Study on the prediction of the cumulative deformation of high-speed railway subgrade under the cyclic dynamic loads of vehicle

High-speed railway subgrade inevitably produces cumulative deformation under repeated vehicle loadings, affecting the in-service performance of railway track-subgrade structure and operation quality of high-speed train. To investigate the spatial distribution characteristics and long-term development laws of cumulative deformation of high speed railway subgrade under cyclic dynamic vehicular loads, a prediction model for vehicle-induced cumulative deformation of high speed railway subgrade was established, which mainly consisted of two sub-modules: 1) a time-varying dynamic model of high-speed railway vehicle-track-foundation coupling based on multibody dynamics and finite element method; 2) based on the established vehicle-track-subgrade dynamic interaction model, a subgrade cumulative deformation prediction model was introduced to predict the deformation of subgrade and its spatial distribution law under different vehicle load cumulative cyclic times by using the cyclic jumping method. For the interaction of the two modules, after each cyclic jump, the subgrade cumulative deformation was mapped to the track system. The spatial mapping additional geometric irregularity of the track and dynamic matrix of interaction system was updated simultaneously, which established the correlation between the vehicle-induced subgrade cumulative deformation and the dynamic responses of the system. The results show that the calculation model presented in this paper can well reveal the evolution law of subgrade cumulative deformation under cyclic dynamic vehicular loads. The research results show that the calculation model proposed in this paper can well reveal the evolution law of the cumulative deformation of the foundation soil under cyclic vehicle dynamic loads. The maximum cumulative deformation of the subgrade calculated by the cyclic jump method is 2.606 9 mm, while the maximum calculated without adopting the cyclic jump method is 1.7 mm, which corresponds to an underestimation of 34.8%. The cumulative deformation of the subgrade developed rapidly in the early stage. In the later stage, due to the continuous compaction of the soil, the evolution of the cumulative deformation shows a slowing trend, and the cumulative deformation rate decreased from 0.035 mm/cycle to less than 10−6 mm/cycle. In the region with initial differential subgrade deformation, the amplitude of the cumulative deformation of the subgrade is larger than that without initial differential subgrade deformation. The cumulative deformation of the subgrade has a significant effect on the vertical dynamic responses of the system, and the dynamic responses show an increasing trend. The cumulative deformation has little effect on the lateral vibration of the system. The method and results presented in this paper can provide technical support for the control and prediction of differential cumulative deformation of high-speed railway subgrade. © 2024, Central South University Press. All rights reserved.