A Theory for Track Maintenance Life Prediction

摘要

The objective of this study is to develop a methodology for predicting cumulative permanent deformation of track structures under traffic loading as a basis for maintenance life determination. This report presents the progress achieved in the second year of the research. A computer model named GEOTRACK was developed that represents the nonlinear elastic deformation of the track system. On the basis of a comparison of the elastic predictions with this model and the dynamic measurements from FAST, the model was considered to provide a resonable representation of the track response. Available information on the elastic and inelastic properties of ballast and subgrade materials under cyclic load was reviewed as a basis for selecting the form of material constitutive relationships required for the track performance predictions. Static and cyclic triaxial tests were then carried out on granite ballast with equivalent stress states determined from the GEOTRACK model. The method of predicting permanent strain accumulation in the ballast layer under the track is then described and predictions using this approach are illustrated by comparing them to measured inelastic strains in the FAST track.