Effect of absorption on active pressure in floury soil

Retaining walls are often built in unsaturated soil at shallow depth above groundwater level. It is critical to define active pressure in unsaturated soil for designing retaining walls, based on the expanded theory of lateral pressure by Rankin, considering interaction between active pressure and absorption of soil. For unsaturated floury soil occurring above groundwater level for a long time, the angle of internal friction is estimated based on the soil–water curve, for various depths of retaining walls and different values of absorption, which is constant and decreases with depth, the active pressures and critical height are determined for foundation pits with vertical unsupported walls. The results confirm that absorption reduces active pressure on a retaining wall and the critical height of the vertical walls of the foundation pits can be increased when absorption grows.