Influence of Preliminary Decompression on Soil Swelling Pressure

The article describes the results of experimental studies of the influence of preliminary decompaction on the magnitude of the swelling pressure of soils of natural and disturbed structure. The determination of the swelling pressure at various degrees of preliminary decompaction was carried out in laboratory conditions for clays of natural and disturbed structure. The conducted researches made it possible to reveal the features of the patterns of influence on the process of swelling of the mineralogical composition of the soil from its initial density and moisture content. In montmorillonite clays, decompaction reduces the swelling pressure as more, as more montmorillonite is included in their composition. In the soil of a disturbed structure, the initial density and moisture do not affect the dependence of the relative magnitude of the swelling pressure on the degree of preliminary decompaction of the soil. In a soil of natural structure, an increase in the initial density contributes to a more significant decrease in the swelling pressure from preliminary decompaction compared to the pressure developed by the soil in the complete absence of swelling deformations. Structural cohesion in soils of natural composition prevents the decrease in swelling pressure during decompaction. It was revealed that the relationship between the relative magnitude of the swelling pressure and the degree of preliminary decompaction of the soil can be described by an exponential function. The values of the coefficients of this function are determined.