Earth pressure at rest of expansive soil against retaining wall

Centrifuge modeling tests were performed to study earth pressure at rest against a retaining wall backfilled with unsaturated expansive soils. Expansive soils with combination of different initial densities and water contents were prepared in different models to investigate the earth pressures. As the changing patterns of earth pressure after inundation are the focus of the study, infiltration is simulated by filling the surface of backfill with water in flight. Based on the analysis of test results, two coefficients to define earth pressure at rest of unsaturated soils are proposed, one being k(sigma), related to the overburden pressure, and the other being k(s), related to matric suction. Therefore the changing patterns of earth pressure of expansive soils after inundation could easily be estimated by using the formulated equation with the two coefficients, which may be of use in the design of fixed retaining walls in the area of expansive.