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| Experimental Analysis of Long － term Stability of Soaking Subgrade for High Speed Railway |
| CHEN Shang － yong，SUN Hong － lin |
| China Railway Siyuan Survey and Design Group Co． Ltd，Wuhan，Hubei 430063，China |
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Abstract Research purposes: Compared with general subgrade，the long － term stability of soaking subgrade would be threatened when it suffered flow impact，scour，erosion，water softening of the roadbed fill，adverse effects of water level change and cyclical loading by train． So a dynamic experiment system is built to study the behavior of soaking subgrade under cyclical loading by train for high speed railway． Then，some testing indexes containing subgrade dynamic stress， elastic deformation，plastic deformation，dynamic pore water pressure，the natural frequency and so on are analyzed． At last，the long － term stability of the soaking subgrade is evaluated and the reliability and reasonableness of the design scheme is verified．
Research conclusions: A dynamic test system is established according to the loading boundary conditions of soaking subgrade paved with CRTS II slab ballastless track for a top speed of 350 km / h． After 5． 5 million times dynamic loading of 9 ～ 13 kPa，the dynamic stress，the dynamic pore pressure and the elastic deformations of the roadbed are in stable states，and the plastic deformation is 0． 48 ～ 0． 56 mm． The results of the sweeping frequency test indicate that the resonance will not happen as the natural vibration frequency of the subgrade is more than train ＇s dynamic loading frequency and the subgrade keep good performance because the natural vibration frequency decreases less after the dynamic test． The design of the experiment about soaking subgrade protection and filling is feasible． The long － term soaking subgrade has stable performance and can meet the strength and deformation requirements of the roadbed with ballastless track．
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Received: 01 July 2011
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2011, Vol. 28 
