement allowance for installation of the grillage must be at least 50 cm.

The nuances of constructing a columnar foundation are presented in the video:

In order for the house to have a long service life, be strong and reliable, and also not give uneven shrinkage, it is necessary to reinforce the columnar foundation and grillage. All calculations must be made depending on the type of soil and the weight of the future house.

From this article you will learn why reinforcement of driven reinforced concrete piles is needed. We will consider all types of reinforcement of reinforced concrete structures, get acquainted with the technology of industrial reinforcement of reinforced concrete piles and study in detail the calculation methodology and the sequence of work on reinforcing bored piles with our own hands.

Classification of driven reinforced concrete pilesused for the construction of foundations and foundations for buildings and technical structures is carried out not only based on the shape of the structure, but also depending on the method of reinforcement that was used in the production of the pile.

Pile pillars with longitudinal reinforcement are used for immersion in medium-dense soils - sandy loam, loam, clay soil. Such piles, due to the use of less reinforcement, are cheaper, but have low resistance to tensile and bending loads, which is sufficient for the construction of foundations for ground structures, but not enough for the construction of hydraulic structures.

Rice. 1.1:

The working surfaces of metal formwork are coated with a lubricant (Emulsol);
Reinforcement frames are placed in the compartments of the metal mold;

Rice. 1.8

The reinforcement is pre-tensioned with a hydraulic jack - first by 40% of the maximum force, then the position of the reinforcement is checked, after which the sides of the metal mold are closed;
The reinforcement is tensioned equal to the maximum design force. The rods are maintained under this load for 5 minutes;
The metal mold is filled with concrete mixture and the concrete is vibrated;
The time required for the concrete to set is maintained, after which the hydraulic jacks are turned off and the reinforcement is compressed to its original state;
The metal mold is placed in a steaming chamber, in which the concrete hardening process is significantly accelerated;
Using crane equipment, finished piles are removed from the metal mold.

Rice. 1.9

Reinforcement of bored piles

The calculation is made based on the following initial data:

Pile length - 150 cm;
Pile diameter - 300 mm;
The step between pile pillars is 1.5 meters;
The height of the pile pillar is 30 cm.
The perimeter of the foundation is 27 m.

The pile pillar will be strengthened using a reinforced frame consisting of four longitudinal reinforcing rods 180 cm long (150 cm for the part of the pillar located in the soil, and 30 cm for the outlet), connected by three turns (top, middle and bottom) of smooth reinforcement .

Rice. 2.0

27/1.5 = 18 pcs.

Based on the fact that the length of the longitudinal reinforcement rod in the frame is 1.8 m, and there should be 4 such rods in total, we calculate the amount of reinforcement per frame:

1.8*4 = 7.2 m.

Knowing the number of piles and the length of longitudinal reinforcement per frame, we can calculate the total length of the reinforcing bars:

7.2*18 = 129.6 m.

To connect the longitudinal rods to each other, we need smooth reinforcement with a diameter of 7-8 mm. Based on the frame diameter of 300 mm, the length of one smooth reinforcement bar will be about 95 cm.

The number of connecting elements of the reinforced frame is 3 pcs. (bottom, middle and top). We determine the required length of smooth reinforcement for one frame:

0.95*3 = 2.85 m.

18*2.85 = 51.3 m.

Based on the calculations, we determined that to reinforce the bored piles we will need 130 meters of corrugated reinforcement and 52 meters of smooth rods.

Required tools and materials

Work on reinforcing bored piles does not require the use of any special construction equipment. The only thing you need is a welding machine and a grinder (for cutting reinforcing bars).

If you do not have a welding machine, you can use another type of connection - fixing the frame elements using a binding wire.

Rice. 2.1

All reinforced frames for piles produced in industrial conditions are fastened by welding, so there is no need to worry about welding joints. The only significant drawback of this method is the metal’s susceptibility to corrosion (at welding points), however, this problem can be eliminated by coating the reinforcement with a regular metal primer.

Rice. 2.2

And so, to create a reinforced frame for a bored pile with your own hands, you will need the following tools:

Bulgarian;
Welding machine;
Tape measure and pencil;
Paint brush.

Consumables include corrugated and smooth reinforcement rods, anti-corrosion primer and, if necessary, tie wire.

Sequence of work

The algorithm for creating a reinforced frame is as follows:

We prepare the reinforcement - we cut the corrugated and smooth rods into sections of the required length using a grinder. When working with this tool, we must not forget about safety precautions;
Then the smooth reinforcement is bent - mark four equal-sized sections on the rods, wedge it in a vice and, using a lever (an ordinary metal pipe put on the reinforcement will do), give the rod the required shape;

Rice. 2.3

After forming the fixing squares, we take two corrugated rods and place them parallel to each other on the working surface. The distance between the rods must correspond to the design dimensions of the reinforced frame;
We put pre-prepared squares on the longitudinal rods so that the rods are placed in the inner corners of the workpiece, and fix them using welding or knitting wire;
We turn the resulting structure over and weld the two remaining longitudinal rods;
We coat the reinforced frames with an anti-corrosion primer.

The bottom of the well drilled under the pile is covered with a layer of geotextile;
A compacting bedding 20 centimeters thick is placed on the surface of the geotextile: the first layer is sand, the second is crushed stone or gravel;
Then the formwork is placed in the well, into which concrete will subsequently be poured. The formwork is made from roofing felt, twisted into a cylinder of the required dimensions.

Rice. 2.4

A reinforced frame is installed in the formwork;
The last stage is concreting the pile. For pouring, a cement-sand mixture based on cement grades M300-M400 is used. After the formwork is filled with concrete to the required height, the concrete is bayoneted with reinforcement, this helps remove air cavities from the mixture.

Rice. 2.5

After pouring the bored pile, before proceeding with subsequent work, you need to wait the time necessary for the concrete to completely harden.

To drive most reinforced concrete piles, a wheeled pile driver is used. Thanks to its wheelbase, it is easily delivered to the work site and quickly fulfills the daily requirement.

Our services

The main services of the Bogatyr company are piling works and leader drilling. We have our own fleet of drilling and piling equipment and are ready to deliver 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 a request:

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A reinforcement frame for piles is a structure made of metal reinforcement; most often it is made from rods of the same direction, but from different spheres of reinforcement of the reinforced concrete element. The reinforcement is connected to each other by transverse or oblique rods and clamps, thus creating a solid metal structure. The most popular pile size ─ from 0.6 to 6 m ─ is determined based on the calculation of conditions to ensure the strength of the structure.

The reinforcement cage is used to reinforce reinforced concrete structures, in particular, at the pouring stage. This makes it possible to significantly increase the strength of the product and the resistance of the structure to mechanical loads of varying degrees of intensity and duration.

Types of reinforcement cages

On the left in the photo there are flat frames, on the right - volumetric frames for piles.

Currently, two types of reinforced frames are used in construction: volumetric and flat.

Volumetric frames There are different purposes: square and round shapes for piles, volumetric metal structures of a cellular type, which are used during the construction of industrial buildings when pouring large quantities of concrete.

The photo shows rectangular frames

This type of frame is a three-dimensional structure made of several gratings with connections between them in the form of metal rods attached perpendicular to the plane of the grating.

To manufacture this type of frame, rods with diameters of 8 and 12 mm are required, this makes it possible to form piles with a diameter corresponding to the specific type of work.

Depending on the shape, production methods are also distinguished: large frames are made individually, and frames for piles are made using automated welding lines.

Flat reinforcement cages have the form of two or three longitudinal layers of reinforcing mesh, welded to each other using rods. Longitudinal rods are fixed with inclined, transverse (“ladder”), continuous (“snake”) or steel rods.

The main scope of application of frames is strengthening linear structures without significantly changing their mass, laying foundations (including strip foundations) and reinforcing reinforced concrete.

Manufacturing of reinforcement cages

The following materials are used as the main material in the manufacture of frames for piles:

hot rolled wire rod,
corrugated and smooth reinforcing rod,
wire VR-1,
corrugated and smooth coil fittings with a diameter of 6-12 mm.

Metal rods are sometimes coated with special anti-corrosion protection, but most often metal rods or rods made of low-carbon steel without coating and alloying additives are used for this purpose. Individual metal rods are connected by welding or tied with wire. Volumetric frames are assembled from ready-made flat components.

The production of reinforced frames can be carried out both by specialized enterprises and directly during the construction of objects. This allows you to create not only a standard frame shape, but also a special one, precisely calculated for the future product. Today, spatial frames are manufactured using two main technologies:

1. Automated factory assembly includes the following parameters:

section type: prismatic or cylindrical;
length ─ 14 m - maximum;
weight – up to 4.5 tons;
Section diameter – 20 -150 cm;
working reinforcement: 1.2-4 cm, spiral: 0.6-1.6 cm;
type of connection – auto welding.

2. Manual assembly frames assumes the following parameters:

section type – unlimited;
weight – up to 10 tons;
length – up to 16 m;
dimensions of working and spiral reinforcement;=
type of connection - by fixing with wire or welding - semi-automatic.

In the production of round frames, welding of load-bearing rods with spirally wound reinforcement is used. The use of these technologies allows us to achieve ideal geometric shapes of the reinforcement frame, high-quality welding and high productivity.

Taking into account the fact that today many construction sites have restrictions on the use of driven piles, foundations are laid using modern technology based on bored piles.

The pile structure is created directly in the ground. For this purpose, a reinforced frame is installed in the already prepared well, then this base is filled with concrete. When the solution hardens and the structure reaches its design strength, the bored pile is ready to accept the maximum design loads. This technology for installing a bored pile has a low noise level, this makes it possible to lay foundations on piles in places where driven piles are not used due to the high noise level it is impossible to use.

The video shows the installation of the reinforced frame of a bored pile using a vibrating hammer

To reinforce bored piles, a round reinforcement cage is most often used. Main parameters of reinforcement cages:

diameter of the overall frame;
pile diameter;
spiral pitch;
spiral diameter;
diameter of longitudinal bars;
maximum frame weight.

Use of reinforced frames

The main area of use of reinforcement cages is the creation of new durable and reliable reinforced concrete structures or strengthening those that are already in operation.

Reinforced frames have gained wide popularity in the construction of various types ─ industrial and residential complexes, bridges and other specialized buildings.

At the stage of pouring the foundations of reinforced concrete structures, a reinforcing frame for the base is necessarily used, and beams for floors are usually made on the basis of standard 3- and 4-sided frames. The reinforcement frame can be volumetric, row or flat, and the frames for piles are made with a square or round cross-section.

In the photo - pouring concrete for the reinforced frame of a bored pile inside the casing pipe

Bored piles are used in the construction of foundations with a significant depth of solid soil. A bored pile has the form of a cylindrical structure consisting of reinforced circles with a small diameter and longitudinal reinforcements of a large diameter.

Advantages of using reinforcement frames

The widespread use of reinforced frames has undeniable advantages:

increasing installation speed when installing reinforced concrete structures;
reduction of the production cycle;
possibility of using waste fittings;
Possibility of use on any type of surface;
increase in labor productivity;
increase in production profitability.

Additionally, pile frames made of reinforcement are successfully used in construction in the vicinity of built houses, this makes it possible to remove the dynamic load from them during the construction of a new foundation. Thanks to the use of piles, spot construction wins where other technologies cannot be used, even in the most cramped conditions.

Driven pile foundation- a type of foundation in which the immersion of pile pillars is carried out without first removing soil for installation. The classic installation method is hammering piles. For this purpose, special piling equipment is used - hydraulic, steam-air or diesel hammers. In some cases, other methods are used to drive piles. These include installation by vibration and indentation. The ground part of the piles is fastened with a grillage.

Ready-made pile pillars, using special equipment, are driven into the ground to the required depth.

Made during foundation construction. At the installation sites, a well is drilled to the immersion depth of the future pile. Then reinforcement is installed in the well, after which the hole is filled with cement mortar. Sometimes, when constructing a foundation on unstable soils, for additional reliability, a metal pipe is placed in the well and only then concreting is carried out.

Advantages and disadvantages of a driven pile foundation

Operational features, as well as advantages and disadvantages, depend primarily on the material and manufacturing technology of the piles. But there are also common characteristics.

Advantages of a driven foundation

Possess high strength and are able to withstand heavy loads, especially foundations on reinforced concrete piles.
Foundation installation does not require serious site preparation and extensive earthworks.
Perfect suitable for flooded areas, since it is possible to raise the house above the flood level.
Installation work, despite the labor intensity, is carried out in short time.
When constructing a driven foundation, the soil does not loosen, but on the contrary, it is compacted, thereby increasing the reliability and stability of the structure.
Loads on the foundation are transferred to deep dense soils. This increases the bearing capacity of the base.

Flaws

The need to attract special equipment.
There may be difficulties with the equipment of the basement.
Foundation not reliable enough on swelling and subsiding soils.
Possible uneven shrinkage foundation. The reason may be differences in soil density and different loads on the piles.

Classification of driven piles

By section type pillars are:

whole;
tubular (the diameter of which does not exceed 80 cm and which have a soil core);
H-shaped;
with closed end.

According to the material of manufacture can be:

made of wood;
of steel;
reinforced concrete.

Features of a wooden driven foundation

Wooden driven piles are used in cases where the base of the foundation is located below the groundwater table.

To make pile posts, resinous and rot-resistant tree species are used - pine, oak, spruce, tansy, cedar, etc.

Wooden piles most often have a cross-sectional width of 25 to 30 cm, and immersion in the soil can reach 12 meters. The end that plunges into the soil must be pointed. If the foundation is being built on dense soil, a steel cap is placed on the pointed end. The ground part of the pole is decorated with a head or steel yoke.

There are three types of driven wooden piles.

Singles. Classic wooden posts that are mounted one at a time.
Batch. A pile consists of several beams (usually 3 or 4 pieces) placed together.
Piles from laminated veneer lumber. The main advantage of this type is the ability to make a pile pillar of any length. The manufacturing technology of laminated veneer lumber involves gluing dried and planed boards. Bio- and water-resistant adhesives are used for work, which increases the durability and performance characteristics of the product.

The wooden post must be buried to a depth of at least 1.2 meters. The level of soil freezing must be taken into account - the pile is immersed below it by at least 0.5 m.

Advantages and disadvantages of a wooden driven foundation

The main disadvantage of such a base is the susceptibility of wood to rot. Regularly changing soil moisture levels significantly reduce the service life of wood piles.

The advantages of wooden bases include:

environmental friendliness;
the ability to restore previous properties after some pressure;
ease of installation;
low cost.

Features of a driven foundation on reinforced concrete piles

Reinforced concrete piles come in two types - solid and hollow. Hollow ones are made using a centrifuge, are most often round in shape and are used in the construction of one-story buildings. Not suitable for building foundations in seismically active zones or peat soils. Unlike solid ones, hollow pile pillars have less weight, which greatly simplifies working with them.

Marking of reinforced concrete piles in accordance with GOST

« WITH» - pillars with transverse reinforcement.
« SK» - round piles with a cavity.
« JV» - the pillars are square in shape and have a round cavity, thereby reducing their weight. Reinforced using both prestressed and conventional methods.
« SG» - rectangular piles made of heavy concrete. Due to the increase in cross-sectional area, they have a greater load-bearing capacity than square ones.
« SC» - piles with a square cross-section without transverse reinforcement.
« 1SD» - columnar piles.
« 2SD» - columnar piles designed for installation along the middle axes.
« CCH», « NNE» - composite pile pillars.

Solid reinforced concrete piles

Solid piles come in several shapes - H-shaped, round, square or rectangular configurations.

Features of reinforcement

Hydraulic concrete and steel reinforcement are used for production. Reinforcement can be either ordinary or tension.

The peculiarity of reinforcement using prestressed reinforcement is that the metal element, before being concreted, is stretched using a jack or other device.

Also, stretching can be enhanced by using electricity - a huge current is passed through the reinforcement, which leads to heating of the metal and it expands. The reinforcement is fixed in this state throughout the entire cycle of concreting the pile.

After the concrete hardens, the voltage is removed from the metal element - the current supply is stopped or the fixation with the jack is weakened. This method increases the strength of the product.

Tension arises between concrete and metal, as the metal element tries to compress, and the concrete, to maintain its position, tries to stretch the metal to its previous state. This makes it possible to partially pull the reinforcing element at the bend and increase the strength of the entire structure.

Depending on their position, piles are reinforced in two ways.

Longitudinal reinforcement. It represents the main working fittings.
Transverse reinforcement. Its purpose is to combine the longitudinal reinforcement and absorb the impact load during the pile driving process.

Application of driven concrete foundations

Reinforced concrete pile foundation is the most common type of foundation. It is used for:

construction of private houses;
construction of industrial buildings and structures;
construction of multi-storey and low-rise buildings;
for buildings made of brick, wood, aerated concrete, foam blocks and other materials;
as a foundation for frame houses, garages, gazebos and other outbuildings.

Features of reinforced concrete foundations

Concrete piles have high strength and endurance. According to GOST, the strength of a concrete pillar must be at least 200 kgf/cm2. The minimum weight that a pile can support is 125 tons.
Concrete is prone to destruction in unfavorable environments - soils with a high content of chlorides, calcium, sulfates and other mineral salts and alkalis.
The large weight of reinforced concrete piles makes transportation and installation difficult.
The use of one type of pile or another for the foundation depends, first of all, on on soil characteristics.

Selection of the type of reinforced concrete base for the soil

Pile columns of stressed reinforcement are used for installation in soils of medium density.
Piles of conventional reinforcement - for installation on sandy and clay soils.
Pile columns of longitudinal unstressed reinforcement - on soils prone to compression, without clay and boulders.
Columnar piles are used on clay and medium-density soils.
Round hollow-section piles - for one-story buildings on stable soils.

Steel driven piles

They are made from various profiles - channels, pipes, etc. The lengths are divided into short, long and compound.

They are used for foundations for any buildings, both private and special purpose, and are also used in cases where it is not possible to build a foundation on reinforced concrete piles.

By design, steel piles are:

root-shaped;
conical;
anchor;
columns.

Most often, conical piles are used in the construction of driven foundations.

Advantages and disadvantages of foundations on steel piles

Steel pile foundations can be built in difficult geological conditions, such as high-density soils.

TO main advantages relate:

Light weight.
Possibility of installation at a depth of up to 90 m.
Possibility of building a foundation year-round.
Long service life.

The disadvantage of a foundation on metal piles is its susceptibility to corrosion. The foundation can collapse in a very short time if the construction technique is incorrect, the operating environment is highly aggressive and the anti-corrosion coating is of poor quality.

Stages of construction of a driven pile foundation

Before proceeding with the installation of the foundation, it is necessary to calculate the necessary parameters and draw up a design for the building and the foundation itself, taking into account the weight, layout and other features of the future construction.

Several factors are taken into account during the design.

Soil features.

depth of groundwater;
aggressiveness of the environment;
soil flooding level, etc.

The weight that the foundation will have to support.

the mass of the structure itself;
weight of the roof, attic floor, etc.

Pile locations. The piles are located:

at each corner along the outer perimeter;
at the intersections of internal walls and the joints of external and internal walls;
additional piles are located around the perimeter of the building and interior spaces, the distance between piles should be no more than 3 meters.

Installation process

Driving piles is the main installation stage in the construction of this type of foundation.

Stage 1. Preparatory.

Before starting installation work, the area is prepared, groundwater is drained and a pit is dug. The territory is marked, the places where the piles are to be installed are marked with pegs.

Stage 2. Driving piles.

The piles are lifted using special equipment and installed in designated areas. The pillars are then driven into the ground using a pile driver.

Stage 3. Alignment.

Installed piles are checked for deviations and trimmed to the required level.

Stage 4. Grillage equipment.

The ground part of the pile pillars is connected by a grillage, most often concrete. For its installation, formwork is installed, reinforcement and concreting are carried out. The grillage can also be made of wooden beams or metal, depending on the material used to make the piles.

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