| In the passed several decades, high speed railway developed at an unprecedented rate all around the world. However, as the train-speed developes, problems caused by vibration of the train begin to show themselves. On one hand, obviously, the improvement of the train-speed leads to increment of vibrating load and so dynamic stability should be improved. On the other hand, vibrating load acts on the track-tunnel system, altimatly on the surounding stratum. When the tunnel is surounded by saturated sand, liquefaction may occur due to cyclic load, which will lead to failure of structure and pose danger to passing trains. Therefor, reserch of dynamic response of shiled tunnel under vibration load of high speed railway is quite significant. Based on the project of Shiziyang shield tunnel of Guangshengang high speed railway, main research work includes as follows.(1) Based on research before, the external excitation loads of moving trains onto the track plate are obtained by train-track system model and beam-plate model on the elastic foundation of ballastless track. Acconding to the mechanism and characteristics of saturated sand liquefaction, the saturated sand is liquefied by the rule of cyclic mobility.(2) Contrast analyse of Dynamic response has been undertaken for taking water into acount or not. It shows that fluid-particle coupling effect should be considered in the case of saturated stratum. The effects of many factors on dynamic response of shield tunnel, such as the number of trains, parameters of surrounding rock, depth of burial, are numerical modeling, and rules of variation in corresponding parameters are analyzed.(3) A fine model has been established under the condition of portal of Shizivana shield tunnel. The cases under action of two cross trains and under action of one single train are caculated respectively. The settlement of lining, the fluid-particel coupled consolidation, and the possibility of sand liquefaction have been studied respectively. |
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