A constitutive model for cyclic densification of coarse-grained soil filler for the high-speed railway subgrade considering particle breakage

Purpose–This study aims to propose a semiempirical and semitheoretical cyclic compaction constitutive model of coarse-grained soil filler for the high-speed railway(HSR)subgrade under cyclic load.Design/methodology/approach–According to the basic framework of critical state soil mechanics and in view of the characteristics of the coarse-grained soil filler for the HSR subgrade to bear the train vibration load repeatedly for a long time,the hyperbolic empirical relationship between particle breakage and plastic work was derived.Considering the influence of cyclic vibration time and stress ratio,the particle breakage correction function of coarse-grained soil filler for the HSR subgrade under cyclic load was proposed.According to the classical theory of plastic mechanics,the shearing dilatation equation of the coarse-grained soil filler for the HSR subgrade considering particle breakage was modified and obtained.A semiempirical and semitheoretical cyclic compaction constitutive model of coarse-grained soil filler for the HSR subgrade under cyclic load was further established.The backward Euler method was used to discretize the constitutive equation,build a numerical algorithm of“elastic prediction and plastic modification”and make a secondary development of the program to solve the cyclic compaction model.Findings–Through the comparison with the result of laboratory triaxial test under the cyclic loading of coarse-grained soil filler for the HSR subgrade,the accuracy and applicability of the cyclic compaction model were verified.Results show that the model can accurately predict the cumulative deformation characteristics of coarse-grained soil filler for the HSR subgrade under the train vibration loading repeatedly for a long time.It considers the effects of particle breakage and stress ratio,which can be used to calculate and analyze the stress and deformation evolution law of the subgrade structure for HSR.