Vibration Response And Long-term Settlement Of Deep Cutting Subgrade Under Load Induced By Heavy-haul Train

The heavy haul for freight in railway has become a main trend of the development of railway in the world today. Because of advantages of preferable benefit, large freight volume, high efficiency and low energy consumption, heavy haul railway has developed rapidly in our country. At present, the research for basic rules of dynamic response and the prediction method of the long term settlement of subgrade of common railway has done more work, but lack of further study for heavy haul railway, especially for subgrade of heavy haul railway with groundwater. Therefore, it is necessary to study the dynamic response and long-term settlement of subgrade. The groundwater has unfavorable effect on subgrade and reduces the stability of subgrade. Therefore, this paper chooses typical section of deep cutting subgrade with groundwater of Bazhun heavy-haul railway as the research object, uses numerical simulation method to study the dynamic response of subgrade under the cyclic loading of heavy haul train and empirical anticipating model to calculate the long-term settlement of subgrade. The paper has done the following work:(1) Based on FLAC finite difference program, the paper take the typical section of deep cutting subgrade with groundwater of Bazhun heavy-haul railway as object to establish the coupling model the stress field and seepage field of subgrade under groundwater’s and then consider the influence of groundwater’s seepage on deep cutting subgrade.(2) Using self-made numerical model of car-track-subgrade dynamic coupling system, the paper calculates time-history curve of sleeper force of heavy haul train as input load of subgrade model with groundwater and gets the basis laws of attenuation of the dynamic response in depth and analysis the influence of train speed and the thickness and stiffness of subgrade bed surface and bottom parameters on the dynamic response.(3) The paper divides cumulative plastic deformation into two parts: subgrade bed and subgrade primitive. Prediction model of cumulative plastic deformation of two parts are founded.It uses the layer-wise summation method to calculate the total settlement of subgrade and analysis the influence of train speed and the thickness and stiffness of subgrade bed surface and bottom parameters on the long-term settlement of subgrade.