All problems associated with the subgrades of the pavements arise from the effect of water on the properties of soil. Water, at high concentrations, acts as a lubricating agent in the soil mass. Subsurface water moves upwards from soil formation into structural sections through capillaries. For the longevity of pavement, sub-surface water drainage system is vital. Such drainage system needs to be well designed for quick and efficient removal of sub-surface water. Deep side drain with well designed filter system is necessary to lower the sub-soil water level. Such drain should be minimum 1.20 metre below the pavement sub-grade to effectively lower the sub-soil water level.
展开▼
