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Results of calculations and experimental researches of suffosion stability of sandy soils are provided in the article. The authors have assessed the prospects for the application of standard methodologies to demonstrate the need to take account of the filtrate properties in the course of projecting potential suffusion process development patterns typical for sandy soils. The principal attention must be driven to the value of the kinematic viscosity of filtered liquids. Any assessment of filtration-related interaction of the flow of liquid with sandy soils must be backed by the gradation analysis of soils and the analysis of their homogeneity, as well as the mineralogical and morphological analysis. The morphological study of sands of various geneses, performed hereunder, is based on the methodology that takes account of both the shape of sand particles and the structure of their surface.
The proposed methodology makes it possible to assess extensive sand specimen rather than separate sand particles to assure the representative sampling to assure the accuracy of the morphological analysis. The authors provide the data that cover the research of sands of various geneses demonstrating varied granulometric and mineral composition, as well as various morphological peculiarities of correlation with the filtrates that have different values of kinematic viscosity. The methodological research completed by the authors has indicated an urgent need to perform laboratory and field researches of suffosion instability of sandy soils in varied geoecological environments typical for urban lands exposed to anthropogenic pollutions.

The paper deals with the formation of limiting bulk densities of sandy soils of different origin against different values of humidity and varying structural features. The authors have identified that the optimum moisture content is typical for sands and clays exposed to mechanical compaction. The nature of this dependence is different from the one between the density and humidity of clay soils. These differences are driven by the peculiarities of formation of bound water shells in the event of low humidity. A linear dependence between the optimal humidity of sands and maximal molecular moisture capacity has been identified. The authors make a statement based on the proven de
pendence between the maximal molecular moisture capacity and the morphology of sands. Their statement is that the formation of bound water shells in the low humidity environment is dependent not only on the fineness of particles, but, to a higher extent, on the peculiarities of the shape and the nature of the surface of sand grains. Another important factor of impact on the density of sandy soils in the natural environment consists in their humidity.
Multiple researchers believe that the correlation between density and humidity of sands is to be the subject of research. It is noteworthy that limit densities of air-dried sands are to be assessed. Therefore, any sands have some particular bound water content, and the lower the intensity of treatment of sand particles, the higher the water content. The findings demonstrate that in most cases typical coagulatory and transitory contacts of non-saturated sands are to be considered in line with the ideas expressed by V.I. Osipov, as the above contacts determine the formation of effective stresses from the prospective of the physicochemical theory.