Deformations of loess soils caused by changes in the microaggregate structure

Abstract

Protracted degradation of the loess structure during technogenesis leads to changes in the microaggregate composition, density, and moisture. We have developed a model that predicts the value of the porosity coefficient of loess in a degraded state. The model is based on the previously obtained results of applying fractal theory to soils. The loess areas of Dnipro city (Ukraine) and its environs were studied. The granulometric composition of the samples was determined before and after filtration, compression. According to the results of the pipet analysis of one sample, the number of aggregates, the number of particles composing the aggregates, and the number of free particles (nonaggregates) were calculated for each of the fractions. The values of the fractal dimension of the particle size distribution function were also calculated. The predicted values of the porosity coefficient in the state of complete decomposition of microaggregates were calculated according to the new model. The difference of the porosity coefficients in the initial (natural) and predicted states characterizes the value of the volume deformation of the soil. The obtained results of calculations of volumetric deformation of loess do not contradict the known data on the deformation features of the deposits of the region formed in the epochs of interglacial and terrestrial glaciation.