Discrete Element Analysis of Shape Effect on the Shear Behaviors of Ballast

Railway ballast layer is an indispensable component of railway transport. Ballast morphology plays an important effect in ballast-sleeper interaction and the durability of ballast layer. In this study, four types of ballast with different morphological parameters were generated and discrete element method was adopted to investigate the direct shear behaviors. The initial packing states were studied by analyzing the porosities and the normal contact force distributions. The shear results were verified by the reported testing results. On the other hand, one-way ANOVA tests were performed to explore the impact of ballast shape on the initial packing behaviors and the direct shear performance. Results indicated that for all four parameters, aspect ratio (AR), sphericity (& phi;), roundness (RD) and convexity (CON), the initial porosities decreased first and increased subsequently along with the increase of the parameters. The four parameters could significantly affect the internal friction inside the assemblies. For each parameter, the larger the parameter, the insignificant the internal friction effect. One-way ANOVA tests revealed that all the four parameters were significant in affecting the initial porosities and the internal friction. Moreover, during the direct shear process, the larger the AR or & phi;, the smaller the coordination number, which was mainly ascribed to the ballast shapes.

Automated summary

This study investigates the direct shear behaviors of ballast with different morphological parameters using the discrete element method. The initial packing states and shear results are analyzed, and one-way ANOVA tests are conducted to explore the impact of ballast shape. The results show that the four parameters significantly affect the internal friction and porosities. Additionally, the ballast shape affects the coordination number during the direct shear process.