Les exposés écrits du congrès ont été publiés dans la langue dans laquelle ils ont été soumis à l’ATC.
Railways have been an integral mode of reliable transport for freight and people for centuries. The design of railway embankments is essential in ensuring their stability and performance, particularly their resiliency and safety. Geosynthetics are widely used in rail embankments to optimize embankment thickness and maintain necessary layer separation. Cellular confinement systems (CCS), commonly known as geocells, with their three-dimensional geometry, provide additional confinement effects to increase the modulus of stabilized layers, improve bearing capacity, and reduce the lateral spread of these layers. By confining and stabilizing the ballast, CCS improves load distribution and prevents lateral movement, thereby reducing track settlement and lateral deformation over time. CCS also helps to reduce embankment thickness, lowering material costs while enhancing track performance under heavy loads and high-speed trains.
Another aspect that has recently garnered attention among engineers is the vibration attenuation benefits provided by CCS. In railway operations, one challenge that requires attention during track maintenance is the fouling of ballast and contamination of sub-ballast, which occurs due to particle abrasion and the migration of fines. While a separation geotextile layer can nearly eliminate the vertical migration of fines, lateral migration intensifies with the lateral spreading and vibration from a passing locomotive load. Vibration plays a crucial role in the development and migration of fines. CCS vibration attenuation has been shown to reduce the time-dependent change in particle distribution within the embankment.
The performance of any reinforcement depends on its material properties. Soil reinforcements are typically made of plastic materials with a viscoelastic character. Viscoelastic materials accumulate strain even when the load is within the elastic limit. As strain increases, the modulus of the material decreases, leading to a quicker accumulation of higher strain. This effectively reduces the stabilization effect, resulting in increased maintenance costs. For design engineers, it is important to understand and correlate the material index properties with the performance life of an embankment. The current paper studies each of the mechanisms of CCS and links them to fundamental material properties. The dynamic modulus and rate of cumulative strain accumulation play a vital role in overall design performance. The concept was implemented while designing a short span of the Big Sky Rail track at Eston and Pasqua loop in Saskatchewan, Canada, in 2019. The four-year visual observation and subsequent maintenance cycles validated the design considerations.