Modelling cyclic compression of ballast aggregates using bounding surface model.

The bounding surface model is commonly employed to simulate the monotonic and cyclic loading behavior of granular materials. However, it faces challenges in accurately capturing drained cyclic compression behavior under a high number of loading cycles, especially as the void ratio approaches its minimum physical limit-a critical factor in evaluating the long-term performance of railway ballast aggregates. This study examines the triaxial drained monotonic and cyclic compression behavior of ballast aggregates through laboratory testing on natural gabbro and electric arc furnace (EAF) slag. Additionally, stress-strain data from ballast materials of various geological origins were compiled from the literature. Based on this dataset, the drained cyclic compression behavior is modeled using the bounding surface framework, incorporating a terminal state parameter and its associated limiting maximum friction angle, along with the evolution of the plastic modulus. The model, calibrated using experimental results, demonstrates a strong ability to reproduce key characteristics of the ballast's stress-strain response under drained high-cycle loading conditions.