<p>In order to investigate the cyclic behavior of geogrid-reinforced sand under train-induced loading, a series of multi-stage cyclic triaxial tests were conducted with varying numbers of reinforcement layers, confining pressures, and mesh sizes. The study examined the evolution of cumulative plastic strain, cyclic pore water pressure, volumetric strain, and hysteresis characteristics. Results indicate that increasing the number of reinforcement layers or confining pressure, or reducing the mesh size, significantly reduces cumulative plastic strain, cyclic pore pressure buildup, and volumetric contraction. The improvement in the reinforcement effect coefficient exhibits diminishing returns with additional reinforcement layers. During cyclic loading, pore water pressure initially decreases rapidly with increasing cyclic stress amplitude, followed by a stable growth phase. The fluctuation amplitude of pore pressure increases with higher stress amplitudes, though this effect is less pronounced under elevated confining pressures. Volumetric strain accumulation accelerates with increasing cyclic stress amplitude, as evidenced by the transition from sparse to dense patterns in the strain-cycle relationship. Hysteresis loop characteristics are strongly influenced by testing conditions. Both increasing reinforcement layers and number of loading cycles reduce the hysteresis area and increase loop inclination, indicating enhanced structural stability. These findings provide valuable insights for settlement deformation analysis and stability assessment of reinforced soil subgrades under railway loading conditions.</p>