Papers

@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{ramos_predicting_2023,

title = {Predicting Critical Speed of Railway Tracks Using Artificial Intelligence Algorithms},

author = {Ana Ramos and Alexandre Castanheira-Pinto and Aires Colaço and Jesús Fernández-Ruíz and Pedro Alves Costa},

url = {https://www.mdpi.com/2571-631X/6/4/53},

doi = {10.3390/vibration6040053},

issn = {2571-631X},

year  = {2023},

date = {2023-12-01},

urldate = {2026-08-13},

journal = {Vibration},

volume = {6},

number = {4},

pages = {895–916},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Motivated by concerns regarding safety and maintenance, the operational speed of a railway line must remain significantly below the critical speed associated with the track–ground system. Given the large number of track sections within a railway corridor that potentially need to be analyzed, the development of efficient predictive tools is of the utmost importance. Based on that, the problem can be analyzed in a few seconds instead of taking several hours of computational effort, as required by a numerical analysis. In this context, and for the first time, machine learning algorithms, namely artificial neural networks and support vector machine techniques, are applied to this particular issue. For its derivation, a reliable and robust dataset was developed by means of advanced numerical methodologies that were previously experimentally validated. The database is available as supplemental data and may be used by other researchers. Regarding the prediction process, the performance of both models was very satisfactory. From the results achieved, it is possible to conclude that the prediction tool is a novel and reliable approach for an almost instantaneous prediction of critical speed in a high number of track sections.},

keywords = {Artificial intelligence, critical speed, numerical modeling, Railway dynamics, scoping tool},

pubstate = {published},

tppubtype = {article}

}

@article{castanheira-pinto_predicting_2023,

title = {Predicting the non-linear critical speed for high-speed railways in singular geotechnical scenarios},

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

url = {https://www.sciencedirect.com/science/article/pii/S026772612200567X},

doi = {10.1016/j.soildyn.2022.107722},

issn = {0267-7261},

year  = {2023},

date = {2023-02-01},

urldate = {2023-02-01},

journal = {Soil Dynamics and Earthquake Engineering},

volume = {165},

pages = {107722},

abstract = {Studying and predicting the non-linear critical speed in high-speed railway lines is very costly in terms of computational efficiency. To overcome such particularity, the authors have proposed a simplified methodology based on dispersion curves combined with degraded ground properties, which is capable of predicting the non-linear critical speed with a low computational cost and a very acceptable accuracy. However, the application of this methodology is limited to normally dispersive geotechnical profiles. In this paper, the authors present and experimentally validate a novel methodology, similar to the one already published, which can be applied to any geotechnical scenarios.},

keywords = {Dispersion curve, Non-linear critical speed, Non-linear soil behavior, Railway dynamics, Semi-analytical methodology},

pubstate = {published},

tppubtype = {article}

}

@article{colaco_combination_2022,

title = {Combination of experimental measurements and numerical modelling for prediction of ground-borne vibrations induced by railway traffic},

author = {A. Colaço and A. Castanheira-Pinto and P. Alves Costa and Jesús Fernández-Ruíz},

url = {https://www.sciencedirect.com/science/article/pii/S0950061822015999},

doi = {10.1016/j.conbuildmat.2022.127928},

issn = {0950-0618},

year  = {2022},

date = {2022-08-01},

urldate = {2026-08-10},

journal = {Construction and Building Materials},

volume = {343},

pages = {127928},

abstract = {Noise and vibration are considered as the biggest externalities of rail transport, increasing conflicts and problems for residents. Versatile and accurate prediction models are essential for the delimitation of problematic cases and the consideration of possible mitigation measures. Regarding the specific case of vibrations, and in order to minimize the uncertainty level associated with the prediction procedure, the formulation of a hybrid approach is presented, combining numerical and experimental results. This approach is applied to an experimental case study, where for the first time this kind of prediction methodologies are fully validated, involving the track, the ground and the building. Also, as a novelty, a deep discussion about the influence of the number of point source transfer mobilities for the line source transfer mobility is presented. For this purpose, different scenarios are analysed, namely the scenario where it is intention the prediction of the vibration levels inside of a planned building or to evaluate the impact of the construction of a new railway track in the vicinity of an existing building. The satisfactory results achieved by the comparison between experimental and estimated results highlight the practical application of the methodology.},

keywords = {Building response, Hybrid prediction tool, Railway dynamics, Vibrations},

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}

}