Shaking Table Tests on Dry and Saturated Sand with Large Embedded Objects

As a result of earthquakes, underground structures have been found to float up above the ground. In order to evaluate the mechanisms involved with the earthquake-induced uplift of buried structures, shaking table tests were conducted on a deposit of Ottawa sand containing large objects in the form of cylinders and spheres. The large objects were found to float to the surface of the sand regardless of whether the sand was dry or saturated. The time needed for the objects to appear at the surface of the sand was related to the unit weight of the objects: the heavier the object, the larger the time needed to appear at the surface. The results of the tests were evaluated using a method designed to calculate the stresses that an elastic material containing a large circular inclusion develops when subjected to an overall shear stress similar to the one induced by an earthquake on soils in the field.