The paper considers an example of solving a plane problem of the theory of plasticity as applied to concrete, which occurs when an absolutely rigid stamp acts on a concrete base. In this case, the solution was sought in the form of isolines of characteristics, the position of which made it possible to determine the stress state of the foundation. In this case, three areas were distinguished, differing in the stressed state. In the work, it was possible to analyze the effect of friction on the surface of the stamp on the boundaries of these regions and the isolines of stresses in them. Three conditions were considered: friction is absent, friction is constant, friction is proportional to the greater principal stress. The influence of various boundary conditions on the surface of the stamp on the stress state of the concrete base is revealed.

Keywords: concrete, theory of plasticity, plane problem, stress-strain state, stresses, friction, corner punch