ESTIMATE OF STATIC TRACK MODULUS USING ELASTIC FOUNDATION MODELS

A new method for calculating the track modulus by using elastic properties of the individual track support components is developed. The properties include (a) the stiffness of the rail pad, (b) the vertical stiffness and bending rigidity of the tie treated as a beam on both a Winkler foundation and two-parameter foundation, and (c) the Young's moduli and Poisson's ratio values of the soil layers underlying the track. Semi-infinite elastic foundation theories are used to estimate the equivalent ballast/subgrade stiffness distributed along the length of the tie. Track modulus charts and application examples are given for typical track support structures used in North America. A practical benefit of the new approach proposed is that it eliminates the need to carry out relatively expensive field tests. An overview of some existing methods to determine track modulus is also presented. The validation of the proposed method is currently in progress.

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