Abstract:

To investigate the influence factors of the soil dynamic properties under cyclic loading, a series of undrained dynamic triaxial tests are conducted at different cyclic stress levels, cycle numbers and confining pressures. The test results show that while being subjected to cyclic loading, the soil’s stiffness softening occurs more or less when the cycle number increase. There are three types of double amplitude strain of saturated soft clay under cyclic loading with different dynamic stress levels, such as stable type, destructive type and critical type. A new backbone curve model concerning cycle number, confining pressure, and cyclic stress level, is constructed to consider the stiffness softening feature of remoulded soil subjected to cyclic loading. Compared with the traditional backbone curve model, the simulative results computed from the dynamic backbone curve model, which can reflect the phenomenon of stiffness softening feature of soil, agree well with the experimental data.

Key words: soft clay, cyclic loading, dynamic triaxial test, dynamic stress, dynamic strain, backbone curve