Sand Liquefaction in Triaxial and Simple Shear Tests

Data from cyclic loading simple shear and triaxial tests indicate that the important variable controlling the incidence of liquefaction in a given number of cycles in a saturated sand at a particular void ratio is the initial effective stress ratio; the ratio of the peak alternating shear stress to the initial effective mean normal stress. Contrary to previously published results, equal resistances to liquefaction are obtained in both kinds of tests. This agreement is considered to be due to three things: (1) Representation of the confining pressure in the simple shear test by the mean normal stress in the plane of deformation; (2) the improved model of the simple shear apparatus used; and (3) the use of experimental techniques which insures the development of uniform strains in the simple shear test. The experimental techniques used evolved from a fundamental study of the deformation of samples in the simple shear apparatus.