Influences of stress magnitude and loading frequency on cyclic behavior of K0-consolidated marine clay involving principal stress rotation

• A series of cyclic torsional shear tests are carried out by HCA.
• Heart-shaped stress paths are used to simulate traffic load.
• Stress magnitude affects pore water pressure and strain development.
• Frequency affects pore water pressure and strain development.
• Hysteresis loop and resilience behavior marine clay are discussed.

Traffic load causes the change of magnitude and the rotation of principal stress and leads to a heart-shaped stress path in deviatoric stress space. To study the undrained behavior of natural clay under traffic load, a series of cyclic torsional shear tests were performed on Wenzhou marine clay. The specimens were first K0-consolidated and then sheared and compressed under different cyclic stress magnitudes and loading frequencies. Experimental results show that both the stress magnitude and loading frequency have significant effects on accumulations of pore water pressure and strain development. Larger cyclic stress magnitude causes higher pore water pressure and larger vertical strain. The soft clay specimen reaches failure when the cyclic stress magnitude increases to a certain value. However, a decrease in loading frequency leads to an increase of pore water pore and vertical strain. When applied stress is small, hysteresis loop is almost closed. With the increase of the stress magnitude, the opening of hysteresis loop becomes clear, which means the increase of plastic strain. The higher the frequency is, the smaller the vertical elastic deformation is produced. Compared to cyclic stress magnitude, the impact of frequency on resilience behavior is not that significant.