Dynamic Response and Long-Term Settlement of Coarse Grained Chloride Saline Soil Subgrades Under Traffic Loading

This study focuses on the dynamic response and long-term settlement of subgrades constructed with coarsegrained chloride saline soil (CGCSS) under traffic loads. Dynamic triaxial tests were conducted to investigate the evolution of dynamic parameters (dynamic modulus, damping ratio) and cumulative deformation patterns of CGCSS subjected to long-term cyclic loading. Subsequently, a three-dimensional finite element model was developed using ABAQUS to simulate the CGCSS subgrade system. This model was employed to analyze the dynamic stress distribution within the subgrade, including vertical stress attenuation with depth and horizontal stress propagation patterns. A cyclic loading model was integrated to predict long-term settlement, with a three-line model demonstrating effectiveness in capturing soil deformation characteristics across different vibration frequency. Results show that traffic loads influence subgrades to a depth of 2.2 meters. Vehicle speed was found to have a minimal impact on stress distribution, whereas the lateral superposition effect of coaxial wheel loads significantly alters the stress field. Long-term settlement behavior showed that deformation is dominated by the early loading stage, with cumulative settlement remaining below 1.5 mm even after 1 million cycles, thus confirming the favorable durability of CGCSS subgrades under prolonged cyclic traffic loading. This establishes a theoretical framework and provides practical design strategies for CGCSS subgrade engineering in high-altitude salt lake regions, with findings that can be extended to similar saline soil infrastructure projects globally.