To organize the pile foundation, it is necessary to perform work on the pressing of reinforced concrete supports into the ground. After this, a monolithic slab or tape is erected, which will distribute the load. A similar design is called a grillage. But for starters, builders are constructing a pile field on which beams or slabs are installed. It is on the quality of the calculation and markup that the technical parameters of the facility being built depend.
general information
Pile field - a special construction that is being built so that the concrete base of the building is solid. If a foundation is being screwed, reinforced concrete or bored, then in any case, such a plant will have to be built initially. The design is used as the basis for the construction of residential or industrial buildings after the construction of the grillage.
If there is problem soil at the construction site, then most often they build steel supports under the house - elements that distribute the load of the structure to the soil layer, where the underground part of the structure will be located. To comply with the technical conditions of the product, structures should be hammered to a depth of 3 to 15 meters, since only in this case they will be in a stable and deep layer.
You should know: the construction of the walls begins after the construction of the grillage, the bearing surface for which is the pile grid.
Location of supports in the foundation
The load of the supporting structures of the structure and the shape of the grillage are factors that determine how metal, reinforced concrete or wooden rods will be placed in the pile field of the foundation. There are such ways of positioning the supports:
- Pile bush - a method in which piles are combined into one compact design. In this case, the grillage is made in such a way that the ratio of its sides does not exceed 1: 5. If you need to build columns, racks, chimneys and other tall objects, it is recommended to use this method.
- Pile strip is a support device technology that is used to erect bases for extended structures (for example, for embankments or concrete fences).
- Pile field - for the house it is recommended to build supports using this method if it is planned to erect a monolithic grillage.
Construction device
The finished pile field will be located at the construction site where the support was previously driven in accordance with the design documentation. Steel or reinforced concrete products in the structure are located in this way:
- staggered - to organize a large foundation;
- in rows - for driving a small number of supports.
The extreme axial lines of the rods when installing the pile field should be installed so that they are located in relation to the outer edge of the constructed grillage at a distance equal to the diameter of the supports in plan.
Project creation
Before making a pile field, it is necessary to draw up a drawing, a work plan and check the soil at the construction site. It is necessary to examine the soil for such data:
- density;
- freezing depth of the earth;
- bearing abilities;
- soil saturation;
- groundwater depth;
- bedding of various types of land on a construction site.
It is simply impossible to calculate the bearing capacity of one rod, knowing only what material the product is made of, since the resistance force of the soil is usually less than the load-bearing index of the pile. Therefore, it is necessary to carry out geodetic work in order to calculate the technical properties of the supports, taking into account the characteristics of the land in which they will be installed.
Counting technique
The initial stage of work is the calculation of the pile field. The purpose of this procedure is to analyze the distribution of the rods at the construction site and find out how many supports are required. To do this, you need to perform several steps:
- Calculate the total load that will act on the concrete base during the operation of the building.
- Determine the bearing capacity of each pile, taking into account the parameters of the building material from which the support is made.
- Divide the final load by the calculated indicator of the bearing characteristics of the rod to determine the number of supports.
- Draw up a project in which the location of the piles along the perimeter and walls of the constructed object will be indicated.
To determine the total load, it is necessary to calculate the mass of the room, taking into account the specific gravity of the involved building materials and the area of the structural parts of the building.
The next stage is the calculation of the load using approved state standards and developed projects. The documents indicate that for residential buildings this indicator is approximately 150 kg / m 2 of overlap, and for industrial facilities - 200 kg / m 2 . If the building is planned to be built with two or more tiers, then the mentioned technical parameter should be calculated taking into account all floors.
After this, it is required to calculate the temporary snow load, the value of which directly depends on the region where the building is being constructed. To do this, it is necessary to multiply the area of the roof of the room by the average weight of the snow layer, pressing on 1 m 2 of the floor surface. Further, the resulting amount must be multiplied by the reliability coefficient, which is 1.2.
The next step is to calculate the bearing capacity of the piles, taking into account information about the characteristics of the soil on the site. When all indicators are known, a final calculation should be made. To do this, the total mass of loads should be divided by the load-carrying capacity of the product. As a result, a number is obtained that indicates the required number of supports on which the pile-grillage foundation should be erected.
In the design documentation, all calculated indicators should be indicated.
Pile Type Selection
For the construction of the foundation most often used solid reinforced concrete products, the cross section of which is 300 x 300 mm. Such supports are used for the construction of structures of these types:
- Many and low buildings.
- Industrial type objects.
In addition, these supports are acquired when it is necessary to strengthen the pile foundation. But for the construction of massive structures, rods with a section of 400 x 400 mm are sometimes used as rods. If the floor on the pile foundation will be made of lumber, it is recommended to use piles with dimensions of 250 x 250 mm.
Square rods are most often used in the construction process of buildings located on these types of soil:
- heaving (soil expanding in winter, so it puts great pressure on the foundation in the cold season);
- peat bogs;
- boggy and silty soils;
- in areas where the soil undergoes horizontal displacements.
Sometimes builders organize a pile field from composite products, if the site has low-density and moist soil with a thickness of more than 10 cm. In this case, the length of solid rods to build a reliable foundation is simply not enough. The craftsmen even make connected supports that immerse them in the soil to a depth of 20 meters.
Markup
This is an important stage that builders spend before starting the installation of piles. To technically correctly markup, you must perform the following tasks:
- Mark the base lines or contours of the foundation of the pile field at the construction site - the design scheme is useful in this matter.
- Mark in the places where the supports will be installed. It should be remembered: for each individual element there will be its own clogging point.
- Determine the zero mark with which you can align the piles after installation in the ground.
Marking should be carried out using a castoff. This is a temporary wooden structure with which center axes are mounted. In the drawing, the points on which the piles should be installed should be determined. Using equipment - an electronic total station - a specialist will determine the location of the supports on the construction site, and then mark these points with the help of fittings. Sometimes masters use ordinary roulette to do these jobs.
The main thing is to securely install each armature so that the product does not move from a given area, otherwise you will have to call the surveyor again.
Construction erection
After the markup is completed, activities should begin that include the following processes:
- transportation of necessary equipment;
- acquisition, transportation and unloading of piles;
- digging a pit.
The next stage is the deepening of the supports into the soil with the help of a special construction machine, which is called a pile driver. The specified process of the master is performed in the following order:
- The pile driver is installed in the area where the points of installation of the supports were marked, and the piles are moved using a winch installed on the machine.
- Workers help to make a support line.
- The pile rises vertically at the point of penetration.
- The product is fixed on the copra mast and connected to a pile driver. The next step is to drive the support into the ground to a depth, the required size of which is indicated in the design documentation.
- After installation of all piles, it is necessary to align them at the set zero mark. As a rule, such work is carried out using jackhammers.
The main thing is that a design drawing has been previously drawn up, since this document provides instructions with which all construction work is carried out.
Pile field acceptance
The following information is required for acceptance of the structure:
- information on geodetic verification of clogged supports in height and in plan;
- the number of hammer blows per pile.
The engineer must enter the data into a special journal. And if you compare the information and test results (static and dynamic), then when designing the project, you should establish:
- the need to remove the upper parts of piles to the indicated marks;
- the suitability of the installed supports and their compliance with the carrying capacity of the general loads of the building;
- the need to install additional piles.
Floor device
On the pile field, you can equip the flooring when the grillage is completed. In this case, the main thing is to use wooden battens to form gaps, with the help of which the structure will be protected from condensation.
To install the flooring, you should purchase an edged board, the thickness of which is more than 28 mm, however, masters advise using at least 36 mm products. In addition, you need to purchase high-quality elements for fastening lumber.
The next step is the laying of OSB boards, since with this material it is easiest to level the floor surface. Flooring insulation is an important process, the implementation of which should be taken care of upon completion of the arrangement of the supporting structure. Therefore, it is recommended to use mineral wool from a thickness of 20 cm.
Conclusion
Responsibility and attentiveness are the main requirements that must be observed during construction. The process of erecting a residential building, the foundation of which will be built on the installed pile field, is especially important, therefore, the technique for performing these works is described in the article.