EFFECT OF DRYING SPEED ON THE DESATURATION OF SWELLING ROCK

The paper presents the results of a numerical study of the influence of drying speed and hydraulic conductivity of swelling rock on the development of the desaturated zone. Swelling rock refers to natural material in which montmorillonite is the predominant type of mineral. Previous tests have unequivocally shown that a fully saturated swelling rock with a high swelling potential will not swell when wetted with water of the same chemical composition as the pore water. The swelling potential can be activated only after the desaturation of the swelling rock. The geohazard of swelling of such materials represents a very serious problem. The behavior of swelling rock is modeled as a combined hydraulic-mechanical process that includes vertical one-dimensional water flow in saturated and unsaturated conditions, with a change in the volume due to a change in the water content. As part of previously conducted laboratory research, a model of swelling was developed, which realistically represents the behavior of swelling material at the level of laboratory samples. With the developed model, it is possible to forecast the changes in moisture content that will occur during drying at the depth of the desaturated zone. Numerical simulations have clearly shown that the depth of the desaturated zone depends on the drying speed, that is, that significant depths of the desaturated zones can only be realized at low and long-term drying speeds. With the increase in the hydraulic conductivity of the swelling rock, the depth of the desaturated zone increases, and the time required for the development of such a zone increases to the same extent.