The coefficient of earth pressure at rest

Laboratory experiments on undisturbed specimens of a large number of soft clay deposits, as well as previous measurements on clays and granular soils, were used to examine and explain the magnitude and behavior of the coefficient of earth pressure at rest, K_o. Empirical equations provide reasonable estimates of K_o for clays and granular soils after secondary-compression aging, after preconsolidation by unloading, and for soft clay deposits that display a preconsolidation pressure σ′_p greater than in situ effective vertical stress σ′_vo. Proposed empirical equations and methods successfully predict K_o of presheared clays. -from Authors