Published: Građevinar 78 (2026) 3
Paper type: Original scientific paper
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Synergistic evolution of microstructure and coupled multiphysics mechanical responses in railway subgrades

Railway subgrades in desiccated salt lake regions are prone to swelling hazards under complex environmental conditions. To investigate the water–salt–thermal–mechanical multi-field coupling responses and the synergistic evolution of microstructure, this study examined saline soils from the Lop Nur salt lake area. A multi-physical field coupling experimental system was established to analyse mechanical responses under different environmental coupling conditions, factor sensitivity affecting mechanical parameters, microstructural evolution, and the regulatory role of pore structure in mechanical stability. Results indicate that in high-temperature zones (≥ 20°C), shear strength is negatively correlated with water content, whereas in low-temperature zones (≤ 0°C) a positive correlation exists. Lower temperatures also markedly suppress cumulative plastic strain. Low-temperature-induced microstructural evolution of saline soil systems proceeds through four stages: initial nucleation, chain-like growth, dynamic reconstruction, and critical failure. The synergistic evolution of multi-field coupling responses and microstructure is primarily reflected in pore structure development. These findings provide a scientific basis for evaluating mechanical stability and guiding the design and maintenance of railway subgrades in cold, arid salt lake environments.

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