Determination of deformation properties of soils as input parameters for calculation

When designing the foundations of any building structure, it is important to know not only the load of the structure, but also the deformation characteristics of the subsoil. Their underestimation leads to incorrect design of the foundations or even to failures, the reparation of which requires considerable financial costs. The real values of the deformation soil properties gained from the geotechnical investigation often do not match the tabulated values used in the design. In this contribution, actual and tabular values of selected soil properties in the bedrock in the locality of Kosicka kotlina are compared. Simple buildings designed according to the 1st geotechnical category are in the described location predominantly based on Neogene clay of intermediate plasticity class F6 and less on clays class F8. These are soils sensitive to changes in their natural moisture – they swell when exposed to water, thus become unstable. It is therefore important to use the most accurate values in the calculation of the foundations. The analysis of 130 measured values confirmed that 52% of the all measured values are outside the indicative table data. The use of inaccurate input values can bring a risk and threat to safety, reliability and proper use of any construction. It is therefore necessary to carry out the appropriate geotechnical investigation of soils for all types of buildings.