Kelvin body, comprised of a spring and a dashpot and connected in a parallel arrangement, is quite widely used for the representation of visco-elastic behavior of soils. Parameters of the Kelvin model include a spring constant and a dashpot constant. These constants are usually required in any time dependent soil-foundation-structure interaction analysis which helps in predicting the variation of stress resultants in the foundation and structure with time. In the present paper, an attempt has been made to estimate these material parameters of a non-linear Kelvin body using the triaxial test data. The conceptual background of the material constants has been presented and the procedure for analysis of triaxial test data to obtain these constants has been laid down. Triaxial tests were conducted under — i) constant total stress condition and ii) the hydrostatic stress condition and the test data were analyzed by employing the proposed approach. Hydrostatic and the deviatoric stresses have been related to the material parameters. An example for analysis of a pile-raft system has been worked out and it has been found that the settlement from the present study is higher than that obtained from Terzaghi's one-dimensional consolidation theory. Application of the proposed approach in finite element analysis has also been mentioned.