Effects of principal stress rotation on stress-strain behaviors of saturated clay under traffic-load-induced stress path

摘要

A series of cyclic torsional shear tests using hollow cylinder apparatus (HCA) were performed to investigate the effect of principal stress rotation (PSR) on the stress-strain behaviors of saturated soft clay. The traffic-load-induced shear stress path was used in the cyclic test and the investigation mainly concerned the influence of PSR on the shear stiffness and non-coaxiality. It indicated that the effects of PSR substantially depends on the magnitude of deviatoric stress (q = {[(sigma(1) - sigma(2))(2) + (sigma(2) - sigma(3))(2) + (sigma(1) - sigma(3))(2)]/2}(1/2)) as well as the intermediate principal stress ratio (b = (sigma(2) - sigma(3))/(sigma(1) - sigma(3))). At low deviatoric stress, the trajectory envelope of deviatoric strain path translates with a nearly constant size, showing constant shear stiffness and strong non-coaxiality. However, at high deviatoric stress, the trajectory envelope of deviatoric strain rapidly expands towards instability, showing degenerating shear stiffness and weak non-coaxiality. Moreover, the excess pore water pressure increases and the shear stiffness decreases more rapidly as b value increases. The results can provide an experimental basis for constitutive modelling of clays under traffic-induced loadings. (C) 2018 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.