Nonhomogeneity of the physical-mechanical properties of soil medium composed of tertiary clays and quaternary loesses

The properties of typical soils occurring in Poland and Ukraine are analysed in this paper. The Tertiary maritime clays from Krakowiec and Quaternary eolic loesses of the porosity lying within the range of 25-60% and of the laminar and skeletal microstructures, respectively, have been tested. They often constitute foundations of buildings, and therefore, their physical-mechanical parameters should be determined. The analysis of nonhomogeneity has been limited to the presentation of statistical coefficient of variation for basic parameters used in design of foundations of engineering objects. Nonhomogeneity of soils is caused by geological conditions of their origin. The results presented indicate that the tested loesses and clays from Poland and Ukraine are very similar from the viewpoint of their parameters nonhomogeneity. The parameters of soils change within a wide range. The physical parameters vary within the range below 30-40%, whereas the coefficient of variation for mechanical parameters often exceeds 100%. The coefficient of variation becomes smaller when the subsets of samples are extracted from the whole testing set. In view of engineering-geological properties of soils, for the purpose of engineering calculations one may assume that the homogeneous soils are those for which the values of coefficient of variation do not exceed the limit values for particular parameters (Table 5).