The viscous fluid flow model for estimating the stress-strain state of potassium salt in the bulk stress state at a sufficiently high level of acting stresses allows us to describe the behavior of salt massifs, in particular the process of flowing (contour convergence) of workings in the massif thickness over time. The stated solution is valid only for small displacements compared to the thickness of the rock layer. In addition, it is assumed that the layer thickness is much smaller than its transverse dimensions. In this case, the selected form of the current function gives a satisfactory agreement with the experimental data. The proposed method can be used for natural measurements of Poisson's ratio on rather thin layers of potassium salt in a volumetric stressed state with axial load exceeding 60 MPa or on targets with diameter to height ratio over 5 In this case, the behavior of potassium salt corresponds quite well to the viscous fluid model.
