Abstract: To investigate the dynamic response of the track and saturated soil under moving train loading, a coupling model was developed to analyze the rail structure and underground railway tunnel in the saturated soil by using the analytical method. The train load was simulated by a series of moving constant or harmonic load according to the geometry of a real train. The tunnel was simulated as a thin cylindrical shell of infinite length, and the soil was treated as a saturated poroelastic medium using Biot’s theory. The tracks consisted of two beam units, i.e., an upper Euler-Bernoulli beam to account for the rails and a lower Euler-Bernoulli beam to account for the slab. The tracks and soil medium were coupled by the force and displacement compatibility conditions at the tunnel invert. The different dynamic characteristics of elastic soil medium and saturated soil medium were analyzed. The effects of soil permeability, moving velocity of load, and natural frequency on track responses, rail displacements, and pore pressures of saturated soil were investigated. It is found that the dynamic response of saturated soil medium with a low permeability is different from that of elastic soil medium. But soil model has limited effects on the track responses. The pore pressure increases with decreasing soil permeability. The track responses and pore pressure of the saturated soil are greatly influenced by the velocity and excitation frequency of the moving load.

Key words: saturated soil, tunnel structure, floating slab tracks, dynamic responses, moving loads