Centrifuge Modelling of Dynamic Soil Structure Interaction in Layered and Inhomogeneous Liquefiable Soil

In this paper the results of a series of dynamic centrifuge tests are reported. These tests were performed on different types of soil stratifications supporting a nuclear containment structure. Test results indicate that accelerations transmitted to the structure base are dependent on the stiffness degradation of the supporting soil. It is also conclusively shown that even partial liquefaction can be dangerous and the structure can tilt and rotate. Steady build up of excess pore pressure leads to softening of the soil, which decreases the shear modulus and shear strength and subsequently changes the dynamic responses. The characteristic frequency of the soil deposit gradually decreases to values that are closer to the natural frequency of the deposit. The presence of the structure reduces the translational component of the input base motion and induces rocking of the structure. Thus it can be concluded that rigid structures may not be as safe as believed