The paper studies the inelastic deformations of porous and layered macrostructure and their influence on the deformation behaviour of the structure. For this purpose, the effects of relaxation deformations of elements on the operational parameters: filling fluid pressure, porosity and degree of saturation were first considered. Numerical analyses were then carried out assuming that the structure is a homogeneous, deformable medium with no external operational influences. Particular attention was paid to the changes in the parameters of deformation behaviour at different stages of operation. The results obtained in the research show that the relaxation process has a significant influence on the deformations of the structure, especially at high initial pressure of the filling fluid. The average relaxation parameters determine the nature of the change in deformation behaviour during operation. Thus, the study emphasises the need to take into account relaxation effects in the design of porous and laminated structures, especially under conditions of high medium saturation and significant pressure.