What kind of soil are there

Baunetz_Knowledge

Building ground
The construction ground on which a structure is to be erected is important in terms of its structure and condition for the choice of the type of foundation. Soils differ according to their material components in organic and inorganic soils, whereby the soil types can mix within a plot of land. Soils are mixtures of mineral grains of various shapes and sizes and organic particles. Organic soils such as humus, peat and lignite are not suitable as building ground, as settlement is to be expected. Inorganic soils consist of sand, gravel and rock and are suitable as building ground.

Deep compaction
In the case of extensive construction work, the subsoil must be compacted. For this purpose, it is prepared by means of a device for the large loads in the deep compaction. Probably the most important methods of deep compaction with their respective variations include:

  • the vibro method (gravel columns)
  • the vibration pressure compaction (deep vibrator)
  • dynamic intensive compaction (falling plate compaction)
Soil types
When erecting structures, the structural engineer must take into account the load-bearing behavior of the subsoil. A distinction is made between natural soils, rocks and poured soils. Grown soils are pristine soil that has been created by deposits over a long period of time. Rock is a dense, firmly stored rock that consists of all types of rock such as sandstone, granite, marble, basalt. Backfilled soil is the result of backfilling or flushing. It can be of any composition and compacted fill from natural soil.

Load capacity
The load-bearing behavior of the subsoil is significantly influenced by whether it is cohesive or non-cohesive soil.

Non-cohesive soil
A non-cohesive soil is relatively insensitive with regard to its load-bearing capacity, even when there is a supply of water. It consists of grains of different sizes that touch each other, as is the case with sand or gravel, for example. The soil is unable to store water. The friction that occurs between the grains, which is essential for the load-bearing capacity of the soil, is hardly affected. Since non-cohesive soils do not soften even when water is supplied (from groundwater, rain or snow), their load-bearing capacity does not depend on the soil moisture, but only on the density of the storage. Non-cohesive soils are e.g. sand, gravel, stones.

Cohesive soil
Cohesive soil significantly loses its bearing capacity due to the ingress of water. It consists of silt (also known as "loam") and clay with a platelet-like structure (clay platelets). Due to the nature of the surface of the clay platelets, the soil can absorb and also store water. Cohesive soil has a tendency to become "muddy". The surface of the clay platelets softens, the friction between the platelets is significantly reduced, the consistency changes from firm to soft, and the load-bearing capacity drops dramatically as a result. In the worst case, there is no longer any load-bearing capacity, so building in the "muddy" subsoil is not possible. If a cohesive soil dries off again, the load-bearing capacity becomes significantly better again due to the increasing friction between the clay tiles. If the soil is completely dry, it is very firm and has a relatively high load-bearing capacity. Cohesive soils are loam, clay, marl and silt.

Expertise on the subject

founding

Shallow foundations

In the case of a shallow foundation, the structural loads are transferred to the foundation surface in a flat manner by foundations. The ...

founding

Deep foundations

In the case of deep foundations, the structural loads are transferred to deep, load-bearing soil layers. The load is transferred ...

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