Abstract: In order to study the properties of anisotropically consolidated silt subjected undrained cyclic principal stress rotation, series of tests are performed. The tested hollow cylinder silt samples have the initial relative density of 70%, and are consolidated with different consolidation ratio(Kc) before cyclic principal stress rotation.The results show that for the samples with Kc≤1.5, they collapsed at low or medium strain and liquefied, but when Kc > 1.5, the samples’ strain increases stably and the pore water pressure developed into dynamic equilibrium states; and the peak values of pore pressure in dynamic equilibrium states are lower than those in the liquefaction failure states. On the other hand, differing from the isotropically consolidated samples, the samples with Kc between 1.1 and 1.5 have the maximum pore water pressure at liquefaction lower than the initial effective spherical stress. Furthermore they decrease with the increase of Kc, but barely dependent of dynamic shear stress. So do the pore water pressure at collapse states. The collapse cycles of anisotropically consolidated samples are larger than that of the isotropically consolidated ones with the same shear stress level. But there are no monotonic relationship between collapse cycles and Kc. Finally, a model of pore water pressure development for the anisotropically consolidated silt under cyclic principal stress rotation is put forward, which could reflect the collapse characteristics as well as the effects of consolidation ratio and dynamic shear stress level.

Key words: principal stress axis rotation, consolidation ratio, silt, collapse, pore water pressure