Semianalytical Solution for Dynamic Responses of Railway Track System on Unsaturated Poroelastic Half-Space Subjected to Moving Trainload

A track-unsaturated ground model was proposed to study the dynamic responses of the unsaturated subgrade induced by moving trainloads. The subgrade was modeled by an unsaturated poroelastic half-space, and the railway track system comprises a rail, sleepers, and ballast. The double Fourier transform was applied to solve the governing equations of the entire system in the frequency domain. The semianalytical results in the time domain were further obtained using the fast inverse Fourier transform. The effects of saturation, train speeds, and intrinsic permeability of soil on the dynamic responses were studied in both the time and frequency domain. It was found that the effects of saturation and train speed on the responses of displacement, acceleration, and pore-water pressure are significant. For low saturation, the vertical displacement response of unsaturated half-space is similar to that of the elastic half-space, and the intrinsic permeability has little effect. While for high saturation, the amplitude of vertical displacement increases with the increase of intrinsic permeability of the soil.