High-speed Railroad Foundation Under Freeze-thaw Cycles Coupled With Train Dynamic Load

With the high speed development which our country railway network constructs, the railroad traversing seasonal frozen soil area quantity and the running speed are enhancing increasingly. The high-valence railroad roadbed subsidence initiates the harm even more seriously, although it has brought attention to people, the related studies has not yet penetrates. Especially,to studies the high-valence railroad roadbed subsidence question from the quantification seasonal frozen soil constitutive has not been reported in domestic and foreign at present.In the paper,taking the high-speed railroad in Shenyang as the study example , on the base of the scene examination, the indoor large-scale thaw-freeze cycle experiment and the seasonal frozen soil vibration triaxial test, using theoretical knowledges which include strain energy, J integral, soil body dynamics, thermodynamics, conversion of energy principle and the MIDAS numerical simulation software, it has completed the study on settlement law of high-speed railroad foundation under freeze-thaw cycles coupled with train dynamic load. The structural quantitative indicator including variable-temperature freezing, temperature freezing, variable-temperature melting, temperature melting is established,achieved coupling with three field Taking into account to the soil structural and verified the reasonable which calculate the amount of foundation soil settlement by structural quantitative indicator using the actual monitoring in the period of construction .It was pointed that stability and variability exist in the same state of the soil in, quantitative indicators and soil structural strain to meet the linear correlation. By observation of soil micro-structure in freezing and thawing process ,it can be achieved that Soil will also be a partial segregation phenomena during the freezing process without water supply and soil salts will be redistributed by a freeze-thaw cycle. Freeze-thaw cycles were included the quantitative indicators of equations, which is used to calculated the settlement of foundation under different freeze-thaw cycles and compared the numerical results with it .The result prove it feasibility . Through the uniform design experiment, the anti frost damage measures is obtained that fill the best values in the seasonal frozen soil area are: replacement of frozen-thawed layer depth is 50% ~ 60%in the sphere of influence,the thickness is 20%～25% of the affected areas ,the water table should be outside the scope of freeze-thaw effects.