Study On Dynamic Characteristics And Deformation Of High-speed Railway Embankment In Western Liaoning Seasonal Frozen Soil Regions

The Fuxin section of Beijing-Shenyang high-speed railway located in the seasonal frozen soil areas with widespread aeolian soil.Aeolian soil is characterized by soil homogeneity,large porosity and structure loose.The aeolian soil subgrade settlement induced by the temperature loads and train loads is overwhelming,and it directly related to running speed and the safety of train.Therefore,the research on resilient and plastic behavior of subgrade has a very practical significance.Based on the background of seasonal frozen in the Fuxin section of Beijing Shenyang high-speed railway,theoretical analysis,laboratory tests and numerical simulation are taken to investigate the dynamic response and dynamic deformation characteristics of frozen and thawing aeolian soil.The study is presented in detail as follows.(1)Based on the dynamic triaxial experiments,the influence of loading conditions and physical features of soil on the resilient and plastic strain behavior of frozen aeolian soil are investigated.The relation model between resilient modulus and the parameters(frozen temperature,dynamic stress amplitude,confining pressures,water content and different loading frequencies as frozen temperature,dynamic stress,confining pressures)is proposed,and the function of the cumulative plastic strain of frozen aeolian soil is also established through back-fitting of a series of testing results.(2)Through the freezing-thawing cycle experiment,the change laws of resilient strain,resilient modulus and cumulative plastic strain for soils are investigated under different dynamic stress amplitudes,the times of freezing-thawing cycles,confining pressures,water content.Moreover,the function of subgrade resilient modulus and cumulative plastic strain of thawing aeolian soil under train loading are established.(3)Taking the Beijing-shenyang high speed railway(BSHSR)embankment as the object of this study,a visual user element program(DISP)is compiled and introduced into ABAQUS to analyze the temperature distribution of BSHSR embankment.Then,the train loads are imposed on the three-dimensional subgrade model to study the characteristics of dynamic response of BSHSR embankment(i.e.vertical acceleration,velocity,stress and displacement).By considering the coupling of plastic and creep deformation,a subroutine CREEP was compiled based on the experimental results and it was used to predict the subgrage settlement under the effect of train loads and freezing-thawing cycles(4)Based on the above finite element model,the isothermal line distributions of the high speed railway embankment coving the concrete layer in different seasons are obtained,and the dynamic responses of BSHSR embankment in different depths and horizontal distances are studies under the train loads.