In-situ test and analysis of vibration of subgrade for Wuhan-Guangzhou high-speed railway

Abstract

In order to study the vibration characteristics of ballastless-track subgrade for Wuhan-Guangzhou high-speed railway,in-situ train-induced vibration tests are performed in the Huchang-Xianning test section.Magnitudes of vertical vibration acceleration and dynamic stress of all the measuring points are obtained when bullet trains units and track inspection trains run in the test section respectively.Distribution laws of dynamic response in the tested subgrade are summarized.Natural frequencies of the tested subgrade are obtained.Furthermore,incorporating wavelet analysis method,vibration characteristics of the tested subgrade are analyzed in the frequency domain.The results show that the increase in train speed enhances the vibration at the top surface of the tested subgrade,especially at 260-320 km/h.After attenuating over 2.7 m high embankment,magnitudes of dynamic response and vibration energies of the tested subgrade are very little,and the influence of train speeds is not obvious to them.The graded broken stone layer can effectively inhibit the propagation of vibration with depth in subgrade.With the increase in train speed,vibration of subgrade is mainly controlled by wheelbase and track smoothness.Axle loads effect magnitudes of dynamic response and vibration energies more significantly than train speeds.Increase in axle loads concentrates vibration energies in a more narrow frequency band.