Centrifuge shaking table tests on evolution mechanism of sand mesostructure during earthquake liquefaction

The existing studies demonstrate that the history of earthquake liquefaction is an important factor affecting the liquefaction resistance of sand. The researchers think the intrinsic mechanism of these effects is the generation of stable or unstable sand mesostructure after the previous liquefaction event. However, few studies have directly given the experimental results of the evolution behaviors of the sand mesostructure during the whole process of liquefaction. In this study, the centrifuge shaking table tests are conducted to model the earthquake liquefaction of a saturated sand deposit. The pore pressures and accelerations at different depths and the settlements of the sand deposit are measured. Besides, the mesoscopic digital images of the sand mesostructure are recorded simultaneously by a mesoscopic image acquisition system. The experimental results show that the small shaking increases the contacts and decreases the voids among sand particles. The particle contacts are reconstructed and the voids are redistributed with the larger shaking. Approximately vertically and horizontally linked large voids are caused by the upper seepage effects of the pore fluid. The sand particles nearby the approximately vertically large voids rotate vertically under the seepage effects.