The ballast consists of angular particles whose main function is to transmit and distribute train loads to the soil. However, under repeated loads, these particles wear down and break, causing permanent settlement, reducing track stability, and increasing maintenance. Characterizing stresses and deformations under monotonic and cyclic loading is essential to predict short- and long-term performance of railway systems. This numerical study evaluates the behavior of improved ballast materials, considering particle breakage. A hybrid Finite Difference and Discrete Element model was used to simulate the multiscale response of the track system under realistic loading conditions. The model was calibrated using data from laboratory tests conducted by various researchers. The performance of conventional ballast was compared with alternative mixtures, analyzing vertical displacements, stress distribution, safety factor, and particle breakage rates. Results show that the basalt-rubber composite significantly enhances ballast performance by reducing settlements and subgrade stresses while improving resistance to particle breakage. The FDM-DEM coupled approach effectively captures micromechanical interactions and breakage mechanisms, offering valuable insights for optimizing track design based on quantifiable performance criteria. Overall, the findings indicate the hybrid model and breakage–contact criteria approximated system behavior, while alternative ballast compositions improved durability, reduced maintenance, and supported resilient railway solutions.

The performance of ballasted railway tracks under cyclic loading is a critical issue in urban railway systems, where high traffic frequency and geometric constraints accelerate track degradation, which, in turn, leads to accumulation of plastic deformations that potentially reduce operation efficiency. This study presents a numerical framework for rail track performance assessment based on two complementary modeling approaches: a fully continuous Finite Difference Method (FDM) model, and a hybrid Discrete Element Method–Finite Difference Method (DEM–FDM) model. The continuous FDM simulations are employed to evaluate the global mechanical response of the track support system and to compute conventional stability indicators, including the factor of safety (FS). In parallel, the hybrid DEM–FDM simulations explicitly represent the ballast layer using DEM to capture inter-particle interactions, accumulation of permanent deformation, and particle fragmentation under cyclic loading, while rails, sleepers, sub-ballast, and subgrade are modeled using FDM to describe system-level load transfer. Ballast performance is assessed by linking safety factors obtained from the continuous models with mechanically derived permanent deformation and stress measures extracted from the hybrid simulations. This dual-modeling framework enables a systematic investigation of the influence of ballast layer thickness and material type on deformation accumulation, stress transmission, and granular degradation mechanisms. The results reveal distinct behavioral trends among different ballast materials, showing that increased ballast thickness generally improves track performance, while material-specific degradation mechanisms govern the evolution of permanent deformation under repeated loading. The proposed approach establishes a quantitative bridge between traditional stability-based design metrics and deformation-based performance indicators, providing a rational basis for performance-based evaluation, comparison, and optimization of ballast configurations, through a set of robust numerically derived relationships for railway track design abstract should be an objective representation of the article and it must not contain results that are not presented and substantiated in the main text and should not exaggerate the main conclusions.

The performance of ballasted railway tracks under cyclic loading is a critical issue in urban railway systems, where high traffic frequency and geometric constraints accelerate track degradation, leading to the accumulation of plastic deformations that may reduce operational efficiency. This study presents a numerical framework for rail track performance assessment based on two complementary modeling approaches: a fully continuous Finite Difference Method (FDM) model, and a hybrid Discrete Element Method–Finite Difference Method (DEM–FDM) model. The continuous FDM simulations are employed to evaluate the global mechanical response of the track support system and to compute conventional stability indicators, including the factor of safety (FS). In parallel, the hybrid DEM–FDM simulations explicitly represent the ballast layer using DEM to capture inter-particle interactions, accumulation of permanent deformation, and particle fragmentation under cyclic loading, while rails, sleepers, sub-ballast, and subgrade are modeled using FDM to describe system-level load transfer. Ballast performance is assessed by linking safety factors obtained from the continuous models with mechanically derived permanent deformation and stress measures extracted from the hybrid simulations. The proposed dual-modeling framework enables a systematic investigation of the influence of ballast layer thickness and material type on deformation accumulation, stress transmission, and granular degradation mechanisms. The results reveal distinct behavioral trends among different ballast materials, showing that increased ballast thickness generally improves track performance, while material-specific degradation mechanisms govern the evolution of permanent deformation under repeated loading. The proposed approach establishes a quantitative bridge between traditional stability-based design metrics and deformation-based performance indicators, providing a rational basis for performance-based evaluation, comparison, and optimization of ballast configurations through a set of robust numerically derived relationships for railway track design.

Ground failure during major seismic events associated with soil liquefaction can lead to major structural damage to both the columns and the bridge upper deck due to large seismic-induced displacements in the support foundation. Liquefaction-driven ground motion incoherence during the dynamic event and permanent soil deformations are key variables in the observed damage. This paper summarizes a numerical study of an alternative bridge foundation design proposed to reduce support displacements and bearing capacity failure during and after an earthquake, as well as relative settlement associated with partial loss of bearing capacity when the bridge column is founded on a potential liquefiable layer. Three-dimensional numerical models were developed using FLAC^3D. The seismic environment was characterized by a uniform hazard spectrum, UHS, for intraplate and interplate earthquakes, as presented in the current construction Mexico City regulations. Initially, a one-dimensional analysis was performed using SHAKE to evaluate liquefaction susceptibility. Results show that the structured cell foundation reduces excess pore-pressure generation by up to 42% compared to shallow foundations and 25% compared to pile systems. This improvement is associated with (i) restriction of cyclic shear strain, (ii) modification of deformation patterns, (iii) partial confinement of pore-pressure development within the enclosed soil mass, and (iv) preservation of effective stresses during shaking. Additionally, the system reduces shear strain localization and decreases acceleration transmitted to the superstructure by up to 14–33%. The findings demonstrate that structured confinement systems can significantly influence the mechanisms governing liquefaction, offering a promising alternative for bridge foundations in seismic regions.

Ground failure during major seismic events associated with soil liquefaction can lead to major structural damage in both the columns and the bridge upper deck, due to large seismic-induced displacements in the support foundation. Liquefaction-driven ground motion incoherence during the dynamic event, and permanent soil deformations are key variables in the observed damage. This paper summarizes a numerical study of an alternative bridge foundation design proposed to reduce support displacements and bearing capacity failure during and after an earthquake, as well as relative settlement associated with partial loss of bearing capacity when the bridge column is founded on a potential liquefiable layer. Three-dimensional numerical models were developed using FLAC3D. The seismic environment was characterized by a uniform hazard spectrum, UHS, for intraplate and interplate earthquakes, as presented in the current construction Mexico City regulations. Initially, a one-dimensional analysis was performed using SHAKE to evaluate liquefaction susceptibility. Results show that the structured cell foundation reduces excess pore pressure generation by up to 42% compared to shallow foundations and 25% compared to pile systems. This improvement is associated with (i) restriction of cyclic shear strain, (ii) modification of deformation patterns, (iii) partial hydraulic isolation of the confined soil, and (iv) preservation of effective stresses during shaking. Additionally, the system reduces shear strain localization and decreases acceleration transmitted to the superstructure by up to 25%. The findings demonstrate that structured confinement systems can significantly alter the mechanisms governing liquefaction, offering a promising alternative for bridge foundations in seismic regions.