Frozen soils and sediments microstructure X-ray tomography study: methods, approaches, perspectives

Processes of cyclic freezing and thawing make considerable contribution to configuration of soils and rocks. X-ray tomography method allows us to research undisturbed soil samples in frozen condition. Because of difference in x-ray attenuation coefficient we can separately study mineral matrix, ice inclusions and pore space. This fact essentially increases opportunities for investigations of soil and rock cryogen deformations. In this paper we present the results of model experiment with bulk soil samples of different genesis investigated by a method of X-ray tomography. This experiment revealed the specificities of the soil structure and its pore space dynamics in conditions of freezing and thawing cycle. We developed a research scheme for structure and pore space dynamics, and studied the soil structure and pore space dynamics after different number of cycles of freezing and thawing. Example of kaolin and sand mixture shows the ring-shaped sorting of sand particles and their movement to ice schlieren surface. We postulated that the matter of soil of different genesis has different reaction on freezing and thawing impact. The rank from major to minor cryogenic changes in soil material: Albiluvisol - Chernozem - Solonetz.