Deformation Characteristics Of Fillers And Subgrade For Heavy Haul Railway In Seasonal Frozen Region

The heavy haul for freight in railway has become a main trend of the developmentof railway in the world today. Because of advantages of preferable benefit, large freightvolume, high efficiency and low energy consumption, heavy haul railway has developedrapidly in our country. Meanwhile, a great number of problems occurred in the heavyhaul railway construction of the seasonal regions. China belongs to the temperate zonecontinental monsoon climate, where there are four distinct seasons. It is harm to theconstruction and operation for railway subjected freezing-thawing cycles. The foundationbed, which is an important part of the railway engineering, is on the surface of thesubgrade, so it experience one freezing-thawing cycle at least each year. Therefore, it isextremely important to ensure the stability of subgrade for the operation normally underfreeing-thawing cycles. At the moment, many researches have been studied for thebehavior of fine-grained soil. However, a little bit of literature is about the subgrade ofGroup A subjected to freezing-thawing cycles. The study of this paper has certainsignificance to the value of science and also has certain consulting significance in thepractical engineering. The main contents are followed:First of all, combined with the engineering practice and theoretical research results,the subgrade fillers of Group A which can be used for the foundation bed of heavy haulrailway was obtained, and then the static triaxial test was operated. The papersummarized the change regulations of the strength parameters and deformationcharacteristics under different freezing-thawing cycles, different moisture content anddifferent degree of density. The results showed: with the increasing of the freezing-thawing cycles and moisture content, and with the decreasing of the degree of density,the strength of the subgrade fillers of Group A is decreased.Then, a piecewise function which was used to represent the nonlinear stress strainrelationship of the cement soil was introduced, and it is used to describe the stress strainrelationship of subgrade fillers of Group A with post-peak softening. On the basis of theresults of the static triaxial test, the model parameters could be obtained. The resultsshowed: the fitting data and the experimental data are in good agreement. From theanalysis of the parameters, the influence of the freezing-thawing cycles, moisture content,degree of density and confining pressures was investigated. The change regulations ofmodel parameters are studied in the way of numerical fitting, and the results could be used for predicting the stress strain curve.According the actual situation of DK97+454section of Bazhun heavy haul railwayto establish the finite element model of dynamic response of high embankment underload of heavy haul train. The mathematical model for subgrade fillers of Group A verifiedin this paper and the finite element method was used to analyze the deformation of heavyhaul railways subgrade. The results showed: it is influence for the deformation of thesubgrade due to the change of freezing-thawing cycles, moisture content and degree ofdensity, but the large impacts took place from the surface of the foundation bed to thedepths of5meters. Therefore, it has important significance to control the deformation ofthe heavy haul railway subgrade through setting anti-freezing layers and water-resistinglayers.