Experimental study on the combined influence of geogrid and rubber granules on the shear behavior of railway ballast
摘要
Geogrid is one of the most widely used geoinclusions in railway engineering to improve the bearing capacity of ballasted tracks. However, its effectiveness in mitigating ballast degradation, recognized as the most critical engineering challenge, remains limited, particularly in the context of the increasing demand for faster and heavier haul transportation nowadays. Rubber granules (RG), manufactured from waste rubber tires, possess high energy-absorbing properties that dampen vibration, reducing the stresses on ballast particles and helping to prevent ballast degradation. In order to explore the practical methods to delay the degradation of ballast and improve the performance of track bed, in this study, a series of large-scale direct shear tests were conducted on ballast aggregates with different geogrid-inclusion conditions and various RG content to investigate the shear behavior and performance of ballast under different configurations. The results show that while the RG effectively reduces the breakage of ballast particles, it negatively impacts the development of shear strength in aggregates, with or without geogrid reinforcement. As RG content increases, ballast aggregate exhibits lower peak shear strength, smaller maximum volumetric dilation, and greater volumetric contraction during shearing. For geogrid-reinforced ballast, incorporating 5% rubber granules (by volume) results in a reduction of aggregate shear strength by approximately 12%, while simultaneously mitigating ballast breakage by more than 30%. By balancing the enhancement of ballast durability with the maintenance of adequate shear strength, a 5% RG content by volume is recommended as a suitable proportion for practical applications. Based on experimental observations, a set of empirical equations has been proposed to estimate the shear strength and volumetric deformation of geogrid-reinforced ballast in the presence of RG. The findings from this study provide valuable insights for improving the design and performance of ballasted railway tracks, particularly in addressing ballast degradation and ensuring track resilience under modern loading demands.
Graphical Abstract