This paper presents a plenty of modeling results on the cyclic deformation characteristics of natural soil samples obtained from laboratory tests by RO and HD models. The G〜γ and h〜γ curves simulated by RO and HD models were compared with cyclic deformation test results for the natural soil samples. The G〜γ curve simulated by the HD model is better corresponds to the test results than that of the RO model at a large strain level. The h〜γ curves simulated by the HD model well agree with the test results. A simplified evaluation method of the modeling constants for HD model was described in order to estimate the cyclic deformation characteristics for natural soils without laboratory tests. The modeling constants for HD model, τ_<max> and h_<max> can be determined from the confining pressure, in-situ shear wave velocity and sand contents. By using the method proposed here for the determination of HD model constants, the equivalent G〜γ, h〜γ relations for natural soils can be well estimated by the HD model.
