Wzmacnianie podłoża w gruntach zapadowych i nienasyconych

Strengthening collapsible and unsaturated substrates. Summary In this work there are presented physical properties of multiphase material under negative pressure in the pores, affecting the flow of water, considered as the relationship between the saturation of the pores and the value of matric suction. The process of moisture content changes is supplemented by the description of the strength properties of the partially saturated substrate. The effective stresses are based on Terzaghi’s dependence, regarding modification made by Bishop for consideration of the negative pore pressure. Theoretical calculations are based on the criterion of the strength of the unsaturated soil in correlation with the Fredlund’s concept along with subsequently followed modifications. In the part concerning the features of unsaturated soil, the problem of the group of piles cooperating with the pile cap under the vertical load has been solved. The numerical modeling algorithm was made in correlation with symmetry and then calibrated what was based on numerous field experiments. The applicability of well-documented issues concerning saturated soil mechanics was extended while taking into account substrates with negative air pressure in the pores. The author paid attention to methods for strengthening the eolic collapsible material – loess, as the particular part of unsaturated soils. The following list presents the wide choice of possible solutions that have been experimented on field tests: • bored multilayer soil columns, • bored multilayer soil columns reinforced by adding fibers to their core and shell, • the triplet method, which seems to be an option considering soil columns after the process of a high-energy consolidation and deep humidification of the substrate, • the above methods supplemented with geotextiles additionally. The work presents three-dimensional numerical models, including FEM, FDM, allowing the tracking of processes which take place in the contact between structural components and soil. There are options for an improved substrate including the reinforcement with geotextiles and analytical models that are convenient to use. The work is focused on forecasting the flow in the substrate material and detecting possible sources of water. The randomness has got a significant role in the process 156 Strengthening collapsible and unsaturated substrates. Summary of water transportation in capillaries such as distribution, diameter, length, and relations between them. As a result, this seems to introduce a complementary component for calculations and considerations in the area of reliability analysis. The special reliability methods are used in case of nonlinear material in order to detect and obtain small failure probability values. In the technological core part, the problem of preventing failures of embankments on sensitive soils is taken into consideration. The key issue seems to be bored multilayer soil columns along with analytical solutions which try to offer a highly effective way to improve loess substrate. They give a long-lasting effect of the increased value of stiffness strength, which results in increased resistance of the constructed structure both to overload and hydration. The technologies presented might be characterized by a small number of supplements as well as by small energy and labor consumption. The reinforced base material is deprived of sensitivity to any changes in saturation and has got better strength parameters.