Each building needs a foundation and undergoes subsidence over time depending on the soil. It is necessary to correctly calculate the draft in accordance with the soil. If the calculation is not so, then this threatens uneven subsidence. As a result, there is a threat of the destruction of the building, the appearance of cracks and the like. Carefully read about all the subtleties and learn the basic methods of organizing precipitation.
Description
Foundation sinking is a very important characteristic; it changes over time and depending on the soil. There are reasons why an uneven subsidence usually occurs:
- Saving on foundation materials and buying cheap and low-quality materials.
- Cheap and unskilled labor.
- Incorrect calculations of the depth of the foundation, the level of proximity of groundwater.
- No drainage system.
The objectives of determining precipitation:
- determine the drawdown value;
- perform an accurate calculation of precipitation for the foundation of different materials;
- calculate possible deformations and physical changes.
Soil characteristics
There are two types of soil:
- Natural - lies under the foundation and ensures stability of the base evenly.
- Artificial - specially strengthened: rammed, dried and the like.
Two groups of soils:
- Downy - clay, sand, small.
- Non-porous - gravel, large and medium, do not contain clay.
There are types:
- Rocky - solid, durable, waterproof, perennial.
- Coarse - gravel, pebbles, boulders.
- Sandy - loose and dry breeds.
- Clay - very ductile and creates a smooth surface.
- Loam is a clay but brittle material.
- Sandy loam is fragile and not elastic, but contains a small amount of clay.
Types of foundation
The choice of foundation is the main part of the construction of the building. Reliability and strength of a building depend on strength, calculation of draft and integrity.
In order to choose the foundation of a house, you need to take into account several important qualities: the type and type of soil, the distance to groundwater, grubina depends on the height of the building.
Types of foundations:
- tape - a tape between all load-bearing walls around the perimeter of the entire building;
- columnar - during the construction of a light building and low loads on the foundation;
- pile - it makes sense to use mainly on non-solid soils.
Precipitation calculation
Calculation of precipitation is a very important measure in the construction of a building. After all, the foundation is the foundation of the house, so the reliability and safety of operation depend on its integrity.
The drawdown 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 beyond this norm can be fraught with the appearance of cracks, the destruction of load-bearing 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 health or life of a large number of people.
It is almost impossible to make calculations on your own, but you can do this in a special, simplified way. You can see an example of precipitation calculation in the video below.
Pile foundation
With unstable soil, if you need a cheap reliable and simple foundation, choose pile. It is cheaper than the rest and is able to maintain the integrity of the building, located on unstable soil.
What is he like? Vertical reinforced concrete supports that are immersed in the ground. Usually they are connected with a monolithic plate. There are two types of piles: hanging and retaining. The choice of type depends on the installation capabilities and soil hardness, retaining are considered the most reliable. They are installed very simply. Quick installation, an economical option and a minimum of earthwork - dig or drill places.
Sediment pile foundation is determined by calculating the depth of 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 laid on the foundation during the operation of the building, possible climatic changes and dangerous weather conditions that affect the integrity of the housing.
The layer-by-layer summation method is best suited to calculate the settlement of the pile foundation.
Creation of documentation and making calculations is carried out using special computer programs.
Precipitation methods
Engineers who are involved in the calculation and design of the foundation carefully study the terrain, buildings and, depending on key factors, calculate the time and scale of precipitation using two main methods:
- Layer summation.
- Equivalent layer.
Let us examine in more detail the method of layer-by-layer summation, since it is the main method for calculating precipitation in most of the territory of Russia.
Layer Summation
The method of layer-by-layer summation of the foundation sediment is described and recommended by the Code of Norms and Rules for construction. Mainly suitable for pile foundations. Also, this method will be the best solution if the building is separate, and it is possible to take into account soil resistance.
What is the basic principle? The base of the piles is conventionally taken as a monolithic structure, the dimensions are considered according to the location of the extreme points.
Approximate calculation scheme:
- Design of the overall layout of the base.
- Calculation of the length and width of the base.
- Further, the obtained parameters are used to calculate the possible pressure on the foundation supports.
- Based on the latest data, soil resistivity is distinguished.
If, as a result of comparing the pressure and possible loads, equality is obtained with the norms specified in SNiP, then special diagrams of the loads on the piles are compiled, and from all these data the value of the base settlement is the most important parameter sought.
How to fix the problem
If the obtained numbers of the base settlement values exceed the maximum dimensions, then it is necessary to make adjustments to the foundation design and increase the length of piles to increase strength and increase possible loads. Then all the parameters will converge and will correspond to the latest edition of SNiP.
Precise determination of the foundation settlement occurs empirically. In fact, such an actual calculation is made through laboratory tests, statistics are compiled on their basis. How is all this done? The supports are made artificially by pressure - using a jack. In this way, critical loads can be determined very accurately and the maximum possible settlement of the foundation foundation can be calculated.
To avoid rainfall, builders strengthen the foundation. Such protective measures allow you to fix the foundation, built on the wrong calculations. This can be done by increasing the resistance of the soil with concrete pipes, filled with a special silicate solution, 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 appearance of computer programs, professional software. But, as always, the most reliable is the knowledge obtained experimentally, and these parameters are taken as a standard and critical information.
When constructing a building, be sure to pay special attention to the foundation and its important parameter, such as settlement, since it affects the strength and reliability of the structure.