Acoustic emission induced by sand liquefaction during vibration loading.

The article deals with the study of poorly graded sand samples of different grain content subjected to liquefaction. The research results show the V-shaped behavior of the AE parameters that correspond to the three-stage sand behavior: Phase A is associated with microfractures/displacements between sand grains caused by an increase in pore pressure before the liquefaction point. Phase B (the stage of AE silence just before the liquefaction point) reflects the equality between pore pressure and stress in the confining chamber. Phase C (the stage of increase in AE parameters' values) is explained by intense friction between sand grains during their movement caused by liquefaction. Our results show that the AE behavior before, at, and after the liquefaction point is significantly affected by the sand grain content. The change in the sand composition from the poorly graded dune sand to "extremely poorly graded sand" significantly increases the time for the creation of the liquefaction state while the coarser the sand grains become, the longer duration of vibration loading is required to reach the liquefaction state.