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Indexed by:期刊论文

Date of Publication:2010-09-01

Journal:CHINA OCEAN ENGINEERING

Included Journals:SCIE、EI、ISTIC、Scopus

Volume:24

Issue:3

Page Number:523-538

ISSN No.:0890-5487

Key Words:undisturbed saturated soft clay; complex stress condition; stiffness degradation; three-directional anisotropic consolidation; continuous rotation of principal stress axes; cyclic coupling shear test; cyclic torsional shear test

Abstract:Stiffness degradation will occur due to the generation of accumulated pore pressure in saturated soft clays under cyclic loading The soil static-dynamic multi-purpose triaxial and torsional shear apparatus in Dalian University of Technology was employed to perform different types of test on the saturated soft mantle clay in the Yangtze Estuary Undisturbed samples of the clay were subjected to undrained cyclic vertical and torsional coupling shear and cyclic torsional shear after three-directional anisotropic consolidation with different initial consolidation parameters Investigated were the effects of the initial orientation angle of the major principal stress, initial ratio of deviatoric stress, initial coefficient of intermediate principal stress and continuous rotation of principal stress axes on the stiffness degradation It is found that the degradation Index decreases (or degradation degree increases) significantly with increasing initial orientation angle of the major principal stress and initial ratio of deviatoric stress Compared with the effects of the initial orientation angle of the major principal stress and initial ratio of deviatoric stress, the effect of mural coefficient of intermediate principal stress is less evident and this trend is more clearly reflected by the results of the cyclic torsional shear tests than those of the cyclic coupling shear tests At the same cycle number the degradation index obtained from the cyclic torsional shear test is higher than that from the cyclic coupling shear test The main reason is that the continuous rotation in principal stress directions during cyclic coupling hear damages the original structure of the sod more than the cyclic torsional shear does Based on a series of experiments, a mathematical model for stiffness degradation is proposed and the relevant parameters are determined