Experimental study on stress-strain behavior and yield characteristics of marshy and lacustrine clay

Abstract:

To investigate the stress-strain behavior and yield characteristics of marshy and lacustrine clay under the influences of soil structure and anisotropy, the effects of soil structure and stress path on stress-strain behavior of marshy and lacustrine clay were analyzed, and the yield characteristics of marshy and lacustrine clay were systemically studied by means of stress path tests. Results show that the stress-strain behavior of marshy and lacustrine clay was significantly affected by bonding and fabric of soil. When the soil was in a stress path under positive mean effective stress increments, bonding and fabric of soil bore the mean effective stress together, which improved the compressive strength of the soil and reduced the compressive deformation. When the soil was in a stress path under negative mean effective stress increments, fabric could not bear the tensile stress and only bonding bore the tensile stress, which improved the ability of soil to bear tensile stress and produced large expansion deformation. Due to the interaction between mean effective stress and deviatoric stress under different stress paths, there was a little difference between the orientations of strain and stress paths. However, since there was a good orthogonality between plastic strain increment and yield loci, the correlation flow rule could be used for marshy and lacustrine clay. Finally, the yield loci of marshy and lacustrine clay was a rotating and distorting ellipse, which intersected to the p′ axial on the left of the origin of q-p′ plane along with the critical state line, because of the effects of K₀ consolidation and bonding during sedimentation.