Effect of rock strength on the degradation of ballast equipped with under sleeper pad using discrete element method

This study investigates the influence of Uniaxial Compressive Strength (UCS) of ballast rock cores and the Bedding Modulus of Under Sleeper Pads (USP-BM) on railway track deterioration, investigating key factors such as settlement and aggregate fragmentation through Discrete Element Method (DEM) simulations. These simulations encompass three scenarios representing different types of ballast aggregates: without a pad, with a soft pad, and with a hard pad, with rock cores categorized by UCS values into soft (159 MPa), medium (210 MPa), and hard (285 MPa) classes. The model involves cyclic loading of a sleeper section embedded in ballast, subject to fluctuating vertical loads between 3 and 43 kN at a frequency of 3 Hz, with a total of 15 load cycles applied to emulate real-world conditions, and its accuracy is confirmed through experimental validation. The study concludes that a soft USP is most effective in mitigating ballast settlement and breakage, highlighting the pivotal role of UCS values of ballast rock cores in the management of track deterioration.