Train-induced vibration and subsidence prediction of the permafrost subgrade along the Qinghai-Tibet Railway

Railway track design and maintenance researchers have been pursuing reliable methods for predicting the long-term performance of the Qinghai-Tibet railway (QTR) subgrade. Based on theoretical analysis, numerical simulation, field monitoring and laboratory tests, this paper studied the train-induced vibration response characteristics of the Beiluhe subgrade of the QTR to evaluate the impact of railway vibration loads on the ice-rich permafrost layer. The results show that increasing the embankment height can significantly reduce the additional dynamic stress of the ice-rich permafrost layer. Moreover, increasing the mean annual ground temperature (MAGT) and decreasing the embankment height will aggravate permafrost table vibration-induced subsidence. This study also analysed the relationships between the train-induced permafrost table vibration subsidence and the MAGT, the ice-rich permafrost layer thickness and the embankment height and predicted the permafrost table vibration subsidence in the DK1136 test section under different global warming conditions. The analyses and prediction demonstrate that the appropriate embankment height of the DK1136 section is 3–3.5 m, and the application of engineering measures for actively cooling the permafrost foundations is the best choice for reducing vibration-induced subsidence, thawing settlement and compression deformation.