Ivstigation On Stability Of High Speed Railway Embanmkent Under Wetting-drying And Dynamic Load Using Model Test

High-speed railway(HSR)is one of the most convenient way to travel in China.As the main supporting body for high-speed trains,HSR embankment subjects to dynamic train loadings and is exposed to atmosphere all year round.The atmospheric conditions,such as precipitation and evaporation,would affect the moisture migration,pore-water pressure and suction of the embankment.Seasonal drying and wetting may damage the filling soil properties of embankment,which would reduce the stability of the embankment.As a result,investigation on dynamic stability of HSR embankment is essentially important for practical engineering.In this study,the dynamic stability of a typical section of Beijing-Shanghai HSR under drying-wetting and HSR loading is investigated through laboratory model tests.The main research findings are summarized as follows.1.A laboratory model test system for HSR embankment is developed.6 wetting-drying tests and 5 dynamic loading tests are conducted.2.The model test results show that the volumetric water content,pore-water pressure,soil suction and temperature respond correctly to the simulated atmospheric conditions.The responses of dynamic earth pressure and soil acceleration are related to the loading characteristics.The dynamic soil pressure distribution can be summarized as follows.In the vertical direction,the dynamic soil pressure decrease with depth.In the horizontal direction,the maximum value occurs right under the rail in shallow depth while under the middle of the track in deeper depth.The maximum response of acceleration occurs at the top of the embankment slope.It is decreasing from the top to the bottom of the slope.3.The infiltration makes the fine grand particle-kaolin in the filling material migrate to the toe of the slope.The sandy soil then collapses because of the loss of cohesion provided by kaolin.As the fine particle content decreasE with the increase of wetting-drying cycles,the water retention capacity of filling material gradually reduceS.Wetting-drying history has a great influence on the acceleration response of the embankment slope.The peak amplitude of acceleration is positively associated with the times of wetting-drying cycles.The acceleration response is also influenced by the wet and dry state of embankment slope.The amplitude under the wet state is larger than that under the dry state.