Erection of houses on unstable soils is carried out using a special pile technology. It provides proportional distribution of the load of the building structure mass on the soil. There are different types of pile foundations. For their device, a special technique is used.
The main elements of the foundation are piles in the form of pillars or rods.
The cross-section of the products can be round or square. The supports are deepened at a certain angle of inclination or strictly vertically. The technology for constructing pile foundations is quite simple. The choice of foundation design depends on various factors:
The order of installation of supports is regulated by SNiP 2.
02.03-85 . Most often, they are used for the construction of frame, panel board and wooden low-rise buildings. In the construction of multi-storey buildings, the base is made of reinforced concrete piles. Houses erected using pile technology do not have basements.
Table 1. Advantages and disadvantages of the pile foundation.
|Possibility of the device on difficult ground and mountainous terrain||Special equipment is required for the construction of the foundation|
|Installation of the foundation can be carried out in any weather||The pile foundation is not recommended for the construction of houses on a horizontal moving soils|
|Minimum draft||Difficulties in the construction of basement floors|
|Economical and reliable||Impossibility of verification installed piles for damage|
The classification of supports and foundations erected with their help is carried out according to various criteria. By the type of material used for their manufacture, piles are distinguished:
The most reliable structures are considered, consisting of combined supports.
They retain their original performance for the longest time. Wooden piles have the least strength and durability. Most of them are made from coniferous wood. The metal screw supports are made of ferrous metal. Before installation in the ground, the surface of wooden and metal piles is treated with special means.
By bearing loads, piles are distinguished:
According to the method of immersing supports in the ground, foundations are subdivided into:
Interesting! Pile foundations are capable of withstanding seismic loads up to 7 points . For their device, not only factory-made supports are used. Bored rods are poured with concrete at the site of the foundation.
Driving technology is used in the construction of multi-storey buildings. For the installation of their structures, rods made of reinforced concrete are used.
In low-rise construction, it is allowed to use this technology for the construction of wooden and metal supports. Most often, they have a square section with a side size from 150 to 500 mm . Standard leg lengths are from 3 to 25 m . Their lower end is sharpened. This greatly simplifies the process of driving piles into the ground.
The upper part of the supports is equipped with a head. It takes hammer blows when hammering in products and protects them from deformation. The choice of piles depends on the properties of the soil and the structure of the building being erected. Their immersion in the ground is carried out all the way into a solid earth layer. This ensures the strength of the structure and does not allow the base of the buildings to "float".
The advantages and disadvantages of driven foundations depend on the type of piles used for the device. Among the advantages common to all types of supports:
When erecting a pile foundation, the soil is not loosened, but compacted. Among the main disadvantages of driven structures:
The technology is used for the construction of structures on plastic-frozen and hard-frozen soil.
Work on the installation of the base is carried out at a temperature not lower than 0.5 ° C . The work technology provides for the installation of rods in pre-drilled wells. Their diameter should exceed the pile section by 50-100 mm . Soil drilling is carried out with special equipment.
Important! The diameter of the drill must be at least 10 cm greater than the width of the support. After installing the rod in the well, the voids in the hole are filled with binder solutions. They increase the stability of the structure.
The technology is used in the construction of light and medium buildings on all types of soil. In often flooded areas, this is the only possible way to build houses.
Installation of screw bases for buildings of various types was invented in the XIX century . It is widely used in the construction of marinas and houses on the water.
Construction with screw technology can be carried out at any time of the year. For the installation of the structure, metal piles with a different number of blades are used. To immerse them in the ground, no special equipment is required.
The piles are manually screwed into the ground. The main advantages of the technology are quick installation and minimal costs for the foundation.
Bored technology is used in the construction of heavy structures on soft soils. When driving piles using this method, there is no vibration effect on adjacent buildings. It is also possible to build objects using bored technology in areas with difficult terrain.
Requirements for these types of bases are defined in the Code of Rules SP 50-102-2003 . The construction of foundations is carried out using:
Piles for the foundation are poured with concrete directly into the wells prepared for them. The technology can be applied on hollow soils.
Before pouring concrete into the well, reinforcement is made in it and its walls are strengthened from crumbling earth. The bored technology of pile foundations is considered the most difficult.
B piles and slabs are used for the construction of foundations. Foundations of this type are erected on collapsible soils in accordance with the Code of Practice 22. 13330 .
A distinctive feature of the design is the complete support of the slab on the ground. The grillage does not touch the ground.
The layout of the piles in the ground is determined by the configuration of the building being erected. By the method of their placement, structures are distinguished:
Designed to support the walls of buildings.
GOSTs for pile foundations and screw piles in the Russian Federation have been replaced by SNiP 2. 02.03-85 and SNiP 24.13330.
2011 .Reinforced concrete piles of industrial production are produced according to GOST 19804-2012 .
Several standards are used in the production of piles:
Requirements for products by regulatory documents take into account the characteristics of the soils for which they are intended. Screw piles produced in accordance with GOST are subdivided according to their design features.
Products are grouped by:
The grillage is not an obligatory structural element. It connects the supports of the base to each other, giving the structure additional rigidity. There are 3 main types of grillages:
Grillages are distinguished according to the assembly method:
They are welded steel beams, which are used in the construction of lightweight buildings with a short service life.
They are single structures in the form of a closed or open tape. They are used in the construction of residential low-rise buildings.
Before starting to build a house, you need to decide on the type of foundation. When choosing it, the type of soil intended for the construction of the territory is taken into account. It can be determined using geological research.
Among other determining factors:
Pay attention! The foundation to be erected must withstand the loads of the entire structure of the house and the environment planned for placement in it. The main hazard to a pile foundation is soil swelling . The most difficult is the construction of bored structures.
When designing the foundations, the pile driving depth is determined.
Many developers are building houses on screw piles in an effort to reduce construction costs. This allows them to save significant amounts on the purchase of building materials. Screw bases can be erected without geological research.The length of the foundation rods is selected depending on the depth of immersion of the supports from the earth's surface to the soil layer with normal bearing capacity. The lower base of the rod should rest against it and be below the freezing mark.
The estimated cost of building houses built using pile-screw technology is 30-40% less than conventional methods of building houses. Structures are erected without excavation. The maintainability of the elements of the pile-screw foundations is 100% . The disadvantage of the pile base is the need for a basement and blind area at least 70 cm wide around the building. The task of the blind area is to protect the facing of the pile foundation from surface pollution.
The material of the supports and the type of soil affect the bearing capacity of the base of the structure. The basis of the screw structures is made up of tubular supports. They are commercially available with diameters 133, 108 and 89 mm . It affects the bearing capacity of the base together with the length of the pipe and the diameter of the blades. It is not recommended to erect heavy structures on pipe supports.
Driven piles are used as supports for multi-storey buildings with a height of up to 60 m . The length of such piles may exceed 10 m . This is the most reliable type of pile foundation. In private housing construction, driven reinforced concrete supports are used extremely rarely due to the high cost of renting the special equipment necessary for their installation.
Step 1 .
We calculate the amount of material required for construction. The number of supports is determined in 2 directions:
For calculations, it is better to draw up a plan of the foundation. The pile installation markings are applied to it. The distance between them should not exceed 2-3 m .
The greater the mass of the structure being erected, the closer the supports are located to each other. Their number is determined by dividing the total mass of the house with the things filling it by the value of the permissible load per 1 pile. This is a reference value. You can find it in special tables or in the manufacturer's technical documentation for the product. On the Internet, you can find online calculators that calculate the number of supports required for the foundation when entering the necessary parameters.
Step 2 . We prepare the necessary material and tools for work.
Step 3 . We mark the site for the installation of supports. It is done according to the general plan of the construction site and the scheme of the 1st floor of the house with marks for the location of the piles.
They always begin to make the markup from the corner supports, the remaining installation points are evenly distributed over the entire area of the base. In the event that too large gaps are obtained between the supports, additional supports are installed in them.
Step 4 . We screw the piles into the ground according to the established mark. In areas with soft soil, this can be done manually, on harder soil, screwing in piles is performed using special devices.
They are buried in the ground to the level of solid ground. The supports should enter the ground in a strictly vertical position.
Step 5 . The top of the supports must be level. It is checked after the last pile is screwed into the ground.
Height differences are not allowed. Supports that deviate from the set level are trimmed or built up. When leveling the height, it is strictly forbidden to lift up the piles already screwed into the ground.
Step 6 . We install hollow horizontal planes on the aligned supports and fill them with concrete.
Step 7 . To drain excess moisture from the structure, we drain the base. It is a small trench dug along the perimeter of the structure, with a branch outside the site.
It is better to screw the piles into the ground manually by three people. During burial, they are difficult to maintain upright.
Two people act on the lever, and the third monitors the angle of entry of the support into the ground. Periodically, you need to fix it and analyze the depth of immersion. It is not recommended to screw piles to a depth less than 1 meter . With such a deepening of the supports, there is a high probability of skewing of the structure.
The most important parts of the base are its corners.
The deepening of the supports at these points should be maximum. Additional structural strength is achieved by concreting the foundation. A big drawback of screw piles is the impossibility of making a foundation from them for building houses on soils with layers of stones or limestone. For such construction sites, piles with welded ends are used.
At the same time, we recommend that you familiarize yourself with the material on the topic - Ebb tides for the basement base.
The service life of pile foundations depends on the material of their execution. In favorable conditions, they can be operated from 300 to 400 years . .
Posted By: Work Style |09, Nov 2020
Posted By: Work Style |10, Nov 2020
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Posted By: Work Style |04, Nov 2020
Posted By: Work Style |09, Nov 2020