Dynamic characteristics of soft clay under traffic load

To investigate the influence factors of the soil dynamic characteristics under traffic load, a series of undrained dynamic triaxial tests are conducted, at different cyclic stress level, cycle number and confining pressure. The research shows that while being subjected to dynamic loading, such as traffic load, the soil's stiffness softening is occurring more or less when the cycle number is increasing. There are three experimental types of saturated soft clay under dynamic loading with different cycle stress level, such as stable type, destructive type and critical type. The critical type of stress is called critical dynamic stress. There is little difference on numerical value between two critical dynamic stresses which identified by strain and pore pressure respectively. Meanwhile, it shows that dynamic shear modulus falls as dynamic strain increases, and the relationship between dynamic shear modulus and cycle number is influenced by cycle number. So when we design the foundation, dynamic shear modulus should be decided according to dynamic strain and cyclic number. Damping ratio increases as long as dynamic strain increases. The confining pressure has little influence on the relationship between dynamic shear modulus and cycle number.