Unreasonable design: The design of the subgrade must consider the characteristics and bearing capacity of the foundation soil. If the design is unreasonable, such as insufficient subgrade width, too high fill, too deep excavation, etc., it will lead to instability of the subgrade, resulting in cavity disease.
Irregular construction: If the construction of the subgrade is not standardized, such as uneven excavation, uneven filling, insufficient compaction, poor drainage, etc., it may lead to instability of the subgrade, and then form cavity diseases.
Natural factors: Natural factors are also an important cause of subgrade cavity diseases, such as earthquakes, rising groundwater levels, soil shrinkage, freezing and thawing, etc., will cause deformation, settlement and cracks in the subgrade, thus forming cavity diseases.
Vehicle load: Vehicle load is another important cause of subgrade cavity damage. The dynamic load effect of vehicle load on subgrade will cause stress change and deformation of subgrade soil, which will lead to subgrade cavity damage under long-term action.
Other factors: There are some other factors that may also cause voids in the subgrade, such as environmental factors, infiltration, and material aging.
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