ABSTRACT
Water flows through various layers in a pavement, each of which has certain flow characteristic. The basic property that governs the flow in porous media is hydraulic conductivity. The flow of water through a given soil-gradation and unsaturated conditions is dictated by its matric suction. Material properties include drainage characteristics: soil water characteristic curve and hydraulic function whereas the geometric-section properties include the flow length and flow gradient. The average variation of matric suction along the flow length is assumed as a generalized parabola and an analytical equation for estimating the time-to-drainage is derived in terms of geometric-section properties, drainage characteristics of the base material and a matric suction distribution parabola parameter. The major parameters of precipitation specifically, its intensity and duration, govern the movement of moisture in pavement subsurface. The degree of saturation produced by a rainfall event and other inflows can be estimated by simulating the process of infiltration and drainage simultaneously.
