Transition zones in high-speed railways suffer from abrupt stiffness variations that induce irregular dynamic responses and accelerate infrastructure deterioration. This study presents a surrogate-assisted multi-objective optimization framework that combines finite element (FE) simulations, a neural network-based surrogate model, and the NSGA-II algorithm to address this challenge. A validated 3D FE model of prefabricated epoxy asphalt cured track beds (PEACT) was used to generate 341 layout scenarios covering 13 response parameters. These data were used to train a neural network, which served as a static surrogate predictor for evaluating layout performance during the optimization process. The results show that module layout has a limited effect on peak responses but significantly improves smoothness, with three categories of optimal configurations identified. Compared with direct FE-based optimization, the proposed framework achieves substantial computational efficiency and provides data-driven design guidance for PEACT transition zones. This framework exemplifies the potential of hybrid data–simulation approaches to enhance adaptive and efficient railway infrastructure design.

The dry-mixed rubberized epoxy asphalt mixture (DREAM) has demonstrated superior mechanical properties. The addition of crumb rubber (CR) improves the damping performance and toughness characteristics of DREAM while offering significant potential for recycling waste materials. However, cracking remains a critical issue for DREAM, necessitating further experimental investigations into its crack resistance performance, especially regarding the sensitivity of evaluation indicators. In this study, semi-circular bending tests were conducted on DREAM with varying CR content under three loading rates and two test temperatures. P-values were utilized to evaluate the sensitivity of nine indicators. Results suggest that not all fracture performance indicators exhibit significant differences due to the varying toughness resulting from the CR content in DREAM. Normalized parameters, such as the pre- and total cracking resistance index (CRI^pre,CRI), tensile stiffness index (TSI), and tensile strength (TS) demonstrate superior performance in distinguishing the effects of CR content and test temperature. Meanwhile, TSI, CRI, and CRI^pre can only significantly distinguish the effects of loading rate in DREAM with high CR content. Moreover, the addition of CR reduces the load-bearing capacity and stiffness of DREAM while increasing its flexibility and crack propagation resistance. Among the effective indicators, TSI is more sensitive to changes in loading rate and test temperature compared to CRI^pre and CRI. This study aims to enhance the understanding of the crack resistance performance and indicator adaptability of DREAM via macro-mechanical experiments and provides guidance for its future applications.

The rapid advancement of high-speed railway (HSR) has imposed significantly higher demands on rail tracks' performance and vibration mitigation capabilities, necessitating the design of track systems that can withstand extreme operational conditions while ensuring passenger comfort. Precast epoxy asphalt-cured track (PEACT) has emerged as a promising solution, offering superior mechanical properties and environmental adaptability. In this study, a full-scale finite-element model of PEACT is established and validated. Four dry-mixed rubberised epoxy asphalt mixtures (DREAMs) are incorporated, with their material parameters (e.g., modulus, density, damping) explicitly defined. Several modelling enhancements are implemented beyond conventional response analysis, including: (i) DREAM-grade-specific Rayleigh damping calibration derived from modal analysis, (ii) a stability-first boundary–mesh prescription. These strategies improve modelling fidelity for non-uniform transition zones. The results show that PEACT dynamic responses remain within acceptable ranges, and that DREAMs provide substantial vibration attenuation, contributing an additional ∼40% reduction on top of the fastener system. From a design perspective, these findings provide practical evidence that graded DREAM layouts can effectively control vertical surface displacement to below 0.5 mm under 350 km/h loading, facilitating smoother stiffness transitions, reduced maintenance demand, and more reliable HSR operation.

Rubberized epoxy asphalt trackbeds, incorporating crumb rubber (CR) particles within the cured matrix, demonstrate superior vibration damping and deformation resistance characteristics. Current research remains predominantly focused on macroscopic properties, leaving a critical knowledge gap regarding the particulate-scale mechanisms controlling their dynamic performance under high-speed rail loading. This study bridges this gap through advanced discrete element modeling,developing two-dimensional DEM representations of four sleeper-asphalt composite units with varying CR concentrations (0%, 2%, 4%, and 6%). The models demonstrate exceptional validation accuracy against finite element analyses, with track stiffness predictions within 96.7−152.4 kN/mm range (maximum deviation <2.07%). Our particle-scale investigation of 350 km/h loading cycles reveals three key phenomena: (1) CR content proportionally increases dynamic deformation (stabilizing at 0.5 mm for 6% CR after three loading cycles), while simultaneously enhancing elastic recovery and cumulative deformation resistance; (2) CRparticles redistribute contact forces (0−100 N), with 4% content as a critical threshold shifting behavior from aggregate-dominated to CR-controlled; (3) This transition optimizes stress distribution and force chain homogeneity, achieving optimal balance between flexibility and stability. The findings provide essential insights for designing high-performance rubber-modified railway trackbeds.

Rubberized asphalt mixture effectively reduces vibrations in railway track due to the elasticity of crumb rubber (CR) and the viscoelasticity of asphalt binder. This study aims to design a rubberized epoxy asphalt mixture using the modified volumetric mix-design method named the multi-point supported skeleton for asphalt mixtures (V-S method). The feasibility and vibration attenuation of the precast epoxy asphalt track was evaluated through a 3D FEM simulation at a 350 km/h speed. By combining the V-S method with the equivalent volume replacement principle between CR and coarse aggregate, four types of rubberized epoxy asphalt mixtures were proposed using the dry method. Indoor test results confirm that these mixtures meet the required specifications. The FEM results demonstrate that the designed epoxy asphalt track meets the design criteria and the components of the EA-4CR track structure demonstrate superior vibration reduction performance among the cases with the same increment in CR content.

Asphalt overlays have been widely employed in airport runway maintenance in recent years due to their ability to minimize traffic disruption. However, they continue to face the challenge of reflective cracks originating from the expansion joints of the underlying cement concrete runway. To better understand the cracking behavior of asphalt overlays under the combined temperature variations and aircraft loads, this study developed a finite element (FE) model. with the model incorporate two types of landing methods and typical temperature conditions. Simulation results indicate that critical loading positions are located at the edges of original cement concrete slabs, where shear stress is identified as the primary driver of crack evolution, with the peak stress coinciding with the arrival of aircraft load. Furthermore, findings suggest that the use of asphalt overlays significantly reduces the stress intensity in crack-prone areas, particularly under rough landing conditions. Reflective cracks predominantly manifest as type II shear cracks, While aircraft loading and initial crack length exert a relatively limited impact on crack propagation compared to temperature effects, the horizontal location of the initial crack substantially influences both the direction and speed of crack propagation. To mitigate crack propagation, increasing the linear shrinkage coefficient of the overlay material and the thickness of the asphalt overlay are effective strategies for enhancing the cracking resistance of airport runways with asphalt overlays. The methodologies and findings of this study provide valuable insights for engineering practices involving similar structural configurations and materials.