Cyclic Response of Loose Anisotropically Consolidated Calcareous Sand under Progressive Wave–Induced Elliptical Stress Paths

Abstract

Observations of the performance of coastal and marine structures in weather events that produce standing and/or progressive waves have pointed to liquefaction of the seabed as a contributing cause of damage. The cyclic response of marine sediments under wave loading can serve to improve the understanding of seabed liquefaction triggering and its consequences. This paper presents the results of an experimental study of the cyclic behavior of loose isotropically and anisotropically consolidated calcareous sand under elliptical stress paths representing progressive waves. Various ratios, λ, of the axial stress difference and torsional shear stress amplitudes were investigated in a hollow-cylinder torsional shear apparatus. The results indicate that the failure mode of isotropically and anisotropically consolidated (IC and AC, respectively) specimens are cyclic mobility and residual deformation failure, respectively. The difference in the observed failure mode appears to be related to particle shape and is independent of λ. However, the cyclic resistance of the calcareous sand is strongly influenced by λ and increases with decreasing consolidation stress ratio, Kc. The cyclic resistance of IC specimens is relatively independent of the orientation of elliptical stress paths, whereas the AC specimens exhibited a marked dependence. The terminal peak excess pore pressure ratio, ru,t, and shear work required for cyclic failure, Wf, are independent of λ; however, ru,t and Wf increases with increasing and decreasing Kc, respectively. Moreover, the relationship between the normalized peak excess pore pressure ratio and normalized shear work is related to the type of soil, but is independent of λ and Kc.