关键词: 非均布列车荷载, 软土路基, 饱和多孔介质, Fourier变换, 振动

Abstract:

The ground vibration of soft subgrade subjected to a non-uniformly distributed train load is investigated analytically. Based on field test data, 5 sleepers bear the dynamic loads transferred from rail, an expression of a non-uniformly distributed load is deduced by assuming that train load is distributed to sleepers with a certain proportion. Taking the ballast as elastic single-phase layer and the soft subgrade as water-saturated poroelastic half space governed by the Biot’s theory, the governing equations of motion are solved by employing the Helmholtz decomposition theorem and the Fourier transform technique. The exact analytical solutions of the displacements, stresses, and the pore pressure of the soft subgrade are obtained in the form of integral. By introducing fast Fourier transform algorithm, the numerical results are derived; and the influences of load distribution, the position of observation, the ballast parameters and the permeability coefficient on the responses are discussed in detail. It is shown that a moving load with a high speed will generate a larger response in soft subgrade than a lower speed load; and special attention should be paid to the pore pressure in the vicinity of soft subgrade surface.

Key words: non-uniformly distributed train load, soft subgrade, saturated poroelastic medium, Fourier transform, vibration