Long-term prediction of track geometry degradation in high-speed vehicle-ballastless track system due to differential subgrade settlement

To predict long-term track degradation of ballastless track due to evolution of differential subgrade settlement in high-speed railway, an iterative approach is put forward. A detailed vehicle-track coupled dynamic model taking account of track weight and local contact loss between track and subgrade is employed to obtain the short-term behavior of the system in terms of wheel-rail interaction, vehicle acceleration and interlaminar forces of track structures. The calculated track-subgrade dynamic stresses induced by a high-speed vehicle are imported into an empirical power model for long-term subgrade settlement. The profile of the subgrade settlement is updated by a self-adaptive passing number of vehicles governed by a settlement threshold, and the dynamic responses of the coupled system are re-calculated consequently. On this basis, a demonstration case is carried out aiming at a typical Chinese high-speed vehicle-double-block ballastless track system with an initial subgrade settlement described by the cosine wave. The attained results reveal the high resistance of deformation on highspeed rail subgrade, together with the significant influence of the initial differential subgrade settlement on track geometrical evolution, in particular, the initial condition with severe unsupported areas between track and subgrade. The abnormal dynamic responses inflicted by the differential settlement are gradually alleviated during the long-term operation.