The object of research is a sand cushion with contour reinforcement placed in a viscoelastic clay soil base. The work aims to analyze the stress-strain state of the reinforced soil massif. Method. Research of the soil array at the first stage of work is carried out on small-scale models in laboratory conditions. Quantitative assessment of the stress-strain state is performed on large-scale foundation models in the field. Results. Based on the results of experimental data, the dependences of the deformation of a soil mass reinforced with a sand cushion with contour reinforcement were established. A decrease in the vertical settlement of the foundation was revealed due to a decrease in shear deformations in the body of the sand cushion. A comparison of numerical modeling with experimental results showed good convergence, with a discrepancy between the results by 20-30%. A constructive solution for strengthening a weak base in the form of a sand cushion with contour reinforcement makes it possible to reduce the creep of the base, increasing the linear stage of its work.