Research on the mechanism and dynamic response of frost heave prevention in foamed concrete cuttings for high-speed railways in seasonally frozen soil regions

To address the issues of frost heave damage in high-speed railway cut slopes in seasonally frozen regions and deformation settlement caused by train dynamic loads, this study employs basalt-silvergrass composite natural fiber foam concrete (BS-FC) as the frost-resistant thermal insulation layer. At the same time, a coupled model of heat-moisture-force in high-speed railway embankments and train dynamic loads were constructed based on COMSOL software, deeply revealing its mechanisms under extreme climate and cyclic dynamic loads. Research shows that:1) the BS-FC board has a significant effect on blocking cold and insulating, reducing the maximum frost depth and maximum frost heave from 2.33 m and 7.4 mm to 1.86 m and 0.6 mm, respectively, greatly controlling frost;2) Under the dynamic load of the train, the high-modulus BS-FC board acts as a rigid board, transforming the lateral settlement pattern of the embankment from a sharp "V" shape to a gentle "U" shape, thereby suppressing local deformation differences;3) The BS-FC board has excellent stress diffusion capabilities, significantly reducing the dynamic stress transmitted to the underlying soil, thereby mitigating the risk of plastic cumulative settlement in the deep soil;4) After undergoing a million cycles of dynamic loading, the peak tensile stress at the bottom of the board is far below the fatigue limit of 1.513 MPa, demonstrating the BS-FC board's extremely high fatigue resistance. This study provides new methods and theoretical support for the green construction and full life cycle stability of high-speed railways in seasonally frozen regions.