| China is a large frozen country,the seasonally frozen area is more than half of the national land area.In recent years,the rapid development of high-speed railway in China,the high-speed railway to the track of the high and high stability of the roadbed put forward a higher demand,and the cold area roadbed filler heave caused by the track irregularity is one of the important factors to limit the development of high-speed railway.At the same time,China's abundant coal resources,a large number of coal gangue mountains on the environment and society have a great impact,on the rational recycling of coal gangue,the realization of effective and rational allocation of resources is the current urgent needs.At present,there is little research on the frost heave of the coarse-grained soil in the high speed railway roadbed,and the application of coal gangue in high-speed railway engineering should be advanced.On the basis of this,a unidirectional freezing test of high railway base filler and coal gangue modified high railway based on different conditions was carried out.In this paper,the temperature and water variation in different positions of soil during freezing process are analyzed,and the finite element model considering the gas water transfer is established based on the interaction between water and heat,and the main work and the result are as follows:(1)A unidirectional freeze-thaw cycle test system was developed,and a unidirectional freezing test was carried out on the system.The temperature and moisture of soil under different initial water content and water recharge conditions were obtained,and the results showed that the cooling rate in the filling of high speed railway roadbed was higher and the temperature was rapidly reduced when the freezing process began however,there will be pore ice inclusions on coarse grains,and significant positive water migration will occur at the same time.Under the condition of water recharge,the frost heave amount of soil is larger than that of the closed condition,and the final frost heave amount decreases with the increase of the initial water content of soil mass.The initial water content in a middle reaches the maximum.(2)To complete the one-way freezing test of the coal Gangue modified high railway base filler,and compare the temperature and water variation law of the coal Gangue modified high railway base filler and ordinary filler under freezing condition.Under freezing conditions,the general change law of temperature and moisture in coal gangue filler is basically consistent with that of ordinary filler.But the coal gangue improved the high railway base filler in the initial cooling rate is small,the final frost heave quantity is higher than the corresponding condition under the general high railroad base filler's final heave amount is slightly bigger.(3)A numerical model of hydro-thermal coupling of the frozen water in the high speed railway subgrade is established,and the rationality of the model is validated by the test results.In the model,the hydro-thermal coupling of the freezing process is realized by connecting the mass transfer equation of soil mass,the heat transmission equation and the contact equation.Considering the gaseous water migration and phase change latent heat,it is more reasonable to describe the freezing hydro-thermal interaction of the roadbed filler;through the transformation of the hydrothermal coupled differential equation,the corresponding equivalent integral "weak" form is obtained,which makes the numerical model more easy to achieve convergence. |
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