Summary:

In the article Author characterized the calculating conditions of boundary slope coefficient of critical scour line below hydraulic structures, used to estimation of the buildings safety. Boundary values of these coefficients were computed for two schemes: equivalent stability, range active tensions zone. The field studies were made for different hydrological, hydraulic and exploiting conditions, so the time was the only independent factor. Computed coefficients of critical line and some of the result of field study are compared. The safety states of analysed objects in different stages of their exploitation were defined after the comparison of real coefficients witch took of field measurements with counted values.