Table 1 Definition of HSR Subgrade Defect.
From: A Georeferenced Dataset for Mapping and Assessing Subgrade Defects in China’s High-Speed Railways
Type of defect | Definition | 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. |
Soil extrusion | This deformation occurs when sub-ballast soil undergoes shear failure under the load of the train, leading to lateral squeezing. | Slope failure | Slope slipping and collapsing refer to the shallow sliding or collapse of soil slopes. |
Deterioration of protection structures | These defects in retaining structures occur due to natural environmental factors, uneven settling of foundations, and issues in construction and design. | Poor drainage | Poor or insufficient drainage leads to rainwater penetrating into or eroding the subgrade, deteriorating the quality of the subgrade or its stability. |
