Numerical Study of Subgrade Humidity Field Evolution Under Different Initial Groundwater Depths

As one of the issues, the evolutions of humidity field must be studied to avoid roadbed water damage. To study the influences of groundwater depth differences on the subgrade humidity field infiltrated by rainfall, five scale-down laboratory subgrade physical models with different initial groundwater depths were tested. The effects and mechanisms of different initial groundwater depths on the humidity values of disturbed zone, extended distances, and humidity gradients were explored. The results show that the influences of initial depths on humidity fields get more significant along with subgrade depths. With decrease of initial depths, the amplifications of subgrade humidity maximum differences increase quadratically to a steady value while the extended distances of humidity disturbed zone decrease quadratically to a steady value. A balanced groundwater depth should exist according to a given field situation. The influences of groundwater on humidity fields are vary slight while initial depths are deeper than the balanced one, otherwise, with increase of initial depths the amplifications of subgrade humidity increase logarithmically and the humidity gradients increase linearly.