ABSTRACT
This chapter presents models and methodologies that have been developed to characterize and predict behaviors and responses of track and subgrade components under various load environments. The first section of this chapter describes models that can be used for analysis of stress, strain, and deformation in track and subgrade under wheel loads. The second section is focused on the resilient behavior or, more specifically, on the estimation of resilient modulus of granular ballast materials and fine-grained subgrade soils. The third section of this chapter discusses the prediction of plastic or permanent cumulative deformation for both granular ballast and fine-grained subgrade soils, as a result of repeated wheel load applications. Plenty of examples are given in this chapter to illustrate how track and subgrade responses, resilient modulus, and cumulative deformation can be analyzed and predicted. Particular attention is given to illustrate what factors significantly affect track and subgrade behaviors and responses. Understanding of the fundamental mechanics as described in this chapter is essential for design, construction, and maintenance of railway track and subgrade.
