What foundation to build on subsidence soil

What foundation to erect on subsiding soilsTable of contents:

  • 1 Types of subsidence soils
  • 2 Choice of foundation
  • 3 solution options
  • 4 videos

It is known that a competent choice of foundation for future structures involves a detailed analysis of the characteristics of the soil in place construction work. Based on the results of such research, you can safely choose one or another type foundation construction used to strengthen the foundation future structure. At the same time, both professional builders and ordinary developers often encounters soils capable of change their characteristics over time and called in circle of specialists subsidence.

In this regard, it is natural our desire to deal with which foundations are being built on subsidence soils, as well as familiarize you with well-known ways to strengthen the footing. Title a site with unstable soil layers speaks for itself, warning the user about the possibility of subsidence of the future buildings. Moreover, the porosity characteristic of such soils plus increased humidity leads to a noticeable reduction in soil volumes under the foundation, which should be taken into account in the calculations loads on him. Thus, in addition to the possible precipitation of soil the cause of the external load should be taken into account and its subsidence due to soil moisture.

Types of subsidence soils

Subsidence soilSubsidence soil

Depending on the causes of the occurrence of a drawdown, all known soils are divided into two types:

  • areas with drawdown caused by external influences (while subsidence due to its own weight may not be taken into account);
  • zones of subsidence caused by the combined action of both factors (weight and humidity).

If there is any suspicion of possible problems with soil in the place of work you need to apply for consultations with experts in geological exploration. Only they can correctly assess the parameters of subsidence soil subsidence (including its high-quality composition) and prepare all the necessary data for selection type of foundation foundation.

Foundation selection

We take into account the level of freezingWe take into account the level freezing

The foundation for subsidence soil is selected based on data obtained from the analysis of the composition of the latter. Depending on the a particular situation, it can be either pile or plate or traditional – tape. When making a final decision on the type of foundation base must take into account the following moments:

  • the presence of layers of individual soil layers;
  • the relative drawdown at a given load;
  • groundwater depth;
  • indicators of freezing soil;
  • design data on the size of the foundation;
  • the location of the sole of the base.

After all the data is prepared – you can go to the construction of a table of pressures exerted by the soil throughout the thickness the studied reservoir (up to the groundwater bed). In this the table should also include data on pressures received part of the soil at full building load (house plus foundation).

After summing all the data obtained (for each layer soil) you can get the total value of the drawdown. A final conclusion on the type of foundation should be made taking into account the value obtained from the summation results.

Decision options

How to choose a foundationHow to choose a foundation

The following options are possible:

  1. In the case when the layer of unstable soil is relatively small – the foundation under it can serve as a support for the foundation hard layer. In this situation, the most acceptable is considered option of using pile or columnar supporting structures. At the same time, the possibility of choosing other types is not excluded. foundation foundations (strip or slab).
  2. In some cases, it is possible to replace part of the subsidence soil on the material having higher rates for compression resistance (sand, for example). Sand layer may play the role of a kind of pillow for slab, columnar or tape support structures.

Arrangement of pillows under the stoveArrangement of pillows under stove

With full confidence in the results of the studies not shall exclude the option of arranging shallow foundation (with the replacement of part of the soil with sand and with the expansion of the supporting base design).

Thus, an analysis of what foundations are being built on subsidence soils, allowed us to verify the following:

  1. Soils considered by us are the most difficult from the point of view view of the preparation of a reliable foundation for future buildings.
  2. Proper selection of the support base is possible only after consultations with a specialist or with neighbors in the site, who already have experience in preparing foundations on a similar soil characteristics.

A full survey of the soil is impossible without involving representative of specialized companies. Such option will cost you more, but then you get one hundred percent guarantee the correctness of the choice made.


Additionally, we suggest watching a video where you will receive tips for choosing the foundation for the home:

Also a little about the benefits of screw piles:

Also a little about the benefits of screw piles:

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