Publicacións

@article{fernandez-ruiz_non-linear_2024,

title = {Non-linear critical speed in high-speed ballasted railways with ground reinforcement},

author = {Jesús Fernández-Ruíz and Cláudio Pereira},

url = {https://www.sciencedirect.com/science/article/pii/S2214391224001466},

doi = {10.1016/j.trgeo.2024.101325},

issn = {2214-3912},

year  = {2024},

date = {2024-09-01},

urldate = {2026-04-28},

journal = {Transportation Geotechnics},

volume = {48},

pages = {101325},

abstract = {When constructing or upgrading high-speed railway lines on soft soils, reinforcing the soil foundation becomes crucial. This not only involves small track displacements but also increases the critical speed, thereby ensuring safe and efficient regular operations. Nevertheless, existing studies on the critical speed phenomenon in high-speed railway tracks with ground reinforcement are limited, and they all assume a linear elastic behavior for both the soils and reinforcement materials. The main novelty of this research is that it presents the first study on the effect of non-linear soil behavior on the critical speed of high-speed railway ballasted tracks with soil reinforcement and introduces a novel simplified approach based on an equivalent homogeneous soil layer by replacing the soil layer containing inclusions/columns. To accomplish this, a full 3D non-linear numerical model was developed and experimentally validated. The findings from a detailed and comprehensive parametric analysis demonstrate a significant influence of non-linear behavior on the critical speed, resulting in reductions of up to 30% compared to the linear elastic scenario. Furthermore, it is found that the soil-reinforcement stiffness contrast, the area replacement ratio, and the plasticity index of the soil foundation play a crucial role in the critical speed. Other aspects such as the installation pattern and the thickness of soft soil have a relatively lower impact on the critical speed.},

keywords = {Ground reinforcement, High-speed railways, Railway critical speed, Railway dynamics, Soil stiffness non-linearity},

pubstate = {published},

tppubtype = {article}

}

@article{fernandez-ruiz_influence_2022,

title = {Influence of non-linear soil properties on railway critical speed},

author = {Jesús Fernández-Ruíz and Alexandre Castanheira-Pinto and Pedro Alves Costa and David P. Connolly},

url = {https://www.sciencedirect.com/science/article/pii/S095006182201162X},

doi = {10.1016/j.conbuildmat.2022.127485},

issn = {0950-0618},

year  = {2022},

date = {2022-06-01},

urldate = {2026-08-10},

journal = {Construction and Building Materials},

volume = {335},

pages = {127485},

abstract = {The design of high-speed railway lines involves geotechnical challenges, one of which is the risk of dynamic track amplification, for example on track sections where the train speed approaches the track-ground critical speed. In these cases, soil strains increase significantly with an increase in train speed, far exceeding the limits of linear elastic behaviour. This can result in a non-linear reduction of soil stiffness. To better understand this relationship, this paper studies the influence of soil non-linearity on the critical speed of concrete slab and ballasted tracks. To perform an in-depth analysis into non-linear critical speed, two models are used: a 3D FEM approach, and a novel dispersion curve technique. Using the models, the effect of soil plasticity on non-linearity is studied, with different ranges of plasticity found to play an important role. Secondly, the influence of soil thickness and loading magnitude are evaluated. It is shown that ballasted tracks are deeply affected by the non-linear soil behaviour, compared to a concrete slab track. Further, it is shown that for the ballasted tracks, the relationship between the critical speed and shallow upper soil layer thickness can be weak.},

keywords = {High-speed railways, Plasticity index, Railway critical speed, Railway dynamics, Soil stiffness non-linearity},

pubstate = {published},

tppubtype = {article}

}