Study on the dynamic performance of heavy-load railway reinforced subgrade under flood condition

Abstract

To mitigate the subgrade deterioration induced by water infiltration, geosynthetics are employed to reinforce overloaded railway subgrades. Indoor model experiments were conducted to simulate dynamic loads under different axle weights, investigating the impacts of immersion on the dynamic characteristics of reinforced subgrades. Results demonstrated that immersion significantly increased the subgrade's stress, settlement, and acceleration. Compared to submerged unreinforced subgrades after immersion, the geocell-reinforced subgrade exhibited a 33 % reduction in additional stress, while the composite-reinforced subgrade, comprising geocell and geotextile, exhibited a 35 % decrease. The geotextile was placed beneath the ballast layer, with the geocell positioned below the geotextile. Additionally, settlement at the middle sleeper was reduced by 29 % for the geocell-reinforced subgrade under 30 t load and 38 % for the composite-reinforced subgrade, demonstrating that reinforcement enhanced subgrade strength, stabilized the upper structure, and mitigated subgrade acceleration. After immersion, geotextiles play a crucial role in maintaining the integrity of the ballast layer and minimizing ballast contamination. A modified model for the additional stress distribution within the ballast layer has been proposed, whereby the additional stress at any point outside the projected surface of the ballast layer can be calculated based on the distances from both the side and front of the sleeper.