The escalating environmental noise pollution along urban rail transit corridors, exacerbated by rapid urbanization, necessitates innovative and efficient noise control measures. A comprehensive investigation was conducted that utilized field measurements of train passing-by noise to establish a statistical energy analysis model for evaluating the acoustic performance of both vertical (VB) and fully enclosed (FB) barrier configurations. The study incorporated Maa’s theory of micro-perforated plate (MPP) parameter optimization and developed a neural network surrogate model focused on insertion loss maximization for barrier geometric design. Key findings revealed significant barrier-induced near-track noise amplification, with peak effects observed at the point located 1 m from the barrier and 2 m above the rail. Frequency-dependent analysis demonstrated a characteristic rise-and-fall reflection pattern, showing maximum amplifications of 1.47 dB for VB and 4.13 dB for FB within the 400–2000 Hz range. The implementation of optimized MPPs was found to effectively eliminate the near-field noise amplification effects, achieving sound pressure level reductions of 4–8 dB at acoustically sensitive locations. Furthermore, the high-precision surrogate model (R² = 0.9094, MSE = 0.8711) facilitated optimal geometric design solutions. The synergistic combination of MPP absorption characteristics and geometric optimization resulted in substantially enhanced barrier performance, offering practical solutions for urban rail noise mitigation strategies.

Due to their proximity to track structures, over-track buildings in depot areas may experience adverse vibrations from train operations, which can negatively impact residential comfort and the performance of precision equipment. As the test line typically involves the highest train speeds within the depot and features distinct operating conditions such as constant-speed cruising, accelerating, and braking, this study aims to investigate the influence of different train operation modes on the vibration excitation of over-track high-rise buildings through field measurements at both the central and end sections of the test line. Three operational modes were examined, including cruising, accelerating, and braking. Vibration signals were systematically collected using sensors installed in the free field, on the ground above the building foundation, and at the bases of the shear walls. A time-varying frequency phenomenon was observed at measurement points on the ground above the foundation and at the shear wall bases during train acceleration and braking. Field data indicate that vertical vibrations in the free field at the end section of the test line were significantly greater than those at the middle section, whereas vertical vibrations at the shear wall bases were comparable between the two sections. Notable vibration transmission loss occurs as the vibration propagates into the building structure, with peak values reaching 20 dB at 80 Hz during cruising operations and 35 dB at 125 Hz during acceleration and braking. This study offers valuable insights for assessing train-induced vibration transmission into high-rise over-track buildings.

Squeezed branch piles, originally developed for building and bridge foundations, have been downsized and deployed at larger pile spacing for reinforcing embankments over soft soils. However, the working mechanism of squeezed branch pile-supported embankments remains unclear. In this study, a three-dimensional numerical model of this embankment was established based on field tests. The analyses consider different pile types (squeezed branch piles and straight piles) and pile-head structures (beam-type cap and plate-type cap). These concrete components were modeled utilizing an advanced concrete model, which captures the strain-softening/hardening and yielding behavior. Simulation results show that squeezed branch piles provide better settlement control in the subsoil beneath the embankment than straight piles for the studied cases. The beam-type cap with squeezed branch piles behaves as a pile-beam foundation that reduces maximum settlement by around 38% compared to that of the plate-type cap, while the plate-type cap system functions as a composite foundation that enhances surcharge capacity by about 35–40%. The instability of the embankment is driven by tensile failure in concrete: The beam-type cap leads to a localized failure along the ground beam, and the plate-type cap system induces a progressive failure centered on the squeezed branch piles. Within the plate-type cap, the dimensions of the pile-head plate significantly influence settlement control and the stability of the embankment in soft soil.