Relevance of the work. Estimation of the stability of free face is an important task due to the fact that part of headings of tube railroad is erected by mining, with the forehead of the face fixed manually, while indirect methods of forecasting engineering-geological and hydrogeological conditions before the forehead of the face indicate the presence of local softening and watering capable affect sustainability. Purpose of the work. Estimation of the zone of influence and the type of drainage of the element of heterogeneity on the stability of the tunnel face passed in the array of Proterozoic clays. Method and methodology. The finite element method used in the PLAXIS software package was chosen as the research method. The Hardening Soil Small Strain hardening soil model was selected as a geomechanical model of soil behavior. The design situations of deforming the unfixed forehead of the face approaching the water-saturated element of heterogeneity, are considered when simulating an element with a capacity of 1 and 4 m and changing the nature of water filtration along the element. Results of the work. When deformation properties of the calculated soil elements differ by 30% with the given level of groundwater, both in the case of drainage and nondrainability, an increase in displacements occurs when the tunneling face approaches the zone of influence of heterogeneity. The size of the zone of influence depends on the chosen type of drainage of the element of heterogeneity. Applicable scope of the results described in the paper. The results described in the paper (subject to determining the parameters of the model that meet the conditions of penetration) can be used to estimate the stability of the forehead of the tunnel face in the area of heterogeneity, which is the water supply canal. Conclusion. When designing construction of a linear underground facility in an area of heterogeneity, it is necessary to evaluate the stability of the forehead of the face using numerical modeling. When modeling an element of heterogeneity, it is necessary to take into account the degree of water saturation, the thickness of the element of heterogeneity and the nature of permeability of water along the element of heterogeneity.