SigurOur Erlingsson[3], Mihael Brencic and Andrew Dawson
Abstract This chapter describes the relation between road structures and water giving the general water balance equation for the pavement structure. Aquifers are briefly introduced. The pavement and its associated embankment are divided into the saturated zone and the unsaturated zone. Porous media are also described briefly together with their grain size distributions and fundamental properties related to water movements. A short summary of water flow theory for saturated and unsaturated soils is then presented, including relevant discussion of the soil water characteristic curve and permeability of unsaturated soils.
Keywords Roads ■ water flow ■ porous media ■ saturated ■ unsaturated ■ permeability ■ soil water characteristic curve
During the planning, design, construction, operation and maintenance of roads, water can be an important environmental and constructional constraint that can significantly influence the bearing capacity of the pavement, the safe operation of traffic and have a large influence on the operational costs of roads.
Due to their length, roads interact with various water phenomena. Interaction between roads and water phenomena can be conceptualized on the basis of the recharge area of the water that intercepts the road. These phenomena of water road interaction can be divided into three groups:
(i) the road’s own waters;
(ii) hinterland waters; and
(iii) remote waters.
The road’s own water is the runoff that arises as a consequence of precipitation falling onto the carriageway and onto the associated embankment. Hinterland waters come from the near-road environment (e. g. slopes from a cutting) and those which are flowing towards the road embankment. Remote waters have recharge areas far away from road but are crossing the line of the road (e. g. rivers, lakes, subterranean groundwater flow, etc.).
