ABSTRACT

This chapter discusses the formula of Darcy's law based on the equilibrium equation with the assumption that seepage resistance is proportional to seepage velocity. It incorporates the formula with the mass conservation condition of pore water. The chapter analyses the pressure distribution of static pore water in the unsaturated and saturated soil layers ground water level and understood that pore water pressure presents a continuously linear distribution along the height above and below ground water level. The expression of the seepage force for unsaturated soils is analyzed as follows. The seepage in unsaturated soils includes the seepage of pore water and pore air. The air pressure inside the closed air bubble is relevant to the normal stress of the soil outside the air bubble. In the meantime, the radius of the air bubble affect the air pressure while the surface tension of the contractile skin itself on the boundary of the air bubble is considered.