Rationale for the choice of a soil model for studying the stability of railway subgrade under seismic impact

Abstract

   The problem of numerical modeling of the stress-strain state of a soil structure taking into account seismic impact is considered. Justification of the choice of a soil model that ensures correct modeling of seismic impact on a railway embankment for the subsequent development of measures to increase the seismic resistance of the subgrade by using damping layer.
   Based on the analysis of the graphs of the dependence of axial deformation on the stress deviator,the main differences between some soil models (linear elastic, Mohr-Coulomb, hardening soil and hardening soil with stiffness at small deformations) and the features of their operation under dynamic cyclic impact are analyzed. The stress-strain state of a railway roadbed in the form of a 15 m high embankment made of medium-sized sand was simulated during seismic impacts of varying intensity.
   The finite element method is used to simulate standard stabilometric and compression tests to analyze the dependence of axial deformations on stresses. The obtained calculation graphs are assessed for compliance with theoretical curves and laboratory test data.
   The difference in the results of calculations of the stress-strain state of the medium-sized sand embankment in the considered models was established according to the following criteria: displacement of the subgrade surface, stress in the zone of formation of the sliding surface.
   It was proven that the soil model with stiffness at small deformations is the most suitable among considered for studying the influence of seismic action on the subgrade stress-strain state.