Coupling effects of cyclic deviator stress and cyclic confining pressure on deformation behaviour of saturated clay

A series of partially drained cyclic triaxial tests under coupling of cyclic deviator and cyclic confining pressure are performed on typical Wenzhou soft clay by using GDS cyclic triaxial apparatus. The coupling effects of cyclic deviator and cyclic confining pressure on the partially drained cumulative plastic strain of saturated clay are studied. The experimental results show that under partially drained condition, compared to that of the conventional CCP tests, coupling of cyclic deviator stress and cyclic confining pressure expedites the accumulation of cumulative plastic strain with the increase of confining pressure amplitude, and the increase of the ratio of cyclic confining pressure to cyclic deviator stress of 2/3 will induce an increment of 32% in the cumulative plastic strain. On the basis of the experimental results obtained, an empirical formula incorporating the coupling effect of cyclic deviator stress and variable confining pressure is proposed to estimate the cumulative plastic strain in the partially drained cyclic tests.