Shear modulus (Gmax) degradation of marine clay during recompression and swelling

This paper presents the secant shear modulus (G_max) response of a normally consolidated undisturbed marine clay cyclically loaded during recompression to the past effective overburden pressure and swelling stages after consolidating to a new pre-consolidation pressure. The strain-controlled undrained dynamic cyclic simple shear tests were performed on undisturbed marine clay obtained from offshore Indonesia. The clay samples were consolidated to OCR of 2.3 and 4.6 during the loading stage up to in-situ past effective stress of 230kPa and allowed to swell to the same OCR values after consolidating to new past effective stress of 700kPa. The cyclic shear loading was applied with shear strains ranging from 0.025% to 0.5% at 0.5Hz. The results revealed that for the same effective axial stress and OCR, the G_max in the swelling stage is more than in the recompression stage.