Moisture stabilization of embankment subgrade with capillary barrier cover under dry and rainy weathers

Abstract

Water loss from subgrade soil subjected to dry weather is possible to cause pavement desiccation cracking. On the contrary, intruded water will cause pavement failures because of the wetting swelling or collapsing of the subgrade soils. Therefore, avoiding the excessive fluctuations of the soil moisture in subgrade soils could increase the service life of the pavement. In this paper, the capillary barrier cover (CBC), consisting of the overlying fine-grained layer and the underlying coarse-grained layer, was newly used to maintain moisture stabilization of embankment subgrade under dry and rainy weathers. A group of physical model experiments were conducted to investigate the availability of this method. The results suggest that the CBC laid on the subgrade slope can effectively resist the moisture releasing from the subgrade during drying process, which is rarely reported and fully investigated at present. Meanwhile, the fine layer of CBC with low thermal conductivity can maintain a relatively stable temperature field, which is beneficial to uniform the moisture in subgrade. On the other hand, the CBC can also prevent water infiltration into subgrade during rainfall, even though cracks developed in the fine layer of CBC. Comparing to the subgrade without CBC, that subgrade with CBC has a more stable moisture field and a better performance under climatic variations.