Cumulative deformation of saturated soft clay subjected to cyclic rotation of principal stress axis

The magnitude and direction of the principal stress of roadbed soil element will chang simultaneously under traffic loading. The traditional model based on tri-axial cyclic loading test data can not reflect the phenomenon of the principal stress rotation. After the axial stress-controlled equation and the circumferential shear stress-controlled equation are derived, a series of consolidated undrained cyclic shear tests are performed under the condition that the value of the general shear stress is constant and the principal stress angle is rotating. At the same time the cyclic torsional shear tests are performed under the condition of consolidation. The element affecting the plastic accumulative strain is analyzed. The test that the value of the general shear stress is constant and the angle of the principal stress is rotating is equivalent to those that the static deviatoric stress and dynamic stress are different. The explicit strain model in the 12^th reference is verified to calculate the accumulative strain caused by the cyclic loading of the principal stress axis.