Discrete Element Modeling of Reliquefaction Behavior of Sand Under Undrained Cyclic Simple Shear Considering the Effects of Reconsolidation Degrees

Abstract Since the Niigata earthquake in 1964, a series of site surveys [4,5,13,14] have shown that sand liquefied during the mainshocks may reliquefy during the aftershocks. As there is an uncertain interval between the two consecutive earthquakes, the excess pore pressure built up during the mainshock dissipates partially or completely, which means the soil will be reconsolidated to different degrees prior to the aftershock. However, it has been reported that the damage of sand reliquefaction caused by aftershocks may exceed that caused by mainshocks [2,5,13,14] even if the sand was reconsolidated until the excess pore water pressure dissipated completely. To gain more micromechanical insights into the reliquefaction behaviors of sand, a series of discrete element simulations [1] of undrained cyclic simple shear tests were carried out on granular specimens [3,9] with different degrees of reconsolidation and liquefaction history.