EFFECTS OF OVERCONSOLIDATION AND K0 CONDITIONS ON THE LIQUEFACTION CHARACTERISTICS OF SANDS

When overconsolidation is induced in a horizontal deposit of sand by the removal of surcharge pressure or by other events, the lateral deformation is prevented and the coefficient of earth pressure at rest, K0, increases. To evaluate effects of the overconsolidation ratio as well as increased K0-value on the liquefaction resistance of sand deposits, several series of cyclic torsion shear tests were carried out on samples of clean sand overconsolidated to different degrees under various K0-conditions. The results of these tests were summarized in an empirical formula. This formula is used to estimate the cyclic strength of sand at any given OCR- and K0-values, based on the cyclic strength for isotropically and normally consolidated samples.