Every building needs a foundation and is subject to subsidence over time depending on the ground. It is necessary to correctly calculate the draft in accordance with the soil. If the calculation is not made in this way, then it threatens with an uneven drawdown. As a result, there is a threat of destruction of the building, the appearance of cracks and the like. Read carefully about all the intricacies and learn the basic methods of organizing precipitation.
Description
Settlement of the foundation is a very important characteristic, it changes over time and depending on the soil. There are reasons why uneven subsidence usually occurs:
- Saving on foundation materials and buying cheap and low-quality materials.
- Cheap and unskilled labor force.
- Calculations of the depth of the foundation, the level of proximity to groundwater were incorrect.
- No drainage system.
Draft targets:
- determine the amount of drawdown;
- perform an accurate settlement calculation for foundations made of different materials;
- calculate possible deformations and physical changes.
Soil characteristics
There are two types of soil:
- Natural - lies under the foundation and ensures the stability of the foundation evenly.
- Artificial - specially strengthened: rammed, dried and the like.
Two groups of soils:
- Heaving - clayey, sandy, fine.
- Non-rocky - gravel, coarse and medium, does not contain clay.
There are types:
- Rocky - solid, durable, waterproof, perennial.
- Coarse clastic - gravel, pebbles, boulders.
- Sandy - loose and dry rocks.
- Clay - very ductile and creates a smooth surface.
- Loam is a clayey but brittle material.
- Sandy loam - brittle and not elastic, but contains a small amount of clay.
Types of foundation
The choice of foundation is the main part of building a building. The reliability and strength of the building depends on the strength, calculation of settlement and integrity.
To choose the right foundation for a house, you need to take into account several important qualities: the type and type of soil, the distance to groundwater, the depth depends on the height of the building.
Types of foundations:
- tape - a tape between all load-bearing walls along the perimeter of the entire building;
- columnar - when erecting a light building and lowfoundation loads;
- pile - it makes sense to use mainly on unstable soils.
Draft calculation
Settlement calculation is a very important measure in the construction of a building. After all, the foundation is the basis of the house, therefore, the reliability and safety of operation depend on its integrity.
The settlement of a new building on homogeneous soil can be 10-12 centimeters.
There are several basic accepted norms: if the soil is heterogeneous, then the sediment without consequences can be 5 centimeters, for multi-storey buildings - 2-3 cm.
Any subsidence in excess of this norm can be fraught with the appearance of cracks, destruction of supporting structures. This affects the safety of people in the building, the operation of the premises. If the house is multi-storey and residential, then there is a risk of losing the he alth or life of a large number of people.
It is practically impossible to make calculations on your own, but you can do it in a special simplified way. You can watch an example of precipitation calculation in the video below.
Pile Foundation
With unstable ground, if you need a cheap, reliable and simple foundation, choose a pile. It is cheaper than others and is able to maintain the integrity of a building located on unstable ground.
What is it? Vertical reinforced concrete supports that are immersed in the ground. Usually they are connected with a monolithic slab. There are two types of piles: hanging and retaining. The choice of type depends on the installation possibilities and the hardness of the soil, retaining ones are considered the most reliable. Very easy to install. Fast installation, economical option and minimum excavation - dig or drill places.
The settlement of the pile foundation is determined by calculating the depth of the piles depending on a large number of factors. There are two most basic parameters:
- Low bearing capacity of soil under piles.
- The number of loads that will be placed on the foundation during the operation of the building, possible climatic changes and dangerous weather conditions affecting the integrity of housing.
The method of layer-by-layer summation is best for calculating the settlement of a pile foundation.
Creating documentation and making calculations is done using special computer programs.
Settlement methods
Engineers who calculate and design foundations carefully study the terrain, buildings and, depending on key factors, calculate the time and extent of settlement in two main methods:
- Layer-by-layer summation.
- Equivalent layer.
Let's take a closer look at the method of layer-by-layer summation, since it is the main method for calculating precipitation in most of Russia.
Layer-by-layer summation
The method of layer-by-layer summation of foundation settlements is described and recommended by the Code of Construction Norms and Rules. Mainly suitable for pile foundation. Also, this method will be the best solution if the building is separate, andit is possible to take into account the resistance of the soil.
What is the basic principle? The base of the piles is conditionally taken as a monolithic structure, the dimensions are calculated according to the location of the extreme points.
Approximate calculation scheme:
- Designing the dimensional scheme of the base.
- Calculate the length and width of the base.
- Further, the obtained parameters are used to calculate the possible pressure on the foundation supports.
- Based on recent data, soil resistivity is highlighted.
If, as a result of comparing pressure and possible loads, equality with the norms specified in SNiP is obtained, then special diagrams of loads on piles are compiled, and from all these data the value of the settlement of the base is derived - the most important parameter sought.
Troubleshooting
If the obtained numbers of the base settlement exceed the limit dimensions, then it is necessary to make adjustments to the design of the foundation and increase the length of the piles to increase strength and increase possible loads. Then all parameters will converge and will correspond to the latest edition of SNiP.
Precise determination of foundation settlement occurs empirically. In fact, such an actual calculation is made by laboratory tests, statistics are compiled on their basis. How is all this carried out? Pressure is applied artificially to the supports - with the help of a jack. In this way, critical loads can be determined very precisely andcalculate the maximum possible settlement of the foundation base.
To avoid settlement, builders are strengthening the foundation. Such protective measures allow you to correct the foundation, built according to incorrect calculations. This can be done by increasing the resistance of the soil with concrete pipes filled with a special silicate mortar, steel pipes in the soil.
Conclusion
All calculation options are good in their individual cases. At the moment, all these design processes are simplified due to the emergence of computer programs, professional software. But, as always, the most reliable is the knowledge gained by experience, and these parameters are taken as a standard and critical information.
When building a building, be sure to pay special attention to the foundation and such an important parameter as settlement, as it affects the strength and reliability of the structure.
