Study On Dynamic Response Of Permafrost To Railway Subgrade

More than one half of existing railway is located at the permafrost region in ourcountry, with the integrated development of the national infrastructure construction, themileage of railway construction has increased substantially year by year, and theengineering disease of railway roadbed in permafrost region is always a difficult problemin frozen soil research and engineering fields. Therefore, it is necessary to research on theproblem of vibration response and subgrade deformation of roadbed under the action oflong round-trip orbit traffic load in the frozen ground.In the paper, the method which is a combination of laboratory experiments, theoreticalanalysis and numerical simulation is used to do some related research on the dynamicresponse problem of the permafrost roadbed under the train loads, which is hoped toprovide some help to settle the roadbed deformation problems and deal with subgradeengineering disease in the frozen ground. The main research is as follows in this paper:(1) Through the dynamic tri-axial test at low temprature, the related dynamicparameter is analyzed by research on dynamic properties of frozen silty clay in thepermafrost, such as the influence of cyclic matrix, confining pressure, temperature andfrequency, further research is done by the test method and data processing, all of whichprovide support for dynamic response numerical analysis of subgrade under the train loadsin frozen soil site,also lay the foundation for the further work of subgrade settlement andthe cumulative permanent deformation analysis;(2) Numerical simulation approach is established for the dynamic response ofpermafrost subgrade. Including basic assumptions of the finite element model, selection ofcalculation domain, computational units, determintion of the dynamic load, simulation oftemperature field of frozen soil roadbed, constitutive model selection, determination of thedynamic parameter and boundary condition and so on, which provide some reference forthe dynamic response analysis of numerical simulation results under the train load ofpermafrost subgrade.(3) Analysis of finite element numerical model of temperature field in the frozen soil roadbed and model results of dynamic response in the permafrost subgrade under the trainload. It is mainly for law analysis on the distribution of temperature field in the frozensubgrade, temperature variation with depth, the dynamic stress time history spectrumcurves in two directions of embankment surface under the train load and dynamic stresstime history spectral curves of embankment surface under the train load in differentvelocity.