Prestressed basalt fiber geogrid reinforcement for high-speed railway bridge-embankment transition zone: a shaking table test study

Regarding the insufficient bearing capacity of the bridge-road transition sections of high-speed railways, this paper proposes a new reinforcement method - Prestressed Basalt Fiber Geogrid (PBFG). Through 1:25 scale vibration test on the shaking table, combined with multi-method analyses such as PIV, FFT and HHT, this study for the first time reveals several dynamic response patterns of PBFG reinforced subgrade that are different from those of conventional reinforced embankments. The acceleration amplification coefficient (PAA) within the PBFG reinforcement zone shows a unique distribution of first decreasing and then increasing. This indicates that the prestressed reinforced body can form a local isolation zone, effectively reducing the height amplification effect and suppressing irregular vibrations. The peak dynamic soil pressure does not completely shift to the two sides of the foundation with the increase of seismic excitation, but presents a “controlled migration” feature. The maximum geogrid strain stabilizes at approximately 3/4 of the horizontal length. Based on the full-process analysis of displacement, strain and failure evolution, the earthquake loading is divided into three stages: 0.1 –0.5 g (steady growth, the subgrade is stable), 0.6 g (significant growth, cracks develop), 0.7 –0.8 g (accelerated growth, the right slope completely collapses at 0.8 g). Spectrum and energy analysis show that the central part and toe of the right slope are the most vulnerable critical sections. These findings reveal the unique isolation and load regulation mechanisms of PBFG, providing experimental basis for the seismic design of high-speed railway bridge-road transition sections with prestressed reinforcement technology.