Table 1 Definition of major types of HSR subgrade defect.
From: Multi-defect risk assessment in high-speed rail subgrade infrastructure in China
Type of defect | Definition |
|---|---|
Subgrade settlement | Settlement refers to the vertical deformation that occurs over a small or extensive area due to inadequate compaction of subgrade soil, insufficient depth of foundation treatment, damage between piles, creep of underlying soil layers, or regional settling |
Frost damage | In cold regions, subgrade and its protective structures experience uneven frost heave under low temperature conditions, leading to issues like tilting and cracking of protective structures |
Mud pumping | This defect occurs in areas with poor drainage. Repeated vibrations from train traffic cause softening or thixotropic liquefaction of the sub-ballast, leading to the formation of mud slurry |
Uplift deformation | This happens when expansive soils or rocks within the subgrade or its base react with external moisture, causing the subgrade to arch upwards |
