Railway track and nearby structures in the vicinity of high-speed railway are exposed to low-amplitude small-strain vibrations as high-speed railway traffic construction activities arise. In the finite element (FE) method

how to determine the stiffness tensor E is important to build a rational predicting model to analyze the settlement of track and nearby structures in the vicinity of high-speed railway. Shear modulus G and damping ratio D which will vary with shear strain amplitude are two important stiffness and damping parameters. It is found through resonant column test study that the shear modulus G of soil due to vibrations must be determined by the strain amplitude and the confining pressure

even though under small-strain (shear strain amplitude 10-6 <10-4) vibrations

will still show a remarkable nonlinear characteristic. The Davidenkov model based on the classical Hardin-Drnevich model is proposed to fit the experimental tests of the curves of shear modulus G/Gmax and damping ratio D vs. ? powerfully. However

the shortcoming of the Davidenkov model is that the fitting parameters are too much

and the key parameter ?0 can’t be determined through a definite physical method. This study proposes an simplified two-parameter Davidenkov model through using a reference shear strain ?ref which will be determined through the ratio of the shear strength τf of soil in static triaxial tests versus the maximum shear modulus Gmax at a given stress state instead of the fitting parameter ?0 on the basis of Mohr-Coulomb failure criterion

and verifies the feasibility of the proposed method through tests finally.